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NUT1121 > Week 8 Metabolism pt 2 > Flashcards

Week 8 Metabolism pt 2 Flashcards

(48 cards)

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1
Q

What is the positive energy balance

A

When energy intake exceeds energy output,there is a gain in weight

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2
Q

Where does excess energy come from

A

protein,fator carbohydrate

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3
Q

What is excess protein converted to

A

fat,but this is inefficient and indirect. Its priority is other roles

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4
Q

What is excess carbs converted to

A

fat,but this is inefficient and indirect. Its priority is glycogen stores

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5
Q

What is excess fat converted into

A

fat

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6
Q

Describe the metabolic pathway for each macronutrient during feasting

A

CHO->glucose->liver+muscle glycogen stores/fat stores

Fat->fatty acids->fat stores

protein->amino acids-> body proteins/loss of nitrogen in urin/fat stores

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7
Q

Describe the metabolic pathway for each macronutrient during fasting

A
  • When nutrients from a meal are no longer available to provide energy (about 2 to 3 hours after a meal), the body draws on its glycogen and fat stores for energy.
  • liver+muscle glycogen stores->glucose->energy for brain/nerv system/RBC/energy for other cells
  • body fat stores->fatty acods->energy for other cells
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8
Q

Describe the metabolic pathway for each macronutrient during beyond glycogen depletion

A
  • after 24hrs of starvation
  • protein->amino acids->some loss of nitrogen in urine->glucose->energy for brain/other cells/nervous system/rbc
  • AA->ketone bodies->used for same as glucose
  • fat->fatty acids>energy for other cells
  • FA-> ketone bodies->used for same as glucose
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9
Q

Describe what happens during negative energy balance

A
  • occurs during fasting
  • Low BGL >signal to break down fat and muscles
  • Glucose from glycerol and AA (GNG)
  • when glucose not avail=ketone bodies
  • Suppression of appetite
  • Slowing of the metabolism occurs
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10
Q

What are ketone bodies

A

acetyl CoA fragments derived from fatty acids = alternative energy ketone bodies
- produced and used only in small quantities
- can provide fuel for some brain cells.
- contains an acid group (COOH), is called a keto acid

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11
Q

What is ketosis

A

when keto acid concentration rises, the pH of the blood drops= ketosis,
- induces a loss of appetite

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12
Q

Descirbe 3 steps in ketone body formation

A
  1. condensation of 2 molecules of acetyl CoA and h20+ removal of the CoA’s to form a compound that is converted to the first ketone body, acetoacetate.
  2. Acetoacetate may lose a molecule of carbon dioxide to become another ketone body, acetone.
  3. Or acetoacetate may add two hydrogens, becoming another ketone body (beta-hydroxybutyrate).
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13
Q

What happens to energy balance when weight is stable

A

energy consumed is equal to energy expended

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14
Q

What energy balance causes weight to increase

A

When energy consumed is greater than expended

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15
Q

What energy balance causes weight to decrease

A

When energy consumed is less than expended,

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16
Q

How much kJ in 1 kg of body fat

A

30 000 kJ of energy

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17
Q

What does a direct calorimeter measure

A

the heat energy released

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18
Q

What does a indirect calorimeter measure

A

the amount of oxygen consumed and carbon dioxide expelled

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19
Q

What is Physiological fuel value

A

is the difference between the number of kJs measured with calorimetry and the number of kJs that the human body derives from a food

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20
Q

What is a bomb calorimeter used for

Study These Flashcards
A

measure energy a food provides
- foodburned= energy released as heat
- heat energy measure in kJ

21
Q

What is the common energy expenditure values for females and males

Study These Flashcards
A

F->7 – 9.5 MJ / day (8000 kJ -2000 kcal)
M-> 11.5 – 14 MJ / day (12000 kJ - 4000 kcal)

22
Q

What are the 3 components of energy expenditure and their percentages

Study These Flashcards
A
  • basal metabolism=50-65%
    -physical activites=30-50%
  • thermic effect of food=10%
23
Q

What is basal metabolism

Study These Flashcards
A

-support all the basic processes of life.

24
Q

What is BMR

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A

rate at which the body expends energy for these maintenance activities
- can be measured when the person is awake, but lying still, after a restful sleep and (12- to 14-hour) fast
- highest in people who are growing (children, adolescents and pregnant women) and those with considerable lean body mass (physically fit people and males)

25
What are the 13 factors that affect BMR
- Lean body mass diminishes with AGE, slowing BMR - In tall HEIGHT, thin people, the BMR is higher - In children and pregnant women, the BMR is higher GROWTH - The leaner the tissue, the higher the BMR (which is why males usually have a higher BMR than females). The more fat tissue, the lower the BMR - FEVER raises the BMR - STRESSES (including many diseases and certain drugs) raise the BMR - Both heat and cold raise the BMR - Fasting/starvation lowers the BMRc - Malnutrition lowers the BMR - hormones can lower/rise BMR - Nicotine increases energy expenditure - Caffeine increases energy expenditure -BMR is lowest when sleeping
26
Describe physical activity
Significant in weight loss and weight gain. - larger the muscle mass and the heavier the weight of the body part being moved, the more energy is expended. - Duration, frequency and intensity influence energy expenditure.
27
Describe thermic effect of food TEF
- gi tract acivites speed up when food consumed->requires energy and produces heat=TEF - Different foods have different thermic effects
28
What is adaptive thermogenesis
adjustment in energy expenditure related to environmental changes eg extreme cold, overfeeding, starvation, trauma
29
What are the TEF on the 3 macronutrients and alcohol
CHO = 5–10% Fat = 0-5% PRO = 20-30% Alcohol = 15-20%
30
What is appetite
- initiates eating through the sight, smell, thought or taste of food
31
What is hunger
motivates us to eat and is controlled by the hypothalamus - can be influenced by the presence or absence of nutrients in the bloodstream, the size and composition of the preceding meal, customary eating patterns, climate (heat reduces food intake; cold increases it), exercise, hormones and physical and mental illnesses
32
What does satiation do
causes us to stop eating; receptors in the stomach stretch and hormones such as cholecystokinin (CCK) increase - person begins to feel full
33
What is satiety
supressees hunger, remind us not to eat again until the body needs food
34
What 4 cognitive influences cause overeating
-large portion sizes – memories – intellect – social interactions.
35
What other 3 signals can caused hunger to be suppressed
- stress and how people perceive it – eating disorders – enforced discipline.
36
What 5 foods can sustain satiation for longer
- Protein rich foods - High fibre foods - Low energy density foods – Large salad starter – Wholegrain breads and cereals
37
What causes passive over consumption
eating high fat foods
38
What is the body mass index bmi
- measures relative weight for height - Underweight is a BMI below 18.5. - Overweight is a BMI above 25 (23). - Obese is a BMI above 30 (27.5). Does not reflect body composition so not relevant to all population groups.
39
Describe fat cell development
- During growth, fat cells increase in number. - When energy intake>expenditure, fat cells increase in size. - When fat cells have enlarged and energy intake continues to exceed energy expenditure, fat cells may increase in number again. - With fat loss, the size of the fat cells shrinks but not the number.
40
What is hyperplastic obesity
Obesity due to an increase in the number of fat cells
41
Describe fat cell metabolism
- lipoprotein lipase (LPL) is found primarily on the surface of cells lining muscles and adipose tissue - break down triglycerides -obese=more lpl activity =. efficient fat storage - Men are at increased risk for developing central obesity and women are at increased risk for lower body fat. - Weight loss may increase LPL action, difficulty for losing weight. -
42
What is a set point
- Body prefers to maintain weight at a ‘setpoint’. - Set point moves gradually overtime for long-term weight loss.
43
How does genentic cause obesity/overweight
– True causative role in very few cases – Prader-Willi syndrome characterised by excessive appetite, massive obesity – Genetic factors make a person more or less likely to gain or lose weight – Researchers have identified an obesity gene expressed in adipose tissue and codes for the protein leptin
44
How does leptin cause obesity/overweight
– Leptin – signals sufficient energy stores to hypothalamus, suppresses appetite and increases energy expenditure -> Released from adipose tissue and stomach cells in response to meals
45
How does adiponectin cause obesity/overweight
- secreted by adipose, correlates inversely with body fat ->Less body fat=higher adiponectin -> Inhibits inflammation, protects against insulin resistance
46
How does ghrelin cause obesity/overweight
- secreted in stomach cells, stimulates appetite - Blood grehlin rises before meal and fall after in proportion to kJs consumed - Lean people have high grehlin levels/anorexia exceptionally high - Obese people have low grehlin levels/levels don’t decline as much after a meal - On average Grehlin levels are high whenever in –ve e balance - Lack of sleep increases grehlin and decreases satiety hormone Leptin
47
How does Peptide YY cause obesity/overweight
- secreted from GI cells after a meal in proportion to kJs consumed, suppresses appetite * Grehlin levels decrease in response to PYY * PYY signals satiety, levels lower in obesity
48
What 3 health conditions will health improve if weight lost
- Heart disease. * Type 2 diabetes. * Sleep apnoea.

NUT1121 (12 decks)

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