Endocrine

Question 1

Peptide hormones

Answer 1

WATER SOLUBLE
structure: chains of amino acids.

Synthesis:
prehormone–>prohormone

Packaging:
prohormone–>hormone

Storage in vesicles:
(water soluble as either hormone or prohormone)

Secretion by exocytosis:
either as hormone, fragments, or prohormone.

Question 2

Catecholamine

Answer 2

WATER SOLUBLE
structure: amines

Synthesis:
tyrosine–>dopamine

Packaging:
dopamine–>noradrenaline–>adrenaline

Storage in granules:
water soluble

Secretion by exocytosis

Question 2

Steroid Hormone

Answer 2

LIPID-SOLUBLE
structure: 4 hydrocarbon rings

Stimulus:
another hormone binds to cell receptors

Synthesis:
cholesterol–>steroid hormone

Diffusion out of the cell
lipid soluble, bound to carrier proteins.

Question 3

Thyroid hormones

Answer 3

LIPID-SOLUBLE
structure: like catecholamines but more rings

Synthesis:
tyrosine–>thyroglobulin(TGB) (made in follicles)

Packaging:
iodine reacts with tyrosine in TGB

Storage in vesicles:
lipid soluble, 2 worms; T3-active, T4-common

Secretion by exocytosis:
travel bound to Thyroid-binding globulin(TBG), to target cells.

Question 4

Signal transduction mechanisms of water-soluble hormones

Answer 4

1. change in membrane potential
2. increase in calcium concentration
3. phosphorylation of proteins
4. increase in gene transcription

Question 5

Receptor tyrosine kinase

Answer 5

binding triggers conformational change, activating tyrosine kinase portion.
phosphorylates it’s own tyrosine residues.
Proteins dock to the pTyrosines, and are phosphorylated.

Question 6

Tyrosine kinase associated receptor:

Answer 6

When bound, causes a conformational change in the JAK kinase
JAK kinase activates, and phosphorylates other proteins.

Question 7

G-Protein coupled receptors

Answer 7

transmembrane protein associated with 3 subunits(a,B& gamma)
a binds GTP&GDP, acts like a GTPase.
a subunit binds GTP, dissociates from other proteins and interacts with effector proteins.

3 types;
Gs, Gi, Gq.

Question 8

Hormone effects(on other hormones - cooperation)

Answer 8

Permissive - one hormone enables the full effect of the other.
Synergy - maximum combined response>sum of individual effects.