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Digestive and Renal Sciences > Metabolic fate of nutrients > Flashcards

Metabolic fate of nutrients Flashcards

1
Q

Why is nutrition important?

A

Key to develop and maintain state of health

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2
Q

What is nutrition?

A

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

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3
Q

What are Macromolecules?

A

Proteins
Fats
Carbohydrates

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4
Q

What are micromolecules

A

Minerals

Vitamins

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5
Q

What is the basal metabolic rate?

A

12 hours after eating
Number of calories needed at rest for normal body function
50-70% calories needed per day.

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6
Q

What is the thermic effect of food?

A

Energy required for the digestion and absorption of food

5-10% of energy expenditure

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7
Q

What are the main energy requirements in the body?

A

Basal metabolic rate
Thermal effect of food
Physical activity
Other factors - temperature changes, pregnancy, lactation

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8
Q

What is the preferential source of energy?

A

Glucose since it is readily available primary source of energy for the CNS and RBCs

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9
Q

How is glucose stored?

A

As glycogen by glycogenesis

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10
Q

How much ATP can come from 1 molecule of glucose in aerobic respiration?

A

36-38 ATP molecules

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11
Q

What is the main use of energy from fats?

A

Used in tissue activity and for the maintenance of body temperature

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12
Q

Why are fats important?

A 
body structure - cell membranes
Protection
insulation
Satiety
Fat soluble vitamins
Energy storage in adipose tissue
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13
Q

Why are fats a calorie dense nutrient?

A

Large amounts of O2 required to metabolise

Insoluble in water so difficult to access

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14
Q

How much ATP is produced from 1 mole of palmitic acid?

A

130 ATP molecules

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15
Q

Why are proteins important?

A 
Amino acid pool
Converted to other AAs
Manufacture new proteins
Build new tissue
Oxidised to produce energy
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16
Q

What is Nitrogen balance?

A

Balance = N intake - N excreted

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17
Q

What are the results of a positive nitrogen balance?

A

Pregnancy
Growth
Recovery

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18
Q

What are the results of a negative nitrogen balance?

A

Starvation
Trauma/ infection/ sepsis
Tissue destruction

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19
Q

What are some non energy supplier nutrients?

A

Essential for life

Dietary fibre

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20
Q

Why are insoluble fibres important?

A

Provides bulk to the gut to prevent constipation

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21
Q

Why are soluble fibres important?

A

Absorbs water in the intestine to soften stool which helps waste move along colon
Lowers cholesterol

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22
Q

What are the water soluble vitamins?

A

B complexes

vitamin C

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23
Q

What are the fat soluble vitamins?

A

A,E,D,K

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24
Q

Why are water soluble vitamins important?

A

Anti-oxidants

enzyme cofactors

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25
Q

Why are fat soluble vitamins important?

A

Development of immune system
Calcium metabolism
Blood clotting

26
Q

What are the main essential minerals?

A

Fe, Ca, Mg, Mn, Na, K, Zn

27
Q

What are some vitamin deficiencies

A

Rickets (vitamin D deficiency)
Poor mineralisation of bone

Scurvy (chronic Vitamin C deficiency)

28
Q

What causes pernicious anemia?

A

Vitamin B12 deficiency

29
Q

How do we regulate body mass?

A

Energy intake = energy expended + energy stored

intake - expenditure = 0

30
Q

What happens if energy intake > expenditure?

A

Positive balance, therefore add stored energy increasing body mass –> obesity

31
Q

What happens if energy intake < expenditure?

A

Negative balance

Lose weight / starvation

32
Q

What maintains consistent body weight?

A

neuroendocrine regulation of the process of feeding (appetite and satiety)

Appetite - Desire to eat food, felt as hunger
Satiety - Absence of hunger

33
Q

How does the brain regulate hunger and satiety?

A

Controlled by hypothalamus

Glucostatic:
decrease glucose = hunger
Increase glucose = satiety

Adipostatic:
increased fat stored = satiety

34
Q

What is the hormone that stimulates appetite?

A

Ghrelin

35
Q

What hormones inhibit appetite?

A

Insulin
Leptin
stopping of Ghrelin release

36
Q

What can change appetite perception?

A

Anemia
Cancer – colon, ovarian, stomach, pancreatic
Depression – although sometimes opposite effect
Intestinal disorders Intestinal parasites Liver disorders
Malabsorption syndrome
Mouth disorders
Taste loss – age, drugs

Stress, anxiety, Love

Altitude, cold

37
Q

How is the majority of energy stored?

A

As adipose tissue (fats)

38
Q

What is the preferred energy store to be used?

A

Glucose

39
Q

What is the blood brain barrier?

A

Highly selective permeable barrier

Endothelial cells have tight junctions Separates blood - brain extracellular fluid CN

40
Q

What is the disadvantage of using FAs over glucose?

A

ATP generated demands more O2
β-oxidation generates superoxide which can destroy cells
Rate ATP generation slower than glucose

41
Q

What energy store is used for high intensity exercise?

A

Glucose due to Type 2 muscles being used and therefore requires anaerobic respiration and glycolysis of glucose

42
Q

What energy store is used for low intensity exercise (marathon)?

A

Type 1 muscles used and therefore fats would be metabolised

43
Q

What are the areas of the main stores of glycogen?

A

Liver

Muscles

44
Q

What effect does insulin have on metabolism balance?

A

initiates anabolism (storage)
Fats -> adipose tissue
Glucose -> glycogen
AA -> New proteins

45
Q

What effect does glucagon have on metabolism balance?

A

Initiates Catabolism (energy)
Fats -> FAs
Glycogen -> glucose
Proteins -> glucose (starvation)

46
Q

What effect does insulin have on the liver?

A

Increased AA uptake
Increase Glycogenesis
Decreased Gluconeogenesis
Increased Lipogenesis

47
Q

What effect does insulin have on the adipose tissue?

A

Increased Glucose Uptake
Increased Lipogenesis
Decrease Lipolysis

48
Q

What effect does insulin have on the muscle tissue?

A

Increased Glucose uptake
Increased AA uptake
Increased Glycogen synthesis

49
Q

What hormones promote lipolysis?

A

Glucagon
Adrenaline
Glucocorticoids

Insulin inhibits this

50
Q

What are the origins of obesity?

A

Innate/Inherited: mutation of leptin

Acquired:
inactivity
overeating
aging
stress
drugs
51
Q

What are the two fates of Acetyl CoA in metabolism?

A

Either enter krebs cycle

or be converted into FAs and triglycerides (fats)

52
Q

What is the problem with low fat diets?

A

They are instead high in fructose

Fructose is metabolised differently and does not stimulate insulin secretion.

No insulin secretion leads to food intake not being inhibited and therefore we eat more leading to over eating

53
Q

What are some treatments to obesity?

A

Drugs altering appetite - Sibutramine (suppresses appetite)

Drugs altering absorption of calories - Orlistat

Restrict food intake - diets, gastric balloon, bariatric surgery.

Exercise

54
Q

What is the origin of starvation?

A

Simple deprivation of calories (no genetic components)

55
Q

What is starvation characterised by?

A

Mechanisms to preserve plasma glucose to maintain brain and spinal cord

56
Q

What is starvation marked by?

A

Increased liver synthesis of glucose and ketone bodies.

Gluconeogenesis
Ketogenesis

57
Q

What happens during starvation when glucose has been exhausted?

A

Rely on synthesis from endogenous sources such as AAs and Fats

58
Q

How can muscle and fat be used as an energy source?

A

Breakdown of muscle to amino acids

Breakdown of fat to release glycerol

59
Q

What is the disadvantage of using muscles and fats as energy sources?

A

Muscle performance declines

Finite resource

60
Q

How are ketone bodies produced?

A

Produced from fatty acid (insoluble)
Ketone bodies - water soluble product
Diffuses via concentration gradient to blood
Taken up from blood (without need for transporters)
Cross blood brain barrier
**Source of Energy used by brain in starvation as well as in type 1 diabetes

61
Q

What are the time stamps of glucose metabolism before starvation?

A

0-6hrs - glucose from blood used as main fuel for brain

6-16hrs - glycogen is broken down in liver to be used as glucose as fuel for the brain

16-72hrs - 1st metabolic shift as very low levels of glucose
Increased gluconeogenesis and lipolysis

2-3 days of fasting - increased lipolysis
liver converts FAs to ketone bodies
Decreased gluconeogenesis

> 24 days - relies on gluconeogenesis due to depletion of fat stores.
Rely on muscles wasting to provide energy.

46-70 days = death

Digestive and Renal Sciences (26 decks)

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