Principles of Hormone Action

Question 1

What are the main steroid hormones?

Answer 1

Sex hormones + progesterone
Androgens
Cortisol
Aldosterone

Question 2

What are amino acid hormones usually derived from?

Answer 2

Tyrosine and tryptophan

Question 3

What type of hormones are catecholamines and thyroid hormones?

Answer 3

Amino acid derivative hormones

Question 4

What are eicosanoids derived from?

Answer 4

Arachidonic acid

Question 5

Why do eicosanoids no stray far from their production site?

Answer 5

They degrade easily

Question 6

What are the main functions of eicosanoids?

Answer 6

Roles in inflammation, blood pressure and clotting.

Question 7

What type of hormone is prostaglandin?

Answer 7

Eicosanoid

Question 8

How are peptide hormones stored?

Answer 8

Stored in vesicles until stimuli signals their release into the blood.

Question 9

What are the two classes of receptor?

Answer 9

Intracellular receptors

Cell surface receptors

Question 10

What are intracellular receptors the primary receptor for?

Answer 10

Steroid hormones as the can diffuse across the phospholipid membrane

Question 11

How do cell surface receptors work?

Answer 11

Perform signal transduction. Converting extracellular signals into intracellular signals.

Question 12

What are the three categories of of cell surface receptors?

Answer 12

1. G protein coupled receptors
2. Enzyme linked receptors
3. Ion channel linked receptors

Question 13

How do ion channel linked receptors work?

Answer 13

1. Ligand binds to a receptor.
2. Changes the structure of the protein channel, allowing ions to pass through into the cell.
3. Ions activate enzymes and voltage sensitive channels producing a response.

Question 14

Which cell surface receptor is heterotrimeric?

Answer 14

G protein coupled receptors

Question 15

What is meant by heterotrimeric?

Answer 15

Means the receptor has three different subunits

Question 16

How does the g protein coupled receptor process work?

Answer 16

1. Ligand binds to GPCR
2. GPCR changes shape
3. alpha subunits exchanges GDP for GTP
4. alpha subunit dissociates and regulates a target protein.
5. alpha subunits activates it’s target protein, the target protein can then send a signal via a second messenger.
6. GTP is hydrolysed to GDP allowing the cycle to repeat.

Question 17

What does RGS stand for?

Answer 17

Regulation of g protein signalling

Question 18

What does RGS do?

Answer 18

RGS accelerates hydrolysis of GTP allowing a new ligand to bind faster.

Question 19

How do enzyme linked receptors work?

Answer 19

Enzyme linked receptors are cell surface receptors with intracellular domains that associate with an enzyme when activated.

Question 20

How do cell surface receptors typically work?

Answer 20

Via a second messenger, involving protein kinases and cyclic AMP.

Question 21

What is down regulation of receptors?

Answer 21

Occurs when a receptor is chronically exposed to a ligand. This results in ligand-induced desensitization or internalisation of the receptor.

Question 22

What is upregulation of receptors?

Answer 22

Cells are super-sensitized due to repeated exposure of an antagonistic drug, or prolonged absence of the ligand.

Question 23

What controls regulation of melatonin?

Answer 23

Melatonin secretion is related to the length of the night.

Question 24

What is increased production of melatonin in winter a sign of?

Answer 24

Seasonally affective disorder