Introduction to Endocrinology

Question 1

What is a hormone?

Answer 1

A molecule that is released in one part of the body, but regulates the activity of cells in other parts of the body.

Question 2

What is an endocrine gland?

Answer 2

A gland that produces and secretes hormones into the bloodstream, through which they travel to affect distant targets.

Question 3

What is an exocrine gland?

Answer 3

A gland which secretes its products into ducts opening onto an epithelium.

Question 4

Name 8 endocrine organs/glands.

Answer 4

1. Hypothalamus
2. Pituitary gland
3. Thyroid gland
4. Parathyroid glands
5. Adrenal glands
6. Testes
7. Ovaries
8. Pancreas

Question 5

Name 4 types of chemical messengers.

Answer 5

1. Neurotransmitters
2. Hormones
3. Neuroendocrine messengers
4. Cytokines

Question 6

What is the difference between a neurotransmitter and a neuroendocrine messenger?

Answer 6

Neurotransmitters are released directly into a synaptic gap, whereas neuroendocrine messengers are released into the blood.

Question 7

What are the 3 major molecular types of hormones?

Answer 7

1. Peptides
2. Steroids
3. Amines

Question 8

What molecular type are thyroid hormones and what molecular type do they behave like?

Answer 8

Thyroid hormones are peptides but they behave more like steroids.

Question 9

What are steroid hormones derived from?

Answer 9

Cholesterol

Question 10

Describe the onset of action of steroid hormones and why this is.

Answer 10

Onset of action for steroid hormones is longer (hours-days) because steroid hormones are not stored - they need to be synthesised when required.

Question 11

What are the 4 steps in the synthesis of steroid hormones?

Answer 11

1. Hydrolysis of esters and release of cholesterol.
2. Conversion of cholesterol to pregnenolone in the mitochondria.
3. Processing in the smooth endoplasmic reticulum.
4. Diffusion out of the cell.

Question 12

Once a water-soluble hormone binds to a receptor on the cell surface, what does this activate?

Answer 12

G protein.

Question 13

After a G protein has been activated by a hormone receptor complex from a water-soluble hormone, what are the next 3 steps? Include examples.

Answer 13

1. G protein activates an enzyme e.g. adenylyl cyclase.
2. This leads to stimulation or inhibition of a signalling molecule e.g. cAMP.
3. This leads to an effect e.g. via activation of protein kinases.

Question 14

What are the two main types of receptors that water-soluble hormones bind to on the cell membrane?

Answer 14

1. G-coupled protein receptors

2. Tyrosine kinase receptors

Question 15

Which is more common in the endocrine system, positive or negative feedback?

Answer 15

Negative feedback.

Question 16

In the endocrine system, what is meant by positive feedback?

Answer 16

The output enhances the original stimulus.

Question 17

In the endocrine system, what is meant by negative feedback?

Answer 17

The output reduces the original stimulus.

Question 18

What is meant by a tropic hormone?

Answer 18

Tropic hormones are hormones that have other endocrine glands as their target.

Question 19

What is an effector hormone?

Answer 19

Effector hormones are hormones that directly stimulate target cells to induce effects.

Question 20

What is meant by ‘resistance’ in the context of endocrinology?

Answer 20

There’s adequate levels of hormone, but a reduced target cell response.

Question 21

What is Cushing’s syndrome?

Answer 21

Cushing’s syndrome is a hormonal disorder caused by high levels of the hormone cortisol in your body.

Question 22

List 4 metabolic effects of cortisol.

Answer 22

1. Stimulates glucose production in the liver.
2. Stimulates the breakdown of fats and proteins.
3. Increases plasma concentrations of glucose, amino acids, and fatty acids.
4. Decreases muscle mass, maintains muscle function.

Question 23

List 3 cardiovascular effects of cortisol.

Answer 23

1. Maintains blood volume
2. Maintains cardiovascular responsiveness to catecholamines.
3. Maintains cardiac output.

Question 24

How does cortisol affect prostaglandin synthesis and the immune system in general?

Answer 24

Cortisol inhibits prostaglandin synthesis and is immunosuppressive.

Question 25

List some signs and symptoms of Cushing’s syndrome.

Answer 25

1. Central weight gain
2. Proximal weakness
3. Moon face
4. Insomnia
5. Poor libido
6. Thin skin
7. Easy bruising
8. Back pain
9. Polyuria
10. Depression/ psychosis
11. Susceptible to infections

Question 26

What is ACTH and which gland produces it?

Answer 26

Adrenocorticotropic hormone, produced by the pituitary gland

Question 27

Which hormone would be in excess with secondary Cushing’s syndrome?

Answer 27

ACTH

Question 28

What is the difference between Cushing’s disease and Cushing’s sydrome?

Answer 28

Cushing’s disease is a specific type of Cushing’s syndrome. It occurs when a pituitary tumour causes the body to make too much cortisol.

Question 29

Which disease is associated with hypoadrenalism?

Answer 29

Addison’s disease.

Question 30

Is Addison’s disease caused by a primary or secondary defect? Is this the same as or opposite to Cushing’s disease?

Answer 30

Addison’s disease is caused by a primary defect, whereas Cushing’s disease is caused by a secondary defect (pituitary gland tumour).

Question 31

List some signs and symptoms of Addison’s disease.

Answer 31

Weight loss
Anorexia
Weakness
Postural dizziness
Depression
Nausea/vomiting
Confusion
Back pain
Abdominal pain
Hyperpigmentation

Question 32

Why is hyperpigmentation a symptoms of Addison’s disease?

Answer 32

The pituitary gland will be secreting high levels of ACTH in an effort to stimulate the secretion of cortisol from the adrenal glands. The ACTH bind to melanocytes in the skin, giving a tanned appearance.

Question 33

What is the main treatment for Addison’s disease?

Answer 33

Life-long oral steroid replacement.