Anatomy And Physiology

Anatomy Physiology



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Shock is a medical term which describes a condition where blood flow, and more importantly, oxygen supply to tissues, is inadequate to meet the metabolic needs of those tissues. There are several factors which affect the ability of oxygen to be delivered to the tissues of your body. If any one of these factors fails, oxygen will not be properly supplied to your body. When this happens a person will enter in to a state of shock. This is a medical emergency and can quite easily lead to death very quickly.

The three primary factors involved in proper oxygen delivery to the tissues include; the proper functioning of the heart (known as cardiac output), proper saturation of your red blood cells with oxygen, and adequate circulation of the blood to your tissues. Failure of any or all of these three mechanisms can lead to shock.

A person in shock will exhibit distinct signs and symptoms. Heart rate is almost always elevated as your body senses a lack of oxygen to its tissues and responds by attempting to push more blood to your organs. Urine output is decreased in an attempt to preserve fluid volume in your body. Skin is often cold and clammy. Changes in mental status, including agitation, are quite common as well.

There are four major categories of shock. Each of these categories involves the failure of one or more of the factors involved in oxygen delivery described above.

Hypovolemic Shock

The first type of shock is known as hypovolemic shock. Hypovolemic shock results in decreased volume of blood circulating in your arteries and veins. This blood loss can be rather obvious, as is seen any trauma or acute bleeding, or it can be insidious and hard to spot if the bleeding is internal. Your body will attempt to compensate for the lack of blood volume by constricting the size of the veins and arteries. However, this compensation can only go so far. If you lose over 15% of your total blood volume, your body will no longer be able to compensate properly. This will lead to a drop in blood pressure (known as hypotension), and if it progresses far enough, to shock.

Cardiogenic Shock

Cardiogenic shock results from the failure of the heart to pump blood properly. This is seen during a heart attack, or any other disorder which causes disruption of the normal beating of the heart. If the heart is no longer able to push blood around your body, the red blood cells which are carrying oxygen will not be able to reach your tissues. Obviously this is a medical emergency and needs to be corrected immediately or you will soon die.

Obstructive Shock

Obstructive shock is a rather broad category of conditions which cause a rapid decrease in cardiac output from the heart. Fluid or blood leaking into the sack surrounding the heart can put pressure on the heart preventing it from pumping properly. A tension pneumothorax, which involves improper leaking of air in to the chest cavity, can also put pressure on the heart and prevent it from pumping blood properly. A pulmonary embolism, which is a clot blocking blood flow, can also obstruct proper circulation. All of these conditions are medical emergencies and must be corrected immediately in order to restore proper circulation.

Distributive Shock

The final category of shock has two subcategories. Distributive shock comes in two forms; septic shock, and neurogenic shock. Both forms of distributive shock involve a reduction in blood flow.

Septic shock occurs during widespread infection in your bloodstream. It is extremely dangerous and has a mortality rate between 50 and 80%. Patients in septic shock will present with fever, chills, decreased blood pressure, altered mental status, and elevated heart rates. Most septic shock is caused by bacteria such as E. coli and other gram-negative and gram-positive bacteria. Neurogenic shock occurs after traumatic damage to the spinal cord. This damage affects the ability of the body to regulate blood pressure and tone within the vascular system.

No matter what the cause, shock is always a medical emergency and must be dealt with promptly and efficiently. Mortality rates for all forms of shock can be quite high. A person in shock is not receiving adequate blood supply to the tissues of their body. This condition can only last for a short time before permanent damage or death occurs.

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