overview of different hormones Flashcards
Synthesis and release of polypeptide hormones
- Messenger RNA on ribosomes of ER binds amino acids into a peptide chain
= preprohormone - The chain is directed into the ER lumen by a signal sequence of amino acids
- Enzymes in the ER chop off the signal sequence, creating an inactive prohormone
- The prohormone passes from the ER through the golgi apparatus
- Secretory vesicles containing enzymes and prohormone bud off golgi.
The enzymes chop the prohormone into one or more active peptides plus additional peptide fragments - The secretory vesicle releases its contents by exocytosis into extracellular space
- the hormone moves into circulation for transport to its target
Steroid hormones make up:
Cholesterol
Steroid hormones - type of hormone?
Lipophilic
Steroid hormones with or without protein carrier?
With protein carrier in plasma
Steroid hormones type of protein carrier:
- corticosteroid binding
- globin/albumin
Steroid hormones - how do they enter cells?
Unbound, free hormone diffuses into target cell
Steroid hormones receptors
cytoplasmic or nuclear receptors
Steroid hormones- type of response
- genomic response
- activates DNA for protein synthesis
Steroid hormones- half life?
Slower acting, longer half-life (60-90min)
- if carried with protein = longer half life
Steroid hormones- examples
cortisol
estrogen
testosterone
Steroid hormone - aldosterone has a shorter half life, why?
It occurs in the plasma as free and bound to carrier proteins (mineral corticols)
Do all cholesterol-containing organs produce steroid hormones?
No, need enzymes to produce specific hormone
Steroid hormones can also have a non-genomic response. what does this mean and which hormones?
- hormones bind to receptors on cell membrane instead of inside of cell.
- This produces a signalling cascade
- estrogen and aldosterone
Describe estrogen and aldosterones non-genomic response
Amine hormones are made up of?
1-2 amino acids
Examples of amine hormones and what they’re made of
melatonin – tryptophan
catecholamines – tyrosine
thyroid hormones – 2 tyrosine + iodine atoms
Amine hormones- receptors
Catecholamines:
- mem. receptors
- epinepherine, norepinephrine, dopamine
Thyroid hormones:
- intracellular receptors that activate genes
Why are thyroid hormones an exemption from the ‘rules’ of amine hormones?
- it acts like a steroid hormine
- it has an intracellular receptor
(instead of a mem. receptor)
Different types of control pathways (4)
- simple nervous reflex
- neurohormone reflex
- neuroendocrine reflexes
- simple endocrine reflex
Parathyroid hormone control
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.
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
