Lecture 2: Hormone Chemistry and Regulation Flashcards
Amines:
- What is the half-life
- State two examples and their derivative amino acid.
Amines (half life: 2-3 minutes)
Catecholamines: derived from single tyrosine
Indoleamines: derived from single tryptophan
What are the 4 types of hormones?
- Amines
- Thyroid Hormones
- Peptides/Proteins
- Steroids
Thyroid hormone:
- What is the half-life
- State what amino acid is their derivative.
- LONG half life - 8 days for T4, 24 hours for T3
2. 2 tyrosine molecules
What is the half life of the following:
- Peptides/proteins
- Steroids
- 4-170 minutes
2. minutes to several hours - bound to binding proteins in the blood
State the following for catecholamines & indoleomines:
- Half life (long or short)
- How do they travel in the blood?
- What is their main difference
- Half life is VERY short
- Travel FREELY in the blood
- always bind to membrane receptor to activate messenger signaling pathways - Main difference is SYNTHESIS
- tyrosine or tryptophan
- tyrosine hydroxylase or tryptophan hydroxylase
Catecholamines = SINGLE tyrosine
Indoleamines = single TRYPTOPHAN
What are some example of tyrosine derived CATECHOLAMINES?
What is the rate limiting enzyme?
What is it converted to from tyrosine?
What is the next precursor?
What kind of stimulation is required?
- Dopamine
Norepinephrine
Epinephrine - Tyrosine Hydroxylase
- L-DOPA
- Dopamine
- then Norepinephrine
(in adrenal medulla)
then EPINEPHRINE
REQUIRES SYMPATHETIC STIMULATION
What are the 2 body organs that dopamine is made in?
What is the action of dopamine in these two areas? (NT or hormone)?
- Brain
- Substantia Nigra (parkinsons)
- Arcuate Nucleus
- VTA
NEUROTRANSMITTER
- regulates multiple brain functions such as reward/attention mood
- Adrenal Gland:
- adrenal medulla converted to NE!!
HORMONE: inhibits prolactin release from anterior pituitary
In the arcuate nucleus,
tyrosine hydroxylase is constitutively active
THEREFORE
Dopamine is produced at high levels and released into blood
tonically inhibits ______ release
PROLACTIN
What is the tonic inhibitor of prolactin?
Why?
Where do these neurons arise from?
- DOPAMINE
- tyrosine hydroxylase is consitutivly active in the Arc. Nucleus
- ARCUATE NUCLEUS
Dopamingergic neurons arise from_____.
Dopamine is released into _______.
Arcuate Nucleus
Hypophysial capillary bed
-Dopaminergic neurons in the arcuate are distinct from those in other parts of the brain – TH is constitutively active maintaining high DA concentrations in
Norepinephrine:
Functions as what?
Requires _____ nervous system stimulation
Most tissue concentrations equal that of the synapse – conversion takes place primarily in neurons
_______ catalyzes reaction:
DOPAMINE to NOREPINEPHRINE
- NT and hormone
- Sympathetic
- B-hydroxylase
NE acts through both ___ and ____ receptors.
This is paracrine or autocrine?
NE acts through both alpha- and beta-adrenergic receptors
-PARACRINE AFFECT
_______ cells of adrenal medulla are homologous to postsympathetic neurons – release hormone into blood
Chromaffin
Indoleamines:
- Rate limiting enzyme is?
- What are 2 hormones that are indoleamines?
- Tryptophan Hydroxylase
- Serotonin
( both NT and hormone) - Melatonin
- hormone produced in pineal gland
(rate limiting enzyme = SNA - N acetyl transferase)
What converts tryptophan to seratonin?
To melatonin from serotonin?
- Tryptophan Hydroxylase (TPH)
2. SNA - N acetyltransferase
Most (95%) of the serotonin in the body is produced by _______ cells in gut
What are its functions?
Enterochromaffin
- Vasoconstictor
Stimulates smooth muscle contraction in intestine