Hypothalamus and Pituitary Tutorial Flashcards

1
Q

what is a ENdocrine gland

A

secretes its hormones directly into the bloostream

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2
Q

what is an EXocrine gland

A

secrete their hormones into a collection of ducts which are carried around the body

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3
Q

what is the difference in onset and duration of action of endo vs exocrine glands

A

exocrine quicker response

endocrine longer duration as taken to kidney to made available for absorption

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4
Q

match each hormone to its class:
steroid
protein and peptide
amine

insulin
adrenaline
testosterone

A

steroid- testosterone
protein and peptide- insulin
amine- adrenaline

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5
Q

true or false- amine peptides and proteins are only synthesised on demand

A

false

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6
Q

true or false- steroid hormones are mainly bound to proteins in the plasma

A

true

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7
Q

true or false- amines, peptides and proteins stimulate and act on intracellular receptors

A

false - have cell surface receptors

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8
Q

list these from shortest to longest half lives:
steroid
amine
peptide

A

amine- seconds
peptide- minutes
steroid- hours

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9
Q

what connects the hypothalamus to the pituitary

A

the pituitary stalk

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10
Q

what is the adenohypophysis

A

anterior pituitary

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11
Q

what in the neurohypophysis

A

posterior pituitary

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12
Q

what synthesises posterior hormones in the hypothalamus

A

supraoptic and paraventricular nuclei (neuroendocrine)

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13
Q

how do hormones from the hypothalamus get to the anterior pituitary

A

cell bodies secrete into via portal veins

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14
Q

what are the ‘releasing’ stimulatory hypothalamic hormones

A
growth hormone releasing hormone (GHRH)
prolactin releasing hormone (PRH)
thyrotrophin releasing hormone (TRH)
corticotrophin releasing hormone (CRH)
gonadotrophin releasing hormone (GnRH)
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15
Q

what are the inhibitory hypothamalic hormones

A

somatostatin and dopamine

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16
Q

what class are the hypothamalic hormones

A

all peptides except dopamine which is an amine

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17
Q

what does dopamine inhibit

A

the release of prolactin (ant pit)

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18
Q

what does somatostatin inhibit

A

growth hormone (ant pit)

19
Q

what is released from the anterior pituitary

A
GH 
ACTH (andenocorticotrophic hormone)
TSH
PRL
FSH (follicle)
LH (lutenising)
20
Q

what is released from the posterior pituitary

A

oxytocin

anti-diuretic hormone (ADH)

21
Q

what is the function of oxytocin

A

milk secretion and uterine contractions

22
Q

what is the function of ADH

A

increases water reabsorption at kidneys

vasoconstriction at vascular smooth muscle

23
Q

what are the actions of growth hormone

A

increases blood glucose by increasing gluoneogenesis in the liver
releases insulin GF (IGF-1) from the liver
decreases glucose uptake in muscles cells- increases it in brain cells
increases the rate of lipolysis in fat cells
has anabolic effect on the body
increase glucose and fatty acids
increased protein synthesis
decreased fat storage
increased soft tissue growth
increased bone growth

24
Q

what are common conditions in growth hormone excess

A

diabetes (T2), carpal tunnel syndrome, hypertension

25
Q

what does IGF-1 cause

A

increased bone growth
increased soft tissue growth
increased protein synthesis

26
Q

what changes can be seen in acrogmegaly

A
increase in hand and foot size 
prominent brow 
large nose and jaw 
pronounced cheekbones 
skin changes (thickens, sweating, acne)
oral manifestations (enlargement of tongue and swelling of larynx, interdental separation)
27
Q

how can acromegaly’s oral manifestations cause presentations

A

deep or coarser voice

obstructive sleep apnoea

28
Q

how is movement affected in acromegaly

A

joint pain, proximal muscle weakness, lethargy decreases movement
decreased movement in hands and pain/ tingling sensations

29
Q

what behavioural problems arise in acromegaly

A

lethargy

polydispsia and uria

30
Q

why do you get hypertension in acromegaly

A

increased plasma fatty acids causes patty plaques

31
Q

what nerve is affected in carpal tunnel

A

median nerve

32
Q

what provides negative feedback for GH

A

IGF-1 negative on ant pit

GH negative on Hypothalamus

33
Q

what causes acromegaly

A
pituitary tumour (micro <1cm or macroadenoma >1cm)
ectopic tumour
34
Q

what is gigantism

A

when children have a growth hormone secreting tumour of the pituitary gland- epiphyseal plates not closed so large bone growth

35
Q

in acrogmegaly what hormone can also be secreted in excess

A

prolactin (in one 1/3rd of patients)

36
Q

why can GH nnot diagnose acromegaly

A

as released in pulsatile manner - highest when asleep and in times of stress

37
Q

when is growth hormone low normally

A

in pregnancy

38
Q

what is the definitive test for acromegaly

A

oral glucose tolerance test

39
Q

how does oral glucose tolerance test diagnose acromegaly

A

oral glucose should suppress GH to <1 microgram/litre

if no suppression then acromegaly

40
Q

what can IGF-1 test show

A

mean 24 hour secretion of growth hormone

41
Q

what scan is done to see if there is a tumour in acromegaly

A

MRI of the pituitary fossa

42
Q

what is the treatment for acrogmegaly

A

surgery- trans-sphenoidal

radiotherapy- (with/without surgery)

dopamine agonists (bromocriptine and cabergoline)

somatostatin receptor agonists (octreotide and lanreotide)

growth hormone antagonists (pegvisomant)- works on GH receptors not on tumour

43
Q

what can cause hypopituitarism

A

pituitary tumour
radiation damage
trauma
infective (meningitis, syphilis, encephalitis)
immunological (autoimmune)
infiltrative (haemachromoatosis, sarcoidosis, secondary mets lesions)