Functions of the Cardiovascular System:
http://www.youtube.com/watch?v=UztBWnRY8l0
Knowing the functions of the cardiovascular system and the parts of the body that are part of it are critical in understanding the physiology of the human body. The cardiovascular system is the system that keeps life pumping through you with its complex pathways of veins, arteries, and capillaries. The heart, blood vessels, and blood help to transport vital nutrients throughout the body as well as remove metabolic waste. They help to protect the body and regulate body temperature.
Knowing the functions of the cardiovascular system and the parts of the body that are part of it are critical in understanding the physiology of the human body. The cardiovascular system is the system that keeps life pumping through you with its complex pathways of veins, arteries, and capillaries. The heart, blood vessels, and blood help to transport vital nutrients throughout the body as well as remove metabolic waste. They help to protect the body and regulate body temperature.
The cardiovascular system consists of the heart, blood vessels, and blood. This system has three main functions:
Transport of nutrients, oxygen, and 
hormones to cells throughout the body and removal of metabolic wastes (carbon dioxide, nitrogenous wastes, and heat).
Protection of the body by white blood cells, antibodies, and complement proteins that circulate in the blood and defend the body against foreign microbes and toxins. Clotting mechanisms are also present that protect the 
body from blood loss after injuries.
Regulation of body temperature, fluid pH, and water content of cells.
hormones to cells throughout the body and removal of metabolic wastes (carbon dioxide, nitrogenous wastes, and heat).
Protection of the body by white blood cells, antibodies, and complement proteins that circulate in the blood and defend the body against foreign microbes and toxins. Clotting mechanisms are also present that protect the 
body from blood loss after injuries.
Regulation of body temperature, fluid pH, and water content of cells.
The structure of the Cardiovascular System:
Embryologically the heart, like the rest of the cardiovascular system, develops from a tubular 
channel. Its basic organization of tissues is divided into three layers called endocardium, myocardium and epicardium, corresponding roughly to the tunicas intima, media and adventitia, respectively, of the blood vessels. As in blood vessels, the lining is endothelium and the remaining tissues are muscle, connective tissue nerves and blood vessels.
The endocardial layer is thin and consists of endothelium on the surface with underlying collagenous and elastic tissue. The myocardium is the thickest layer and consists of cardiac muscle with intervening connective tissue, blood vessels and nerves. Between the endocardium and myocardium is the subendocardial layer, where nerves and the impulse-conducting system (Purkinje fibers) are located in a bed of connective tissue. The epicardium or outer layer consists of connective tissue with a large amount of adipose tissue covered on its outer edge by a mesothelium which lines the pericardial cavity. Coronary vessels and nerves are present in the epicardium.
Look for groups of larger, paler-staining Purkinje fibers located between the main mass of myocardium and the endocardium. These are conducting fibers in the subendocardial layer. The Purkinje fibers are modified cardiac muscle fibers and have an accumulation of glycogen in the central portions of the cell. The myofibrils are pushed to peripheral locations, leaving a pale "empty" center around the nucleus since the glycogen is lost during sample preparation.
Under high magnification, examine the endocardium. The endothelium is not readily visible over the entire endocardial surface because of damage, but a few flattened nuclei may be located. The endocardial layer also contains collagenous and elastic fibers. The extent of the heart skeleton at the base of the aortic valve. It is thickest at the base of the valve and extends as a collar along the initial part of the aorta. The alternating light and dark staining stripes are a sectioning 
artifact reflecting the fact that this is a relatively hard structure. Endothelium extends over the surface of the valve, covering both surfaces and continues on to form the lining of the aorta. The elastic fibers are more numerous on the ventricular side of the valve, the side which expands most when the valve is closed and blood in the aorta exerts backward pressure. Their elastic recoil helps to open the valve. The collagenous fibers, with more tensile strength, are on the aortic or "holding" side of the valve.
the heart
The human heart is a four-chambered muscular organ, shaped and sized roughly like a man's closed fist with two-thirds of the mass to the left of midline.
The heart is enclosed in a pericardial sac that is lined with the parietal layers of a serous membrane. The visceral layer of the serous membrane forms the epicardium.
Layers of the Heart Wall
Three layers of tissue form the heart wall. The outer layer of the heart wall is the epicardium, the middle layer is the myocardium, and the inner layer is the endocardium.
Chambers of the Heart
The internal cavity of the heart is divided into four chambers:
Right atrium
Right ventricle
Left atrium
Left ventricle
The two atria are thin-walled chambers that receive blood from the veins. The two ventricles are thick-walled chambers that forcefully pump blood out of the heart. Differences in thickness of the heart chamber walls are due to variations in the amount of myocardium present, which reflects the amount of force each chamber is required to generate.
The right atrium receives deoxygenated blood from systemic veins; the left atrium receives oxygenated blood from the pulmonary veins.
Valves of the Heart
Pumps need a set of valves to keep the fluid flowing in one direction and the heart is no exception. The heart has two types of valves that keep the blood flowing in the correct direction. The valves between the atria and ventricles are called atrioventricular valves (also called cuspid valves), while those at the bases of the large vessels leaving the ventricles are called semilunar valves.
The right atrioventricular valve is the tricuspid valve. The left atrioventricular valve is the bicuspid, or mitral, valve. The valve between the right ventricle and pulmonary trunk is the pulmonary semilunar valve. The valve between the left ventricle and the aorta is the aortic semilunar valve.
When the ventricles contract, atrioventricular valves close to prevent blood from flowing back into the atria. When the ventricles relax, semilunar valves close to prevent blood from flowing back into the ventricles.
Pathway of Blood through the Heart
While it is convenient to describe the flow of blood through the right side of the heart and then through the left side, it is important to realize that both atria contract at the same time and both ventricles contract at the same time. The heart works as two pumps, one on the right and one on the left, working simultaneously. Blood flows from the right atrium to the right ventricle, and then is pumped to the lungs to receive oxygen. From the lungs, the blood flows to the left atrium, then to the left ventricle. From there it is pumped to the systemic circulation.
Blood Supply to the Myocardium
The myocardium of the heart wall is a working muscle that needs a continuous supply of oxygen and nutrients to function with efficiency. For this reason, cardiac muscle has an extensive network of blood vessels to bring oxygen to the contracting cells and to remove waste products.
The right and left coronary arteries, branches of the ascending aorta, supply blood to the walls of the myocardium. After blood passes through the capillaries in the myocardium, it enters a system of cardiac (coronary) veins. Most of the cardiac veins drain into the coronary sinus, which opens into the right atrium.
Blood Vessels:
The structure of the various blood vessels is closely related to their function. The vessels which receive blood from the heart, the elastic arteries, have thick, strong walls to cope with the sudden high pressure produced during diastole; they contain abundant elastic material to allow stretch so that the vessel lumen may accommodate the change of volume. They also have a thick, outer coat of collagenous connective tissue whose tensile strength prevents over-distension of the elastic tissue. The elastic recoil of these elastic arteries is responsible for maintaining a continuous, though decreased, flow of blood to smaller vessels during systole.
Further along the arterial system, elastic components gradually diminish. Most of the muscle is arranged circularly, in the middle layer of the vessel wall (the tunica media). These muscular arteries contribute to the regulation of the amount of blood flowing into a region.
Maintenance of blood pressure and the control of blood flow into capillary beds is affected through the action of nervous and humoral agents on the smallest vessels in the arterial system, the arterioles. The amount of muscle present decreases gradually from about 3 layers of muscle cells, to only 1 around the smallest precapillary arterioles.
Capillary beds are the major site of the exchanges between blood and tissues. The walls of the capillary vessels consist of a layer of flattened endothelial cells, pericytes, a basement membrane and a few associated connective tissue fibers. The lumen of the smallest capillaries is just large enough to allow the passage of erythrocytes in single file. Exchange of materials across the capillary wall depends on the nature of the vessel; in discontinuous capillaries the endothelial cell poses no barrier; in continuous capillaries transport involves facilitated transfer across the endothelial cell by vesicles. Fenestrated capillaries have pores which are usually covered by a diaphragm and are intermediate in permeability between continuous and discontinuous capillaries.
The capillary networks drain into thin-walled venules made up of an endothelium surrounded by connective tissue. Muscle cells appear as the venules unite, forming larger vessels and they eventually develop a continuous muscle coat. Some elastic fibers may be present in the larger veins; however, at no point are the muscular and elastic components as abundant or as clearly organized as in arteries of comparable size.
Elastic Arteries:
The innermost layer is the tunica intima which can be recognized as having a smooth more sharply defined free-edge than the opposite surface and no visible blood vessels. The intima is seen to be covered by the vessel lining, a layer of thin endothelial cells which may have been torn off in many places.
The tunica media contains bundles of elastic fibers with gaps between them lying within a background of very fine collagen; the elastic membranes stain a deeper red-purple than the collagen. The cellular components of this layer consist of smooth muscle cells which will be difficult to see.
The outermost layer, the tunica adventitia, consists of connective tissue with thick collagenous fibers. The adventitia contains numerous blood vessels (vasa vasorum; or blood vessels of the blood vessels) and nerves.
Muscular Arteries:
Good examples of muscular arteries with their accompanying veins can be seen within the connective tissue of the gall bladder. Even though many of the vessels contain blood cells, the flattened endothelial cells are visible. In these arteries, the intima is composed of the endothelium and a small amount of connective tissue which are bounded by the red staining internal elastic membrane. The wavy appearance of this elastic membrane is probably due to vessel contraction during fixation since in living vessels it appears as a smooth line. The media consists of smooth muscle arranged in a tight helix and some collagen and elastic fibers.
Veins:
There will be blood veins which accompany the muscular arteries. At low magnification, compare the relative thickness of the vessel walls. It should be obvious that for vessels with comparable sized lumens, the veins have a thinner wall and lack an internal elastic membrane. Practice distinguishing arteries and veins.
Arterioles, Venules & Capillaries:
The definition of what constitutes an arteriole is extraordinarily variable.
The smallest branches of the vascular system can be observed scattered throughout the adipose and connective tissue. Arterioles have 1 to 3 layers of muscle in the media. The endothelial cells border a vessel lumen that has a very regular, round appearance. The smallest arterioles have a single muscle layer and the lumen diameter (10 µm) is slightly larger than that of an erythrocyte (6 µm). The adventitia is composed of collagenous connective tissue.
At high magnification, capillaries can be located in the connective tissue. In cross-section, capillaries consist of a circular lumen made up of a very thin wall and, sometimes, a single endothelial cell nucleus can be seen. Look for longitudinal sections in which the lumen is only about 1 red cell diameter in thickness.
In venules, the endothelial cells rest on connective tissue and their irregular lumens are the diameter of 2–3 erythrocytes. There is usually no smooth muscle present in the smallest venules.
Several large lymphatic vessels are present with characteristic thin irregularly shaped walls and valves that extend into the lumen. The shape of the lumen is irregular and it may contain lymph, a few white blood cells and, occasionally, erythrocytes.
Atrium is covered by endocardium which includes some pectinate muscles. Under very low power, locate the epicardial and endocardial surfaces. The endocardial surface consists of compact, pink-staining tissue made up of fine closely woven collagen and elastic fibers while the epicardial surface appears ragged by comparison since it contains loosely arranged bundles of coarser collagenous fibers. Both the mesothelial covering of the epicardium and the endothelium of the endocardium have been damaged during tissue preparation and will probably not be seen. The myocardium consists of widely spaced groups of cardiac muscle fibers interspersed with loose connective and adipose tissue. It is much thinner than the ventricular myocardium and relatively large blood vessels and nerves may be seen within abundant connective tissue. The loosely packed muscle fibers are thinner than those of the ventricle.
Cardiovascular Diseases:
What are cardiovascular diseases?
Cardiovascular diseases include coronary heart disease (heart attacks), cerebrovascular disease, raised blood pressure (hypertension), peripheral artery disease, rheumatic heart disease, congenital heart disease and heart failure. The major causes of cardiovascular disease are tobacco use, physical inactivity, and an unhealthy diet.
Globally, cardiovascular diseases are the number one cause of death and is projected to remain so. An estimated 17.5 million people died from cardiovascular disease in 2005, representing 30 % of all global deaths. Of these deaths, 7.6 million were due to heart attacks and 5.7 million due to stroke. About 80% of these deaths occurred in low- and middle-income countries. If current trends are allowed to continue, by 2015 an estimated 20 million people will die from cardiovascular disease (mainly from heart attacks and strokes).
What causes heart attacks and strokes?
Heart attacks and strokes are mainly caused by a blockage that prevents blood from flowing to the heart or the brain. The most common cause is a build-up of fatty deposits on the inner walls of the blood vessels that supply the heart or brain. The blood vessels become narrower and less flexible, also known as atherosclerosis (or hardening of the arteries). The blood vessels are then more likely to become blocked by blood clots. When this happens, the blocked vessels cannot supply blood to the heart and brain, which then become damaged.
What are common symptoms of cardiovascular diseases?
Often, there are no symptoms of the underlying disease of the blood vessels. A heart attack or stroke may be the first warning of underlying disease.
Symptoms of a heart attack include: pain or discomfort in the centre of the chest; pain or discomfort in the arms, the left shoulder, elbows, jaw, or back. In addition the person may experience difficulty in breathing or shortness of breath; feeling sick or vomiting; feeling light-headed or faint; breaking into a cold sweat; and becoming pale.
Women are more likely to have shortness of breath, nausea, vomiting, and back or jaw pain.
The most common symptom of a stroke is sudden weakness of the face, arm, or leg, most often on one side of the body. Other symptoms include sudden onset of: numbness of the face, arm, or leg, especially on one side of the body; confusion, difficulty speaking or understanding speech; difficulty seeing with one or both eyes; difficulty walking, dizziness, loss of balance or coordination; severe headache with no known cause; and fainting or unconsciousness.
People experiencing these symptoms should seek medical care immediately.
Why does fat build up in blood vessels?
There are three main reasons for fatty build-up, all controllable:
Smoking and other tobacco use
Unhealthy diet; and
Physical inactivity.
An early form of fatty deposits, known as ''fatty streaks'', can even be found in some children younger than 10 years. These deposits get slowly worse as the person gets older.
Key messages to protect heart health:
Heart attacks and strokes are major - but preventable - killers worldwide.
Over 80% of cardiovascular disease deaths take place in low-and middle-income countries and occur almost equally in men and women. Cardiovascular risk of women is high particularly after menopause.
Tobacco use, an unhealthy diet, and physical inactivity increase the risk of heart attacks and strokes.
Cessation of tobacco use reduces the chance of a heart attack or stroke.
Engaging in physical activity for at least 30 minutes every day of the week will help to prevent heart attacks and strokes.
Eating at least five servings of fruit and vegetables a day, and limiting your salt intake to less than one teaspoon a day, also helps to prevent heart attacks and strokes.
High blood pressure has no symptoms, but can cause a sudden stroke or heart attack. Have your blood pressure checked regularly.
Diabetes increases the risk of heart attacks and stroke. If you have diabetes control your blood pressure and blood sugar to minimize your risk.
Being overweight increases the risk of heart attacks and strokes. To maintain an ideal body weight, take regular physical activity and eat a healthy diet.
Heart attacks and strokes can strike suddenly and can be fatal if assistance is not sought immediately.
Nutrition:
http://www.youtube.com/watch?v=w8cuYEathvA
Bread, Cereal, Rice and Pasta Group
This food group is the largest portion of the daily recommended amounts. They provide carbohydrates, a main source of energy for the body. B vitamins, minerals and fibers are also provided by this food group.
Vegetable Group
Vegetables are the main source for vitamins (A and C in particular), fiber and are not high in fat content.
Fruit Group
Fruits are also a rich source of vitamins, mainly C. They are low in both fat and calories.
Milk, Yogurt and Cheese Group
Calcium, an extremely important nutrient, fills the foods in this group. Protein and Vitamin B12 are also contained in this group.
Meat, Poultry, Dry Beans, Eggs and Nuts
Animal products and the other members of this food group are good sources of protein, iron, zinc, and B vitamins.
Fats, Oils and Sweets
Providers of calories with no other nutritional value.
Digestion
The digestive system can be looked at from many of the jobs taking place in it, all of which will be discussed here. The simplest way to look at the digestive system is by concentrating on the anatomical sites which can be separated into the alimentary canal and the accessory organs.
The alimentary canal is the path the things you eat and drink take from the time the enter your body until the time they leave it. Digestion takes place in most of the alimentary canal through the use of enzymes that are secreted by accessory glands.
Mouth - Physical breakdown begins here with chewing. The teeth and tongue are used at this stage to collect the food into a ball called a bolus. The digestion of starches begins here with the help of salivary amylase this is secreted from the salivary glands. The salivary glands also secrete water and mucus that are helpful in forming and moistening the bolus. Collectively, the substance secreted by the salivary glands is called saliva.
Esophagus - The esophagus is a simple passageway for the bolus from the mouth to the stomach.
Stomach - The stomach, with an acidic pH of 1-2, kills germs with its high acidity and further breaks down the bolus. Gastric glands, located in the walls of the stomach, secrete hydrochloric acid (HCl), responsible for the low pH, and pepsinogen, an inactive enzyme that reacts with the acid and becomes an enzyme that helps in the breakdown of protein. Ulcers form when the mucus lining of the stomach is insufficient and the acid and enzymes damage the stomach walls. The food, now a mushy substance called chyme, then enters the small intestine.
Small Intestine - Bile, produced in the liver and stored and concentrated in the gallbladder, as well as many enzymes secreted by the pancreas, react with the chyme in the small intestine. Bile works to break down fats by physical, not chemical, means. The pancreas secretes amylase to digest carbohydrates, lipases for fats and proteases for protein. Bicarbonate is also secreted by the pancreas, a basic substance, which neutralizes the acidity of the chyme to allow the enzymes to work. Internal folds inside the small intestine greatly increase the surface area allowing nutrient absorption to occur.
Large Intestine - The chyme at this point as finished digesting and the large intestine, also known as the colon, absorbs water before excreting the feces.
Anorexia Nervosa is a mental, health and eating disorder. The individual believes him/herself to be fat, while to have this disorder the weight of the person is 85% or lower than what is expected for that age and height. Depression, irritability, withdrawal, the inability to accept change and responsibility often accompany this disorder of extreme weight-loss. Anorexia Nervosa has the ability to kill.
Bulimia is another mental, health and eating disorder. The individual binge eats for a certain period of time and follows this time with rapid weight loss, either with the use of vomiting, laxatives, exercise or fasting. The person becomes hungry, binge eats, and restarts the cycle. Overall weight, if Anorexia Nervosa is not present, may be maintained. As Anorexia Nervosa, this disorder has the ability to kill.
Binge Eating Disorder is often found in individuals with a predisposition to weigh more, people who have failed many diet attempts, or as a means of comfort. The obsessive eating, or constant snacking, usually causes the individual to become obese and depressed. Diet programs are not helpful in stopping Binge Eating. Suggested by the March 2002 New England Journal of Medicine, a genetic flaw may be responsible for many binge eaters.
Other less well-known eating disorders:
Anorexia Athletica (Compulsive Exercising)
Body Dysmorphic Disorder (Bigorexia)
Chewing and Spitting
Cyclic Vomiting Syndrome
Gourmand Syndrome
Infection-triggered Auto Immune Subtype of Anorexia in Children
Night-Eating Syndrome
Nocturnal Sleep-related Eating Disorder
Orthorexia Nervosa
Pica
Prader-Willi Syndrome
Rumination Syndrome
Diets
The Low-Carb Food Pyramid
Exercise:
http://www.youtube.com/watch?v=u65T3xf9J_c
Physical activity is a medium for fitness and good health which keeps away a heart specialist from an individual. Exercise not only helps to fight heart disease, but for sedentary people, just adding a little exercise to the daily routine reduces the risk of high blood pressure, osteoporosis, breast and colon cancer, depression, anxiety and stress. The greatest benefit from physical activity is seen in people who formerly did no activity and then start to do activities such as walking, cycling, swimming and yogic exercises.
What are the benefits of physical activity?
Regular physical activity-
improves the strength of heart which makes the heart to work more efficiently during exercise and at rest. The more activity people do, the greater is their capacity for exercise and the stronger is the heart which keeps away any heart problem. This leads to reducing of high blood pressure, controlling blood cholesterol levels, controlling diabetes by improving the body’s ability to metabolize glucose. helps weight reduction by mobilizing excess fat from the body. indirectly encourages people to quit smoking for maintaining proper health and fitness. improves flexibility and builds muscle. decreases total and LDL cholesterol ("bad cholesterol") raises HDL cholesterol ("good cholesterol")
increases energy store in the body increases tolerance to anxiety, stress and depression controls / prevents the development of diabetes decreases risk of orthopedic injury by improving flexibility helps building healthy bones, muscles and joints. reduces the risk of colon cancer.
How to design a fitness program?
There are many programs which can be followed to improve physical fitness. Most generalized program recommended for fitness group, heart patients as well as sedentary population follows FIT formula:
The FIT Formula:
F = Frequency (number of days per week)
I = Intensity (level of exercise like low, moderate or heavy)
T = Time (duration of exercise per day)
FREQUENCY: 3-5 days per week. Exercise can be extended up to six days in a week but not recommended for all seven days in a week since the body requires proper rest to tolerate exercise stress.
INTENSITY: Intensity should be decided on the basis of target heart rate.
Calculation of Target Heart Rate (THR)
THR = 60% of Maximum heart rate = 0.6 x (220 – age).
(220 – age = Predicted maximum heart rate)
Example: For a person of 40 years old, predicted maximum heart rate is 220 - 40 = 180. The THR = 0.6 x 180 = 108 beats per minute.
Therefore, it is recommended to go for continuous activity (jogging, walking, cycling, stair climbing, rowing, aerobics, and swimming etc) at such a speed that heart will pump at the rate of around 108 beats per min or within the range of 105 to 112 beats per min. To check this- stop for a while after 5 min of exercise and check the pulse for 6 sec and multiply the pulse with 10 to make it beats per min. In case the heart beat is less than 105 beats/min then increase the speed of exercise and recheck the pulse. If heart beat is more than 112 beats /min then slow down and recheck.
Once the patient feels comfortable with this level of exercise, gradually the intensity may be increased by 5% after consultation with a doctor. But the upper limit should not be exceeded more than 80% of the maximum heart rate. However, physical activity should not be overdone, since too much exercise can result in injury.
TIME (Duration): For beginners the exercise should be 5 to 10 min per day but slowly it can be increased to a minimum of 30 min per day and preferably 60 min per day.
What are the modes of exercises?
jogging, running, brisk walking, stair-climbing, aerobics.
bicycling, rowing and swimming.
Recreational games such as football, handball, basketball and tennis etc that include continuous running
What is an Aerobic Exercise
The term "aerobic" indicates ‘atmospheric oxygen’ and includes activities that enable the body to utilize oxygen to produce energy needed to perform the activities. Aerobic exercise consists of continuous rhythmic movements of large group of muscles that can be sustained for a prolonged period of time. These activities increase the heart rate and breathing rate and train the heart, lungs and muscles to utilize oxygen more efficiently. Aerobic exercise conditions the cardiovascular system and is also referred to as endurance exercise because it increases one's energy and capacity to perform work. Aerobic exercise is important to develop and maintain basic fitness. It benefits a heart patient when recovering from a heart attack or surgery because it specifically strengthens the heart.
When a person should consult a doctor about exercise?
In case of the following physical and physiological complaints, it is advised to consult a doctor before going for an exercise program.
Heart disease.
Chest pains with activities especially.
Extreme shortness of breath after activities.
Very high blood pressure.
Prone to loose consciousness or get very dizzy.
Bone or joint pains that could be made worse by activity.
Insulin-dependent diabetes which is not properly controlled.
Planning to vigorously exercise after a long period of inactivity
How much exercise is recommended following a heart attack or bypass surgery? A minimum of 30 minutes low to moderate-intensity aerobic activity (jogging, walking, cycling, stair climbing, rowing, aerobics, and swimming etc) three to five days a week is recommended. Exercise should not be done all the seven days in a week. After a cardiac event, exercise should be started by walking 5 to 10 minutes per day. Once the patient feels comfortable with this level of exercise, gradually the duration may be increased up to five minutes each week. The speed of walking can also be increased slowly.
What can be done to prevent heart problems in the future?
Exercising regularly, making changes in daily schedule like avoiding high caloric diet and avoiding smoking risk of heart disease can be decreased in the future. Regular exercise reduces high blood pressure and cholesterol levels and helps maintaining fitness and health.
What are the symptoms of angina or heart attack?
Severe chest pain or discomfort that lasts for more than a few minutes and is not relieved by rest. The symptoms of a heart attack usually last longer and are more severe. Immediately consult a doctor. Avoid all physical activity.
What are the dos and don’ts of exercising at home?
· Always make your body warm (warm-up) before exercise.
· Follow the target heart rate during exercise.
· Always cool down after the exercise program
· Keep an exercise diary and record your resting and exercise heart rates.
· Do not exercise within two hours after a meal.
· Don’t drink alcohol two hours before an exercising program
· Don’t smoke before an exercising program.
· For any abnormal symptoms, such as irregular heart beats, excessive shortness of breath or lightheadedness stop and rest. If the symptoms do not subside in a few minutes immediately consult a heart specialist.
channel. Its basic organization of tissues is divided into three layers called endocardium, myocardium and epicardium, corresponding roughly to the tunicas intima, media and adventitia, respectively, of the blood vessels. As in blood vessels, the lining is endothelium and the remaining tissues are muscle, connective tissue nerves and blood vessels.
The endocardial layer is thin and consists of endothelium on the surface with underlying collagenous and elastic tissue. The myocardium is the thickest layer and consists of cardiac muscle with intervening connective tissue, blood vessels and nerves. Between the endocardium and myocardium is the subendocardial layer, where nerves and the impulse-conducting system (Purkinje fibers) are located in a bed of connective tissue. The epicardium or outer layer consists of connective tissue with a large amount of adipose tissue covered on its outer edge by a mesothelium which lines the pericardial cavity. Coronary vessels and nerves are present in the epicardium.
Look for groups of larger, paler-staining Purkinje fibers located between the main mass of myocardium and the endocardium. These are conducting fibers in the subendocardial layer. The Purkinje fibers are modified cardiac muscle fibers and have an accumulation of glycogen in the central portions of the cell. The myofibrils are pushed to peripheral locations, leaving a pale "empty" center around the nucleus since the glycogen is lost during sample preparation.
Under high magnification, examine the endocardium. The endothelium is not readily visible over the entire endocardial surface because of damage, but a few flattened nuclei may be located. The endocardial layer also contains collagenous and elastic fibers. The extent of the heart skeleton at the base of the aortic valve. It is thickest at the base of the valve and extends as a collar along the initial part of the aorta. The alternating light and dark staining stripes are a sectioning 
artifact reflecting the fact that this is a relatively hard structure. Endothelium extends over the surface of the valve, covering both surfaces and continues on to form the lining of the aorta. The elastic fibers are more numerous on the ventricular side of the valve, the side which expands most when the valve is closed and blood in the aorta exerts backward pressure. Their elastic recoil helps to open the valve. The collagenous fibers, with more tensile strength, are on the aortic or "holding" side of the valve.
the heart
The human heart is a four-chambered muscular organ, shaped and sized roughly like a man's closed fist with two-thirds of the mass to the left of midline.
The heart is enclosed in a pericardial sac that is lined with the parietal layers of a serous membrane. The visceral layer of the serous membrane forms the epicardium.
Layers of the Heart Wall
Three layers of tissue form the heart wall. The outer layer of the heart wall is the epicardium, the middle layer is the myocardium, and the inner layer is the endocardium.
Chambers of the Heart
The internal cavity of the heart is divided into four chambers:
Right atrium
Right ventricle
Left atrium
Left ventricle
The two atria are thin-walled chambers that receive blood from the veins. The two ventricles are thick-walled chambers that forcefully pump blood out of the heart. Differences in thickness of the heart chamber walls are due to variations in the amount of myocardium present, which reflects the amount of force each chamber is required to generate.
The right atrium receives deoxygenated blood from systemic veins; the left atrium receives oxygenated blood from the pulmonary veins.
Valves of the Heart
Pumps need a set of valves to keep the fluid flowing in one direction and the heart is no exception. The heart has two types of valves that keep the blood flowing in the correct direction. The valves between the atria and ventricles are called atrioventricular valves (also called cuspid valves), while those at the bases of the large vessels leaving the ventricles are called semilunar valves.
The right atrioventricular valve is the tricuspid valve. The left atrioventricular valve is the bicuspid, or mitral, valve. The valve between the right ventricle and pulmonary trunk is the pulmonary semilunar valve. The valve between the left ventricle and the aorta is the aortic semilunar valve.
When the ventricles contract, atrioventricular valves close to prevent blood from flowing back into the atria. When the ventricles relax, semilunar valves close to prevent blood from flowing back into the ventricles.
Pathway of Blood through the Heart
While it is convenient to describe the flow of blood through the right side of the heart and then through the left side, it is important to realize that both atria contract at the same time and both ventricles contract at the same time. The heart works as two pumps, one on the right and one on the left, working simultaneously. Blood flows from the right atrium to the right ventricle, and then is pumped to the lungs to receive oxygen. From the lungs, the blood flows to the left atrium, then to the left ventricle. From there it is pumped to the systemic circulation.
Blood Supply to the Myocardium
The myocardium of the heart wall is a working muscle that needs a continuous supply of oxygen and nutrients to function with efficiency. For this reason, cardiac muscle has an extensive network of blood vessels to bring oxygen to the contracting cells and to remove waste products.
The right and left coronary arteries, branches of the ascending aorta, supply blood to the walls of the myocardium. After blood passes through the capillaries in the myocardium, it enters a system of cardiac (coronary) veins. Most of the cardiac veins drain into the coronary sinus, which opens into the right atrium.
Blood Vessels:
The structure of the various blood vessels is closely related to their function. The vessels which receive blood from the heart, the elastic arteries, have thick, strong walls to cope with the sudden high pressure produced during diastole; they contain abundant elastic material to allow stretch so that the vessel lumen may accommodate the change of volume. They also have a thick, outer coat of collagenous connective tissue whose tensile strength prevents over-distension of the elastic tissue. The elastic recoil of these elastic arteries is responsible for maintaining a continuous, though decreased, flow of blood to smaller vessels during systole.
Further along the arterial system, elastic components gradually diminish. Most of the muscle is arranged circularly, in the middle layer of the vessel wall (the tunica media). These muscular arteries contribute to the regulation of the amount of blood flowing into a region.
Maintenance of blood pressure and the control of blood flow into capillary beds is affected through the action of nervous and humoral agents on the smallest vessels in the arterial system, the arterioles. The amount of muscle present decreases gradually from about 3 layers of muscle cells, to only 1 around the smallest precapillary arterioles.
Capillary beds are the major site of the exchanges between blood and tissues. The walls of the capillary vessels consist of a layer of flattened endothelial cells, pericytes, a basement membrane and a few associated connective tissue fibers. The lumen of the smallest capillaries is just large enough to allow the passage of erythrocytes in single file. Exchange of materials across the capillary wall depends on the nature of the vessel; in discontinuous capillaries the endothelial cell poses no barrier; in continuous capillaries transport involves facilitated transfer across the endothelial cell by vesicles. Fenestrated capillaries have pores which are usually covered by a diaphragm and are intermediate in permeability between continuous and discontinuous capillaries.
The capillary networks drain into thin-walled venules made up of an endothelium surrounded by connective tissue. Muscle cells appear as the venules unite, forming larger vessels and they eventually develop a continuous muscle coat. Some elastic fibers may be present in the larger veins; however, at no point are the muscular and elastic components as abundant or as clearly organized as in arteries of comparable size.
Elastic Arteries:
The innermost layer is the tunica intima which can be recognized as having a smooth more sharply defined free-edge than the opposite surface and no visible blood vessels. The intima is seen to be covered by the vessel lining, a layer of thin endothelial cells which may have been torn off in many places.
The tunica media contains bundles of elastic fibers with gaps between them lying within a background of very fine collagen; the elastic membranes stain a deeper red-purple than the collagen. The cellular components of this layer consist of smooth muscle cells which will be difficult to see.
The outermost layer, the tunica adventitia, consists of connective tissue with thick collagenous fibers. The adventitia contains numerous blood vessels (vasa vasorum; or blood vessels of the blood vessels) and nerves.
Muscular Arteries:
Good examples of muscular arteries with their accompanying veins can be seen within the connective tissue of the gall bladder. Even though many of the vessels contain blood cells, the flattened endothelial cells are visible. In these arteries, the intima is composed of the endothelium and a small amount of connective tissue which are bounded by the red staining internal elastic membrane. The wavy appearance of this elastic membrane is probably due to vessel contraction during fixation since in living vessels it appears as a smooth line. The media consists of smooth muscle arranged in a tight helix and some collagen and elastic fibers.
Veins:
There will be blood veins which accompany the muscular arteries. At low magnification, compare the relative thickness of the vessel walls. It should be obvious that for vessels with comparable sized lumens, the veins have a thinner wall and lack an internal elastic membrane. Practice distinguishing arteries and veins.
Arterioles, Venules & Capillaries:
The definition of what constitutes an arteriole is extraordinarily variable.
The smallest branches of the vascular system can be observed scattered throughout the adipose and connective tissue. Arterioles have 1 to 3 layers of muscle in the media. The endothelial cells border a vessel lumen that has a very regular, round appearance. The smallest arterioles have a single muscle layer and the lumen diameter (10 µm) is slightly larger than that of an erythrocyte (6 µm). The adventitia is composed of collagenous connective tissue.
At high magnification, capillaries can be located in the connective tissue. In cross-section, capillaries consist of a circular lumen made up of a very thin wall and, sometimes, a single endothelial cell nucleus can be seen. Look for longitudinal sections in which the lumen is only about 1 red cell diameter in thickness.
In venules, the endothelial cells rest on connective tissue and their irregular lumens are the diameter of 2–3 erythrocytes. There is usually no smooth muscle present in the smallest venules.
Several large lymphatic vessels are present with characteristic thin irregularly shaped walls and valves that extend into the lumen. The shape of the lumen is irregular and it may contain lymph, a few white blood cells and, occasionally, erythrocytes.
Atrium is covered by endocardium which includes some pectinate muscles. Under very low power, locate the epicardial and endocardial surfaces. The endocardial surface consists of compact, pink-staining tissue made up of fine closely woven collagen and elastic fibers while the epicardial surface appears ragged by comparison since it contains loosely arranged bundles of coarser collagenous fibers. Both the mesothelial covering of the epicardium and the endothelium of the endocardium have been damaged during tissue preparation and will probably not be seen. The myocardium consists of widely spaced groups of cardiac muscle fibers interspersed with loose connective and adipose tissue. It is much thinner than the ventricular myocardium and relatively large blood vessels and nerves may be seen within abundant connective tissue. The loosely packed muscle fibers are thinner than those of the ventricle.
Cardiovascular Diseases:
What are cardiovascular diseases?
Cardiovascular diseases include coronary heart disease (heart attacks), cerebrovascular disease, raised blood pressure (hypertension), peripheral artery disease, rheumatic heart disease, congenital heart disease and heart failure. The major causes of cardiovascular disease are tobacco use, physical inactivity, and an unhealthy diet.
Globally, cardiovascular diseases are the number one cause of death and is projected to remain so. An estimated 17.5 million people died from cardiovascular disease in 2005, representing 30 % of all global deaths. Of these deaths, 7.6 million were due to heart attacks and 5.7 million due to stroke. About 80% of these deaths occurred in low- and middle-income countries. If current trends are allowed to continue, by 2015 an estimated 20 million people will die from cardiovascular disease (mainly from heart attacks and strokes).
What causes heart attacks and strokes?
Heart attacks and strokes are mainly caused by a blockage that prevents blood from flowing to the heart or the brain. The most common cause is a build-up of fatty deposits on the inner walls of the blood vessels that supply the heart or brain. The blood vessels become narrower and less flexible, also known as atherosclerosis (or hardening of the arteries). The blood vessels are then more likely to become blocked by blood clots. When this happens, the blocked vessels cannot supply blood to the heart and brain, which then become damaged.
What are common symptoms of cardiovascular diseases?
Often, there are no symptoms of the underlying disease of the blood vessels. A heart attack or stroke may be the first warning of underlying disease.
Symptoms of a heart attack include: pain or discomfort in the centre of the chest; pain or discomfort in the arms, the left shoulder, elbows, jaw, or back. In addition the person may experience difficulty in breathing or shortness of breath; feeling sick or vomiting; feeling light-headed or faint; breaking into a cold sweat; and becoming pale.
Women are more likely to have shortness of breath, nausea, vomiting, and back or jaw pain.
The most common symptom of a stroke is sudden weakness of the face, arm, or leg, most often on one side of the body. Other symptoms include sudden onset of: numbness of the face, arm, or leg, especially on one side of the body; confusion, difficulty speaking or understanding speech; difficulty seeing with one or both eyes; difficulty walking, dizziness, loss of balance or coordination; severe headache with no known cause; and fainting or unconsciousness.
People experiencing these symptoms should seek medical care immediately.
Why does fat build up in blood vessels?
There are three main reasons for fatty build-up, all controllable:
Smoking and other tobacco use
Unhealthy diet; and
Physical inactivity.
An early form of fatty deposits, known as ''fatty streaks'', can even be found in some children younger than 10 years. These deposits get slowly worse as the person gets older.
Key messages to protect heart health:
Heart attacks and strokes are major - but preventable - killers worldwide.
Over 80% of cardiovascular disease deaths take place in low-and middle-income countries and occur almost equally in men and women. Cardiovascular risk of women is high particularly after menopause.
Tobacco use, an unhealthy diet, and physical inactivity increase the risk of heart attacks and strokes.
Cessation of tobacco use reduces the chance of a heart attack or stroke.
Engaging in physical activity for at least 30 minutes every day of the week will help to prevent heart attacks and strokes.
Eating at least five servings of fruit and vegetables a day, and limiting your salt intake to less than one teaspoon a day, also helps to prevent heart attacks and strokes.
High blood pressure has no symptoms, but can cause a sudden stroke or heart attack. Have your blood pressure checked regularly.
Diabetes increases the risk of heart attacks and stroke. If you have diabetes control your blood pressure and blood sugar to minimize your risk.
Being overweight increases the risk of heart attacks and strokes. To maintain an ideal body weight, take regular physical activity and eat a healthy diet.
Heart attacks and strokes can strike suddenly and can be fatal if assistance is not sought immediately.
Nutrition:
http://www.youtube.com/watch?v=w8cuYEathvA
Bread, Cereal, Rice and Pasta Group
This food group is the largest portion of the daily recommended amounts. They provide carbohydrates, a main source of energy for the body. B vitamins, minerals and fibers are also provided by this food group.
Vegetable Group
Vegetables are the main source for vitamins (A and C in particular), fiber and are not high in fat content.
Fruit Group
Fruits are also a rich source of vitamins, mainly C. They are low in both fat and calories.
Milk, Yogurt and Cheese Group
Calcium, an extremely important nutrient, fills the foods in this group. Protein and Vitamin B12 are also contained in this group.
Meat, Poultry, Dry Beans, Eggs and Nuts
Animal products and the other members of this food group are good sources of protein, iron, zinc, and B vitamins.
Fats, Oils and Sweets
Providers of calories with no other nutritional value.
Digestion
The digestive system can be looked at from many of the jobs taking place in it, all of which will be discussed here. The simplest way to look at the digestive system is by concentrating on the anatomical sites which can be separated into the alimentary canal and the accessory organs.
The alimentary canal is the path the things you eat and drink take from the time the enter your body until the time they leave it. Digestion takes place in most of the alimentary canal through the use of enzymes that are secreted by accessory glands.
Mouth - Physical breakdown begins here with chewing. The teeth and tongue are used at this stage to collect the food into a ball called a bolus. The digestion of starches begins here with the help of salivary amylase this is secreted from the salivary glands. The salivary glands also secrete water and mucus that are helpful in forming and moistening the bolus. Collectively, the substance secreted by the salivary glands is called saliva.
Esophagus - The esophagus is a simple passageway for the bolus from the mouth to the stomach.
Stomach - The stomach, with an acidic pH of 1-2, kills germs with its high acidity and further breaks down the bolus. Gastric glands, located in the walls of the stomach, secrete hydrochloric acid (HCl), responsible for the low pH, and pepsinogen, an inactive enzyme that reacts with the acid and becomes an enzyme that helps in the breakdown of protein. Ulcers form when the mucus lining of the stomach is insufficient and the acid and enzymes damage the stomach walls. The food, now a mushy substance called chyme, then enters the small intestine.
Small Intestine - Bile, produced in the liver and stored and concentrated in the gallbladder, as well as many enzymes secreted by the pancreas, react with the chyme in the small intestine. Bile works to break down fats by physical, not chemical, means. The pancreas secretes amylase to digest carbohydrates, lipases for fats and proteases for protein. Bicarbonate is also secreted by the pancreas, a basic substance, which neutralizes the acidity of the chyme to allow the enzymes to work. Internal folds inside the small intestine greatly increase the surface area allowing nutrient absorption to occur.
Large Intestine - The chyme at this point as finished digesting and the large intestine, also known as the colon, absorbs water before excreting the feces.
Anorexia Nervosa is a mental, health and eating disorder. The individual believes him/herself to be fat, while to have this disorder the weight of the person is 85% or lower than what is expected for that age and height. Depression, irritability, withdrawal, the inability to accept change and responsibility often accompany this disorder of extreme weight-loss. Anorexia Nervosa has the ability to kill.
Bulimia is another mental, health and eating disorder. The individual binge eats for a certain period of time and follows this time with rapid weight loss, either with the use of vomiting, laxatives, exercise or fasting. The person becomes hungry, binge eats, and restarts the cycle. Overall weight, if Anorexia Nervosa is not present, may be maintained. As Anorexia Nervosa, this disorder has the ability to kill.
Binge Eating Disorder is often found in individuals with a predisposition to weigh more, people who have failed many diet attempts, or as a means of comfort. The obsessive eating, or constant snacking, usually causes the individual to become obese and depressed. Diet programs are not helpful in stopping Binge Eating. Suggested by the March 2002 New England Journal of Medicine, a genetic flaw may be responsible for many binge eaters.
Other less well-known eating disorders:
Anorexia Athletica (Compulsive Exercising)
Body Dysmorphic Disorder (Bigorexia)
Chewing and Spitting
Cyclic Vomiting Syndrome
Gourmand Syndrome
Infection-triggered Auto Immune Subtype of Anorexia in Children
Night-Eating Syndrome
Nocturnal Sleep-related Eating Disorder
Orthorexia Nervosa
Pica
Prader-Willi Syndrome
Rumination Syndrome
Diets
The Low-Carb Food Pyramid
Exercise:
http://www.youtube.com/watch?v=u65T3xf9J_c
Physical activity is a medium for fitness and good health which keeps away a heart specialist from an individual. Exercise not only helps to fight heart disease, but for sedentary people, just adding a little exercise to the daily routine reduces the risk of high blood pressure, osteoporosis, breast and colon cancer, depression, anxiety and stress. The greatest benefit from physical activity is seen in people who formerly did no activity and then start to do activities such as walking, cycling, swimming and yogic exercises.
What are the benefits of physical activity?
Regular physical activity-
improves the strength of heart which makes the heart to work more efficiently during exercise and at rest. The more activity people do, the greater is their capacity for exercise and the stronger is the heart which keeps away any heart problem. This leads to reducing of high blood pressure, controlling blood cholesterol levels, controlling diabetes by improving the body’s ability to metabolize glucose. helps weight reduction by mobilizing excess fat from the body. indirectly encourages people to quit smoking for maintaining proper health and fitness. improves flexibility and builds muscle. decreases total and LDL cholesterol ("bad cholesterol") raises HDL cholesterol ("good cholesterol")
increases energy store in the body increases tolerance to anxiety, stress and depression controls / prevents the development of diabetes decreases risk of orthopedic injury by improving flexibility helps building healthy bones, muscles and joints. reduces the risk of colon cancer.
How to design a fitness program?
There are many programs which can be followed to improve physical fitness. Most generalized program recommended for fitness group, heart patients as well as sedentary population follows FIT formula:
The FIT Formula:
F = Frequency (number of days per week)
I = Intensity (level of exercise like low, moderate or heavy)
T = Time (duration of exercise per day)
FREQUENCY: 3-5 days per week. Exercise can be extended up to six days in a week but not recommended for all seven days in a week since the body requires proper rest to tolerate exercise stress.
INTENSITY: Intensity should be decided on the basis of target heart rate.
Calculation of Target Heart Rate (THR)
THR = 60% of Maximum heart rate = 0.6 x (220 – age).
(220 – age = Predicted maximum heart rate)
Example: For a person of 40 years old, predicted maximum heart rate is 220 - 40 = 180. The THR = 0.6 x 180 = 108 beats per minute.
Therefore, it is recommended to go for continuous activity (jogging, walking, cycling, stair climbing, rowing, aerobics, and swimming etc) at such a speed that heart will pump at the rate of around 108 beats per min or within the range of 105 to 112 beats per min. To check this- stop for a while after 5 min of exercise and check the pulse for 6 sec and multiply the pulse with 10 to make it beats per min. In case the heart beat is less than 105 beats/min then increase the speed of exercise and recheck the pulse. If heart beat is more than 112 beats /min then slow down and recheck.
Once the patient feels comfortable with this level of exercise, gradually the intensity may be increased by 5% after consultation with a doctor. But the upper limit should not be exceeded more than 80% of the maximum heart rate. However, physical activity should not be overdone, since too much exercise can result in injury.
TIME (Duration): For beginners the exercise should be 5 to 10 min per day but slowly it can be increased to a minimum of 30 min per day and preferably 60 min per day.
What are the modes of exercises?
jogging, running, brisk walking, stair-climbing, aerobics.
bicycling, rowing and swimming.
Recreational games such as football, handball, basketball and tennis etc that include continuous running
What is an Aerobic Exercise
The term "aerobic" indicates ‘atmospheric oxygen’ and includes activities that enable the body to utilize oxygen to produce energy needed to perform the activities. Aerobic exercise consists of continuous rhythmic movements of large group of muscles that can be sustained for a prolonged period of time. These activities increase the heart rate and breathing rate and train the heart, lungs and muscles to utilize oxygen more efficiently. Aerobic exercise conditions the cardiovascular system and is also referred to as endurance exercise because it increases one's energy and capacity to perform work. Aerobic exercise is important to develop and maintain basic fitness. It benefits a heart patient when recovering from a heart attack or surgery because it specifically strengthens the heart.
When a person should consult a doctor about exercise?
In case of the following physical and physiological complaints, it is advised to consult a doctor before going for an exercise program.
Heart disease.
Chest pains with activities especially.
Extreme shortness of breath after activities.
Very high blood pressure.
Prone to loose consciousness or get very dizzy.
Bone or joint pains that could be made worse by activity.
Insulin-dependent diabetes which is not properly controlled.
Planning to vigorously exercise after a long period of inactivity
How much exercise is recommended following a heart attack or bypass surgery? A minimum of 30 minutes low to moderate-intensity aerobic activity (jogging, walking, cycling, stair climbing, rowing, aerobics, and swimming etc) three to five days a week is recommended. Exercise should not be done all the seven days in a week. After a cardiac event, exercise should be started by walking 5 to 10 minutes per day. Once the patient feels comfortable with this level of exercise, gradually the duration may be increased up to five minutes each week. The speed of walking can also be increased slowly.
What can be done to prevent heart problems in the future?
Exercising regularly, making changes in daily schedule like avoiding high caloric diet and avoiding smoking risk of heart disease can be decreased in the future. Regular exercise reduces high blood pressure and cholesterol levels and helps maintaining fitness and health.
What are the symptoms of angina or heart attack?
Severe chest pain or discomfort that lasts for more than a few minutes and is not relieved by rest. The symptoms of a heart attack usually last longer and are more severe. Immediately consult a doctor. Avoid all physical activity.
What are the dos and don’ts of exercising at home?
· Always make your body warm (warm-up) before exercise.
· Follow the target heart rate during exercise.
· Always cool down after the exercise program
· Keep an exercise diary and record your resting and exercise heart rates.
· Do not exercise within two hours after a meal.
· Don’t drink alcohol two hours before an exercising program
· Don’t smoke before an exercising program.
· For any abnormal symptoms, such as irregular heart beats, excessive shortness of breath or lightheadedness stop and rest. If the symptoms do not subside in a few minutes immediately consult a heart specialist. 
Your skeletal system also protects your internal tissues and organs from trauma. The skull, vertebrae, and ribs create protective cavities for the brain, the spinal cord, and the heart and lungs, respectively. Bones store minerals such as calcium and phosphorus, which are important to the health and strength of the skeleton and to various esential processes in your body. Bone marrow, a connective tissue within bones, produces new red blood cells and white blood cells. '
Examples of long bones include bones of the arms and 
The common characteristic of irregular bones is not that they are similar to each other in appearance, but that they can't be placed in any of the other bone categories.
develop directly from mesenchyme, thereby bypassing the cartilaginous stage. These types of bone are called 
Finally, bones are classified based on texture. Smooth, hard bone called compact bone forms the outer layer of bones. Inside the outer compact bone is cancellous bone, sometimes called the 
Cancellous bone appears open and spongy, but is actually very strong, like compact bone. Together, the two types of bone produce a light, but strong, skeleton. 
BONES HAVE A JELLY LIKE RED AND YELLOW MARROW. YELLOW BONE MARROW STORES FAT AND SUGAR. THE OUTER LAYER IS CALLED HARD BONE AND THE SPONGY BONE IS A HONEYCOMB OF BONE CELLS WITH SPACES BETWEEN THEM.
Like other systems in the body, the nervous system is composed of organs, principally the brain, spinal cord, nerves, and
Activity that is higher in intensity, with possible duration decreasing as intensity increases, ATP production can switch to anaerobic pathways, such as the use of the 
Anaerobic ATP production produces ATP much faster and allows near-maximal intensity exercise, but also produces significant amounts of 
An impulse from a nerve cell causes calcium release and brings about a single, short 
A coordinated and fine tuned response to a specific circumstance will involve controlling the precise number of motor units used. While individual muscle units contract as a unit, the entire muscle can contract on a predetermined basis due to the structure of the motor unit. Motor unit coordination, balance, and control frequently come under the direction of the 
