- When muscles relax, the lumen widens thus decreasing B.P
- There is no pulse and pressure is low.
- Valves prevent backflow.
A person’s risk of developing coronary heart disease can be reduced by:
CONTROLLING BLOOD PRESSURE
Insoluble cholesterol combines with proteins to form soluble lipoproteins so that it can be carried in the bloodstream.
Eating both monounsaturated and polyunsaturated fats reduces the level of LDLs in the blood.
Lipids contain the elements carbon, hydrogen and oxygen. They are insoluble in water but soluble in organic solvents (ethanol).
They provide twice as much energy as carbohydrates and supply the body with essential fatty acids. Vitamins are often found dissolved in lipids.
The most common type we eat and use as energy storage is triglycerides: made up of 3 fatty acids joined to 1 glycerol:
ENERGY BUDGET + DIET
Carbohydrates, proteins, lipids and alcohol all contain energy: used to be measured in calories; the SI unit is the Joule.
Dietary Reference Values encourage balanced & healthy diets and indicate the amount of energy derived from different foods.
The basal metabolic rate (BMR) varies between individuals.
The body mass index (BMI) doesn’t have an exact correlation to each individuals fat levels thus it isn’t very accurate.
Waist – to – hip ratio is a better measure of obesity b/c has a continuous positive correlation against diseased groups.
Larger W – T – H ratio = more likely to get a heart attack
20% of the population are obese – excess dietary fat and inactivity are likely causes.
Obesity increases the risk of cardiovascular disease, Type II diabetes, raises B.P and raises lipid levels.
How is Tissue Fluid formed?
How does fluid return to the blood?
Not all the tissue fluid returns to the blood capillaries. There’s excess that is drained away into the lymphatic system. 20% of the tissue fluid returns to the circulation via the lymph system.
If B.P increases (hypertension) more fluid is forced out. The fluid accumulates in the tissues causing oedema. This is a sign of hypertension.
Blood pressure is higher in arteries and capillaries than in veins.
Systolic blood pressure is highest and occurs when the ventricles contract (ventricular systole)
Diastolic blood pressure is at its lowest in the arteries when the ventricles relax (diastole)
Any factor which causes arteries or arterioles to constrict will lead to hypertension. These include:
A larger surface area means that peripheral resistance is greater thus blood pressure drops (veins)
A smaller surface area means that peripheral resistance is less thus blood pressure increases.
Epidemiologist – studies patterns in the occurrence of diseases
Cohort studies – follows a group of people over time to see who develops the risk and who doesn’t
Case-control studies – people with the disease are compared to people without
Features of a good study