This tutorial will take you through the CRH release caused by the Generalized Stress Response.
You will navigate through this tutorial using the buttons at the top of the screen.
The tutorial will ask you questions. Click on your chosen answer to see feedback; click the answer again to make the feedback disappear. When you're finished with one page, click the navigation button for the next page to move ahead.
Have fun! Click on button '1' to see the first page of the tutorial.
CRH stands for
Corticotropin Releasing Hormone
You can tell a lot from this name, if you think back to your Anatomy and Physiology.
Cortico -- means relating to the adrenal cortex
Tropin -- means growth stimulating
Releasing Hormone -- means this hormone will cause the corticotropins to be released.
So the name means, 'a hormone which will cause the release of compounds that make the adrenal cortex grow.'
Releasing Hormones are secreted from the hypothalamus into a tiny network of blood vessels that run to the pituitary. These vessels are called the hypothalamohypophyseal portal system, or the hypophyseal portal system for short.
The anterior pituitary creates and stores many hormones that can control other organs.
Releasing hormones from the hypothalamus tell the anterior pituitary which of these stored hormones to release.
In this case, the Corticotropin Releasing Hormone will tell the anterior pituitary to release Corticotropin, also called Adrenal Corticotrophic Hormone, or ACTH.
Adrenal Corticotrophic Hormone will stimulate the Adrenal Cortex, the part of the adrenal that makes steroid hormones. It makes Aldosterone, Cortisol, and Testosterone.
The hypothalamus and pituitary are trying to keep one of these hormones at a stable value by turning the adrenal cortex on and off. But which one?
What kind of feedback loop would you call this?
Why does the body need cortisol, anyway?
Cortisol is called a glucocorticoid. This is because the first effects of cortisol that were discovered were effects on glucose metabolism.
In fact, though, cortisol affects almost every system in the body.
Here's a list of the effects of cortisol.
EMERGENCY SYSTEMS SPEED UP:
-arterioles are more responsive to the SNS - constrict more
-Heart is more responsive to the SNS -- increased heart strength
-Na+/K+ ATPase activated, reabsorbing Na+ and H2O into the blood and secreting K+ into the urine
-Calcium lost in the urine
STORED NUTRIENTS ARE RELEASED FROM:
-stored glucose is released into the blood
-actin and myosin breakdown
3. Adipose tissue
lipids are released from storage in arms and legs, redeposited in trunk
-decreased bone deposition
-decreased insulin release: blood glucose increases
IMMUNE AND INFLAMMATORY FUNCTION DECREASES
-thymus gland atrophies
-prostaglandin production blocked
-fewer neutrophils leave bloodstream to enter tissues
-monocytes and macrophages less active
Now that you have an idea of what cortisol does, you can identify why it would be an important component of the Generalized Stress Response.
Cortisol helps the sympathetic system raise blood pressure by
increasing heart strength
making arterioles more responsive to the sns.
In short-term emergencies, cortisol also helps the sympathetic system increase muscle strength. How would it do that?
calcium loss in urine
decreased insulin release
One of the main effects of cortisol, however, is on the immune system. How would you best describe cortisol's effect on the immune system?
Cortisol depresses immune and inflammatory function in many ways.
First, it blocks prostaglandin production. This is the compound injured cells use to begin an inflammatory response and attract white blood cells like neutrophils and monocytes (which grow up to be macrophages) into the area.
Then, if neutrophils get to the area anyway, cortisol prevents them from leaving the blood and entering the injured tissue.
It decreases the activity of monocytes and macrophages, so there are fewer of these antigen-presenting cells to alert the immune system to the presence of infection...
and, over the long run, it atrophies the thymus so fewer mature T cells will be produced!
But why on earth would you want to turn off your immune system, just when the body is under attack?
There are a few good things about cortisol depressing the inflammatory and immune responses.
First, the immune response takes a lot of energy. If you're running away from a bear, you don't want your energy to be diverted from the muscles!
Second, the inflammatory response increases blood flow to the injured area. This would divert blood from the muscles -- and it could cause the injured area to bleed more.
Third, when the immune response kicks in, it has effects on the whole body. It can cause a fever, and make you nauseated; it can also give you a feeling of malaise, so you just want to lie around and rest. Not the way you want to be during an emergency!
Congratulations on finishing the Corticotropin Releasing Hormone Tutorial! This is just one of the responses your body uses to handle stress. The others are the Sympathetic Nervous System
, the Renin-Angiotensin-Aldosterone System
, and Antidiuretic Hormone. You can reach them by clicking on their names.