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Endocrine > Biochemistry > Flashcards

Biochemistry 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

There is great variation in the amino acid sequence of insulin between species. True/False?

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

amino acid in muscle, glucose in muscle, lipid in adipose

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7
Q

Insulin inhibits lipolysis. True/False?

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 
Kir6.1
Sulphonylurea receptor (SUR1)
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12
Q

What inhibits the Katp channel? What happens as a result?

A

Intracellular ATP, causing depolarisation (less K efflux), causing opening of Ca channels to allow insulin exocytosis

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13
Q

What is MODY?

A

Maturity-onset diabetes of the young

Genetic defect in beta-cell function, causing early-onset type II diabetes

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14
Q

Which enzyme is impaired in MODY?

A

Glucokinase

causing defective glucose sensing

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15
Q

How are ketone bodies formed?

A

Derived from acetyl-CoA in B-oxidation

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16
Q

Give examples of ketone bodies

A

Acetone
Acetoacetic acid
B-hydroxybutric acid

17
Q

Ketoacidosis is most associated with which diabetes - type 1 or 2?

A

Type 1

18
Q

Sodium follows water everywhere. True/False?

A

False
Water follows sodium!
(WafS)

19
Q

Concentration of Na inside the cell is more than concentration of Na outside the cell. True/False?

A

False

Concn of Na outside cell is greater than inside

20
Q

What does mineralocorticoid activity refer to?

A

Sodium retention in exchange for potassium and/or hydrogen ions

21
Q

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

A

Aldosterone

22
Q

Excess mineralocorticoid activity causes what?

A

Sodium retention

23
Q

What effect does sodium loss have upon water?

A

Sodium loss means water loss (water follows sodium!)

24
Q

Outline what happens in terms of sodium and water when blood pressure drops

A

Decreased blood pressure causes sodium + water retention in order to compensate and bring blood pressure up

25
Q

Which hormone controls water reabsorption?

A

ADH

26
Q

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

A

Causes increased water reabsorption (anti-diuresis), producing low-volume concentrated urine

27
Q

Concentrated/small volume urine has a high omolality. True/False?

A

True

28
Q

What are the main causes of decreased sodium levels?

A

Too much water

Too little sodium

29
Q

What are the main causes of increased sodium levels?

A

Too little water

Too much sodium

30
Q

Decreased sodium levels can be due to too much water. How can this arise?

A

SIAD (inappropriate ADH secretion)

Compulsive water drinking

31
Q

Decreased sodium levels can be due to too little sodium. How can this arise?

A 
Sodium loss (renal insufficiency, gut fistulae)
Decreased sodium intake (rare)
32
Q

Increased sodium levels can be due to too little water. How can this arise?

A 
Water loss (diabetes insipidus)
Decreased water intake
33
Q

Increased sodium levels can be due to too much sodium. How can this arise?

A

IV medication
Drowning in sea
High-salt feeds

34
Q

Outline pathogenesis of Addison’s disease

A 
Adrenal insufficiency;
can't make enough aldosterone;
can't retain enough sodium;
lose sodium + water;
low ECF volume, so patient is dehydrated + dizzy
35
Q

What is the main osmotic stimulus for ADH release?

A

High sodium (high osmolality) causes increased ADH

36
Q

Does hypovolaemia cause increased or decreased ADH release?

A

Increased ADH release (to compensate for loss of fluid)

37
Q

Outline pathogenesis of diabetes insipidus

A 
Disrupted pituitary;
can't secrete ADH;
less water reabsorption;
lots of water lost in urine;
sodium is high to reflect water deficit

Endocrine (19 decks)

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