Metabolism - Lecture Thirty-Nine

Question 1

Body Mass Index (BMI)

Answer 1

weight (kg) / height (m) ^2

Question 2

BMI > 30

Answer 2

Obese

Question 3

BMI 25 to 30

Answer 3

Overweight

Question 4

BMI 20 to 25

Answer 4

Healthy weight

Question 5

BMI < 20

Answer 5

Underweight

Question 6

Energy expenditure =

Answer 6

Metabolic rate

Question 7

Adaptive thermogenesis

Answer 7

Variable, regulated by the brain

Question 8

What does adaptive thermogenesis respond to?

Answer 8

Temperature and diet

Question 9

When does adaptive thermogenesis occur?

Answer 9

In brown adipocyte mitochondria, skeletal muscle and other sites

Question 10

Brown fat

Answer 10

A special thermogenic tissue that is found in hibernating animals e.g. babies that keeps them warm.

Question 11

Where is uncoupling protein (UCP) found?

Answer 11

Originally found in brown fat and is present in inner mitochondrial membrane

Question 12

Uncoupling protein

Answer 12

Are regulated proton channels in the membrane i.e. “holes”
Electrochemical potential gradient dissipates, releasing heat, therefore increasing metabolic rate and burning excess fuels

Question 13

What does uncoupling proteins uncouple?

Answer 13

ATP synthesis from fatty acid oxidation

Question 14

UCP2 and UCP3

Answer 14

Act to raise the metabolic rate and release heat to burn off some excess energy and prevent obesity

Question 15

BAT-oriented strategies to combat obesity

Answer 15

Stimulate existing BAT
Switch on brown fat differentiation and growth
Transplantation of engineered BAT

Question 16

Obese gene

Answer 16

Codes for leptin protein. Leptin is a hormone secreted from “fat” fat cells,

Question 17

What does leptin signal the brain to do?

Answer 17

Decrease food intake and increase energy expenditure, therefore maintain normal animal in energy balance

Question 18

Leptin receptor

Answer 18

Present in the hypothalamus of the brain and in several other tissues
Absent in the obese diabetes spouse and fatty rat

Question 19

Leptin in humans

Answer 19

Humans secrete leptin from adipose tissue and have leptin receptors in the brain
Some obese humans found to have mutant leptin or leptin receptor
Most obese humans appear to be resistant to the leptin signal

Question 20

Severely obese child

Answer 20

Severe early-onset obesity
Constantly demanding food
No serum leptin
Homozygous for frameshift mutation in leptin gene
Recombinant human leptin therapy for 1 year
Decreased food intake
16kg weight loss in 1 year due to fat loss

Question 21

Factors influencing the development of obesity

Answer 21

Monogenic syndromes
Susceptibility genes
Lack of exercise
Increased food intake
Culture