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GI > Post-absorptive Mechanisms > Flashcards

Post-absorptive Mechanisms Flashcards

1
Q

Absorptive state

A

During which ingested nutrients enter the blood from GI tract
Ingested, circulating nutrients provide the energy requirements
Excess is stored in post-absorptive state

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2
Q

Post-absorptive state

A

GI tract is empty
Nutrients come from body stores

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3
Q

How long can glycogen stores last

A

12 hours

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4
Q

How long can lipid stores last

A

3 months

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5
Q

When is tissue protein used as an energy source

A

After prolonged starvation

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6
Q

Which 2 organs require 40% of energy requirement at rest

A

Brain and liver

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7
Q

Energy requirements of brain

A

Glucose
Keton bodies

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8
Q

Energy requirements of muscle

A

Glucose, triacylglycerol, branched chain amino acids
Ketone bodies (at rest)

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9
Q

Energy requirements of liver

A

Amino acids
Fatty acids
Glucose
Alcohol

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10
Q

Why can’t ketone bodies be used by the liver

A

Produced here but have no thiolase

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11
Q

Energy requirements of kidney cortex

A

Glucose
Ketone bodies

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12
Q

Energy requirements of kidney medulla

A

Glucose

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13
Q

Energy requirements of small intestine

A

Ketone bodies (in starvation)
Glutamine

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14
Q

Energy requirements of large intestine

A

Short chain fatty acids
Glutamine

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15
Q

BMI and health

A

As BMI goes up mortality increases exponentially
Cancer/ heart disease/ musculoskeletal/ sleep apnea

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16
Q

Fed state

A

Fuels are oxidised to energy
Any excess is stored
Triglycerides in adipose
Glycogen in muscle or liver
Limited amount to how much glycogen can be stored in muscle and liver so more is converted into adipose

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17
Q

Insulin and the liver

A

Glucose to liver
Insulin promotes uptake of glucose into cells for storage as glycogen
Some glucose used to produce energy

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18
Q

Glucose and liver

A

Stored as glycogen
Used to produce energy = converted to acetyl-CoA to enter kreb’s cycle

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19
Q

Acetyl-CoA and liver

A
  1. Enters kreb’s cycle to produce ATP
  2. Make triglycerides that enter bloodstream as VLDLs
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20
Q

VLDLs

A

Very low density lipoprotein
Triglycerides that enter bloodstream from liver
High glucose = high VLDL levels

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21
Q

Glucose and erythrocytes

A

Glucose taken up but cannot be stored
Glucose converted to pyruvate which can diffuse out of cell or be converted into lactate
Lactate is released from the cell

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22
Q

Post-absorptive state and amino acids

A

Absorption through intestines
Converted into proteins (can be reversed)
Can make hormones and other molecules
Feed into kreb’s cycle to make ATP

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23
Q

Where are amino acids absorbed

A

Intestines

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24
Q

Glucose and adipocytes

A

Glucose taken up (promoted by insulin)
Used to make ATP or stored as triglycerides

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25
Q

Glucose and muscle

A

Glucose stored as glycogen
Uses insulin to promote uptake

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26
Q

Lipoproteins

A

LDL
HDL
VLDL

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27
Q

Absorption of triglycerides

A

Chylomicrons carry triglycerides and lipoproteins
Into the lymphatic system and then blood stream

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28
Q

Glucose and CNS

A

Converted to acetyl-CoA
Enters kreb’s cycle
No energy stored in brain

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29
Q

Fasting state

A

Maintaining blood glucose whilst not eating
Body breaks down its energy stores
Horus to overnight

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30
Q

Pathway of glucose

A

Broken down and absorbed in intestines
Passes through blood in liver
Reaches muscles, brain, erythrocytes and adipocytes

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31
Q

Pancreas

A

Endocrine and exocrine organ

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32
Q

Where is insulin produced

A

Pancreas

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33
Q

Where is glucagon produced

A

Pancreas

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34
Q

Insulin

A

Main anabolic hormone
Energy uptake into cells
Glycogen storage, fat storage and protein synthesis

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35
Q

Glucagon

A

Main catabolic hormone
Energy release
Glycogenolysis, gluconeogenesis, ketogenesis

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36
Q

Where is cortisol produced

A

Adrenal gland

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37
Q

Where is adrenaline/noradrenaline produced

A

Adrenal gland

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38
Q

Cortisol

A

Preparation for stress response
Lipolysis, protein breakdown, gluconeogenesis, glycogen storage

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39
Q

Adrenaline/noradrenaline

A

Fight or flight
Energy into blood stream to be used
Glycogenolysis, gluconeogenesis, lipolysis

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40
Q

Where is thyroxine produced

A

Thyroid gland

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41
Q

Thyroxine

A

Generally controls metabolism
Glycolysis, cholesterol synthesis, glucose uptake, protein synthesis, sensitises tissues to adrenaline

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42
Q

Where is growth hormone produced

A

Pituitary gland

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43
Q

Where is somatostatin produced

A

Pituitary gland

44
Q

Growth hormone

A

Gluconeogenesis, glycogen synthesis, lipolysis, protein synthesis, decreased glucose use

45
Q

Which hormones trigger Glycogenolysis

A

Glucagon
Adrenaline/noradrenaline

46
Q

Which hormones trigger gluconeogenesis

A

Glucagon
Cortisol
Adrenaline/noradrenaline
Growth hormone

47
Q

Which hormones trigger glycogen storage

A

Insulin
Cortisol
Growth hormone

48
Q

What 2 hormones control appetite

A

Leptin and ghrelin

49
Q

Where is leptin released from

A

Adipocytes

50
Q

Where is ghrelin released from

A

Stomach

51
Q

What does leptin act on

A

CNS to influence appetite

52
Q

Leptin in normal weight

A

Suppresses appetite

53
Q

Leptin in obesity

A

Leptin resistance due to continuous high leptin levels (stops responding)

54
Q

Ghrelin

A

When empty ghrelin is released, goes to CNS to stimulate appetite
Release stopped upon stretch of stomach

55
Q

Glycogenolysis

A

Breakdown of glucagon to glucose

56
Q

Glucose - short fast

A

Glycogenolysis
Glucose primarily goes to brain and erythrocytes

57
Q

Longer fast- alternative energy sources for gluconeogenesis to produce glucose

A

Amino acids (from muscles)
Lactate (from erythrocytes)
Glycerol (from adipocytes)

58
Q

Site of gluconeogenesis

A

Liver

59
Q

When does ghrelin release stop

A

Stretch of stomach

60
Q

What hormone controls glycogenolysis

A

Glucagon

61
Q

Lipolysis

A

Triglycerides stored in adipocytes
Break down triglycerides
Produces glycerol and fatty acids

62
Q

Lipolysis- glycerol produced

A

Transported to liver to produce glucose

63
Q

Lipolysis- produces fatty acids

A

Transported to kidneys, muscles and liver
In liver produce ketones

64
Q

Which tissues can use ketones as an energy source

A

Muscles
CNS

65
Q

Ketogenesis

A

Ketones released from liver
Produced from fatty acids
Protein degradation stops to preserve muscle

66
Q

Which tissues can use ketones - prolonged fasting

A

CNS - during starvation
Muscles use less to preserve them for the brain
CNS decreases glucose use to preserve glucose for erythrocytes

67
Q

Glucose-6-phosphate —> glycogen

A

Glycogenesis

68
Q

Glycogen —> glucose-6-phosphate

A

Glycogenolysis

69
Q

Pyruvate —> glucose-6-phosphate

A

Gluconeogenesis

70
Q

Acetyl-CoA —>fats and lipids

A

Lipogenesis

71
Q

Which substances can be measured in blood to give idea about health and disease

A

Glucose
Ketones
Insulin
Lactate
Triglycerides

72
Q

Fats and lipids—> acetyl-CoA

A

Beta oxidation

73
Q

Post-absorptive phase

A

CNS and many other tissues preferentially use glucose, produced from glycogen breakdown

74
Q

Gluconeogenic phase

A

Protein catabolism is used to feed glucose to the CNS, while other tissue feed on ketones and fat

75
Q

Protein conservation phase

A

Protein catabolism is decreased to a minimum, fatty acids are used everywhere and ketones instead of glucose fuel the CNS

76
Q

Energy balance in

A

Food and drink

77
Q

Energy balance out

A

Basal metabolic rate (BMR)
Diet induced thermogenesis (DIT)- energy used to break down food
Activity- uses the most energy

78
Q

Stable weight

A

Energy in = energy out

79
Q

Basal metabolic rate (BMR)

A

Minimum amount of energy to keep body alive

80
Q

How is BMR measured

A

Using O2 consumption whilst awake, restful and fasted for 12 hours

81
Q

How does age affect BMR

A

BMR decreases with age

82
Q

Units of BMR

A

Kcal expended/hr/m^2

83
Q

Factors contributing to obesity

A

Genetics
Environment
Energy dysregulation

84
Q

Which enzyme converts glucose to glucose-6-phosphate in liver

A

Glucokinase

85
Q

Which enzyme converts glucose-6-phosphate to glucose-1-phosphate in liver

A

Phosphoglucomutase

86
Q

What is glucose-1-phosphate converted to in liver

A

UDP-glucose

87
Q

Which enzyme adds UDP-glucose to glycogen chain

A

Glycogen synthase or branching enzyme

88
Q

How much glycogen can be stored in the liver

A

100g

89
Q

What is glucose-6-phosphate converted to in the liver

A

Glucose-1-phosphate

90
Q

What is glucose-1-phosphate converted to in the liver

A

UPD-glucose

91
Q

Lipolysis

A

Break down triglycerides

92
Q

What are the products of lipolysis

A

Glycerol and fatty acids

93
Q

Where is glycerol produced by lipolysis transported to

A

Liver to produce glucose

94
Q

Where are fatty acids produced by lipolysis transported to

A

Kidneys, muscles and liver
In liver produce ketones

95
Q

Which tissues can use ketones as energy

A

Muscles
CNS

96
Q

Ketogenesis

A

Ketones released from liver
CNS uses ketones during starvation
Muscles use less ketones to preserve them for brain
CNS decreases glucose use
Preserves glucose for erythrocytes

97
Q

What do erythrocytes give for gluconeogenesis

A

Lactate

98
Q

What do muscles give for gluconeogenesis

A

Amino acids

99
Q

What do adipocytes give for gluconeogenesis

A

Glycerol

100
Q

Post-absorptive phase

A

The CNS and many other tissues preferentially use glucose, produced from glycogen breakdown

101
Q

Gluconeogenic phase

A

Protein catabolism is used to feed glucose to the CNS, while other tissue feed on ketones and far

102
Q

Protein conservation phase

A

Protein catabolism is decreased to a minimum, fatty acids are used everywhere and ketones instead of glucose fuel the CNS

103
Q

Which glucose transporter is the primary transporter at the gastrointestinal brush border membrane in-between meals

A

SGLT-1

104
Q

A 24-year-old woman is started on oral iron supplements as she is found to be iron deficient. This is her first time taking iron supplements in her lifetime. The patient has heard about many other medications, foods and drinks that can interfere with the absorption of iron.

What substance increases the absorption of the supplement the patient has been prescribed?

A

Vitamin C (ascorbic acid)

105
Q

Carbohydrates are digested in a series of hydrolysis reactions in the gastro-intestinal tract. Starch/glycogen are hydrolysed by salivary and pancreatic amylase to produce disaccharides, which are further hydrolysed to monosaccharides. The absorption of which monosaccharide does NOT require energy from ATP?

A

Fructose

GI (12 decks)

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