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A Level Biology Edexcel A > Lifestyle And Health > Flashcards

Lifestyle And Health Flashcards

Topic 1

1
Q

Why do animals need a heart?

A
  • to generate pressure to pump blood around the body
    -mass transport
    -to overcome the limitations of diffusion
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2
Q

Define an open circulatory system

A

A simple heart pumps blood between cavities. Blood circulates in open areas. Substances diffuse between blood and cells.

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3
Q

Define a closed circulatory system.

A

Blood is enclosed within vessels, generating higher pressure. Blood travels from arteries to arterioles to capillaries and returns by venules to veins.

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4
Q

What are the properties of water that make it a good transport medium?

A

Water is polar as hydrogen is slightly positive and oxygen is slightly negative, forming a dipole. Other polar substances, as well as ionic and hydrophilic substances, can easily dissolve in water.

The specific heat capacity of water is very high to maintain homeostasis.

Water has a high boiling point due to the hydrogen bonds.

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5
Q

Describe the structure of an artery.

A

Narrow lumen, thick walls, more collagen, smooth muscle and elastic fibres

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6
Q

Describe the structure of a vein.

A

Wide lumen, thin walls, valves to prevent backflow.

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7
Q

Describe the structure of a capillary

A

Endothelium is one cell thick, small lumen.

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8
Q

What is the function of the coronary arteries?

A

To supply oxygen rich blood to the heart muscle.

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9
Q

What is the function of the thick smooth muscle layer in the artery?

A

To allow for contraction and relaxation (vasoconstriction) to control blood flow and maintain high blood pressure.

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10
Q

What is the function of the elastic fibre layer in the artery?

A

Allows artery to stretch and recoil and maintain high blood pressure.

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11
Q

What is the function of the smooth endothelium in the artery?

A

Reduces resistance to blood flow.

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12
Q

What is the function of the narrow lumen in the artery?

A

To maintain the high blood pressure

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13
Q

Why is capillary wall very thin (one cell thick)

A

Reduced diffusion distance/ pathway speeds up gas exchange.

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14
Q

Why do capillary walls have pores?

A

To allow the passage of molecules through the wall.

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15
Q

Why do capillaries have very narrow lumens?

A

Decreases the rate of blood flow to allow more time for exchange of substances.

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16
Q

What is the function of the outer collagen coat/ tissue in the artery?

A

Durable and strong to withstand high blood pressure.

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17
Q

Describe atrial systole.

A

High pressure. Atria fill with blood from the Vena Cava/Pulmonary Vein. Atrioventricular valves open. Blood flows into the ventricles. Atria contract.

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18
Q

Describe ventricular systole.

A

High pressure. Ventricles fill with blood. Semi-lunar valves open, atrioventricular valves close. Ventricles contract.

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19
Q

Describe diastole.

A

Low pressure. Atria and ventricles relax. Semi-lunar valves close. Coronary arteries fill.

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20
Q

Describe blood pressure

A

Measure of the hydrostatic force of blood against the vessel walls.

Elevated blood pressure is known as hypertension.

Units are millimetres of mercury - mmHg.

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21
Q

What is peripheral resistance?

A

Contact between the blood and vessel wall causes friction which slows the flow of blood.

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22
Q

What is systolic pressure?

A

The pressure during ventricular systole (highest).

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23
Q

What is diastolic pressure?

A

The pressure during ventricular diastole (lowest).

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24
Q

Describe the process of atherosclerosis.

A

The endothelium becomes damaged.
There is an inflammatory response causing white blood cells to move into the artery wall.
A fatty deposit (atheroma) builds up.
Calcium salts and fibrous tissues build up, causing a plaque.
The artery loses elasticity, narrows and hardens.
Causes a rise in blood pressure and dangerous positive feedback.

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25
Q

Describe the consequences of atherosclerosis.

A

Increases chance of blood clots blocking the artery. Cells are permanently damaged. May result in heart attack, stroke, tissue death or gangrene. An artery may burst due to build up of blood.

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26
Q

Describe the effects of Coronary Heart Disease.

A

Narrowed coronary arteries may lead to angina. Heart muscle lacks oxygen and has to respire anaerobically. Arteries blocked and are ischaemic (not enough blood flowing). If muscle cells are starved of oxygen for too long it results in an infarction.

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27
Q

Describe the clotting cascade reaction.

A

Platelets at the site of the damaged blood vessel release the protein thromboplastin.
Calcium ions and vitamin K from the plasma, with thromboplastin, trigger the conversion of soluble prothrombin protein into enzyme thrombin.
Thrombin then catalyses soluble fibrinogen into insoluble fibrin.
Fibrin is sticky and traps platelets and red blood cells to form a mesh.

Platelets in contact with damaged vessels become spheres instead of flattened discs. They stick to exposed collagen.

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28
Q

Describe the cause of a stroke.

A

If the supply of blood is interrupted, a stroke will happen. Blood clots blocking arteries may cause a stroke.

29
Q

Define a case-control study.

A

A group with the disease and a control group are compared to work out risk factors.

30
Q

Describe risk perception.

A

People will overestimate risk if:
it is out of their control
it is unnatural
it is unfamiliar
it is dreaded
it is unfair
or if the risk is very small.

31
Q

Describe some risk factors of CVD.

A

Age
Hereditary
Physical environment
Social environment
Lifestyle
Behavioural choices.

32
Q

Define a cohort study

A

Follows a large group of people over time to see who develops the disease in order to determine risk factors/the cause.

33
Q

What must a study have?

A

A clear aim
A representative, large sample
Controlled variables
Valid and reliable results.

34
Q

What is used to measure blood pressure?

A

A sphygomanometer

35
Q

Describe oedema.

A

Fluid builds up in tissues leading to swelling. Higher blood pressure leads to more fluid being forced out of capillaries.

36
Q

How are disaccharides formed?

A

Monosaccharides are joined together in a condensation reaction, producing water. They are joined by a glycosidic bond. They can be split by hydrolysis.

37
Q

Which two monosaccharides make maltose?

A

Glucose and glucose.

38
Q

Which two monosaccharides make lactose?

A

Glucose and galactose.

39
Q

Which two monosaccharides make sucrose?

A

Glucose and fructose.

40
Q

Describe the formation of starch.

A

Starch is made up of amylose, which is an unbranched chain, 1,4 glycosidic bonds and is cooked into a spiral, and amylopectin, which has side branches and 1,6 glycosidic bonds. Starch has low solubility in water and is compact.

41
Q

Describe glycogen.

A

Made up of alpha glucose. Has numerous side branches allowing rapid hydrolysis. 1,4 and 1,6 glycosidic bonds. Stored in liver and muscles. Used by bacteria, fungi and animals as an energy store.

42
Q

Describe triglycerides.

A

Insoluble in water but soluble in organic solvent.

Made up of one glycerol and three fatty acids linked by ester bonds in a condensation reaction producing three molecules of water.

43
Q

Describe the difference between saturated and unsaturated hydrocarbons.

A

Saturated hydrocarbons have the maximum number of hydrogens. They are straight, long chains with no double bonds. Solid at room temperature.

Unsaturated hydrocarbons have double bonds, causing kinks in the chain, preventing it from packing closely together. Liquids at room temperature. (Hydrogenation can saturate, addition of hydrogens, uses a nickel catalyst.)

44
Q

Describe low-density lipoproteins.

A

Saturated triglycerides, proteins and cholesterol combine. Transports cholesterol to body cells. May be deposited in artery walls.

Excess LDLs overload membrane receptors.

45
Q

Describe high-density lipoproteins.

A

Unsaturated triglycerides with a higher percentage of protein and a lower percentage of cholesterol. Transports cholesterol from body tissue to the liver, where it can be broken down. Lowers blood cholesterol levels and reduces plaques formed from atherosclerosis.

46
Q

Describe the role of antioxidants.

A

Radicals are highly reactive and damage cells. Vitamins protect against this damage.

47
Q

Explain what is meant by a multifactorial disease.

A

Many factors contribute to its development.

48
Q

Describe smoking as a risk factor.

A

Carbon monoxide binds to haemoglobin instead of oxygen, reducing the supply to cells, increasing heart rate.

Nicotine produces adrenaline, increases heart rate, causes arteries and arterioles to construct, raises blood pressure.

Chemicals in smoke damage endothelium of arteries - atherosclerosis.

Linked with reduced HDL + antioxidants.

49
Q

Describe the benefits of exercise.

A

Halves the risk of CHD.

Raises HDL cholesterol.

Reduces development chance of Type 2 diabetes.

50
Q

Describe salt as a risk factor.

A

Causes kidneys to retain water, higher fluid levels leads to higher blood pressure so can damage endothelium of artery wall.

51
Q

Describe stress as a risk factor.

A

Releases adrenaline, arteries and arterioles constrict, raises blood pressure.

52
Q

Describe excessive alcohol as a risk factor.

A

Leads to raised blood pressure, an irregular heartbeat, direct tissue damage, contributes to obesity increases risk of CVD.

Moderate consumption linked with raised HDL levels.

53
Q

Describe a diet high in saturated fats as a risk factor.

A

Increases cholesterol levels so atheroma formation is more likely.

54
Q

Describe age as a risk factor.

A

Blood pressure may increase.

Some loss of elasticity in blood vessels as age increases.

55
Q

Describe gender as a risk factor.

A

Lower risk of CVD in females before the menopause due to some protective mechanism caused by oestrogen.

56
Q

Describe high blood pressure (hypertension) as a risk factor.

A

Increases risk of damage to endothelium which increases risk of atherosclerosis.

57
Q

Describe obesity as a risk factor.

A

Increases blood pressure, increases cholesterol levels which results in atheromas and increases type 2 diabetes.

58
Q

What are antihypertensives?

A

Drugs which lower blood pressure which reduces the risk of atherosclerosis developing.

59
Q

Describe ACE inhibitors + their side effects.

A

Antihypertensives.

Inhibits synthesis of Angiotensin II which causes vasoconstriction.

Reduces vasoconstriction which lowers blood pressure.

Side effects - dizziness, dry cough, abnormal heart rhythm, reduced kidney function.

60
Q

Describe calcium channel blockers + their side effects.

A

Antihypertensives. Block calcium channels in muscle cells which prevents contraction so no vasoconstriction.

Side effects - headaches, dizziness, abnormal heart rate.

61
Q

Describe diuretics + their side effects.

A

Increases volume of urine. Decreases blood plasma volume and cardiac output, lowers blood pressure.

Side effects - nausea, dizziness

62
Q

Describe statins + their side effects.

A

Inhibits an enzyme producing LDLs which reduces LDL in blood.

Side effects - tiredness, nausea

63
Q

What are anticoagulants?

A

Drugs which prevents blood clotting which reduces risk of an artery becoming blocked.

64
Q

Describe the use of warfarin as an anticoagulant + its side effects.

A

Interferes with Vitamin K production which inhibits blood clotting process.

Side effects - serious bleeding.

65
Q

Describe the use of aspirin as an anticoagulant/ platelet inhibitor + its side effects.

A

Reduces the stickiness of platelets and the likelihood of clot formation.

Side effects - serious bleeding, stomach bleeding.

66
Q

Describe obesity indicators.

A

BMI
Waist-to-hip ratios

67
Q

What is the calculation for waist to hip ratio.

A

Waist circumference divided by hip circumference.

68
Q

Define basal metabolic rate.

A

The amount of energy used, per day, whilst at rest.

69
Q

Describe each component of blood clotting.

Platelet
Thromboplastin
Prothrombin
Thrombin
Fibrinogen
Fibrin

A

Platelet - A cell fragment that releases thromboplastin

Thromboplastin - A soluble enzyme that catalyses the conversion of prothrombin to thrombin (globular)

Prothrombin - A soluble plasma protein (globular)

Thrombin - an enzyme that catalyses the conversion of fibrinogen to fibrin (globular)

Fibrinogen - A soluble plasma protein (globular).

Fibrin - An insoluble (fibrous) protein that forms a mesh to trap red blood cells.

A Level Biology Edexcel A (5 decks)

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