Exercise, aging and disease Flashcards
What can obesity lead to?
Chronic diseases
- Diabetes type II
- CVD
- Cancer
Obesity is increasing in the last 40 years
Can also induce Osteoarthritis and Osteoporosis
What year will British people be the fattest in Europe?
2025
What number is physical inactivity to death worldwide?
Physical inactivity is the 4th major contributor to death worldwide
What are the figures for deaths from non-communicable diseases attributed to physical inactivity?
- 6-10% for all causes
- 30% for ischaemic heart disease (coronary artery atherosclerosis)
What is SeDS?
Sedentary death syndrome
Death due to lack of regular physical activity
How does the body maintain constant weight?
The body has an homoeostatic mechanism
An increase of food intake = increase of energy expenditure
What is adaptive thermogenesis?
Signals from blood nutrients and leptin from adipocytes controlled by hypothalamus
Activates the sympathetic NS and Brown adipose tissue (rodents/infants)
What is leptin?
Leptinis one of the hormones directly connected to body fat and obesity.
Leptin, a hormone released from the fat cells located in adipose tissues, sends signals to the hypothalamus in the brain
Produced by white adipose tissue
Activates the sympathetic nervous system
How is energy utilised in the body?
Obligatory energy expenditure (required for cellular and organ function) - 50%
Physical activity (variable) - 30%
Adaptive thermogenesis (variable, regulated by hypothalamus and responds to diet and temperature) - 20%
Where does leptin act upon in the hypothalamus?
Acts on Ob-Rb receptors
Hypothalamus will encourage the endocrine system
What occurs if there is a mutation in the gene encoding leptin (ob/ob mouse)?
Type 2 diabetes develops
Extremely obese (results in overeating) hyperphagia + decrease in energy expenditure
What is leptin resistance in obesity?
As people gain weight, they develop leptin resistance
How are carbohydrates, lipids and protein ABSORBED as?
Carbohydrate - Mainly glucose
Lipids - Mainly fatty acids + Cholesterol + Phospholipids
Protein - Amino acids
How are carbohydrates, lipids and protein STORED as?
Carbohydrates - Glycogen
Lipids - Mainly triglyercides
Protein - Protein
What are carbohydrates, lipids and protein STORAGE SITES?
Carbohydrates - Liver (100g), Muscle (400g)
Lipids - Liver (limited), Adipose tissue (large quantities), Other cells (limited)
Protein - Very limited in all cells
What is the FATE OF EXCESS of carbohydrates, lipids and protein?
Carbohydrates - Converted to lipid
Lipids - Stored in unlimited quantities as triglyceride
Proteins - Deaminated then converted to CHO (& fat)
What is the normal blood glucose before a meal?
4.0 - 5.9 mM
What is the blood glucose after a meal?
7.8 mM 90+ after a meal
What happens to the brain if glucose levels dip below normal levels?
It leads to a hypoglycemic condition and coma
Type 1 diabetics are at risk of this due to loss of main hormone that controls regulation of diabetes
Where does the body detect glucose?
In the pancreas
B-cells of islets of Langerhans
Glucose is taken up through these cells and promotes the generation of ATP
More glucose = More ATP, inhibits the potassium channel, depolarises the cell and depolaristion of the cell activates the voltage dependent calcium channel resulting in calcium influx and release of insulin
What is insulin?
It promotes glucose uptake
It does this by promoting the muscle to take up glucose
What is the % of glucose load stored after a meal?
70% of glucose load is stored in muscle
What does the liver do?
It converts glucose to glycogen
Inhibits gluconeogenesis
What does adipose tissue do to insulin?
Converts to triglyceride
What does the insulin receptor do?
- Particularly abundant in muscle and adipocytes
- Low insulin: most GLUT4 in vesicles
- Insulin binding causes rapid insertion of GLUT4 into surface membrane
What pathway leads to the insertion of GLUT4 into the Glucose plasma membrane?
PI-3K signalling pathway
Happens quickly
What does the increase of triglyceride storage do in insulin receptors?
It increases the circulating fatty acids (Non-esterified-fatty acids or free-fatty acids)
Reduces insulin sensitivity
There are several proposed targets:
- Glucose transporter
- Early signalling events
- Transfer of GLUT4 transporters from vesicles into the membrane
Is insulin resistance reversible?
Yes, for patients that are becoming insulin resistant, controlling their diet and doing exercise is an important intervention that can reverse pre-diabetic situation to full diabetes