Endocrinology Flashcards

1
Q

endocrine glands

A

cells that synthesise and secrete hormones into blood

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2
Q

hormone

A

chemical secreted into blood, acts on specific target cells to regulate cellular function

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3
Q

3 chemical classifications of hormones

A
peptides/ proteins 
- from DNA transcription and mRNA translation on RER
- exocytosis (hydrophilic)
steroids 
- from cholesterol 
- diffusion (lipophilic) 
biogenic amines 
- from tyrosine (aa) 
- diffusion (lipophilic), exocytosis (hydrophilic)
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4
Q

mechanism of action of hydrophobic hormones

A

e.g. steroid, biogenic amines (thyroid) hormones
bind to intracellular receptors
alters transcription, more/ less protein produced

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5
Q

mechanism of action of hydrophilic hormones

A

e.g. peptides, biogenic amines
binds and activates cell surface receptors
stimulates secondary messenger

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6
Q

two types of endocrine control

A

homeostatic response - homeostatic function e.g. ADH, PTH

adaptive response - adapt to specific stimulus e.g. insulin

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7
Q

regulating simple hormone response

A

involves one endocrine gland
regulated by circular response
e.g. ⬆ blood glucose, ⬆ pancreas insulin, glucose taken up by target cell, ⬇ blood glucose, pancreas stops releasing insulin

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8
Q

regulating complex hormone response

A

involves action of two or more endocrine glands
regulated by
- long, indirect feedback loop - final hormone affects first endocrine secretion
- long, direct feedback loop - final hormone affects second endocrine secretion
- short feedback loop - second hormone affects first endocrine secretion
- negative feedback - hormone output reverses stimulus
- positive feedback - hormone output encourages stimulus

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9
Q

anterior lobe of pituitary connection with hypothalamus

A

portal vessels transport hormones down pituitary stalk from hypothalamus to stimulate synthesis and secretion of hormones from anterior lobe

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10
Q

anterior pituitary hormones

A

synthesised in anterior lobe
tropic hormones - target cell is another endocrine cell
- gonadotrophs e.g. FSH (gametogenesis), LH (steroidogenesis)
- thyrotrophs e.g. TSH (thyroid secretion)
- corticotrophs e.g. ACTH (adrenal cortex secretes cortisol and aldosterone)
non-tropic hormones - directly affect target cell
- somatotrophs e.g. GH (increase glucagon and insulin)
- lactotrophs e.g. PRL (mammary glands, Na+ kidney reabsorption)
all are trophic hormones - induce cell growth in target cell

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11
Q

regulation of hormones from hypothalamus to anterior pituitary

A

controlled by tropic neurohormones of hypothalamus

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12
Q

posterior lobe of pituitary connection with hypothalamus

A

neurosecretory neurons connect posterior lobe of pituitary to hypothalamus

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13
Q

posterior pituitary hormones

A

synthesised in hypothalamus, stored and secreted in posterior lobe
magnocellular neurones synthesise
- ADH (water reabsorptionin kidney)
- oxytocin (uterine contractions)

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14
Q

three ways of hormone excess

A

primary hypersecretion from final endocrine gland
secondary hypersecretion from middle endocrine gland
secondary hypersecretion from first endocrine gland

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15
Q

functions of calcium (6)

A

calcium salt (calcium hyroxyapatite) in bone and enamel
trigger neurotransmitter release (exocytosis)
trigger hormonal secretion (exocytosis)
blood coagulation (cofactor)
enzymatic regulation (cofactor)
muscle contraction

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16
Q

calcium homeostasis in intestine (absorption and secretion)

A

paracellular pathway - Ca2+ passively between epithelial cells of ileum
transcellular pathway - taken up into epithelual cell and actively released into blood in dueodenum and jejunum

17
Q

calcium homeostasis in kidney (filtration and reabsorption)

A

60% actively transported out of proximal tubule
30% diffuse out of loop of henle
9% actively transported out of distal tubule (PTH)
1% urine

18
Q

calcium homeostasis in bone (formation and resorption)

A

remodelling - bone is always formed and resorbed in trabecullar bone to ECF
osteoclast secrete enzymes to resorb bone, Ca2+ into blood regulated by PTH (activate) and calcitonin (inhibit)

19
Q

three primary cell types of trabecullar part of bone

A

osteoblast - form cells, secrete organic bone matrix (collagen, caclium hydroxyapatite)
osteocyte - mature bone cells
oestoclast - release hydrolytic enzymes to resorb bone, release Ca2+ into blood

20
Q

preprohormone

A

preprohormone -> prohormone -> peptide hormone

21
Q

PTH function (3 ways it does its function)

A

increase plasma [Ca2+] (stimulated by low [Ca2+])

stimulates Ca2+ reabsorption in kidney distal tubule
stimulates Ca2+ resorption in bone
stimulates 1-α-hydroxylase which catalyses 1,25 DHCC formation increases Ca2+ reabsorption in small intestine

22
Q

1,25 DHCC formation

A

metabolite of vitamin D3 formed in skin by UV radiation or from diet
PTH triggers 1-α-hydroxylase to form 1,25 DHCC

23
Q

1,25 DHCC function (3 ways it does its function)

A

increase plasma [Ca2+] (stimulated by low [Ca2+])

stimulates Ca2+ reasborption in kidney
stimulates PTH to bone resorb (but inhibits PTH gene expression so not out of control positive feedback)
stimulate Ca2+ absorption in intestine (stimulated by PTH)

24
Q

calcitonin formation

A

in thyroid glands

25
Q

calcitonin function (2 ways it does its function)

A

decrease plasma [Ca2+] (stimulated by high [Ca2+])

inhibits Ca2+ in bone resorption
decreases Ca2+ reasborption in kidney

26
Q

osteoperosis

A

reduced bone density by bone resorption exceeding bone formation

27
Q

osteomalacia/ rickets

A

inadequate mineralisation of bone by vitamin D activity deficiency

28
Q

hypocalcaemia

A

insufficient Ca2+ by deficiency/ resistance to PTH

29
Q

pancreas endocrine/ exocrine

A

exocrine 98% - synthesise and secrete digestive hormones into central duct
endocrine 2% - 3 cell types
- α-cell secrete glucagon
- β-cell secrete insulin
- D-cell secrete somatostatin (aka GIH inhibit glucagon and insulin secretion)

30
Q

glucose taken into target cells when in fed state

A

muscle - glycogen
liver - glycogen, triglyceride
adipose cells - triglyceride
every cell in body is target to insulin except liver and brain (able to take up glucose without insulin)

31
Q

insulin dependent diabetes mellitus (type 1)

A

insulin deficiency due to β-cell destruction

32
Q

insulin independent diabetes mellitus (type 2)

A

abnormal target cell response to insulin

33
Q

Cushing’s syndrome

A

hypercortisolism (excess cortisol produced in zona fasciculata in adrenal glands)

excess lipolysis (fat redistribution to face)
excess protein breakdown/ tissue wasting (weak, thin arms and legs)
excess gluconeogenesis (diabetes) 
surpressed immune response
34
Q

Grave’s disease

A

hyperthyroidism (excess thyroxine) primary hypersecretion

edema causes exophthalmos (wide staring gaze, bulging eyes)