test one week two Flashcards
(88 cards)
how do hypothalamic hormones reach the posterior pituitary?
Hypothalamic hormones reach the posterior pituitary via neurons;
hypothalamic hormones are stored here.
how do hypothalamic-hypophysiotrophic hormones reach the anterior pituitary?
Hypothalamic-hypophysiotrophic hormones reach the anterior pituitary
via the hypothalamohypophyseal portal system; hypothalamic hormones
regulate synthesis & secretion of anterior pituitary hormones.
where is oxytocin synthesized and by what cells?
hypothalamus by magnocellular neurons within the paraventricular nucleus
Neuropeptide of 9 amino acids:
Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly
physiological actions of oxytocin
Oxytocin stimulates contraction of myoepithelial cells within breast tissue
-Specific effect on target cells:
Binds to G-protein receptors on the surface of myoepithelial cells, triggering a g-protein linked phospholipase C pathway, and increased intracellular Ca++. (Gq/11 pathway)
-Causes milk ejection
-Suckling of a nursing baby stimulates tactile receptors within the nipple, which is relayed back to the spinal cord and to the magnocellular neurons of the hypothalamus.
-Other sensory inputs may trigger the milk ejection reflex.
-Positive feedback: increased pressure and stretch of cervix, increased oxytocin
-Oxytocin stimulates contraction of uterine smooth muscle
synthetic oxytocin uses
- Augments labor: faster harder, always with amniotomy (AROM)
- Controls postpartum hemorrhage
Used in management of incomplete spontaneous abortion (incomplete miscarriage)
other oxytocin actions:
linked to sex, monogomy, mother baby pairing
ADH is synthesized where by what?
in the hypothalamus by magnocellular neurons of the supraoptic nucleus
physiological actions of ADH
Stimulates water retention by the collecting ducts of the nephrons of the kidney
-Specific effect on target cells:
Binds to G-protein receptors on the surface of collecting duct cells, triggering a g-protein linked adenylate cyclase pathway
Aquaporins are inserted into the apical membrane of collecting duct cells
-Without ADH, filtrate from nephrons stays dilute and produce a urine that is high in volume and low in solute concentration (up to 20 L/day)
-With ADH, filtrate from nephrons becomes concentrated, and urine is low in volume and high in solute concentration (1.5-2 L/day)
-Diabetes insipidus NOT MELLITUS
Neurogenic (central): ADH not produced (secreting tissue problem)
Nephrogenic (renal): ADH does not stimulate (target tissue problem)
primary endocrine disorder:
Primary disorders: malfunction with bottom level glands (thyroid, adrenal cortex, gonads)
secondary endocrine disorder
Secondary disorders: malfunction of pituitary hormones (TSH, ACTH, LH, FSH)
tertiary endocrine disorder
Tertiary disorders: malfunction of hypothalamic hormones (TRH, CRH, GnRH, GHRH, somatostatin, dopamine)
Growth hormone and prolactin do not follow this same terminology
how is hormone secretion of the hypothalamus-pituitary gland axis controlled?
via negative feedback loops
what inhibits TSH secretion?
GHIH (SS Somatostatin)
TRH stimulates and inhibits what
stimulates release of TSH and prolactin (PRL) but inhibits GnRH
consequences of a GH ademnoma
could cause a rise in GHIH (SS), which then inhibits TSH and then causes a drop in T4
prolactin physiological actions and secretion control?
primarily controlled by negative feedback by PIH (Dopamine)
Prolactin is the only purely non-tropic hormone of the A.P.
Prolactin stimulates the growth and development of the mammary gland and production of milk by mammary epithelial cells by causing:
Amino acid and glucose absorption
Milk protein production (β-caseins and α-lactalbumin)
Lactose and fat (triacylglycerol) synthesis
GH physiological actions
GH is both tropic (via the liver) and non-tropic (directly affecting) on bone, cartilage, and muscle
Adipose: stimulates release of FFA
Skeletal: stimulates AA absorption and protein synthesis
Liver: stimulates IGF and glucose secretion
GH secretion increased during childhood, peaks during puberty, and slowly declines during adulthood
Clinically relevant: use of GH to decrease body fat; historically the abuse of anabolic steroids by athletes/actors is combined with GH
what controls T3 T4 production and release?
controlled by tsh and trh
t3 t4 actions?
Thyroid hormone exists primarily as T4 (tetraiodothyronine or thyroxine) in the blood, but is converted to T3 (triiodothyronine) in peripheral tissues.
Thyroid hormone increases O2 use in mitochondria.
Major determinant in basal metabolic rate, oxygen consumption, and energy use throughout the body
Thyroid hormone has both inotropic and chronotropic effects on the heart
-Heart: Chronotropic and inotropic
Muscle: Stimulates protein catabolism
Adipose tissue: Stimulates fat catabolism
Nervous: Promotes neural development
Skeletal: Promotes normal development
GI: Stimulates carbohydrate (glucose) absorption
Throughout body: Simulates oxygen consumption in many tissues
what pathways do LH and FSH use to effect testes and ovaries?
gpcr
what cells are the primary target of LH?
LH primarily targets theca cells of the ovaries and Leydig cells of the testes
what is the primary target of FSH?
FSH primarily targets Granulosa cells of the ovaries and Sertoli cells of the testes
what controls secretion of acth from the anterior pituitary
CRH
ACTH physiologic role?
ACTH causes the adrenal cortex to secrete a number of corticoids (21 C steroids), including:
Primarily: glucocorticoids (cortisol and corticosterone)
Secondarily: Mineralocorticoids (aldosterone and deoxycorticosterone). Aldosterone secretion is primarily controlled by renin-angiotensin pathway
These steroids from the adrenal cortex are 21 C steroids and are not functionally related to androgens (19 C) and estrogens (18 C)
Corticoids play roles in
Regulating glucose, protein, and fat metabolism in the body
Regulating Na+ treatment by the kidneys
Suppressing the immune system