S9- endocrinology Flashcards
6 main endocrine glands:
- hypothalamus/ pituitary
- Thyroid
- parathyroid
- pancreas
- Adrenal
- ovaries/ testicles
the pititary gland controls…
it can be functionally divided into 2 lobes:
most glands in the body
- anterior pituitary= produces various hormones
- posterior pituitary= stores various hormones (which are preduced in hypothalamus)
5 hormones produced by anterior pituitary
- growth hormone (GH)- for skeletal growth
- Adreno-cortico-trophic hormone (ACTH)- stimulates adrenals to produced steriods
- gonado-trophins (FSH and LH)- stimulates testicles and ovaries to produce sex hormones
- thyroid stimulating hormone/ thyrotrophin (TSH)- stimulate thyroid to produce thyroid hormones
- prolactin (PRL)- stimulates breast milk production
posterior pituitary stores 2 hormones (prodeuced in hypothalamus)
- antidiuretic hormone (ADH)- stimulates water reabsorption by kidneys
- oxytocin- main role is to help uterine contraction during labour
the anterior pituitary gland is under control of…
hypothalamus
4 hormones that are produced by hypothalamus to control anterior pituitary:
- Cortico-trophin releasing hormone (CRH)- stimulates ACTH secretion
- growth hormone releasing hormone (GHRH)- stimulates GH secretion
- thyrotropin releasing hormone (TRH)- stimulates TSH secretion
- Gonadotrophin releasing hormone (GnRH)- stimulates FSH and LH secretion
prolactin releasing hormone does not exist and prolactin is under the…of the hypothalamus
inhibitory effect
pituitary hormones are switched off by…
negative feedback (when the target gland/ organ produces the desired hormone—> stops pituitary gland from producing the stimulating hormone)
4 hormones that swtich off pituitary hormones
- Cortisol= ACTH and CRH
- growth hormone= GH and GHRH
- thyroid hormone= TSH and TRH
- sex hormones= FSH/LH and GnRH
4 glands that are not controlled by the pituitary
- adrenal medulla = produce adrenaline and noraadrenaline
- parathyroid= controls calcium levels
- pancreas= controls sugar levels
- gut hormones
the thyroid gland is composed of 3 parts:
Midline isthmus (below the cricoid cartilage)
right lobe
left lobe
the adrenal cortex is under control of…but the madulla isnt
the pituitary gland
calcium metabolism is mainly controlled by…
4 parathyroid glands sitting behind the thyroid
4 other organs involved in calcium metabolism
- kidneys (calcium excretion and production of active virtamin D)
- Gut (absorption of calcium)
- Bone (storage of calcium)
- thyroid (C cells)
2 parts of the adrenal gland are:
- adrenal cortex 90%
- adrenal medulla 10%
what 3 hormones does the adrenal cortex produce
- Cortico-steroids (cortisol)
- Androgens (male hormones)
- Mineral-o-corticoid (aldosterone)
adrenal medulla produces…
Catechol-amines (adrenaline, noradrenaline (neurotransmitter and hormone-important in fight-or-flight response, dopamine)
catecholamine secretion is not controlled by pituitary, instead it is related to…
Mineralocorticoid secretion is also not controlled by pituitary, instead it is relate to…which controls…
blood pressure
renin-angiotensin system (s a hormone system that regulates blood pressure, fluid and electrolyte balance, and systemic vascular resistance)
blood pressure
ovaries are situated in the…
they contain follicles that contain…
Pelvis on either side of the uterus
an oocyte each (at different stage of maturation)
2 hormones that the ovaries produce that switches off the hypothalamus and/or pituitary gland
inhibin= pituitary only
oestradiol= both glands (stimulates and inhibits)
in adults, testes are found in the…(except in a minority with testicular…)
scrotum
maldescent (ie: undescended testicle)
2 hormones released by testes that switch off the hypothalamus and/or pituitary glands
- inhibin (Sertoli cells)= pituitary only
- testosterone (leydig cells)= both glands
thyroid cells are arranged in…and produce…hormones
thyroid also contains…cells which produce…(..metabolism)
follicles
thyroid hormones (control gene expression and various aspects of organ function)
C cells (parafollicular cell)
calcitonin
calcium metabolism
testes are composed of 3 parts:
- interstitial or leydig cells= produce testosterone
- Seminiferous tubules= has germ cells that produce sperm
- sertoli cells= help in sperm production and produce inhibin
3 types of clinical abnormalities in glands
- hormonal over-secretion (usually beign tumours)
- hormonal under-secretion (due to gland destruction ie: inflammation (autoimmune), infarction (obstruction of blood supply/ less blood to gland= death of tissue), other)
- Tumour/ nodules in gland without affecting hormone secretion
3 types of tests for hormonal abnormalities
- static tests: for thyroid and sex glands (just look at the levels of hormones secreted)
- Stimulation tests: for under-secretion
- supression tests: for over-secretion
hyper-thyroidism=
Hypo-thyroidism=
in primary hyperthyroidism (common)=
in secondary hyperthyrodism=
thyroid hormones (T3, T4) are too high
thyroid hormones (T3, T4) are too low
T3, T4 are higher than normal range but TSH is low/ surpassed (problem is in thyroid gland) (in hypo its low-high)
T3, T4 are higher than normal range and TSH is also high (problem in pituitary gland because it is secreting alot of TSH)
(in hypo its low-low)
hypergonadism and hypogonadism can be primary or secondary (similar to thyroid)
primary if…
secondary if…
testosterone or.. too low or high but the FSH/ LH is opposite
all sec hormones are too high/ too low
prolactin is produced by…
prolactin over-secretion is a…condition and usually is due to…
use a…test to diagnose
anterior pituitary
Common
pituitary tumour secreting prolactin (prolactinoma/ hyperprolactinoma)
3 clinical presentations of hyperprolactinoma
- galactorrhoea (breast milk production)
- amenorrhoea (stops or irregular periods) in women and sexual dysfunction in men
- headaches and visual fields problems with large tumours
2 ways to diagnose hyperprolactinoma
- static test (there is no hormone that stimulates its production)
- pituitary MRI (to check if tumour presses on optic nerve and chiasm which causes visual problems)
mildly raised prolactin can be due to….(5 reasons)
- sexual intercourse
- nipple stimulation
- stress
- Large number of drugs (antipsychotics and antidepressants)
- non-functioning pituitary tumour (compressing hypothalamus and interfering with inhibitory effect on prolactin secretion)
treatment of hyperprolactinoma
(only pituitary over-secreting tumours) treated medically (stop and shrink the tumour) and rarely require surgical intervention
growth hormone oversecretion is very…
it can happen in…or in…
it can be sue to..
Rare (1 in 25,000)
childhood/ adolescent or adulthood
pituitary tumour
in children, GH excess can result in…
- excessive growth spurt and increased size of feet and hands
- if left untreated= lead to gigantism (the most serious consequences)
in adults GH excess affects…
and it can lead to…
skin, soft tissue, skeleton
- Acromegalic face
- wide and large hands/ feet
- increased sweating
ways GH excess can be diagnosed:
- suppression tests= glucose given and GH is measured (in healthy people= glucose inhibits GH secretion)
- imaging to confirm presence of pituitary tumour
treatment of GH oversecretion
surgical removal of tumour
then radiotherapy and medical therapy (sometimes surgery does not remove whole tumour)
Cushing’s syndrome is…
it may be due to…
(ACTH= Adrenocorticotropic hormone= regulates cortisol and androgens)
Rare
1. pituitary secreting ACTH tumour (called cushing’s DISEASE)
2. adrenal tumours secreting cortisol
3. cancers producing ACTH (ie: lung cancer)
5 clinical presentations in cushing’s
- growth arrest in children
- typical facial appearance (round/ moon-like face, acne, hirsutism)
- fat redistribusion (truncal obesity and thin extremities)
- skin abnormalities (thin skin and easy bruising, striae on abdomen)
- complications (hypertension, diabetes, high risk of infection, poor wound healing)
diagnosis of cushing’s
supression tests used (dexamethasone supression test used to confirm failure to suppress endogenous cortisol production)
difference between adrenal and pituitary cushing’s:
pituitary= ACTH high
adrenal= ACTH low
treatment of cushing’s
- for pituitary and adrenal:
- cancer related
surgery and then radiotherapy and medical treatment
treat original cancer
