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Flashcards in Biochemistry Deck (37)
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1

Which cells in the Islets of Langerhans secrete insulin?

Beta-cells

2

Which cells in the Islets of Langerhans secrete glucagon?

Alpha-cells

3

Which cells in the Islets of Langerhans secrete somatostatin?

Delta-cells

4

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

Preproinsulin

5

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

False
Very little variation

6

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

Increases uptake into respective tissues
(amino acid in muscle, glucose in muscle, lipid in adipose)

7

Insulin inhibits lipolysis. True/False?

True

8

Through which transporter does glucose enter beta-cells in the pancreas?

GLUT2

9

What happens to glucose once in the beta-cell in the pancreas?

Phosphorylated to glucose-6-phosphate

10

Which enzymes carry out glucose phosphorylation?

Glucokinase
Hexokinase (RBCs)

11

Which two proteins make up a functional Katp channel?

Kir6.1
Sulphonylurea receptor (SUR1)

12

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

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

13

What is MODY?

Maturity-onset diabetes of the young
Genetic defect in beta-cell function, causing early-onset type II diabetes

14

Which enzyme is impaired in MODY?

Glucokinase
(causing defective glucose sensing)

15

How are ketone bodies formed?

Derived from acetyl-CoA in B-oxidation

16

Give examples of ketone bodies

Acetone
Acetoacetic acid
B-hydroxybutric acid

17

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

Type 1

18

Sodium follows water everywhere. True/False?

False
Water follows sodium!
(WafS)

19

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

False
Concn of Na outside cell is greater than inside

20

What does mineralocorticoid activity refer to?

Sodium retention in exchange for potassium and/or hydrogen ions

21

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

Aldosterone

22

Excess mineralocorticoid activity causes what?

Sodium retention

23

What effect does sodium loss have upon water?

Sodium loss means water loss (water follows sodium!)

24

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

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

25

Which hormone controls water reabsorption?

ADH

26

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

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

27

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

True

28

What are the main causes of decreased sodium levels?

Too much water
Too little sodium

29

What are the main causes of increased sodium levels?

Too little water
Too much sodium

30

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

SIAD (inappropriate ADH secretion)
Compulsive water drinking