endocrine glands 1 and 2 Flashcards
what are the different parts of the pituitary gland
anterior and posterior pituitary
where does the anterior pituitary grow from
the roof of the mouth
where does the posterior pituitary grow from
down from the brain
hypothalamus and anterior pituitary
hypothalamus releases hypothalamic-releasing factors (hormones) into portal vessels to reach the capillary bed of the anterior pituitary. This controls secretion of anterior pituitary hormones
gonadotropin-releasing hormone (GnRH) axis
leads to increase in LH and FSH which leads to gonads producing sex hormone
growth hormone-releasing hormone (GHRH) axis
leads to increase in GH which causes liver to produce more IGF-1
what is somatostatin
global inhibitory hormone
somatostatin axis
inhibits GH and TSH which stops liver/thyroid producing IGF-1/thyroid hormones
TRH axis
increases TSH/ prolactin which causes thyroid to produce more thyroid hormones/ allows mammory tissue to produce milk
what is TRH
thyrotropin-releasing hormone
how is prolactin influenced by the hypothalamus
negatively
dopamine axis
inhibits prolactin to stimulate mammory tissue
what is CRH
corticotropin-releasing hormone
CRH axis
stimulates ACTH which stimulates the adrenal cortex to produce cortisol
posterior pituitary
neurally connected to hypothalamus
actions of vasopressin (AVP) (ADH)
causes vasoconstriction via V1 receptors when higher AVP
actions of Antidiuretic Hormone (ADH) (AVP)
increases permeability and re-absorption of water via v2 receptors
how is oxytocin release stimulated
by suckling of the nipple and by cervical stimulation (parturition)
how does suckling stimulate oxytocin
sensory nerves activated, signal to neuroendocrine cells, signal through neural tract to axon termini and so posterior pituitary releases oxytocin. milk let-down process activated
how does the distention of the cervix stimulate oxytocin
nerve fibres stimulated, signal to neuroendocrine cells etc…. results in contraction of uterine smooth muscle
actions of oxytocin (3)
- stimulates milk let-down and expression of breast milk
- uterine smooth muscle contraction
- parental/reproductive behaviour ?
what does the pineal gland produce
melatonin
what does melatonin do
secreted at night to induce sleep, involved in the body’s circadian rhythm
where is oxytocin synthesised
hypothalamus
what are the thyroid hormones (3)
thyroxine (T4) and tri-iodothyronine (T3), calcitonin
where are the thyroid hormones T3 and T4 made and stored
colloid
what do the parafollicular C cells do
make calcitonin
what do T3 and T4 do (2)
- increase metabolism of the body by increasing basal metabolic rate (BMR) and increasing the metabolism of carbs, proteins and fats
- stimulate growth and development particularly in maturation of CNS
Action of calcitonin
involved in calcium homeostasis by lowering plasma calcium levels
what does the parathyroid gland secrete
parathyroid hormone (PTH)
what is the structure of the parathyroid gland
4 small glands located on the posterior surface of the thyroid gland
what does PTH do
increases plasma Ca2+ levels
what are 2 antagonistic hormones in the thyroid
PTH and calcitonin
where are the adrenal glands located
on top of the kidneys
adernal gland structure
the outside is the cortex and the inside is the medulla
what is made in the adrenal medulla
catecholamines -> e.g. adrenaline, noradrenaline and dopamine
what is made in the adrenal cortex
adrenal steroid hormones -> e.g. mineralocorticoids (aldosterone), glucocorticoids (cortisol), weak androgens (DHEA(S))
what is DHEA(S)
dehydroepiandrosterone
what cells make adrenaline
chromaffin cells
what are chromaffin cells considered to be
modified postganglionic sympathetic neurones (neuroendocrine cells)
what are the 3 zones of the adrenal cortex (outside going inwards)
zona glomerulosa, zona fasciculata, zona reticularis
what hormones does the zona glomerulosa make?
mineralocorticoids e.g. aldosterone
what does aldosterone do
regulates Na+ and K+ balance and is part of the renin-angiotensin-aldosterone system (controls blood pressure)
what hormones does the zona fasciculata make
glucocorticoids e.g. cortisol
what hormones does the zona reticularis make
weak androgens
what do androgens do to women
pubic hair growth and libido
what hormones are the only ones to control the hypothalamus-pituitary-adrenal (HPA) axis
glucocorticoids (cortisol)
what does the suprachiasmatic nucleus (SCN) do
controls endogenous circadian rhythms
what do alpha islets of langerhans produce
glucagon
what do beta islets of langerhans produce
insulin
what do delta islets of langerhans produce
somatostatin
what is synergistic activity
when hormones work together to enhance the response
what is permissive activity
when one hormone is required to allow a second one to act
what is antagonistic activity
when the effects of hormones oppose each other
