Adrenal Glands Flashcards
What is the adrenal cortex?
The outer layer of the adrenal gland.
What is the adrenal gland?
One of a pair of glands lying anterior to the kidneys, which release adrenaline and a number of other hormones known as corticoids (or corticosteroids) such as aldosterone.
What is adrenaline?
A hormone released from the adrenal glands, which stimulates the body to prepare fro fight or flight.
What is the adrenal medulla?
The inner layer of the adrenal gland.
What are the three layers of the adrenal cortex starting from outside in?
Outermost layer - Zona glomerulosa
Middle layer - Zona fasciculata
Innermost layer - Zona reticularis
What does the zona glomerulosa do?
Secretes mineralocorticoids such as aldosterone.
What does the zona fasciculata secrete?
Glucocorticoids such as cortisol.
What does the zona reticularis secrete?
Thought to secrete precursor molecules that are used to make sex hormones.
What does the adrenal medulla secrete?
Adrenaline and noradrenaline.
What does the adrenal cortex used to produce a range of hormones?
Cholesterol
Are the hormones from the adrenal cortex steroid or non-steroid?
Steroid based.
Give the steps of the action of a steroid hormone.
- Hormone passes through membrane of target cell.
- Hormone binds with a specific receptor in the cytoplasm.
- Receptor-steroid hormone complex enters nucleus of target cell and binds to another specific receptor on the chromosomal material.
- Binding stimulates the production of mRNA molecules, which code for the production of proteins.
What do mineralocorticoids do?
Help to control the concentrations of sodium and potassium in the blood. As a result the also contribute to maintaining blood pressure.
What does aldosterone do?
Acts on the cells of the distal tubules and collecting ducts in the kidney. It increases absorption of sodium ions, decreases absorption of potassium ions, and increases water retention so increasing blood pressure.
What do glucocorticoids do?
Helps to control the metabolism of fats, carbohydrates and proteins in the liver.
When is cortisol released and what does it do?
Cortisol is released in response to stress or as a result of low blood glucose concentration.
It stimulates the production of glucose from stored compounds (especially glycogen, fats, and proteins) in the liver.
What do the precursor molecules that are secreted from the zona reticularis do?
They are taken up by the ovaries or testes and converted to sex hormones (testosterone in males and oestrogen in females).
What do sex hormones do?
They help the development of the secondary sexual characteristics and regulate the production of the gametes.
describe the features of adrenaline.
It is a polar molecule derived from the amino acid tyrosine.
Cannot enter cells like a steroid hormone can.
What are the immediate effects of adrenaline being released?
Relaxing smooth muscle in the bronchioles
Increasing SV of the heart
Increasing heart rate
Causes general vasoconstriction to raise blood pressure
Stimulates conversion of glycogen to glucose
Dilates pupils
Increases mental awareness
Inhibits the action of the gut
Causes body hair to stand erect.
