How do water soluble hormones trnasport in the blood and what is their half-life?
Circulate freely in blood
The shortest half-life
- Catecholamines: seconds
- Protein/peptides: minutes
How to lipid and thyroid hormones transport around body and what are their half lives?
Reversibly bind to blood bourne transport proteins.
Steroid/thryoid hormones half life = hours
Are intracellular recpetors of cell membrane receptors faster?
Cell membrance receptors
Brief description of intracellular receptor and action?
- Diffuses across membrane
- Bind lipid soluble hormone
- Hormone-receptor complex binds to DNA sites
- Gene activation/deactivation
- Cell response
Where are the intracellular receptors for steroids?
Cytoplasm and nucleus
Where are the intracellular receptors for thyroid hormones?
Nucelus and mitochondria
Brief description of events in FSHR G Protein-coupled receptor and signal transduction
- FSH bind to receptor-> G Prot activated (GTP replaced GDP)
- Active G Prot activates adenylate cyclase
- Adenylate cyclase converts ATP to PPi + cAMP (2nd messenger)
- cAMP acts on behalf of FSH
- cAMP changes activity of protein kinase A (PKA) enzyme
- PKA phosphorylates target proteins and induces cell response
What does a target cell response depend on?
number of receptors
hormone (ligand) concentration
receptor up and down regulation
What are 3 ways to terminate a hormonal signal (not positive or negative feedback)
- receptor desensitisation
-receptor canalisation (endocytosis)
- second messenger degradation
What nuclei from the hypothalamus release neurohormones in the primary capillary plexus in the hypophyseal portal system?
Which nuclei from the hypothalamus have their axons in the hypothalamo hypophyseal tract releasing neurotransmitter in the posterior pituitary?
How does the anterior pituititary develop?
Evagination of the oropharynx ectoderm toward the brain, “Rathke’s pouch”
Rathke’s pouch gives rise to:
o pars distalis
o pars intermedia
o pars tuberalis
How does the posterior pituitary develop?
derived from a downgrowth of the neuroectoderm of brain floor
proximal part – infundibulum & distal part – pars nervosa
The adrenal cortex secretes ___ Hormones
What does the zona glomerulosa secrete?
What does the Zona fasciculata secrete?
What doesthe Zona reticularis secrete?
What does the adrenal medulla secrete?
What 'weak' androgens does the zona reticularis secrete?
Small amount oestrogen
What would hypersecretion in the zona reticularis cause?
Where is kispeptin 1 made in humans?
Where are Kisspeptin receptor found?
On GnRH-containing neurons in hypothalamic median eminence
What is the molecular type for hypothalamic neurohormones?
What is the moecular type of FSH?
What is the molecular type of LH
What is the source of LH and FSH in the anterior pituitary?
Pars distalis, gonadotrope cells
What is the molecular type of prolactin?
What is the source of prolactin in the anterior pituitar?
Pars distalis, lactotrope/mammotrope cells
What are the target tissues of prolactin?
Breasts, uterus and thymus
What is the molecular type for Adrenocorticotrophic hormone?