Endocrine Flashcards
What is the master control gland in the endocrine system?
pituitary gland
What controls the pituitary gland?
the hypothalamus through a negative feedback loop
Name the two lobes that the pituitary gland is divided into.
- anterior lobe
2. posterior lobe
Another name for the anterior lobe of the pituitary gland.
adenohypophysis
What is the function of the anterior pituitary lobe/adenohypophysis?
secretes the following hormones; ACTH, FSH, LH, GH, TSH, under the influence of releasing factors (except prolactin) from the hypothalamus
What stimulates ACTH?
corticotrophin releasing hormone (CRH)
Two names for ACTH.
adrenocorticotropic hormone or corticotropin
Function of ACTH.
governs synthesis of cortisol and pregnenolone in the adrenal cortex
What syndrome has increased ACTH?
Cushing’s syndrome
What stimulates FSH?
gonadotrophin releasing hormone (GnRH)
Function of FSH?
stimulates the follicles in the ovaries to produce estrogen and stimulates sertoli cells for spermatogenesis
What stimulates LH?
Gonadotrophin releasing hormone (GnRH)
Function of LH?
stimulates ovulation and the production of progesterone in the ovary.
stimulates the interstitial cells of Leydig in the testis to produce testosterone
What stimulates GH?
growth hormone releasing hormone (GHRH)
Another name for GH?
growth hormone of somatotropin
Function of GH?
stimulates bone and tissue growth through somatomedins A-C
What does an increase in GH result in?
gigantism or acromegaly
What does a decrease in GH result in?
dwarfism
What is TSH stimulated by?
thyrotrophin releasing hormone (TRH)
Function of TSH?
stimulates the thyroid to produce thyroxin
What does an increase in thyroxin result in?
hyperthyroidism
What does a decrease in thyroxin result in?
hypothyroidism
What is prolactin affected by?
prolactin inhibiting factor (dopamine) and TRH
Another name for the posterior pituitary lobe.
neurohypophysis
What two hormones are stored (but not secreted) in the posterior pituitary lobe/neurohypophysis?
- oxytocin
2. ADH
What structure is oxytocin secreted by?
the paraventricular nucleus in the hypothalamus
What is the function of oxytocin?
it stimulates contraction of uterine muscles during labor and the myoepithelial cells in the breast (milk ejection) and also plays a role in maternal bonding
released and stimulated by nipple stimulation
oxytocin is controlled by a positive feedback mechanism
Where is ADH released?
the supraoptic nucleus of the hypothalamus
What is the function of ADH?
it acts on the collecting ducts in the kidney and it is released in response to water deprivation
prevents water from being excreted in the urine (diuresis)
What does lack of ADH result in?
diabetes insipidus (polyuria and polydypsia)
Where is the pars intermedia located?
between the anterior and posterior pituitary lobes