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BI0005 > Digestion and Absorbtion 2 > Flashcards

Digestion and Absorbtion 2 Flashcards

1
Q

What does maltose break down into and which enzyme is this reaction catalysed by

A

Glucose and glucose via maltase

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2
Q

What does sucrose isomaltase break down into and which enzyme is this reaction catalysed by

A

Glucose and fructose by sucrose isomaltase

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3
Q

Which two substances are converted to glucose in the liver

A

Fructose and galactose

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4
Q

What does catabolism of glucose produce

A

ATP

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5
Q

What is glycogenesis and where does this process occur

A

The conversion of glucose to glycogen and occurs in skeletal muscle and liver

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6
Q

What is glycogenolysis

A

The breakdown of glycogen to glucose

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7
Q

What is gluconeogenesis

A

When glucose is made from non-carbohydrate precursors such as fats and proteins

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8
Q

What are fully saturated glycogen stores

A

Where glucose is converted to free fatty acids and stored in adipocytes in the form on truglycerides

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9
Q

What are carbohydrates broken down by

A

Salivary and pancreatic amylase and brush border enzymes in the SI

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10
Q

What is glucose anabolism

A

Glucose storage and release, formation of glucose from proteins and fats, excess glucose stored as fat

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11
Q

Which cells rely almost entirely on glucose

A

CNS, retina and germinal epithelium cells

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12
Q

What are normal fasting blood glucose levels

A

3.5-7.5mmol-1

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13
Q

What is the predominant tissue in responding to reduced/ elevated blood glucose levels

A

The liver

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14
Q

What is persistently high blood glucose levels called

A

Hyperglycaemia

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15
Q

What is persistently low blood glucose levels called

A

Hypoglycaemia

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16
Q

What happens if blood glucose levels fall below 3mmol-1?

A

Loss of conciousness (coma)

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17
Q

What happens if blood glucose levels rise above 10mmol-1?

A

Glucose would appear in the urine, pH of blood would fall lead to coma

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18
Q

What happens if there are inadequate levels of glucose in the blood

A

Cells immediately shift to the catabolism of fats for energy

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19
Q

What happens if starvation occurs

A

Proteins are also used for energy after carbohydrate and fats are depleted

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20
Q

Which factors influence blood glucose levels

A

When eating takes place/ type of food eaten. The amount of physical and mental activity. The presence of hormones

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21
Q

Which two hormones are involved in the short term regulation of blood glucose levels

A

Insulin and glucagon

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22
Q

Which 4 hormones are involved in the long term regulation of blood glucose levels

A

Adrenaline, glucocorticoids, growth hormones, thyroid hormones.

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23
Q

What is the glycaemic index (GI) and what does it show

A

It is a rating system for foods containing carbohydrates and shows us how rapidly each food affects blood glucose levels (when that food is eaten on its own)

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24
Q

What are acniar cells and what do they secrete

A

They are in the pancreas and are part of the exocrine system so secrete digestive enzymes

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25
Q

What percentage of the pancreas is made up of Islet of Langerhans

A

2%

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26
Q

Which three types of cells is the Islet of Langerhans made up of

A

Alpha, beta and delta

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27
Q

How much of the islet of Langerhans consists of alpha cells

A

20%

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28
Q

What do alpha cells secrete

A

Glucagon

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29
Q

How much of the islet of Langerhans consists of beta cells

A

75%

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30
Q

What do beta cells secrete

A

Insulin

31
Q

How much of the islet of Langerhans consists of delta cells

A

5%

32
Q

What do delta cells secrete

A

Somatostatin

33
Q

How long is insulin’s half-life and what impact does this have on it’s regulation of glucose

A

Insulin has a 5 minute half-life which means that it provides short term regulation

34
Q

What type of protein is insulin

A

Globular

35
Q

How many amino acids is insulin made from

A

51 amino acids

36
Q

What does insulin respond to

A

High blood sugar levels

37
Q

Which hormone responds to high blood sugar levels

A

Insulin

38
Q

What impact does raised blood glucose levels have on cells in the Islets of Langerhans

A

Raised plasma glucose levels results in depolarisation of the beta cells

39
Q

How long after a meal does plasma glucose reach max levels

A

Approximately 60 minutes after

40
Q

Which elicits a greater response- oral glucose or intravenous glucose

A

Oral glucose

41
Q

What do gastrointestinal hormones ‘incretins’ do

A

They enhance beta cell response to glucose

42
Q

What are the 6 actions of insulin

A
  1. Major targets= liver, adipose tissue and muscle mass
  2. Increases glucose uptake by cells
  3. Stimulates liver to convert glucose into glycogen (glyconeogenesis)
  4. Inhibits gluconeogenesis
  5. Stimulates excess glucose to be converted into fat (lipogensis)
  6. Blood glucose levels drop
43
Q

What is important to note about the CNS and insulin

A

Glucose uptake by the CNS is independent of insulin

44
Q

Which is the most potent hyperglycaemic hormone

A

Glucagon

45
Q

How many amino acids is glucagon made of

A

29 amino acids

46
Q

What is the half life of glucagon

A

6 minutes

47
Q

Describe the actions of glucagon in relation to insulin

A

The actions of glucagon directly oppose insulin

48
Q

Why is glucagon secreted

A

In response to lowered plasma glucose to raise glucose levels

49
Q

Which hormone inhibits glucagon secretion

A

Insulin

50
Q

What are the nine actions of glucagon

A
  1. If blood glucose falls to dangerous levels the alpha cells release glucagon
  2. Glucagon exerts its effects on carbohydrate. fat and protein metabolism
  3. The major target of glucagon is the liver
  4. Glucagon converts glycogen into glucose (glycogenolysis)
  5. It inhibits glycogen synthesis
  6. It activates amino acid uptake and gluconeogenesis
  7. It increases lipolysis
  8. It provides a ready supply of metabolic substances
  9. It enables glucose to be spared for the CNS
51
Q

Changes in plasma glucose that occur during fasting then glucose rich meal

A

First 90 minutes= absorptive state of metabolism, insulin dormant
3-4 hours= post absorptive state of metabolism, glucagon dominant

52
Q

Which hormones apart from insulin and glucagon are involves in the regulation of plasma glucose

A

Adrenal glucocorticoids, growth hormone, catecholamines, thyroid hormone

53
Q

What functions do the hormones other than insulin and glucagon do

A

Maintain glycogen stores, stimulate gluconeogenesis, stimulate the metabolism of fatty acids and proteins. They play a significant role during prolonged fasting and conserve glucose for the CNS

54
Q

What 2 metabolic effects does stomatostain have

A
  1. Suppresses glucagon release from alpha cells

2. Suppresses release of insulin, pituitary tropic hormones, gastrin and secretin

55
Q

What 2 metabolic effects does epinephrine (adrenaline) have

A
  1. Enhances release of glucose from glycogen

2. Enhances release of fatty acids from adipose tissue

56
Q

What 2 metabolic effects does cortisol have

A
  1. Enhances gluconeogenesis

2. Antagonises insulin

57
Q

What 2 metabolic effects does ACTH have

A
  1. Enhances release of cortisol

2. Enhances release of fatty acids from adipose tissue inhibiting uptake by extrahepatic tissues

58
Q

What metabolic effect does growth hormone have

A

Antagonises insulin, inhibiting uptake of extrahepatic tissues

59
Q

What 2 metabolic effects does thyroxine have

A
  1. Enhances release of glucose from glycogen

2. Enhances absorption of sugars from intestine

60
Q

Which is the only hormone that lowers blood glucose levels

A

Insulin

61
Q

What effect do all hormones (apart from insulin) have on blood glucose levels

A

They raise blood glucose levels

62
Q

What is diabetes mellitus

A

A condition in which the body either does not produce enough, or does not properly respond to insulin or both

63
Q

What are the 10 symptoms of diabetes mellitus

A
  1. Always tired
  2. Always hungry
  3. Sexual problems
  4. Sudden weight loss
  5. Wounds that won’t heal
  6. Vaginal infections
  7. Numb/ tingling hands or feet
  8. Always thirsty
  9. Frequent urination
  10. Blurry vision
64
Q

What are the other names for Type 1 diabetes

A

‘Juvenile’ diabetes/ insulin dependent diabetes mellitus (IDDM)

65
Q

What are the other names for Type 2 diabetes

A

‘Adult onset’ diabetes, noninsulin dependent diabetes mellitus (NDDM)

66
Q

Why is type 1 diabetes an organ specific immune disorder

A

It leads to the destruction of pancreatic beta cells resulting in the complete loss of insulin secretion

67
Q

What 4 pros does exercise have in relation to diabetes risk

A
  1. Decreased insulin resistance
  2. Decreased risk of obesity and T2DM
  3. Exercise may enhance insulin’s binding to receptors on the muscle fibre
  4. Thyfault and Booth 2011- increased sitting time leads to a reduction in insulin sensitivity
68
Q

What is type 2 diabetes strongly linked to

A

Obesity

69
Q

What is type 2 diabetes caused by

A

A reduction in pancreatic insulin or an increasing failure of tissues to respond to insulin

70
Q

How can type 2 diabetes be controlled

A

Through diet

71
Q

What is temporary glycaemia

A

Benign and asymptomatic

72
Q

What does long term glyceamia lead to

A

Increased secretion of glucagon (insulin suppression), increase in glycogen breakdown, increase in rate of gluconeogenesis and increased lipolysis. Leads to further raising of blood glucose levels

73
Q

What are the 3 consequences of hyperglycaemia

A

Polyuria, polydipsia, polyphagia

74
Q

What is polyuria

A

Frequent and excessive urination. Osmotic pressure due to glucose in the urine

BI0005 (21 decks)

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