Back To CoursePathophysiology Textbook
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Don't get too scared when I tell you that we'll be discussing many different types of shock in this lesson. It's not as shocking as it sounds since two of the main types I want to teach you about are kind of related to the others and so we'll really only be discussing a couple of main things. That should make it a little bit easier for you. Despite trying to make this lesson easier by combining things, the types of shock you'll learn about aren't easy on your body and are all emergency conditions.
To understand why, it's important to know what shock really is. Shock in a clinical sense has absolutely nothing to do with the emotional shock (good or bad) you may experience when you are proposed to, when you find out how massive your cell phone bill is, or the time you saw a pretty bad car accident. Shock in medicine refers to inadequate tissue perfusion in the body due to any number of causes.
In any case of shock, improper tissue perfusion of an organ results. Perfusion is how well-soaked your organs and tissues are with blood. In a more relatable sense, what I mean is, if a kitchen towel is soaked with water, then it's really well-perfused with water. If it's dry, then it's not well-perfused with water. If the cells, organs, and tissues of your body aren't soaked well enough with blood, then they aren't getting nutrients they need to stay alive. This obviously results in a person's death.
Since we are on the topic of blood here, one type of shock is known as hemorrhagic shock. This is a type of hypovolemic shock resulting from rapid and severe blood loss. Hypovolemic shock refers to improper tissue perfusion as a result of severe blood loss, other fluid loss from the body, or inadequate fluid intake, any of which end up decreasing intravascular fluid volume. By that definition, it should be clear that hypovolemic shock doesn't solely have to occur as a result of a loss of blood due to hemorrhage. Other fluid loss due to severe vomiting, diarrhea, kidney disease, or burns can also result in hypovolemic shock.
An obstruction in the GI tract, thereby limiting fluid intake, can also cause hypovolemic shock. This type of obstruction shouldn't be confused with obstructive shock, which is a completely separate category of shock that refers to obstruction of the outflow of blood from the heart. Hypovolemic shock due to hemorrhage is like having the pipes normally filled with water running throughout your house all of the sudden bursting open. This will lead to a decrease in water pressure and volume and therefore a decreased flow of water to places like your bathroom, kitchen sink, and so forth.
Similarly, in hypovolemic shock, a decrease in blood pressure (hypotension), intravascular blood volume, and adequate blood flow (tissue perfusion) to organs and tissues occurs. Like the pipes all of a sudden bursting open in your house, one similar event in real life that can cause hemorrhagic shock is the bursting open of an aortic aneurysm. An aneurysm is an abnormal distension or dilation of a blood vessel (in this case, the aorta).
Another form of shock is known as septic shock. This is a type of distributive shock resulting from sepsis. Sepsis is an abnormal body-wide inflammatory response to an infection that can result in death, whereas distributive shock is a form of shock in which severe vasodilation despite normal blood volume results in improper distribution of blood flow. Other causes of distributive shock include allergic reactions (anaphylactic shock), endocrine disease (addisonian crisis), and brain or spinal cord injuries (neurogenic shock).
To boil the massive complexities of everything down for you, if you get a severe enough infection with some nasty toxins being produced by the bacteria, then your body launches into a big defensive assault against the bacteria. Your body releases inflammatory mediators all over the place to try and counter this threat. However, these inflammatory mediators end up causing the dilation of blood vessels (known as vasodilation). Dilation of blood vessels results in decreased blood pressure. Decreased blood pressure impairs the delivery of blood to tissue organs, thereby decreasing tissue perfusion.
Let's examine why this is the case really quickly. If you have something like air under high pressure in a gas tank, then when you turn on the nozzle of the air tank, you can easily inflate a balloon. The inflation of that balloon with air thanks to high tank pressure is like the perfusion of an organ thanks to adequate blood pressure. But if the pressure in the tank of air drops, then when you turn the nozzle on, air will flow with very little force into the balloon, and this means the balloon won't inflate very well - that is to say, it won't be perfused with air very well.
All of this is coupled with the fact that the severe inflammatory response produces little blood clots all over the body. These blood clots prevent the flow of blood to your tissues and organs. Once again, this decreases tissue perfusion. It's as if something is stuck in the nozzle of the air tank, thereby preventing any air flow into the balloon.
Finally, the inflammatory mediators cause the blood to be shunted and distributed away from the capillaries responsible for delivering oxygen and taking away waste products produced by the organ. This is similar to having a second nozzle in the air tank. If you turn on one nozzle to inflate the balloon, the air actually goes out the other nozzle, resulting in a lack of inflation of the balloon since the air is shunted out through the nozzle you're not even using!
A person in shock due to any reason may have a combination of the following signs and symptoms:
Treatment of shock is dependent on the cause and needs to be instituted immediately. For example, in cases of hemorrhagic shock, the cause of the bleeding must be evaluated right away, fluids must be administered to account for hypovolemia, and so on. However, what I want you to know pathophysiologically is that shock is a very difficult thing to treat, especially in end-stages of shock. This is because the longer someone is in shock, the less perfused the tissues and organs are with blood.
This means that those tissues and organs begin to die from lack of a proper blood supply. When the cells in the tissues of your body die, they release a lot of dangerous waste products and electrolytes in very high concentrations. This shouldn't be surprising since when your food goes bad it also releases some pretty nasty-looking smells and colors.
If a doctor gives too little or too much of a medication or fluid or improperly times the restoration of blood flow to the dying organs, the person may die from the treatment itself. This is because when blood flow is restored to the dying organ, all of the toxins released by that dying organ enter the bloodstream. That's because this organ wants to do everything it can to rid itself of these dangerous toxins when the blood flow is finally re-established and is therefore able to carry these toxins away. That makes perfect sense. But the problem is that if there are too many toxins released into the bloodstream, they can damage and kill all of the other organs in the body, resulting in a person's sudden and uncontrollable death.
One thing we can control, however, is our review of the important points of this specific lesson. This lesson covered one type of shock that is known as hemorrhagic shock. This is a type of hypovolemic shock resulting from rapid and severe blood loss. Hypovolemic shock refers to improper tissue perfusion as a result of severe loss of blood or other fluid from the body or inadequate fluid intake, any of which decrease intravascular (that is to say, within blood vessel) volume.
Another form of shock we discussed is known as septic shock. This is a type of distributive shock resulting from sepsis. Sepsis is an abnormal body-wide inflammatory response to an infection that can result in death, whereas distributive shock is a form of shock in which severe vasodilation, despite normal blood volume, results in improper distribution of blood flow.
In any case of shock, inadequate tissue perfusion occurs. This means the organs, tissues, and cells in the body do not receive a blood supply that helps to deliver oxygen and nutrients. This same lack of a blood supply means waste products and toxins cannot be removed out of the organ or tissue, either.
At the end of this lesson, you should be able to:
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Back To CoursePathophysiology Textbook
20 chapters | 274 lessons