Endocrine Flashcards
The hypophysis is two parts, ….. & …..
Adenohypophysis (from somatic ectoderm “Rathke’s pouch”, devoid of innervation)
Neurohypophysis (from neuroectoderm “diencephalon”)
Pars nervosa is ….
part of the neurohypophysis, connected by the infundibulum to the hypothalamus (composed of nerve tracts from the latter)
The brain is connected to the adenohypophysis by ….
hypothalamic-hypophysial portal system
Each of these hormones stimulates:
- CRH
- TRH
- GnRH
- GHRH
- ACTH
- TSH & prolactin
- FSH & LH
- GH
Dopamin inhibits ….. release, while ….. inhibits TSH & GH
prolactin
somatostatin
* Dopamine is release by the hypothalamus in the hypothalamic-hypophyseal portal system
Oxytocin and ADH are produced by the ….., transported via the ….. and stored in …. to be released on appropriate stimulation
hypothalamus
nerve tracts (infundibulum)
pars nervosa
What is the difference between tropic and non tropic hormones?
tropic hormones have other gland as their target.
Non tropic hormones act directly on the target cell
* GH is both tropic and non tropic
Example of straight chain peptide with disulfide bridge are … & …
- GH: increases protein synthesis, increases lipolysis (to spare glucose & protein). Has diabetogenic effect
- Prolactin (PR): required for milk synthesis. Also called LTH (luteotropic hormone). Stimulates calcitriol & calcitonin production
see p. 428
What is the difference between gigantism & acromegaly?
Acromegaly: increase GH (A)fter fusion of growth plate
Gigantism: increase GH before closure of growth plates
How is the GHRH and GH are regulated?
by feed back mechansim
* They are secreted in pulses throughout the day
LH, FSH & TSH are example of ……
glycoproteins composed of alpha & beta subunits
What is the effect of LH on both sexes?
Males: testosterone synthesis by Lydig cells
Females: triggers ovulation
* secretion controlled by feed back mechanism
What is the effect of FSH on both sexes?
maturation of germ cells
Glucocorticoids …… GH secretion
inhibit
Example of straight chain polypeptide are … & …..
- ACTH: stimulates glucocorticoid release from adrenal cortex
- MSH: stimulates melanocytes
Addison’s disease is ….
(adrenal insuffeciency) causes high level of ACTH. Due to similarity with MSH, high ACTH causes pigmentation of the skin and oral mucosa
- There’s destruction of the adrenal cortex, most likely autoimmune
- Tx is cortisol (skin lesions disappear, but oral persist)
- Also called primary addison’s disease
Cushion syndrome is …
High ACTH due to pituitary tumor, steroid meds., or ectopic ACTH producing tumors, or adrenocortical adenoma
ADH & oxytocin are synthesized in …. & ….
SON & PVN (hypothalamus)
- unmyelinated axons from the hypothalamus terminate in the posterior lobe of the pituitary gland, where these two hormones are stored to be released on demand.
- These two hormones are synthesized by two different types of cells
Endorphins & enkephalins are ……
endogenous opioid agonists, act as neurotransmitters
Vasopressin primary site of action is ….. & ….. with its action being
DCT & collecting duct
increase permeability to water, leading to its reabsorption (by increasing Na retention)
ADH (vasopressin) release is controlled by …
osmoreceptors in the hypothalamus
- decrease osmolarity ===> decrease ADH release and vice versa
- Alcohol decrease ADH release
Low ADH leads to ….. urine
hypotonic
A small decrease in plasma osmotic pressure is needed to …… ADH, while it takes 10%…. in blood pressure for ADH to be released
decrease
decrease
In volume contraction, …… stimulates thirst
angiotensin II