Heart Attack (myocardial infarction) 
A heart attack (also known as a myocardial infarction) is the death of heart muscle from the sudden blockage of a coronary artery by a blood clot. Coronary arteries are blood vessels that supply the heart muscle with blood and oxygen. Blockage of a coronary artery deprives the heart muscle of blood and oxygen,causing injury to the heart muscle. Injury to the heart muscle causes chest pain and chest pressure sensation. If blood flow is not restored to the heart muscle within 20 to 40 minutes, irreversible death of the heart muscle will begin to occur. Muscle continues to die for six to eight hours at which time the heart attack usually is "complete." The dead heart muscle is eventually replaced by scar tissue.

Approximately one million Americans suffer a heart attack each year. Four hundred thousand of them die as a result of their heart attack.



What causes a heart attack?

Atherosclerosis 

Atherosclerosis is a gradual process by which plaques (collections) of cholesterol are deposited in the walls of arteries. Cholesterol plaques cause hardening of the arterial walls and narrowing of the inner channel (lumen) of the artery. Arteries that are narrowed by atherosclerosis cannot deliver enough blood to maintain normal function of the parts of the body they supply. For example, atherosclerosis of the arteries in the legs causes reduced blood flow to the legs. Reduced blood flow to the legs can lead to pain in the legs while walking or exercising, leg ulcers, or a delay in the healing of wounds to the legs. Atherosclerosis of the arteries that furnish blood to the brain can lead to vascular dementia(mental deterioration due to gradual death of brain tissue over many years) or stroke(sudden death of brain tissue).

In many people, atherosclerosis can remain silent (causing no symptoms or health problems) for years or decades. Atherosclerosis can begin as early as the teenage years, but symptoms or health problems usually do not arise until later in adulthood when the arterial narrowing becomes severe. Smoking cigarettes, high blood pressure, elevated cholesterol, and diabetes mellitus can accelerate atherosclerosis and lead to the earlier onset of symptoms and complications, particularly in those people who have a family history of early atherosclerosis.

Coronary atherosclerosis (or coronary artery disease) refers to the atherosclerosis that causes hardening and narrowing of the coronary arteries. Diseases caused by the reduced blood supply to the heart muscle from coronary atherosclerosis are called coronary heart diseases (CHD). Coronary heart diseases include heart attacks, sudden unexpected death, chest pain (angina), abnormal heart rhythms, and heart failure due to weakening of the heart muscle.

CVA (Stroke)A stroke (cerebrovascular accident, CVA, cerebral vascular accident or brain attack) occurs when a part of the brain is damaged or destroyed because it is deprived of blood.

There are 2 main types of strokes: ischaemic stroke and haemorrhagic stroke.

Ischaemic strokeIschaemic stroke is the most common type of stroke and is caused by a blockage of the blood vessels supplying the brain. This may be due to ‘hardening’ and narrowing of the arteries (atherosclerosis) or by a blood clot blocking a blood vessel.

One type of ischaemic stroke is a thrombotic stroke. This is caused by a blood clot (thrombus) in one of the arteries of the head or neck, which severely reduces the blood flow. The thrombus may be a result of a build-up of fatty deposits (plaques) in the blood vessels.

Another type of ischaemic stroke is an embolic stroke (or cerebral embolism), caused when a blood clot that forms elsewhere in the body (for example, the chambers of the heart) travels through the circulatory system to the brain. The travelling clot is called an embolus.

Haemorrhagic stroke. The most severe type of stroke is a haemorrhagic stroke. It occurs when a blood vessel in the brain bursts, allowing blood to leak and cause damage to an area of the brain. There are 2 types: subarachnoid haemorrhage, which occurs in the space around the brain; and an intracerebral haemorrhage, the more common type, which involves bleeding within the brain tissue itself.

The symptoms of a stroke usually appear suddenly. Initially the person may feel sick, and look pale and very unwell. They may complain of a sudden headache. They may have sudden numbness in their face or limbs, particularly down one side of their body. They may appear confused and have trouble talking or understanding what is being said to them. They may have vision problems, and trouble walking or keeping their balance. Sometimes a seizure (fit) or loss of consciousness occurs.

Depending on what function the damaged part of the brain had, a person may lose one or more of the following functions:

• ability to perform movements — usually affecting one side of the body;
• speech;
• part of vision;
• co-ordination;
• balance;
• memory; and
• perception.

Some strokes are preceded by mini or temporary strokes — transient ischaemic attacks (TIAs). Mini strokes occur when there is a temporary blood clot and part of the brain does not get the supply of blood it needs.

Symptoms occur rapidly and usually last a short time, from a few minutes to a couple of hours. Like a stroke, the symptoms will vary depending on which part of the brain is affected.

The warning signs

• Sudden weakness or numbness of the face, arm and leg on one side of the body.
• Loss of speech, or difficulty talking.
• Dimness or loss of vision.
• Unexplained dizziness, especially when associated with any of the above signs.
• Unsteadiness or sudden falls.
• Headache (usually severe and of sudden onset).
• Confusion.

While the symptoms of a TIA are similar to those of a stroke, they are usually temporary and reversible.

However, mini strokes should not be ignored as people who have had a temporary stroke are much more likely to have a stroke than people of the same age and sex who have not had a temporary stroke.

It is important that you see your doctor immediately when the warning signs of stroke occur. Your doctor will determine whether a stroke, a mini stroke or another medical condition with similar symptoms has occurred, such as a seizure or migraine.

COPD (chronic obstructive pulmonary disease)
Chronic obstructive pulmonary disease (COPD) is one of the most common lung diseases. It makes it difficult to breathe. There are two main forms of COPD:

• Chronic bronchitis, which involves a long-term cough with mucus
• Emphysema, which involves destruction of the lungs over time

Most people with COPD have a combination of both conditions.

CausesSmoking is the leading cause of COPD. The more a person smokes, the more likely that person will develop COPD. However, some people smoke for years and never get COPD.

In rare cases, nonsmokers who lack a protein called alpha-1 antitrypsin can develop emphysema.

Other risk factors for COPD are:

• Exposure to certain gases or fumes in the workplace
• Exposure to heavy amounts of secondhand smoke and pollution
• Frequent use of cooking fire without proper ventilation

Symptoms

• Cough, with or without mucus
• Fatigue
• Many respiratory infections
• Shortness of breath (dyspnea) that gets worse with mild activity
• Trouble catching one's breath
• Wheezing

TreatmentThere is no cure for COPD. However, there are many things you can do to relieve symptoms and keep the disease from getting worse.
Persons with COPD MUST stop smoking. This is the best way to slow down the lung damage.

Kidney Failure (renal disease) Kidney disease is a general term that includes any disease, disorder or condition of the kidneys. The kidneys are vital internal organs located in the upper abdomen. Normally people have two bean-shaped kidneys, which form a part of the urinary tract in the genitourinary system.
Kidney disease is due to a variety of conditions that lead to kidney damage and deterioration of kidney function. Kidney disease can make it difficult or impossible for the kidneys to perform functions that are critical to life and your overall health including:

• Filtering waste products and excess water and salts from the blood, which are then eliminated from the body through the ureters, bladder and urethra in the form of urine
  
  
• Producing certain hormones, such as renin, which helps regulate blood pressure
  
  
• Producing the active form of vitamin D (calcitrol)
  
  
• Regulating electrolytes and other vital substances, such as sodium, calcium and potassium
  
  
• Regulating the level and quality of fluid in the body
  
  
• Stimulating red blood cell production
  
  

There are two general types of serious kidney disease:

• Acute renal failure is a condition in which there is damage and deterioration of kidney function that occurs suddenly, generally over a period of days. Acute renal failure can be caused by such conditions as shock, acute pyelonephritis, urinary tract obstruction, or ingestion of certain toxic substances.  
  
  
• Chronic kidney disease is a condition in which there is damage and deterioration of kidney function that occurs over a long period of time, from months to years. Chronic kidney disease is generally caused by long-term diseases, such as diabetes and hypertension (high blood pressure).
  
  

Rapid diagnosis and treatment of many underlying causes of kidney disease may prevent or slow the progression of serious kidney damage that leads to chronic kidney disease or acute renal failure.

Kidney disease can be a serious or life-threatening condition because it can progress quickly and critically affect the ability of the kidneys to function normally. Seek immediate medical care (call 911)if you, or someone you are with, have symptoms of impaired kidney function, such as severe shortness of breath, bloody stools or urine, decrease in urinating or lack of urinating, or a change in consciousness or alertness. Seek immediate medical care (call 911) if you, or someone you are with, have overdosed on a drug or ingested a toxic substance.
SYMPTOMS    Symptoms of kidney disease vary according to the underlying causes. 

CAUSES   Kidney disease can be caused by a wide variety of underlying diseases, disorders or conditions that lead to kidney damage, such as obstruction, infection, malignancy, inflammation, deformity, toxic ingestion, or a reduced blood supply to the kidneys.
TREATMENTS  Treatment of kidney disease varies depending on the underlying disease, disorder or condition. The goals of treatment are to cure the underlying condition, prevent excessive fluid and waste from accumulating in the body, and stop or slow the progression of damage to the kidneys. Treatment also aims to minimize complications of kidney disease.

HeartThe heart is the organ that helps supply blood and oxygen to all parts of the body. It is divided by a partition or septum into two halves, and the halves are in turn divided into four chambers. The heart is situated within the chest cavity and surrounded by a fluid filled sac called the pericardium. This amazing muscle produces electrical impulses that cause the heart to contract, pumping blood throughout the body. The heart and the circulatory system together form the cardiovascular system.

Brain
The forebrain is responsible for a variety of functions including receiving and processing sensory information, thinking, perceiving, producing and understanding language, and controlling motor function. There are two major divisions of forebrain: the diencephalon and the telencephalon. The diencephalon contains structures such as the thalamus and hypothalamus which are responsible for such functions as motor control, relaying sensory information, and controlling autonomic functions. The telencephalon contains the largest part of the brain, the cerebrum. Most of the actual information processing in the brain takes place in the cerebral cortex. 

The midbrain and the hindbrain together make up the brainstem. The midbrain is the portion of the brainstem that connects the hindbrain and the forebrain. This region of the brain is involved in auditory and visual responses as well as motor function.

The hindbrain extends from the spinal cord and is composed of the metencephalon andmyelencephalon. The metencephalon contains structures such as the pons and cerebellum. These regions assists in maintaining balance and equilibrium, movement coordination, and the conduction of sensory information. The myelencephalon is composed of the medulla oblongata which is responsible for controlling such autonomic functions as breathing, heart rate, and digestion. 

Lungs
The lungs are a pair of spongy, air-filled organs located on either side of the chest (thorax). The trachea (windpipe) conducts inhaled air into the lungs through its tubular branches, called bronchi. The bronchi then divide into smaller and smaller branches (bronchioles), finally becoming microscopic.

The bronchioles eventually end in clusters of microscopic air sacs called alveoli. In the alveoli, oxygen from the air is absorbed into the blood. Carbon dioxide, a waste product of metabolism, travels from the blood to the alveoli, where it can be exhaled. Between the alveoli is a thin layer of cells called the interstitium, which contains blood vessels and cells that help support the alveoli.

The lungs are covered by a thin tissue layer called the pleura. The same kind of thin tissue lines the inside of the chest cavity -- also called pleura. A thin layer of fluid acts as a lubricant allowing the lungs to slip smoothly as they expand and contract with each breath

Liver
The liver is a large, meaty organ that sits on the right side of the belly. Weighing about 3 pounds, the liver is reddish-brown in color and feels rubbery to the touch. Normally you can't feel the liver, because it's protected by the rib cage.

The liver has two large sections, called the right and the left lobes. The gallbladder sits under the liver, along with parts of the pancreas and intestines. The liver and these organs work together to digest, absorb, and process food.

The liver's main job is to filter the blood coming from the digestive tract, before passing it to the rest of the body. The liver also detoxifies chemicals and metabolizes drugs. As it does so, the liver secretes bile that ends up back in the intestines. The liver also makes proteins important for blood clotting and other functions.

Kidneys
The kidneys play key roles in body function, not only by filtering the blood and getting rid of waste products, but also by balancing levels of electrolyte levels in the body, controlling blood pressure, and stimulating the production of red blood cells.

The kidneys are located in the abdomen toward the back, normally one on each side of the spine. They get their blood supply through the renal arteries directly from the aorta and send blood back to the heart via the renal veins to the vena cava. (The term "renal" is derived from the Latin name for kidney.)

The kidneys have the ability to monitor the amount of body fluid, the concentrations of electrolytes like sodium and potassium, and the acid-base balance of the body. They filter waste products of body metabolism, like urea from protein metabolism and uric acid from DNA breakdown. Two waste products in the blood can be measured: blood urea nitrogen (BUN) and creatinine (Cr).

When blood flows to the kidney, sensors within the kidney decide how much water to excrete as urine, along with what concentration of electrolytes. For example, if a person is dehydrated from exercise or from an illness, the kidneys will hold onto as much water as possible and the urine becomes very concentrated. When adequate water is present in the body, the urine is much more dilute, and the urine becomes clear. This system is controlled by renin, a hormone produced in the kidney that is part of the fluid and blood pressure regulation systems of the body.

Kidneys are also the source of erythropoietin in the body, a hormone that stimulates the bone marrow to make red blood cells. Special cells in the kidney monitor the oxygen concentration in blood. If oxygen levels fall, erythropoietin levels rise and the body starts to manufacture more red blood cells.

After the kidneys filter blood, the urine is excreted through the ureter, a thin tube that connects it to the bladder. It is then stored in the bladder awaiting urination, when the bladder sends the urine out of the body through the urethra.

StomachThe stomach is an expanded section of the digestive tube between the esophagus and small intestine. Its characteristic shape is shown, along with terms used to describe the major regions of the stomach. The right side of the stomach is called the greater curvature and the left the lesser curvature. The most distaland narrow section of the stomach is termed the pylorus - as food is liquefied in the stomach it passes through the pyloric canal into the small intestine.The wall of the stomach is structurally similar to other parts of the digestive tube, with the exception that the stomach has an extra oblique layer of smooth muscle inside the circular layer, which aids in performance of complex grinding motions.

In the empty state, the stomach is contracted and its mucosa and submucosa are thrown up into distinct folds called rugae; when distended with food, the rugae are "ironed out" and flat.