L31 Introduction to Endocrinology Flashcards
(18 cards)
what are the main endocrine glands in the body? [6]
hypothalamus/pituitary thyroid parathyroid pancreas adrenal ovaries/testicles
how is the pituitary gland divided and what are their functions?
anterior pituitary which produces hormones
posterior pituitary which stores hormones
which hormones does the anterior pituitary produce and what do they do? [5]
growth hormones (GH) for skeletal growth
adrenocorticotrophic hormone (ACTH) which stimulates the adrenals to produce steroids
Gonadotrophins (FSH and LH) which stimulate ovaries and testicles to produce sex hormones
thyroid stimulating hormone or thyrotrophin (TSH) which stimulates thyroid to produce thyroid hormones
prolactin (PRL) which stimulates breast milk production
which hormones does the posterior pituitary store and where are these hormones produced?
produced in the hypothalamus, stores:
antidiuretic hormone (ADH) which stimulates water reabsorption by the kidneys and
oxytocin which helps uterine contractions during labour
what structure controls the anterior pituitary?
hypothalamus
how do hormones (and which?) secreted by the hypothalamus affect the anterior pituitary? [4]
corticotrophin releasing hormone (CRH) by hypothalamus stimulates ACTH secretion in ant. pit.
growth hormone rels. hormone (GHRH) by hypothalamus stims. GH secr. in ant. pit.
thyrotrophin rels. hormone by hypothalamus stims. TSH secr. by ant. pit.
gonadotrophin rels. hormone (GnRH) by hypothalamus stims. FSH and LH secr. by ant. pit.
prolactin is under the inhibitory effect of the hypothalamus
how are the pituitary hormones:
ACTH and CRH
GH and GHRH
TSH and TRH
FSH/LH and GnRH
switched off?
by negative feedback
cortisol switches off ACTH and CRH
growth hormones switches off GH and GHRH
thyroid hormones switch off TSH and TRH
sex hormones switch off FSH/LH and GnRH
which hormone glands are not controlled by the pituitary and what do they do?
adrenal medulla - produces adrenaline and noradrenaline
parathyroid - controls calcium levels
pancreas - controls sugar levels
gut hormones
where is the thyroid gland and what is its structure?
sits just below cricoid cartilage at front of throat, comprised of a right and a left lobe with a midline isthmus
how are thyroid cells arranged in the thyroid and what other cells are present?
thyroid cells arranged in follicles which produce thyroid hormones
theyre are also C cells which produce calcitonin for calcium metabolism/formation
what is the mechanism for the control of thyroid hormone secretion?
the hypothalamus secretes TRH which activates to the stimulation of TSH in the anterior pituitary.
the TSH activates the thyroid to secrete T3 andT4
T3 and T4 have an inhibitory effect on the hypothalamus and the anterior pituitary, stopping the secretion of TRH and TSH
how is calcium metabolism controlled?
by 4 parathyroid glands sitting behind thyroid and C cells in thyroid
the kidneys contribute to calcium secr. and production of active vit D
gut absorbs calcium
bone stores calcium
what are the adrenal glands made up of and what do they produce?
cortex (90%) and medulla (10%).
majority of cortex produces corticosteroids (cortisols), androgens (male hormones - esp in females), mineralocorticoids (aldosterone)
medulla secretes catecholamines (adrenaline, noradrenaline, dopamine)
which secretions of the adrenal glands are NOT controlled by the pituitary?
catecholamine secr. (medulla) is NOT controlled by pituitary and relates to blood pressure
mineralocorticoid secr. (cortex) related to renin-angiotensin-aldosterone system, which controls bp
what is the mechanism of secretion of female hormones?
hypothalamus secretes GnRH in a pulsatile on/off fashion
GnRH stimulates ant pit to secrete FSH and LH
FSH stim. ovaries to secrete oestradiol and inhibin
inhibin primarily inhibits pituitary from secr. FSH and LH. oestradiol can have a stimulatory or inhibitory affect on both hypothalamus and pituitary
oestradiol inhibits FSH secr, but stims. LH secr
LH secretion stimulates progesterone secretion from ovaries
what is testicular maldescent?
the testicles do not descend, they remain in the abdomen until a later descent. the heat of abdomen kills sperm production
what are the testes composed of and what is their purpose?
interstitial or leydig cells produce testosterone
seminiferous tubules which are made up germ cells produce sperm
sertoli cells help in sperm production and produce inhibin
what is the mechanism of secretion of male hormones?
hypothalamus secretes GnRH on/off which stims pit to secr FSH and LH.
FSH and LH stim testis to secr inhibin from sertoli cells and testosterone from leydig cells
inhibin inhibits the pituitary gland
testosterone inhibits hypothalamus and pituitary gland
