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What Is Cortisol Hormone? - Definition, Function & Levels

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  • 0:00 Definition of Cortisol Hormone
  • 0:45 Functions of Cortisol Hormone
  • 2:14 Deficiency of Cortisol
  • 2:46 Excess Cortisol
  • 4:07 Cortisol & Stress:…
  • 5:13 Lesson Summary
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Lesson Transcript
Instructor: Laszlo Vass
This lesson defines the function of the hormone cortisol. In addition, you will learn about cortisol deficiency and excess and the effects an imbalance has on homeostasis and regulation in the body.

Definition of Cortisol Hormone

Have you ever felt stressed out? I'm willing to bet most of you have. Stress on the body has profound effects on all of your systems. When you're under stress, your body responds by releasing a hormone called cortisol. Cortisol belongs to a group of hormones called glucocorticoids. As a group, these hormones are involved in the regulation of metabolism in the cells, and they also help us regulate various stressors on the body. Cortisol, also known as hydrocortisone, cortisone and corticosterone are all glucocorticoids. Cortisol is a steroid-based hormone and is synthesized from cholesterol. Cortisol is made in the adrenal cortex of the adrenal gland.

Functions of Cortisol Hormone

Cortisol, like all steroid-based hormones, is a powerful chemical. Steroid-based hormones have a common mechanism of action in that they enter cells and modify the gene activity in the DNA. The amount of cortisol in your body is driven by your eating patterns and how much physical activity you get. As a general rule, your highest level of cortisol occurs just after you get up in the morning and the lowest level is in the evening as you are falling asleep.

Cortisol's main function is to provoke the cell to manufacture glucose from proteins and fatty acids. This process is known as gluconeogenesis. What cortisol is doing is saving glucose for the brain and forcing the body to use fatty acids from stored fat as energy.

Cortisol also forces the breakdown of stored proteins into amino acids so that the body can use them for making enzymes or repairing cells. Cortisol increases blood pressure, which increases blood flow and distributes the glucose and other nutrients as quickly as possible to the cells. Finally, cortisol helps the body resist stress and reduces the inflammatory response as well as overall immune response in the body.

Consequently, stress causes a rise in the amounts of glucose, fatty acids and amino acids in the blood, all promoted by cortisol. This latter of which is used to control many inflammatory diseases in the body, such as rashes and allergies (think hydrocortisone cream), as well as more serious autoimmune conditions like rheumatoid arthritis, such as through cortisone injections.

Deficiency of Cortisol

Addison's disease is caused by damage to the adrenal cortex. This condition can lead to the hyposecretion of cortisol. Not enough cortisol affects the function of many systems in the body. Persons affected by Addison's disease have low glucose and sodium levels in their blood and increased potassium. They also tend to lose weight. Addison's disease can also cause low blood pressure and dehydration. Cortisol deficiency is usually treated by corticosteroid replacement therapy to return cortisol to normal levels in the body.

Excess Cortisol

As mentioned, hypersecretion of cortisol in response to stress results in decreased inflammation and immune response. However, there is a more serious condition called Cushing's syndrome/disease, which can cause hypersecretion of cortisol. Instead of stress, the cause of Cushing's syndrome is either a tumor of the pituitary gland or adrenal cortex or excess doses of glucocorticoid drugs.

Cushing's syndrome has some serious side effects including water and salt retention, high blood pressure, swelling, muscle tissue and bone loss, deposits of excess fat in the abdomen and back of the neck and poor wound healing. Arguably the most severe side effect of Cushing's syndrome is the tendency to develop severe infections before the patient shows any symptoms. This is due to the decreased immune response. Treatment is either surgical removal of the tumor or discontinuation of the drugs.

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