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Digestive and Renal Sciences > Metabolic fate of nutrients > Flashcards

Metabolic fate of nutrients Flashcards

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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
Why are fat soluble vitamins important?
Development of immune system Calcium metabolism Blood clotting
26
What are the main essential minerals?
Fe, Ca, Mg, Mn, Na, K, Zn
27
What are some vitamin deficiencies
Rickets (vitamin D deficiency) Poor mineralisation of bone Scurvy (chronic Vitamin C deficiency)
28
What causes pernicious anemia?
Vitamin B12 deficiency
29
How do we regulate body mass?
Energy intake = energy expended + energy stored intake - expenditure = 0
30
What happens if energy intake > expenditure?
Positive balance, therefore add stored energy increasing body mass --> obesity
31
What happens if energy intake < expenditure?
Negative balance | Lose weight / starvation
32
What maintains consistent body weight?
neuroendocrine regulation of the process of feeding (appetite and satiety) Appetite - Desire to eat food, felt as hunger Satiety - Absence of hunger
33
How does the brain regulate hunger and satiety?
Controlled by hypothalamus Glucostatic: decrease glucose = hunger Increase glucose = satiety Adipostatic: increased fat stored = satiety
34
What is the hormone that stimulates appetite?
Ghrelin
35
What hormones inhibit appetite?
Insulin Leptin stopping of Ghrelin release
36
What can change appetite perception?
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
How is the majority of energy stored?
As adipose tissue (fats)
38
What is the preferred energy store to be used?
Glucose
39
What is the blood brain barrier?
Highly selective permeable barrier | Endothelial cells have tight junctions Separates blood - brain extracellular fluid CN
40
What is the disadvantage of using FAs over glucose?
ATP generated demands more O2 β-oxidation generates superoxide which can destroy cells Rate ATP generation slower than glucose
41
What energy store is used for high intensity exercise?
Glucose due to Type 2 muscles being used and therefore requires anaerobic respiration and glycolysis of glucose
42
What energy store is used for low intensity exercise (marathon)?
Type 1 muscles used and therefore fats would be metabolised
43
What are the areas of the main stores of glycogen?
Liver | Muscles
44
What effect does insulin have on metabolism balance?
initiates anabolism (storage) Fats -> adipose tissue Glucose -> glycogen AA -> New proteins
45
What effect does glucagon have on metabolism balance?
Initiates Catabolism (energy) Fats -> FAs Glycogen -> glucose Proteins -> glucose (starvation)
46
What effect does insulin have on the liver?
Increased AA uptake Increase Glycogenesis Decreased Gluconeogenesis Increased Lipogenesis
47
What effect does insulin have on the adipose tissue?
Increased Glucose Uptake Increased Lipogenesis Decrease Lipolysis
48
What effect does insulin have on the muscle tissue?
Increased Glucose uptake Increased AA uptake Increased Glycogen synthesis
49
What hormones promote lipolysis?
Glucagon Adrenaline Glucocorticoids Insulin inhibits this
50
What are the origins of obesity?
Innate/Inherited: mutation of leptin ``` Acquired: inactivity overeating aging stress drugs ```
51
What are the two fates of Acetyl CoA in metabolism?
Either enter krebs cycle | or be converted into FAs and triglycerides (fats)
52
What is the problem with low fat diets?
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
What are some treatments to obesity?
Drugs altering appetite - Sibutramine (suppresses appetite) Drugs altering absorption of calories - Orlistat Restrict food intake - diets, gastric balloon, bariatric surgery. Exercise
54
What is the origin of starvation?
Simple deprivation of calories (no genetic components)
55
What is starvation characterised by?
Mechanisms to preserve plasma glucose to maintain brain and spinal cord
56
What is starvation marked by?
Increased liver synthesis of glucose and ketone bodies. Gluconeogenesis Ketogenesis
57
What happens during starvation when glucose has been exhausted?
Rely on synthesis from endogenous sources such as AAs and Fats
58
How can muscle and fat be used as an energy source?
Breakdown of muscle to amino acids | Breakdown of fat to release glycerol
59
What is the disadvantage of using muscles and fats as energy sources?
Muscle performance declines | Finite resource
60
How are ketone bodies produced?
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
What are the time stamps of glucose metabolism before starvation?
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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