Endocrine Communication + Adrenal Glands

Question 1

What is the endocrine system?

Answer 1

A communication system using hormones as signalling molecules.

Question 2

What are hormones?

Answer 2

Molecules (proteins or steroids) that are released by endocrine glands directly into the blood. They act as messengers, carrying a signal from the endocrine gland to a specific target organ or tissue.

Question 3

What are target cells?

Answer 3

For non-steroid hormones, cells that process a specific receptor on their plasma (cell surface) membrane. The shape of the receptor is complementary to the shape of the hormone molecule. Many similar cells together form a target tissue.

Question 4

What does the endocrine system use to transmit its signals?

Answer 4

The blood circulatory system.

Question 5

What are the signals released by the endocrine system called?

Answer 5

Hormones

Question 6

What are the two types of hormone?

Answer 6

Protein/peptide and steroid.

Question 7

Protein hormones are not soluble in the phospholipid bilayer so therefore what do they do?

Answer 7

Protein hormones need to bind to the cell surface membrane and release a second messenger inside the cell.

Question 8

From what are hormones released?

Answer 8

Endocrine glands.

Question 9

Describe the endocrine glands.

Answer 9

The endocrine glands are ductless glands - they consist of groups of cells that manufacture and release the hormone directly into the blood in the capillaries running through the gland.

Question 10

How come steroid hormones are able to have a direct effect on the DNA in the nucleus?

Answer 10

They are able to pass through the membrane.

Question 11

What is the benefit to having a receptor that is specific to one type of protein hormone?

Answer 11

It means that the hormone is not able to affect other cells that don’t have the receptor as it passes through the system.

Question 12

What are the two types of adrenergic receptor?

Answer 12

Alpha and Beta

Question 13

What do alpha receptors cause?

Answer 13

They are excitatory in smooth muscles and gland cells, but cause relaxation of intestinal smooth muscles.

Question 14

What are first-messengers?

Answer 14

Non-steroid hormones. They are signalling molecules outside of the cell that bind to the cell surface membrane and initiate an effect inside of the cell.

Question 15

What is the second messenger?

Answer 15

The second signalling molecule found inside the cell that is released when the first messenger binds to the cell surface membrane.

Question 16

What does the second messenger do?

Answer 16

Stimulates a change in the activity of the cell.

Question 17

What does the G-protein do once it is activated by the non-steroid hormone?

Answer 17

G protein activation leads to activation of various second messenger systems and intracellular responses, leading to physiological responses of tissues and organisms.

Question 18

What does adenyl cyclase do?

Answer 18

adenylate cyclase is activated and converts ATP to cAMP

Question 19

What does cAMP do?

Answer 19

cAMP activates protein kinase

Question 20

What is the adrenal cortex?

Answer 20

The outer layer of the adrenal gland.

Question 21

What is the adrenal gland?

Answer 21

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.

Question 22

What is adrenaline?

Answer 22

A hormone released from the adrenal glands, which stimulates the body to prepare fro fight or flight.

Question 23

What is the adrenal medulla?

Answer 23

The inner layer of the adrenal gland.

Question 24

What are the three layers of the adrenal cortex starting from outside in?

Answer 24

Outermost layer - Zona glomerulosa
Middle layer - Zona fasciculata
Innermost layer - Zona reticularis

Question 25

What does the zona glomerulosa do?

Answer 25

Secretes mineralocorticoids such as aldosterone.

Question 26

What does the zona fasciculata secrete?

Answer 26

Glucocorticoids such as cortisol.

Question 27

What does the zona reticularis secrete?

Answer 27

Thought to secrete precursor molecules that are used to make sex hormones.

Question 28

What does the adrenal medulla secrete?

Answer 28

Adrenaline and noradrenaline.

Peptide

Question 29

What does the adrenal cortex used to produce a range of hormones?

Answer 29

Cholesterol

Question 30

Are the hormones from the adrenal cortex steroid or non-steroid?

Answer 30

Steroid based.

Question 31

Give the steps of the action of a steroid hormone.

Answer 31

1. Hormone passes through membrane of target cell.
2. Hormone binds with a specific receptor in the cytoplasm.
3. Receptor-steroid hormone complex enters nucleus of target cell and binds to another specific receptor on the chromosomal material.
4. Binding stimulates the production of mRNA molecules, which code for the production of proteins.

Question 32

What do mineralocorticoids do?

Answer 32

Help to control the concentrations of sodium and potassium in the blood. As a result the also contribute to maintaining blood pressure.

Question 33

What does aldosterone do?

Answer 33

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.

Question 34

What do glucocorticoids do?

Answer 34

Helps to control the metabolism of fats, carbohydrates and proteins in the liver.

Question 35

When is cortisol released and what does it do?

Answer 35

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.

Question 36

What do the precursor molecules that are secreted from the zona reticularis do?

Answer 36

Helps produce sex hormones

Question 37

What do sex hormones do?

Answer 37

Sex hormones are responsible for driving sexual development (puberty).

Question 38

What are the immediate effects of adrenaline being released?

Answer 38

Key actions of adrenaline include increasing the heart rate, increasing blood pressure, expanding the air passages of the lungs, enlarging the pupil in the eye, redistributing blood to the muscles and altering the body’s metabolism, so as to maximise blood glucose levels (primarily for the brain).

Question 39

What are exocrine glands?

Answer 39

Glands that secrete chemicals through ducts into organs or to the surface of the body.

Question 40

What is the glycocalyx?

Answer 40

An area of carbohydrate chains outside the cell surface membrane

Question 41

Glycolipid function?

Answer 41

Involved in cell to cell signalling and binding to make tissues

Question 42

Glycoprotein function?

Answer 42

Receptors for chemical signals

Question 43

Why can proteins and peptide hormones be carried in the blood plasma?

Answer 43

They are hydrophilic so water soluble

Question 44

How are steroid hormones carried in the blood? Why?

Answer 44

Bound to specific carrier proteins as they are hydrophobic

Question 45

Describe the second messenger system.

Answer 45

1. water soluble hormone leaves capillary via fenestrations. as it is membrane insoluble it cannot enter the cell but instead binds to a glycoprotein receptor on the cell surface membrane. Hormone = primary messenger
2. The binding of hormone activates a G protein that is intrinsically positioned on the inside of the cell surface membrane
3. The activated G protein activates adenyl cylase
4. This catalyses the conversion of ATP to cyclic AMP (cAMP). It is the cAMP that acts as the secondary messenger.
5. cAMP activates other proteins and triggers a cascade of events in the cell by activating protein kinase
6. Protein kinase activates other proteins by phosphorylating them.

Question 46

Where are the adrenal glands located

Answer 46

above kidneys