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My Flashcards Year 2 > Endo- physiology > Flashcards

Endo- physiology Flashcards

1
Q

where is insulin initially synthesised in the cell

A

rough endoplasmic reticulum of pancreatic beta cells as preproinsulin

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2
Q

what happens to preproinsulin in the RER

A

converted into proinsulin

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3
Q

what are the components of proinsulin

A

A chain
B chain
connecting (C) peptide

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4
Q

which bonds form between the A and B chains of proinsulin

A

disulphide bonds

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5
Q

where is proinsulin converted to mature insulin

A

Golgi apparatus and secretory granules

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6
Q

what is the only cell in the body that makes insulin

A

beta-cell

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7
Q

how does glucose enter pancreatic beta cells

A

through the GLUT2 glucose transporter

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8
Q

what enzyme phosphorylates glucose in beta cells

A

glucokinase

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9
Q

what are islets of langerhans

A

clusters of ~1000 endocrine cells in the pancreas

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10
Q

3 main types of islet of langerhans cells

A

beta cells
alpha cells
delta cells

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11
Q

what do beta cells secrete

A

insulin

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12
Q

what do alpha cells secrete

A

glucagon

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13
Q

what do delta cells secrete

A

somatostatin

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14
Q

in T2DM, the number of secretory granules per beta cell is increased/reduced?

A

reduced- degranulation

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15
Q

action of glucagon

A

acts on the liver to promote hepatic glucose production, raising blood glucose

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16
Q

what is the incretin effect

A

greater increase in insulin production in response to oral glucose than in response to IV glucose

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17
Q

what is the principle incretin hormone

A

GLP-1

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18
Q

what does GLP-1 do

A

increases glucose-induced insulin release by beta cells
promotes beta cell proliferation
suppresses glucagon secretion at high levels

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19
Q

where is GLP-1 secreted from and where

A

secreted from gastrointestinal L-cells
in response to eating

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20
Q

Can GLP-1 stimulate insulin secretion without glucose?

A

no, it only acts in the presence of a depolarising glucose stimulus

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21
Q

through which receptor type does GLP-1 signal

A

a G protein-coupled receptor, using cAMP as a second messenge

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22
Q

which hormone is secreted by the hypothalamus to initiate thyroid hormone production

A

TRH (thyrotropin-releasing hormone)

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23
Q

what does TRH stimulate in the anterior pituitary

A

TSH (thyroid stimulating hormone)

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24
Q

what intracellular signalling pathway is activated by TSH binding

A

activation of G proteins, leading to conversion of GTP to GDP and production of cAMP

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25
what is the role of cAMP in thyroid cells
stimulates production and release of T3 and T4
26
what is one major physiological effect of thyroid hormones
increased basal metabolic rate
27
thyroid hormone production is regulated through positive/negative feedback?
negative feedback
28
what is the structural unit of the thyroid gland and what are found inside these units
the thyroid follicle colloid inside
29
what cells are found between follicles and what do they secrete
parafollicular (C) cells secrete calcitonin
30
what are the two main thyroid hormones
T3 (triiodothyroninenine) and T4 (thyroxine)
31
what percentage of thyroid hormone secretion is T4 and T3
T3- ~10% T4- ~90%
32
what thyroid hormone is more biologically active T4/T3
T3- 4x more potent
33
where is T4 converted to T3
in the liver and kidneys
34
in plasma, what percentage of T3 and T4 is protein bound
>99%
35
what are the main thyroid hormone-binding proteins in plasma
thyroxine-binding globulin ~70% thyroxine-binding pre-albumin ~20% albumin ~5%
36
which hormone, T3 or T4, binds less strongly to plasma proteins
T3
37
what form of thyroid hormone enters cells
only the free (unbound) form
38
which conditions increase TBG levels
pregnancy oral contraceptive pill chronic active hepatitis biliary cirrhosis
39
which conditions decrease TBG levels
androgens cushings syndrome severe systemic illness chronic liver disease
40
how many transmembrane regions do G-protein coupled receptors have
7
41
what are the 10 major endocrine glands
pituitary hypothalamus pineal thyroid parathyroid thymus adrenals pancreas ovary testes
42
which endocrine gland provides the highest level of endocrine control
hypothalamus
43
what do pancreatic alpha cells do when blood glucose levels are high
decrease glucagon secretion
44
what hormones are released during stress and exercise
cortisol and adrenaline
45
what processes do cortisol and adrenaline stimulate in the liver
gluconeogenesis and glycogenolysis
46
what are the 3 classes of hormones
steroids amine-derived peptide
47
what are steroid hormones derived from
cholesterol
48
are steroid hormones hydrophilic or hydrophobic
hydrophobic (lipid-soluble)
49
what is the role of cortisol and where is it secreted from
plays a roll in mediating stress responses secreted from adrenal cortex
50
what is the role of testosterone and where is it secreted from
responsible for male sexual characteristics secreted from gonads
51
what is the role of oestradiol (oestrogen) and where is it secreted from
responsible for female sexual characteristics secreted from placenta
52
examples of steroid hormones
cortisol osterogen testosterone
53
what are amine-derived hormones derived from
amino acids
54
are most amine-derived hormones hydrophobic or hydrophilic
hydrophilic
55
where are amine-derived hormones secreted from
thyroid gland adrenal medulla
56
are steroid hormones stored in the body
no, once synthesized, they are secreted immediately and are not stored.
57
How are steroid, amine-derived, and peptide hormones transported in the blood?
steroid- bound to carrier proteins amine-derived- unbound (free) peptide- unbound (free)
58
how are amine-derived hormones like adrenaline stored in the body
vesicles in cytoplasm
59
examples of amine-derived hormones
adrenaline thyroid hormones
60
are peptide hormones hydrophobic/hydrophilic
hydrophilic
61
what type of hormone account for the majority of hormones produced in the body
peptide hormones
62
where are peptide hormones secreted from
pituitary parathyroid heart stomach liver kidneys
63
examples of peptide hormones
oxytocin ADH growth hormone insulin
64
where is the 'command centre' of the endocrine system
hypothalamus-pituitary complex
65
what are the two main gonadotrophin hormones
FSH LH
66
what does FSH do in males and females
males- stimulates spermatogenesis in the testes females- stimulates growth of ovarian follicles, stimulates ovary to secrete oestrogen
67
what does LH do in males and females
males- stimulates the testes to secrete testosterone females- triggers ovulation, triggers progesterone production
68
what is the role of GnRH (gonadotrophin releasing hormone)
it stimulates the release of FSH and LH from the anterior pituitary
69
where is GnRH synthesised and released from
from GnRH neurone in the hypothalamus
70
How does the pulsatility of GnRH differ between males and females?
males- pulses at constant frequency females- pulses vary during menstruation cycle
71
what regulates GnRH pulsatility
osteogen progesterone testosterone
72
how long does the follicular phase typically last
14 days +/- 7 days
73
how often are GnRH pulses during the early follicular phase
about every 1-2 hours
74
how often are GnRH pulses during the luteal phase
about every 4 hours
75
what do high-frequency GnRH pulses stimulate
stimulate LH release
76
what do low-frequency GnRH pulses stimulate
stimulate FSH release
77
what effect does high oestrogen have on GnRH
increases GnRH pulsatility, promoting LH surge
78
what effect does progesterone have on GnRH
reduces frequency of GnRH pulsatility
79
obesity hormones-
leptin lowers appetite ghrelin gains appetite
80
where is the primary source of testosterone (cell)
leydig cell
81
what is the major metabolic change that stimulates the secretion of growth hormone
a decrease in plasma glucose levels

My Flashcards Year 2 (102 decks)

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