Biochemistry - Endocrine Flashcards

1
Q

which cells in the islets of langerhans secrete insulin?

A

beta cells

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2
Q

which cells in the islets of langerhans secrete glucagon?

A

alpha cells

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3
Q

which cells in the islets of langerhans secrete somatostatin?

A

delta cells

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4
Q

what is the initial structure that is cleaved to form insulin?

A

preproinsulin

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5
Q

true or false: there is great variation in the amino acid sequence of insulin between species

A

false

very little variation

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6
Q

what is the effect of insulin upon amino acids, glucose and lipids?

A

increases uptake into respective tissues

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7
Q

true or false: insulin inhibits lipolysis

A

true

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8
Q

through which transporter does glucose enter beta cells in the pancreas?

A

GLUT2

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9
Q

what happens to glucose once in the beta cell in the pancreas?

A

phosphorylated to glucose 6 phosphate

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10
Q

which enzymes carry out glucose phosphorylation?

A

glucokinase

hexokinase (RBCs)

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11
Q

which two proteins make up a functional Katp channel?

A

Kir 6.1

sulphonylurea receptor (SUR1)

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12
Q

what inhibits the Katp channel?

A

intracellular ATP

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13
Q

what happens as a result of inhibition of the Katp channel?

A

depolarisation, causing opening of calcium channels to allow insulin exocytosis

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14
Q

what is MODY?

A

maturity onset diabetes of the young

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15
Q

what causes MODY?

A

a genetic defect in beta cell function, causing early onset type II diabetes

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16
Q

which enzyme is impaired in MODY?

A

glucokinase

17
Q

how are ketone bodies formed?

A

derived from acetyl-CoA in beta oxidation

18
Q

name three ketone bodies

A

acetone
acetoacetic acid
B-hydroxybutric acid

19
Q

which type of diabetes is ketoacidosis most associated with?

A

type 1

20
Q

true or false: sodium follows water everywhere

A

false

water follows sodium

21
Q

true or false: concentration of sodium inside the cell is greater than outside the cell

A

false

22
Q

what does mineralocorticoid activity refer to?

A

sodium retention in exchange for potassium and/or hydrogen ions

23
Q

what is the main steroid in the body with mineralocorticoid activity?

A

aldosterone

24
Q

what does excess mineralocorticoid activity cause?

A

sodium retention ‘

25
Q

what effect does sodium loss have upon water?

A

sodium loss means water loss

26
Q

outline what happens in terms of sodium and water when BP drops

A

decreased BP causes sodium and water retention, in order to compensate and bring blood pressure up

27
Q

which hormone controls water reabsorption?

A

ADH

28
Q

what effect does ADH have on water reabsorption and thus urine output?

A

causes increased water reabsorption producing low volume concentrated urine

29
Q

true or false: concentrated/small volume urine has a high osmolality

A

true

30
Q

what are the main causes of decreased sodium levels/

A

too much water

too little sodium

31
Q

what are the main causes of increased sodium levels?

A

too little water

too much sodium

32
Q

how can too much water cause decreased sodium levels?

A

SIAD

compulsive water drinking

33
Q

how can too little sodium cause decreased sodium levels?

A

sodium loss

decreased sodium intake

34
Q

how can increased sodium levels be due to too little water?

A

water loss

decreased water intake

35
Q

how can too much sodium increase sodium levels?

A

IV medication
drowning in the sea
high salt foods

36
Q

outline the pathogenesis of addison’s disease

A
  1. adrenal insufficiency
  2. cant make enough aldosterone
  3. cant retain enough sodium
  4. lose sodium and water
  5. low ECFV, patient is dehydrated and dizzy
37
Q

what is the main osmotic stimulus for ADH release?

A

high sodium causes increased ADH

38
Q

does hypovolaemia cause increased or decreased ADH release?

A

increased to compensate for fluid loss

39
Q

outline pathogenesis of diabetes insipidus

A
  1. disrupted pituitary
  2. can’t secrete ADH
  3. less water reabsorption
  4. lots of water lost in urine
  5. sodium is high to reflect water deficit