HPA and HTA Flashcards
where are the hormones released by the posterior pituitary gland made?
hypothalamus
what complex does the hypothalamus and pituitary form?
hypothalamic-pituitary axis
where is the pituitary found?
sella turcica
what is the embryonically origin of the posterior/anterior pituitary gland?
anterior - evagination of ectoderm
posterior - neuroectoderm
how is the posterior pituitary connected?
connected directly to hypothalamus
via pituitary stalk from infundibulum
what 2 hormones does the posterior pituitary produce?
oxytocin - uterine contractions
antidiuretic hormone - reuptake of water kidneys
what cells produce the hormones form the posterior gland?
neurosecretory cells
what is the mediatory point before hormones are stored in the hypophyseal portal system?
median eminence
how is the anterior pituitary connected to the hypothalamus?
hypophyseal portal system
what function do the hormones released from the anterior pituitary display?
autocrine and paracrine
what is the anterior pituitary gland made up of?
hormone producing glandular cells
what are tropic hormones?
hormones from the hypothalamus that stimulate release from anterior pituitary
what are the 6 tropic hormones?
prolactin
growth hormone
thyroid stimulating hormone (TSH)
adrenocorticotropic hormone (ACTH)
follicle stimulating hormone (FSH)
lutenizing hormone (LH)
What feedback system regulates the anterior pituitary hormones?
negative
what are gonadotropes (LH and FSH) controlled by?
gonadotrope stimulating hormone
what are thyrotropes (TSH) controlled by?
tyrotrope stimulating hormone
what are somatotropes (GH) controlled by?
growth hormone releasing hormone
what are lactotropes (Prolactin) controlled by?
dopamin - inhibits
explain the Hypothalamic pituitary adrenal axis (HPA)
hypothalamus releases corticotrophin releasing factor (CRF)
stimulates the anterior pituitary
release of ACTH
stimulates adrenal gland releasing cortisol
causes negative feedback
explain the Hypothalamic pituitary thyroid axis (HPT)
hypothalamus releases thyroid releasing hormone (TRH)
stimulates anterior pituitary
releases TSH
stimulates thyroid releasing T4 and T3, increase metabolism
negative feedback
what does t3 stand for?
triiodothyronine
what does T4 stand for?
thyroxine
explain hypothyroidism (hashimotos)
autoimmune
thyroid peroxidase turns iodine to iodide, destroy TSH receptors
symptoms - tiredness, dry skin, thin hair, bradycardia, goitre
manage - hormone replacement therapy
diagnosis - TSH level, thyroid functions
explain hyperthyroidism (graves)
autoimmune
TSH receptor stimulating antibodies
symptoms - tachycardia, tremor, heat intolerance, protruding eyes
manage - carbimazole
diagnostic - decreased TSH, increases free T4
explain Addisons disease?
autoimmune destruction of adrenal cortex
symptoms - weight loss, weakness, low bp, pigmentation
manage - fluid replacement, hydrocortison
diagnostic - adrenal antibodies, ACTH
what happens if Addisons disease is left untreated?
Hypoadrenal crisis: hypotension, hypoglycaemia, hyponatraemia, dehydration, hyperkalaemia
explain cushings syndrome
group of symptoms occur after long exposure to cortisol
cushings disease - pituitary tumour, incr ACTH
symptoms - moon face, thin arms, striae
diagnostic - 24hr urine cortisol test, measurement of plasma cortisol and ACTH
what is a syncathen test?
normally incr plasma cortisol,
wouldn’t see in Addisons disease
what is a dexamethasone suppression test?
suppression of plasma cortisol >50% seen in cushings disease
