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Digestion and Renal Sciences > Metabolic Fate of Nutrients > Flashcards

Metabolic Fate of Nutrients Flashcards

1
Q

Why is nutrition important?

A

to develop and maintain a state of health

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2
Q

What is nutrition?

A

the process by which a living organism received nutrients from its environment and uses them to promote vital activities

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3
Q

What is food?

A

A substance when eaten, digested and absorbed provides at least one nutrient

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4
Q

What is a nutrient?

A

a substance which is digested and absorbed to promote bodily function

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5
Q

Give examples of macromolecules

A

proteins, fats, carbs

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6
Q

Give example of micromolecules

A

minerals and vitamins

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7
Q

What do we use the energy released from food for?

A
  • muscle activity
  • secretion by glands
  • maintenance of membrane potentials by nerves and muscles
  • synthesis of molecules
  • cell division
  • thermoregulation
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8
Q

What is basal metabolic rate?

A

the number of calories needed at rest for normal bodily function (50%-70% of calories needed per day)

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9
Q

What is the thermic effect of food?

A

energy required for digestion and absorption of food (5-10% of energy expenditure)

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10
Q

What is the other process that uses energy?

A

physical activity

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11
Q

What are other factors that may require energy use?

A
  • temp changes
  • pregnancy
  • growth
  • age
  • health
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12
Q

Why is glucose a preferential source of energy?

A

readily available primary source of energy for CNS and red blood cells and also used in other tissues

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13
Q

What happens to the glucose produced by glycogenolysis by the muscle and liver?

A

muscle- used in muscle

liver- for rest of the body

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14
Q

How is glucose metabolised?

A

by glycolysis

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15
Q

Why are fats a good source of energy?

A
  • high amount of energy stored per gram
  • used in tissue activity and maintenance of body temp
  • not used by brain, spinal cord or RBCs
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16
Q

Why is it difficult to use fat?

A
  • require large amounts of oxygen to metabolise

- insoluble in water so difficult to access

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17
Q

What other roles do fats have?

A
  • used in body structures e.g cell membranes
  • protection
  • insulation
  • some vitamins are fat soluble so carriers assist absorption from intestine
  • satiety (inhibit gastric motility and prevents hunger feeling)
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18
Q

How is fat metabolised?

A
  • triglycerides undergo lipolysis to form fatty acids and glycerol
  • the fatty acids can either be converted into phospholipids or undergo beta-oxidation to form acetyl-CoA to be used in the Krebs cycle
  • glycerol can be converted to glucose and be used in glycolysis
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19
Q

Why do we need protein?

A
  • manufacture new proteins
  • build new tissue
  • can also be oxidised to produce energy (not a main function-usually in starvation)
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20
Q

What does nitrogen anabolism equal?

A

catabolism

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21
Q

When do you need a positive nitrogen balance?

A
  • pregnancy
  • growth
  • recovery
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22
Q

When would you have a negative nitrogen balance?

A
  • starvation
  • trauma/infection/sepsis
  • tissue destruction
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23
Q

Give some examples of insoluble fibre

A

cellulose wheat, rich leafy vegetables and pulses

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24
Q

what is the role of insoluble fibres?

A

provide bulk to the gut (prevents constipation)

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25
Q

Give some examples of soluble fibres

A

proteins, plant gums, mucilage

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26
Q

What is the role of soluble fibres?

A
  • absorb water in intestine this often stools which help waste move along colon
  • lowers cholesterol (binds to cholesterol and prevents absorption)
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27
Q

What other benefits do fibres have?

A
  • slows gastric emptying
  • retards glucose absorption
  • fermentation releases SCFA
  • reduces bowel cancer risk
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28
Q

What are the types of vitamins?

A
  • water soluble

- fat soluble

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29
Q

Can water soluble vitamins be stored?

A

no (so need regular intake)

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30
Q

What is the role of the B complexes?

A

enzyme cofactors

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31
Q

What is the role of vit C?

A
  • protein synthesis

- antioxidant

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32
Q

role of vit A?

A

used in:

  • development
  • immune system
  • vision
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33
Q

role of E?

A
  • antioxidant

- immune function

34
Q

D?

A

calcium metabolism

35
Q

K?

A

blood clotting

36
Q

Where are fat soluble vitamins stored?

A

in the liver and adipose tissue

37
Q

Give examples of fat soluble and water soluble vitamins

A

Water soluble= B complexes and C

Fat soluble=A,E,D,K

38
Q

What is rickets a deficiency of?

A

vitamin D

39
Q

What is rickets?

A

poor mineralisation of bone

40
Q

What is scurvy a deficiency of?

A

Vit C

41
Q

What can scurvy cause?

A
  • destruction of collagen
  • damage to myelin
  • loss/bleeding of tooth sockets
  • sunken eye sockets
  • paralysis
  • death
42
Q

Why is water important?

A
  • prevent dehydration
  • solvent
  • important for metabolism/excretion
  • thermoregulation
  • osmoregulation
43
Q

How do we maintain a consistent weight?

A
  • without conscious effort
  • finely tuned regulatory system
  • involves neuroendocrine regulation of the process of feeding (appetite and satiety)
44
Q

Does the GIT regulate energy intake?

A

no

45
Q

What is energy intake regulated by?

A

hypothalamus and brain stem
-hunger centre
-satiety centre
works through glucostatic (blood glucose) decreased glucose increases hunger
-adipostatic (fat storage) if there is an increase in the fat stored it will cause satiety
-GIT tract can slow down digestion to reduce hunger

46
Q

What hormone stimulates hunger in the hypothalamus?

A

ghrelin

47
Q

What inhibits appetite?

A
  • stopping ghrelin
  • PYY, CCK and GLP-1 release from intestine
  • insulin released in pancreas
  • leptin released from adipose tissue
48
Q

What can override satiety?

A

-visual, smell and taste signals

49
Q

What is loss of appetite called?

A

anorexia

50
Q

What are the physiological factors that can cause loss of appetite?

A
  • anaemia
  • forms of cancer
  • depression
  • intestinal disorders
  • intestinal parasites
  • liver disorders
  • malabsorption
  • mouth disorders
  • taste loss
51
Q

What are the physiological factors that can cause loss of appetite?

A
  • stress
  • anxiety
  • sadness
  • wedding
  • falling in love
52
Q

What are the environmental factors?

A
  • altitude

- acute cold

53
Q

Where is most energy stored?

A

in fats

54
Q

What is the advantage of carbohydrates as an energy source?

A

more ATP can be generated per unit time compared to oxidation of fats

55
Q

Why is glucose required by the red blood cells?

A

no mitochondria so beta oxidation of fats can’t occur

56
Q

Why does the brain use glucose instead of fats?

A

blood brain barrier

57
Q

What do the other organs use for energy?

A
  • can use glucose

- prefer using fats

58
Q

What is the blood brain barrier?

A
  • a highly selective permeable barrier
  • endothelial cells have tight junctions
  • separates blood with the brain and the extracellular fluid of the CNS
59
Q

Whats the disadvantages of using fats in the brain instead of glucose?

A
  • ATP generated demands more O2 (Brain cells need lots of O2)
  • beta-oxidation generates superoxide (which kills brain cells)
  • rate ATP generation is slower than glucose (brain needs a fast energy supply)
60
Q

What type of energy is required for intense high impact exercise?

A
  • glucose

- anaerobic glycolysis

61
Q

Low intensity exercise e.g marathon running?

A

-glycogen until it has been used up
-then fats
(different type of muscle´fibre being utilised)

62
Q

What happens when insulin is released in the liver?

A

it causes the beta cells to:

  • uptake AA and increase protein synthesis
  • increase glycogen synthesis
  • increase lipogenesis
  • decrease gluconeogenesis
63
Q

What happens when insulin is released in the muscles?

A
  • glucose uptake
  • AA uptake
  • protein synthesis
  • glycogen synthesis
64
Q

What happens when insulin is released in the adipose tissue?

A
  • decrease lipolysis
  • increase glucose uptake
  • increase lipogenesis
65
Q

What hormones increase the breakdown of triglycerides?

A
  • glucagon
  • adrenaline
  • glucocorticoids
66
Q

What are the two origins for obesity?

A
  • innate (inherited)

- acquired

67
Q

How does inherited obesity occur?

A
  • monogenic mutation in leptin

- polygenic Prader-Willi syndrome

68
Q

How does acquired obesity occur?

A
  • overeating
  • inactivity
  • ageing
  • stress
  • endocrine disrupters
  • drugs
69
Q

What complicating diseases can occur due to obesity?

A
  • diabetes
  • polycystic ovaries
  • fertility problems
  • hpertension
  • stroke
70
Q

What happens if you eat too much glucose?

A
  • glucose is converted into acetyl CoA

- if you already have enough energy, the acetyl CoA will eb converted into fatty acids which will become triglycerides

71
Q

Fructose is often used in low fat diets, why is it bad?

A
  • sweeter than glucose
  • fructose is not preferred energy source for muscle and brain
  • fructose has a greater conversion than glucose into TGs
  • fructose does not stimulate insulin secretion which increases food uptake (no leptin release)
72
Q

How is obesity treated?

A
  • drugs that alter appetite (some act on the brain, inhibit neurotransmitter and suppress appetite, block endocannabinoid system)
  • drugs alter absorption of calories (e.g inhibit pancreatic lipase)

-restrict food intake
calorie restricted diet, bariatric surgery (gastric band)(full feeling quicker), gastric balloon

-exercise

73
Q

Why does starvation occur?

A
  • deprivation of calories
  • a need to preserve plasma glucose to maintain brain and spinal cord which results in consumption of tissues to preserve energy production
74
Q

What happens when you are in a state of starvation?

A
  • breakdown of muscles releases amino acids to bolster blood glucose (muscle performance declines)
  • breakdown of fat to provide glycerol
  • ketone bodies production
75
Q

How are ketone bodies produced?

A
  • from the breakdown of fatty acids in the liver

- beta-oxidation

76
Q

How do ketone bodies reach the brain?

A
  • water soluble
  • diffuses via con gradient to blood
  • taken up from blood without transporters
  • cross blood brain barrier
77
Q

What happens in the first 6 hours of starvation?

A

glucose from the blood is used as the main fuel for the brain

78
Q

What happens in 6-16 hours?

A

glycogen is broken down in the liver to provide glucose for the brain

79
Q

What happened 16-72 hours?

A

1st metabolic shift (low levels of glycogen)

  • increase gluconeogenesis (increase wasting of muscle)
  • increase lipolysis of TG into FA (fuels other tissues and glycerol converted into glucose for brain)
80
Q

2-3 days?

A

2nd metabolic shift.

  • increase lipolysis of TG into FA
  • liver converts FA into ketone bodies used as fuel for the brain
  • decrease gluconeogenesis
81
Q

After 24 days?

A
  • fat stores used
  • gluconeogenesis relyed on
  • all cells in body break down proteins to provide glucose for the brain
  • basal metabolic rate decreases up to 50%

Digestion and Renal Sciences (13 decks)

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