Lifestyle, Health and Risk

Flashcards on Lifestyle, Health and Risk

Why do many animals have a heart and circulation?

Mass transport to overcome limitations of diffusion in meeting the requirements of organisms.

How does the SA:Volume ratio effect diffusion?

Organisms with a high surface area to volume ratio can meet these requirements by diffusion alone, organisms with a low SA:volume ratio have an inadequate rate of diffusion.

How do circulatory systems improve the rate of supply and removal of substances within organisms?

Transport medium acts as a solvent for biologically important molecules and the heart contracts to put pressure on the transport medium.

How does an open circulatory system work?

The heart contracts increasing the pressure on the haemolymph which moves through the vessels toward the haemocoel.

Closed circulatory systems

Defined by having the transport medium enclosed in blood vessels at all times. The heart contracts to put pressure on the transport medium which is put under higher pressure so it can be moved over greater distances.

Double Circulatory System

Blood moves through the heart twice in each circuit of the body. The blood moves to the gas exchange organs and becomes oxygenated (pulmonary circuit) then returns to the heart, and is then pumped again to the rest of the body (systemic circuit).

Advantages of a Double Circulatory System

Deoxygenated blood can be pumped at a lower pressure to the gas exchange organs (lungs), so they are not damaged. Oxygenated blood can be pumped at a higher pressure in the systemic circuit, so gas exchange is more efficient and organisms can be larger and more metabolically active.

Water as a transport medium

Water is composed of two hydrogen atoms covalently bonded to oxygen. Each O-H bond has a dipole, which makes the water molecule overall, polar. Water molecules have hydrogen bonds, so they are cohesive, and are excellent solvents.

Artery structural features and their functions

Thick layer of elastic tissue to expand and recoil to maintain pressure on blood; folded endothelium to stretch to prevent damage due to high pressure; and a narrow lumen to maintain high pressure on blood.

Vein structural features and their functions

Wide lumen and thin walls allow neighboring skeletal muscles to deform vein and move blood and valves ensure blood flow in the correct direction (prevent backflow).

Capillaries structural features and their functions

Narrow lumen causes blood to flow more slowly and allow exchange of substances and reduces diffusion distance; capillary wall one cell thick reduces diffusion distance; form a large network through tissues to increase surface area.

Cardiac Cycle: Diastole

Heart relaxes, heart has lower pressure than major blood vessels so blood moves from high pressure in vena cava and pulmonary vein into atria and semi-lunar valves in aorta and pulmonary artery prevent blood moving back into ventricles.

Cardiac Cycle: Atrial Systole

Atria contract, so atria pressure is higher than ventricles which causes AV valves to be open and blood moves from atria to ventricles.

Cardiac Cycle: Ventricular Systole

Ventricles contract slightly after atria, ventricular pressure higher than atria so AV valves closed, ventricular pressure higher than arteries, so SL valves open, and blood moves into arteries and NOT atria.

Atherosclerosis

High blood pressure causes damage to artery endothelium, inflammatory response results in WBC being recruited behind endothelial cells, WBC absorb saturated fats and cholesterol, atheroma or fibrous plaque forms, reducing flow of blood, and blood pressure increases to compensate.

Blood-clotting process

Damage to artery endothelium exposes collagen fibres, platelets are activated, form platelet plug and release thromboplastin, prothrombin converted to thrombin, thrombin converts soluble protein fibrinogen into insoluble fibrin, fibrin polymerises to form mesh, trapping more platelets and RBC, until exposed collagen fibres are covered, ending response.

Heart attack (myocardial infarction)

Atherosclerosis or blood clot in a coronary artery reduces blood flow and oxygen supply, inadequate rate of diffusion of oxygen into cells in the heart, low ATP levels, and results in heart cell stop functioning causing a heart attack.

Stroke

Atherosclerosis or blood clot in a brain artery reduces blood flow and oxygen supply, inadequate rate of diffusion of oxygen into cells in the brain, low ATP levels, and brain cells/neurons stop functioning resulting in a stroke.

Factors that increase the risk of cardiovascular disease

Factors such as high salt diet, high energy intake, saturated fat intake, cholesterol, lack of antioxidants, smoking, obesity, high blood pressure, stress, older age, being male, and genetic inheritance.

Critiquing data linking risk factors to illness and mortality

Correlation does not confirm causation, Have other risk factors been ruled out, Are there parts of the graph/data that don’t fit the trend, error bars overlapping, anything in the design of the study, or any bias related to who did the research.

Features of a good study

Clear aim, representative sample that represents the population, large sample size, valid and reliable results with the necessary controls, and all relevant variables considered and controlled.

Energy Explained

Energy is gained in the form of dietary carbohydrates, fat and protein whose stored chemical energy is added to the body. These molecules are broken down in respiration. Energy expenditure is connected to BMR.

Energy imbalances and weight

When energy gain equals energy used there is no net weight gain or loss. When more energy is consumed than used, there is weight gain and when more energy is used than gained, there is weight loss.

Amylose (starch) Structural feature and Related function/properties

insoluble so does not affect water potential of cell and stores glucose (hydrolysed for use in respiration) in plants while being compact.

Amylopectin (starch) Structural feature and Related function/properties

● store of glucose in plants and greater storage of glucose per volume with more terminal ends increases rate of hydrolysis, and rate of supply of glucose for respiration.

glycogen Structural feature and Related function/properties

store of glucose in animals; greater storage of glucose per volume, and more terminal ends increases rate of hydrolysis, and rate of supply of glucose for respiration

Lipoproteins

Lipoproteins are triglycerides surrounded by a layer of phospholipid, protein and cholesterol and transport triglycerides in the blood.

Role of Lipoproteins in CVD

The ratio of HDL to LDL is correlated to CVD and a low HDL/LDL ratio is a risk factor for CVD . A high HDL/LDL ratio is thought to have protective effects against CVD.

Lifestyle changes that can reduce the risk of CVD

Lower BP, exercise more, reduce obesity, balanced energy intake and usage, stop smoking, reduce stress, and lower salt intake.

Investigation of the effect of caffeine on Daphnia heart rate steps

Range of different caffeine concentrations; place daphnia on cotton wool on microscope slide add drop of caffeine solution onto Daphnia; record heart rate in bpm; keep species, age/size, temperature, the same.

antihypertensives

reduce blood pressure reduces risk of damage to artery endothelium and reduces chance of atheroma forming

Diuretics

reduces blood volume, reduces blood pressure, reduces damage to endothelium, and reduces risk of atheroma formation

cholesterol lowering drugs

inhibitis the enzyme that produces LDL cholesterol (in the liver), and reduces risk of atherosclerosis

anti-blood clotting drugs

reduce chance of blood clot forming and reduce chance of blocked artery

What are the risks associated with CVD treatments

Antihypertensives can have side-effects such as dizziness, kidney disease, abnormal heart rhythms. Fluid build-up in the legs

Diuretics can cause dizziness, nausea and muscle cramps.

Statin side-effects include tiredness, vomiting, disturbed sleep, headache and muscle weakness

Anticoagulants drug side effects include high risk of bleeding in the gastrointestinal tract