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Year 2 MBChB Endocrine > Physiology > Flashcards

Physiology Flashcards

1
Q

Hypothalamic neurons secrete … or … hormones into the … … … to the … pituitary.

A

Stimulatory
Inhibitory
Hypophyseal portal system
Anterior

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2
Q

Name the 6 hormones of the anterior pituitary.

A 
GH
Prolactin
TSH
ACTH
LH
FSH
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3
Q

Name the 2 hormones of the posterior pituitary.

A

Oxytocin

Vasopressin/ADH

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4
Q

Explain the thyroid axis.

A

Hypothalamus releases TRH
Anterior pituitary releases TSH
Thyroid releases T3/4
T3/4 have a negative feedback on TRH and therefore TSH

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5
Q

Test for the thyroid axis?

A

TSH assay

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6
Q

Name the 3 secretions of the thyroid gland.

A

Triiodothyronine (T3)
Thyroxine (T4)
Calcitonin

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7
Q

Which cells release calcitonin in the thyroid gland?

A

Parafollicular/ C cells

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9
Q

Oxyphil cells are … and more …/… than chief cells.

A

Larger

Pink/lighter-staining

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10
Q

What do follicular cells make + what amino acids forms this + where is it stored?

A

Thryroglobulin
Tyrosine
Colloid

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11
Q

What do follicle cells do to iodide?

A

Take it up and oxidise it to iodine

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12
Q

What happens to iodide once it has been oxidised to iodine in the follicular cells?

A 
Moves into colloid
Combines with tyrosine residues in thyroglobulin 
Forms monoiodotyrosine (MIT) and diiodotyrosine (DIT)
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13
Q

What components make up T3 and T4?

A

MIT + DIT = T3

DIT + DIT = T4

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14
Q

Does the thyroid gland produce more T3 or T4 + which one is stronger/gets a greater response?

A

Produces more T4

T3 is stronger

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15
Q

What 3 structures convert T4 to T3 + which one accounts for 80%?

A

Liver (80%)
Kidneys
Thyroid

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16
Q

What 3 proteins bind to T3 and T4 bind to + which one most?

A

Thyroxine-binding globulin (TBG)
Pre-albumin
Albumin
Most bound to TBG

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17
Q

Most T3/T4 is bound/unbound but only bound/unbound can enter cells?

A

Bound

Unbound

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18
Q

Name 4 functions of thyroid hormones.

A

Increase BMR
Increase glucose uptake
Increase breathing/heart rate
Controls temperature

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19
Q

Name the secretion of the parathyroid glands + what cell it comes from.

A

PTH

Chief cells

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19
Q

Which hormone and its releasing hormone are dependent on thyroid hormone levels?

A

GH

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21
Q

What is the effect of hypocalcemia on voltage-gated Ca channels?

A

Opens them causing nerve conduction and tetany

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22
Q

Name 3 ways PTH increases blood calcium?

A

Increased release from bone
Decreased release in urine
Increases vitamin D which increases intestinal absorption

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24
Q

What cells secrete GH in the pituitary gland + what does GH stimulate release of and where?

A

Somatotroph

IGF-1 in the liver

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25
Q

What pituitary cell releases prolactin + where does it act on + what inhibits secretion?

A

Lactroph cell
Breast tissue
Dopamine

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26
Q

What are the 2 functions of ADH?

A

Promote water resorption in kidney

Vascontriction

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27
Q

What does increased/ decreased ADH do to volume, concentration and osmolality of urine?

A 
Increased = decreased volume, increased concentration, increased osmolality
Decreased = increased volume, decreased concentration and decreased osmolality
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28
Q

What does osmolality and osmolarity mean?

A

Amount of solute dissolved in 1 kg

Amount of solute dissolved in 1 litre

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29
Q

Osmolality is calculated using the … of a solution whereas osmolarity uses the … of a solution. Osmolarity/osmolality is dependent on temperature and pressure.

A

Mass
Volume
Osmolarity

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30
Q

Describe the sex hormone/HPG axis.

A

Hypothalamus releases GnRH
Anterior pituitary releases FSH and LH
FSH and LH have a negative feedback on GnRH and therefore FSH and LH

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31
Q

How is GnRH released in males vs. females?

A 
Males = constant
Females = variably
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32
Q

What cells do FSH and LH act on in males + name of muscle cell of seminiferous tubules?

A

FSH = Sertoli
LH = Leydig
Myoid cells

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33
Q

High frequency pulses release … and low frequency pulses release …?

A

LH

FH

34
Q

High oestrogen … GnRH and high progesterone … GnRH.

A

Increases

Decreases

35
Q

What does FSH do in males vs. females?

A 
Males = spermatogenesis
Females = oogenesis and oestrogen secretion
36
Q

What does LH do in males vs. females?

A 
Males = testosterone secretion 
Females = formation of corpus luteum and progesterone secretion
37
Q

What 2 structures does oxytocin affect + what female hormone increases its release?

A

Breasts and uterus

Oestrogen

38
Q

What is the name of the first germ cell in females and when is it formed?

A

Primordial germ cell

1st meiotic division

39
Q

What is a polar body?

A

Haploid cell unable to be fertilised

40
Q

Name the 2 stages of the menstrual cycle + how long does the cycle last?

A

Follicular phase
Luteal phase
28 days

41
Q

How long does the follicular phase last?

A

14 days

42
Q

Explain hormonal control of the menstrual cycle up to ovulation.

A

FSH causes oogenesis and increased oestrogen
Increased oestrogen lowers FSH
Oestrogen hits threshold to cause a surge in LH which causes ovulation

43
Q

What is the positive feedback threshold for oestrogen?

A

200

43
Q

Name 3 effects of oestrogen on the the uterus/vagina.

A

Increases endometrial thickness
Reduces vaginal pH
Makes mucous softer

43
Q

What is a primary follicle + secondary?

A

Oocyte covered by granulosa and theca cells

Larger oocyte with follicular fluid

43
Q

Explain hormonal control of the menstrual cycle after ovulation.

A

LH causes formation of the corpus luteum

Corpus luteum secretes progesterone which decreases LH

45
Q

How long does the corpus luteum survive + how does it know to degenerate + what does it become?

A

Up to 14 days
Lack of hCG production of embryo at 12 days
Corpus albicans

47
Q

Name 3 clinical signs to detect ovulation.

A

Rise in progesterone
Peak of LH
1 degree rise in body temperature

50
Q

How does LH increase progesterone levels?

A

Causes angiogenesis to allow more cholesterol to be delivered and form progesterone

51
Q

What do alpha, beta, delta and PP cells make in the pancreas?

A 
Alpha = glucagon 
Beta = insulin
Delta = somatostatin
PP = polypeptide
52
Q

Which 2 words describe what hormone insulin is + what is its initial form?

A

Anabolic peptide

Preproinsulin

53
Q

Which 3 tissues does insulin increase glucose uptake in?

A

Muscle
Adipose
Liver

54
Q

What other 2 substances does insulin increase uptake of + what tissues?

A

Amino acids in muscle

Lipids in adipose

55
Q

Which 3 processes does insulin stimulate and 2 processes it inhibits?

A

Stimulates DNA/protein synthesis, lipogenesis and glycogenesis
Inhibits lipolysis and gluconeogenesis

56
Q

What is the structure of insulin?

A

Alpha and beta polypeptide connected by C peptide and held by disulphide bonds

57
Q

When is the C-peptide lost?

A

When preproinsulin is cleaved to insulin

58
Q

Glucose enters beta cells of pancreas via … … and is … by … to …?

A

GLUT2 transporters
Phosphorylated
Glucokinase
Glucose-6-phosphate

59
Q

Glucokinase Km depends on BG. True or False?

A

True

60
Q

How does glycolysis of glucose in beta cells causes insulin release?

A

ATP from glycolysis closes KATP channels

Ca channels open and influx causes vesicles to secrete insulin

61
Q

What BG level is insulin normally released from vesicles?

A

5 mM or above

61
Q

The KATP channel is an octamer made from a 4 … and 4 … subunits?

A

Kir6.1

SUR1

62
Q

Name a molecule which opens and closes the KATP channel.

A 
Closes = SUs
Opens = diazoxide
63
Q

Secretion has … stages and the first load of insulin comes from the … … … and accounts for …%?

A

2
Readily reversible pool
5%

64
Q

Which 4 hormones increase BG?

A

Cortisol
T3/4
ACTH
GH

64
Q

Name 2 incretins which increase prandial insulin release + where they are released from.

A

GLP-1
GIP
Duodenum

65
Q

Explain the mechanism of action of insulin on tyrosine kinase receptors.

A

Binds to alpha subunit

Causes beta subunits to phosphorylate and dimerise

67
Q

How are ketone bodies formed?

A

Beta oxidation of acetyl-CoA

68
Q

What does the HPA axis control?

A

Cortisol levels

68
Q

What pathway that insulin activates controls glycogen synthesis and gene expression?

A 
GS = P13K/PKB
GE = Ras/MAPK
69
Q

Explain the HPA axis.

A

Hypothalamus releases CRH
Anterior pituitary releases ACTH
Adrenal cortex releases cortisol
Cortisol has a negative feedback on CRH and therefore ACTH

70
Q

Test for cortisol + why?

A

9 am cortisol

Circadian rhythm means random measurements useless

71
Q

What is released from the zona glomerulosa + what controls it?

A

Aldosterone

RAAS

72
Q

Explain the RAAS in 4 steps.

A

Renin from kidneys converts angiotensinogen to angiotensin I
ACE from PVE converts angiotensin I to angiotensin II
Angiotensin II causes vasoconstriction and aldosterone release
Aldosterone causes salt/water resorption

73
Q

What is released from the zona fasciculata + what controls is?

A

Cortisol

ACTH

74
Q

What is the effects of aldosterone on water, Na, K and H?

A

Water release
Na reabsorption
K and H Loss

75
Q

Name 4 functions of cortisol.

A

Increases gluconeogenesis
Increases fat/protein metabolism
Stress response
Maintains BP

75
Q

What is released from the zona reticularis + what controls it?

A

Androgens

ACTH

75
Q

What is the effect of cortisol on bone?

A

Osteoporosis

76
Q

What is released from the adrenal medulla + what controls it?

A

Catecholamines (adrenaline/noradrenaline)

Sympathetic nervous system

Year 2 MBChB Endocrine (14 decks)

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