exercise, ageing and disease

Question 1

what risks are associated with a sedentary lifestyle?

Answer 1

• sedentary death syndrome
• obesity
• diabetes
• CVD
• cancer

Question 2

what is adaptive thermogenesis?

Answer 2

refers to signals from blood nutrients and leptin from adipocytes, controlled by hypothalamus. works to increase energy expenditure in fed conditions and vice versa

Question 3

what does leptin do and where does it act?

Answer 3

produced by white adipose tissue and acts on Ob-Rb receptors in the arcuate nucleus of the hypothalamus. decreases food intake and increases energy expenditure

Question 4

what are the characteristics of the Ob/ob mouse?

Answer 4

• mutation in gene encoding leptin
• extreme obesity due to hyperphagia and decrease in energy expenditure
• mice develop type II diabtes

Question 5

what events occur in the B cells of the pancreas when glucose is present?

Answer 5

in conditions where there is high glucose, there is generation of ATP, which inhibits K+ channels, depolarising the cell to triggerCa influx and release of insulin, which promotes muscular uptake of glucose

Question 6

what is the effect of insulin binding on GLUT4?

Answer 6

promotes insertion into the surface membrane

Question 7

how does obesity promote insulin resistance?

Answer 7

increase in adipose cell mass increases triglyceride levels in proportion to circulating FFAs. this induces insulin resistance through an unknown mechanism

Question 8

how does reducing obesity reduce the risk of diabetes?

Answer 8

• decrease in obesity decreases circulating non-esterified fatty acids
• this prompts a decrease in insulin resistance and associated stress on pancreatic B-cells
• less chance of progression to insulin-dependent diabetes

Question 9

by which three mechanisms does exercise reduce the risk of chronic disease?

Answer 9

• increase in trained muscle
• increase in general health
• decrease in inflammation

Question 10

how does an increase in trained muscle reduce the risk of chronic disease?

Answer 10

• increase in muscle mass corresponds to an increase in glycogen storage, insulin sensitivity and ability to use lipids as an energy source
• this results in a decrease in conversion of glucose to fats, decrease in circulating fats and a decrease in storage of fats

Question 11

how does an increase in general health associated with exercise decrease the risk of chronic disease?

Answer 11

• an increase in physical fitness, wellbeing, brain health and metabolic health
• resist the effects of pathogens and stress- aiding recovery

Question 12

how is a decrease in inflammation associated with exercise?

Answer 12

in exercise, the muscle secretes cytokines (myostatin, BDNF, IL-6, IGF-1)

Question 13

how do we know that myokines are secreted from the contracting muscle?

Answer 13

when patients with a loss of afferent and efferent neural activity perform electrically induced cycling, the same physiological response is stimulated as in uninjured individuals

Question 14

what does myostatin do?

Answer 14

regulates skeletal muscle hypertrophy, metabolic homeostasis and adipose tissue mass

Question 15

what does BDNF do?

Answer 15

(brain derived neurotrophic factor) responsible for neural growth and activity

Question 16

what does IL-6 do?

Answer 16

releases cortisol from adrenal cortex, increases insulin sensitivity

Question 17

what does IGF-1 do?

Answer 17

responsible for osteogenesis

Question 18

what are the protective effects of exercise on the brain?

Answer 18

increase in levels of BDNF, serotonin and dopamine
improves brain plasticity, cognitive tasks.
better for mild-moderate depression than antidepressants

Question 19

how does stress affect the sympathetic nervous system?

Answer 19

• increase in sympathetic output

- increase in HR, breathing rate, diversion of blood to skeletal muscles and brain

Question 20

what are the consequences of chronic activation of the physiological stress response?

Answer 20

constant cortisol -> increase in appetite -> increase in fat storage
constant cortisol -> weakened immune system + cortisol resistance
repeated adrenaline surges -> increase in blood pressure -> endothelial injury -> increased risk of atherosclerosis

Question 21

what is sarcopenia?

Answer 21

age related loss of muscle mass

• decrease in number of muscle fibres
• decrease in area of each fibre

Question 22

what is sarcopenia accompanied by?

Answer 22

increase in fat and connective tissue in the muscle

Question 23

what is myosteatosis?

Answer 23

fat deposition in the muscle

Question 24

what is the effect of inactivity on sarcopenia and myosteatosis?

Answer 24

accelerates it

Question 25

what factors are involved in progression of sarcopenia?

Answer 25

1) neuropathic processes
2) axonal sprouting from remaining motor neurones
3) decrease in growth factors with age
4) decrease in food intake
5) infiltration of fat and connective tissue with age

Question 26

how do neuropathic processes affect sarcopenia?

Answer 26

loss of alpha motor neurones causes muscle denervation and loss of motor units leads to denervation muscle atrophy

Question 27

what is the consequence of axonal sprouting from remaining motor units with age?

Answer 27

re-innervation of denervated muscles causes motor units to be giant, this causes a reduction in fine motor control of motor units when regulating force

Question 28

what is somatopause?

Answer 28

progressive decrease in pituitary function

Question 29

what is motor unit remodelling?

Answer 29

a natural, ongoing process involving selected denervation, sprouting of axon and motor end plate regeneration