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Endocrine > Physiology > Flashcards

Physiology Flashcards

1
Q

normal insulin range

A

4-6mm. >7 is diabetic

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2
Q

production of insulin

A

synthesised in RER of b-cells in islets of Langerhans of pancreas as pro-insulin then cleaved to form insulin

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3
Q

secretion of insulin

A

biphasic- 1st sharp phase, 2nd shorter broader phase. insulin then travels to liver- what is not taken up by liver travels to kidneys to be broken down

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4
Q

action of insulin

A

promotes glucose uptake in muscle and adipose tissue, lipogenesis, glycogen synthesis in liver and muscle

inhibits lipolysis, gluconeogenesis in liver

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5
Q

what are the mechanisms for insulin resistance

A

1: impairment of insulin signalling
2: inflammation results in insulin resistance (obesity)
3: pathway selective hepatic insulin resistance

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6
Q

what is the gold standard for insulin resistance

A

hyperinsulimaeic- euglycaemic clamp

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7
Q

pathogenesis of insulin obesity in T2 mechanims (obesity)

A

obesity > inc inflammation > inc collagen > HA etc > inc extra-cellular matrix signalling > muscle insulin resistance

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8
Q

glucose is produced by…

A

liver glycogen, hepatic gluconeogensis

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9
Q

reaction between glucose and insulin

A

glucose enters b-cell via GLUT1 or GLUT2 transporters > phosphorylated by glucokinase to glucose-6-phosphate (pyruvate)
insulin binding to its receptor causes conformational change = initiating a cascade which recruiters GLUT transporters

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10
Q

these mechanisms can go wrong- describe the different insulin pathologies

A

gestational diabetes
MODY: impaired glucokinase
T1: no b-cells for insulin production
T2: hyperglycaemia so glucokinase cannot work + weakened insulin secretion
Donohue syndrome: mutation to insulin receptor
Rabson Mendenhall: triad of insulin resistance, acanthuses nigrans, developmental abnormalities

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11
Q

what are the 3 groups of hormone types

A

1: proteins and peptides (most diverse- made up of AAs)
2: tyrosine derived hormones (adrenaline, melatonin)
3: steroid hormones (cholesterol as pre-cursor, adrenal or repro glands)

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12
Q

what are the 3 types of receptors

A

G-protein: main regulatory signalling cascades have this receptor

receptor tyrosine kinase:
receptor associated with tyrosine kinase activity/ cytokines linked to TK

steroid hormone receptor: Act within nucleus of cells

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13
Q

ways to check pituitary function

A

bloods (9am cortisol), U&Es, dynamic tests (suppression test, stimulation test), imaging

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14
Q

islets of langerhans…

A

found in pancreas. densely packed and vascularised, have a, b and delta cells

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15
Q

normoglycaemia > fasting/exercise

A

> hypoglycaemia > glucagon inc, dec insulin > inc glucose production

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16
Q

alpha cells and glucagon secretion in low glucose

A

v-gated Ca-channels produce AP of cells and trigger exocytosis of glucagon > acts on liver to inc hepatic glucose production

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17
Q

action of somatostatin

A

paracrine regulation- somatostatin inhibits a and B cells

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18
Q

what is the incretin effect

A

oral glucose secretion induces greater insulin secretion than parenteral admin. the incretin hormones (GLP-1 and GIP) potentiate insulin secretion from b-cells

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19
Q

thyroid is the _____ endocrine gland. it develops at base of _____ and descends from foramen _____ to _______ neck

A

largest, tongue, caecum, anterior

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20
Q

structure of thyroid

A

C5-T1 level. has 2 lobules with thin fibrous septa containing follicles. each follicle surrounded by cuboidal epithelial cells containing thyroglobulin (pink). centre of follicle is colloid. c-cells surround follicles which secrete calcitonin

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21
Q

nerve supply of thyroid

A

supplied by autonomic nervous system

22
Q

hormone synthesis of thyroid

A

iodine taken up by follicle cells and attaches to tyrosine (thyroglobulin residues) > MIT and DIT formed > MIT coupling with DIT = T3, MIT + 2x DIT= T4. these are stored in colloid

23
Q

T/F: T3 is more abundant

A

F: T4 is (90%) but later converted in liver and kidneys to biologically active T3
T3 is much more potent than T4, and rapider onset/offset

24
Q

how are T3 and T4 transported

A

thyroxine-binding globulin, thyroxine binding pre-albumin, albumin

25
Q

how are T3 and T4 degraded

A

de-ionisers- D1 (liver and kidney), D2 (heart and skeletal muscles), D3 (brain)
T4: mainly D1 and D3
T3 mainly D3

26
Q

how do G-protein coupled receptors work

A

hormone binds> conformational change > activation of g-proteins > intracellular amplification> cascade > ions enter/ exit cell

termination: GTP hydrolysed to GDP, adrenaline dissociates > G-protein returns to OG conformation

27
Q

which receptors have fastest response

A

ligand-gated receptors (millisecond) > G-proteins > kinase-linked (hrs)

28
Q

3 regulations of signal molecules

A

autocrine: hormone works on cell that released it
paracrine: chemicals released from cells work on adjacent cells
endocrine: chemicals work elsewhere in body

29
Q

what are the 11 major endocrine glands

A 
hypothalamus 
pituitary 
pineal (melatonin) 
thyroid/ parathyroid 
adrenal medulla
adrenal cortex 
testes 
pancreas
ovaries
placenta
mammary glands
30
Q

steroid hormone structure

A

hydrophobic- transported in blood bound, unbound they become active

31
Q

tyrosine-derived: hydrophobic/hydrophilic?

A

hydrophilic (bind to cell membrane receptors)

mainly secreted by thyroid and adrenal medulla, unbound (thyroid are bound)

32
Q

which hormone type have a ring structure, are hydrophilic and transported unbound

A

peptide hormones

33
Q

name 3 carrier proteins

A

cortisol-binding globulin, thyroxine-binding globulin (T4), sex-steroid binding globulins (testosterone and oestrogen)

34
Q

if tumour on pituitary- what is usually affected

A

optic chiasma, internal carotid, CN 3, 4,6

35
Q

3 phases of ovulation are

A

follicular, ovulation, luteal

36
Q

what is a follicle

A

1 oocyte surrounded by follicular cells

37
Q

ovulation occurs due to a surge in ___

A

LH

38
Q

when does corpus luteum form

A

following ovulation due to LH influence, secreted progesterone

39
Q

action of oestrogen and progesterone

A

oestrogen: thickens vaginal wall, regulates LH surge, dec cervical mucus vsicooty
progesterone: inhibits LH secretion thus preventing maintenance of endometrium, thickens mucus

40
Q

spermatogenesis is under __, __, and ____ control

A

LH. FSH, testosterone

41
Q

what is the purpose of blood-testes barrier

A

prevent AI attack on Sertoli cells

42
Q

T/F: FSH stimulates Leydig cells

A

F: LH> Leydig cells> testosterone > stimulates Sertoli cells

FSH > Sertoli cells> spermatogenesis

43
Q

what controls water retention

A

ADH- secreted by posterior pituitary. acts by reabsorbing water by renal tubules preventing less to be lost in urine

44
Q

dilute urine = _____ osmolarity

A

low

45
Q

what controls Na retention

A

mineralocorticoids (adrenal gland secretion)- aldosterone and cortisol

46
Q

high mineralocorticoid activity = Na

A

gain

47
Q

what are 2 causes of hyponatraemia

A

low [Na] or high H2O

48
Q

hyponatraemia

A

s/s: hypotension, reduced skin elasticity

ix: <120mmol/L**
tx: remove H2O/ give Na

49
Q

what are 2 causes of hypernatareamia

A

high [Na] or low H2O

50
Q

hypernatraemia

A

s/s: oedema, raised JVP

ix: >160mmol/L**
tx: remove Na/give water as dextrose

51
Q

total body fluid rules

A
  1. changes in water vol affect whole body
  2. Na confined to ECF by pump in membrane so changes in [Na] occurs only in ECF
  3. water follows salt so if Na lost in ECF so is water

so… be careful if someone has hyponatraemia, give 0.9% saline as only want to replenish ECF

Endocrine (14 decks)

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