Hormonal mechanisms of action dave's notes only so far

Question 1

By what three steps to hormones affect cell function? Give three examples

Answer 1

1. Entering the cell surface, 2. activating cytoplasmic or nuclear receptors, and 3. modifying mRNAs
   e. g. Thyroid hormones, steroid hormones, vitamin D

Question 2

How do steroid hormones cross membranes and where is their activity?

Answer 2

They can diffuse across or be transported across membranes. The may bind in the cytoplasm or on the nuclear membrane

Question 3

How do steroid hormones affect transcription?

Answer 3

After binding, the receptor may then bind to specific parts of the DNA (SRE???), regulating mRNA transcription

Question 4

To what family do steroid hormones (et al) belong?

Answer 4

The zinc finger protein family

Question 5

List six ways in which hormones may act at the cell surface

Answer 5

1. Altering ion movements
2. Increasing or decreasing adenylate cyclase
3. Increasing guanylate cyclase
4. Activating phospholipase c
5. Acting on tyrosine kinase
6. Linking to intracellular tyrosine kinase

Question 6

How may hormones alter ion movements? Give three examples

Answer 6

(this = often regarded as neurotransmitters). By binding directly to ion channels. E.g. Na-K+, GABA/glycine-Cl-, Ach-nicotinic receptor

Question 7

What does increasing or decreasing adenylate cyclase do and how?

Answer 7

Increasing or decreasing adenylate cyclase leads to increased or decreased production of cAMP, by converting ATP to cyclic AMP which happens via G-proteins. cAMP binds to the regulatory subunit of a specific protein kinase.

Question 8

Give five examples of hormones that increase c-AMP. How?

Answer 8

By increasing adenylate cyclase

1. PTH
2. TSH
3. Glucagon
4. ACTH
5. Catecholamines via beta-1

Question 9

Give one example of hormones that decrease c-AMP. Via what xxx?

Answer 9

Catecholamines via alpha-1 XXX?receptor??

Question 10

What effect does acting on tyrosine kinase have? How? Give three examples.

Answer 10

Increasing tyrosine kinase increases activity. This occurs by spanning the membrane to activate tyrosine kinase.

1. Insulin
2. EGC
3. PDGF

Question 11

Give two examples of hormones that link to intracellular tyrosine kinase

Answer 11

Cytokines

GH

Question 12

What do G-proteins do?

Answer 12

They link hormone binding to the formation of an intracellular signal with three subunits

Question 13

Intracellular calcium is normally very …….

Answer 13

low

Question 14

Intracellular calcium can be altered via..

Answer 14

voltage or ligand gated channels, or from intracellular sources e.g. through IP3

Question 15

Give three intracellular sources of intracellular calcium level modification

Answer 15

Troponin, calmodulin, myosin light chain kinase