Energy?

Question 1

Describe energy storage and demand.

Answer 1

• Organism has energy expenditures: maintenance, repair, growth, activity, thermogenesis
• Organisms has storage of energy: glycogen in liver and muscle and fat in adipose tissue
• If expenditures increase, energy can be taken out of storage
• If activity increases greatly, this may increase the demand
• Increased demand is supplied by eating fats, carbohydrates, proteins, vitamins and minerals
• At rest, principal energy users are the heart, liver and brain
• When active, skeletal muscles are the principle users of energy

Question 2

How are eating behaviours controlled?

Answer 2

1. Energy reserves generate signals of available energy
2. Signals to hypothalamus
3. Behaviour can be modified to either increase/decrease energy in eating or increase/decrease activity, growth, repair and cellular metabolism

Question 3

How is brown fat distinguishable from white fat?

Answer 3

Can turn energy into heat

Question 4

How is intake regulated?

Answer 4

1. Satiety centre inhibits the appetite centre.
2. Appetite centre stimulates feeding behaviours.
3. Modulating input go into both the satiety and appetite regions of the brain.

Question 5

What stimulates the satiety centre?

Answer 5

• Increased glucose and insulin
• Increased CCK, which correlates to fat content of meal]increased stomach distension
• Increased body fat stores
• Leptin from white fat, proportionate with fat reserves
• Peptide YY/PYY from epithelium of small and large bowel, with a release proportional to the meal size

Question 6

What inhibits the satiety centre?

Answer 6

• Smell of desirable food
• Sight of desirable food
• Ghrelin from stomach. Levels increase during fasting

Question 7

What is parabiosis in feeding behaviour?

Answer 7

The anatomical joining of 2 individuals, especially artificially in physiological research. The 2 share a bloodstream.

1. When stable, both animals eat normally.
2. Electrical lesion of ventromedial nuclei in A
3. A becomes obese and B becomes anorexic
4. Unkown substance passes form mouse with lesion/A into the blood stream of the normal mouse/B to reduce feeding behaviour, causing B to starve

Feeding/appetite centre in the lateral nucleus – stimulation causes feeding and lesioning causes disinterest in food.

Satiety centre in ventromedial nucleus – stimulation terminates eating and lesioning causes voracious and constant feeding.

Question 8

How is output regulated?

Answer 8

Eating increases basal metabolic rate and heat production, dietary induced thermogenesis is a process related to secretion, digestion and absorption and uses additional blood supply.

Output/metabolism is measured as oxygen consumption/heat production under eating/basal condition.

With increasing body mass, energy consumption per unit mass and need of food falls. Partly due to heat loss.