overview of different hormones

Question 1

Synthesis and release of polypeptide hormones

Answer 1

1. Messenger RNA on ribosomes of ER binds amino acids into a peptide chain
   = preprohormone
2. The chain is directed into the ER lumen by a signal sequence of amino acids
3. Enzymes in the ER chop off the signal sequence, creating an inactive prohormone
4. The prohormone passes from the ER through the golgi apparatus
5. Secretory vesicles containing enzymes and prohormone bud off golgi.
   The enzymes chop the prohormone into one or more active peptides plus additional peptide fragments
6. The secretory vesicle releases its contents by exocytosis into extracellular space
7. the hormone moves into circulation for transport to its target

Question 2

Steroid hormones make up:

Answer 2

Cholesterol

Question 3

Steroid hormones - type of hormone?

Answer 3

Lipophilic

Question 4

Steroid hormones with or without protein carrier?

Answer 4

With protein carrier in plasma

Question 5

Steroid hormones type of protein carrier:

Answer 5

• corticosteroid binding
• globin/albumin

Question 6

Steroid hormones - how do they enter cells?

Answer 6

Unbound, free hormone diffuses into target cell

Question 7

Steroid hormones receptors

Answer 7

cytoplasmic or nuclear receptors

Question 8

Steroid hormones- type of response

Answer 8

• genomic response
• activates DNA for protein synthesis

Question 9

Steroid hormones- half life?

Answer 9

Slower acting, longer half-life (60-90min)
- if carried with protein = longer half life

Question 10

Steroid hormones- examples

Answer 10

cortisol
estrogen
testosterone

Question 11

Steroid hormone - aldosterone has a shorter half life, why?

Answer 11

It occurs in the plasma as free and bound to carrier proteins (mineral corticols)

Question 12

Do all cholesterol-containing organs produce steroid hormones?

Answer 12

No, need enzymes to produce specific hormone

Question 13

Steroid hormones can also have a non-genomic response. what does this mean and which hormones?

Answer 13

• hormones bind to receptors on cell membrane instead of inside of cell.
• This produces a signalling cascade
• estrogen and aldosterone

Question 14

Describe estrogen and aldosterones non-genomic response

Answer 14

Question 15

Amine hormones are made up of?

Answer 15

1-2 amino acids

Question 16

Examples of amine hormones and what they’re made of

Answer 16

melatonin – tryptophan
catecholamines – tyrosine
thyroid hormones – 2 tyrosine + iodine atoms

Question 17

Amine hormones- receptors

Answer 17

Catecholamines:
- mem. receptors
- epinepherine, norepinephrine, dopamine

Thyroid hormones:
- intracellular receptors that activate genes

Question 18

Why are thyroid hormones an exemption from the ‘rules’ of amine hormones?

Answer 18

• it acts like a steroid hormine
• it has an intracellular receptor
  (instead of a mem. receptor)

Question 19

Question 20

Different types of control pathways (4)

Answer 20

• simple nervous reflex
• neurohormone reflex
• neuroendocrine reflexes
• simple endocrine reflex

Question 21

Parathyroid hormone control

Answer 21

Question 22

Describe the probable chemical composition of any hormone that binds to a membrane receptor. Also describe the manner of its secretion into the plasma, how it is transported in the blood, the length of its half-life as well as how its message is conveyed in the effector cells.

Answer 22

Peptide (chemical structure)
Water soluble
It will be synthesised in advance
It will be stored in secretory vesicles
It will be released via exocytosis
It will have a short half-life
After binding to the membrane receptor a second messenger will be activated which will induce activation of kinases to induce the response
There will be at least one sensor
Sensor can be positioned anywhere in the body