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EDEXCEL BIOLOGY > TOPIC 1: Lifestyle, Health and Risk > Flashcards

TOPIC 1: Lifestyle, Health and Risk Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is mass flow system?

A

transports substances in bulk down a pressure gradient

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2
Q

What are the features of a mass flow system?

A
  1. circulatory fluid
  2. contracting pump
  3. tubes
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3
Q

Why do some organisms require a mass transport system?

A
  • small SA/V ratio, higher metabolic rate, increasing diffusion distance
  • overcome the limits of diffusion
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4
Q

How does blood circulate in an open circulatory system?

A
  • heart pumps blood into cavities

- when heart relaxes, blood is drawn back through valves

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5
Q

Why are closed circulatory systems better? (2)

A
  • blood enclosed in vessels and kept at high pressure throughout the body
  • oxygen concentration gradient high because oxygen and carbon dioxide don’t mix
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6
Q

What is a single circulatory system?

A
  • organs in series

- heart pumps deoxygenated blood to the gills where gas exchange takes place

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7
Q

What is a double circulatory system?

A

pulmonary and systemic circuits (blood passes through twice;

organs arranged in parallel

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8
Q

What is the advantage of organs being arranged in parallel?

A

all organs receive the same blood pressure and oxygen concentration is kept high for all organs

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9
Q

What are the advantages of having a double circulatory system?

A

blood flows through the heart twice so this gives the blood an extra boost, reducing time taken for blood to circulate around the body

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10
Q

Why do birds and mammals have double circulatory systems?

A

high metabolic rate as oxygen and glucose required for metabolic processes can be delivered to cells rapidly to meet organism’s needs

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11
Q

Why is the cardiac muscle on the left side of the heart thicker than the right?

A
  • left side needs to pump blood around the whole body

- pulmonary circuit needs a lower pressure to prevent damage to vessels in the lung

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12
Q

Why would 3 chambers not work for mammals, like they do for amphibians?

A
  • oxygenated and deoxygenated blood mix

- mammals are warm blooded and more active so they have a higher demand for O2

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13
Q

Why does water have a dipole?

A

v-shaped structure leads to uneven charge distribution

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14
Q

Describe water’s solvent properties & why they’re significant

A
  • good solvent for other polar molecules (i.e.salt) so hydrophilic molecules can be transported easily and vital biochemical reactions can take place in cytoplasm
  • bad solvent for hydrophobic molecules so lipid forms bilayer
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15
Q

Describe water’s thermal properties and significance

A
  • high specific heat capacity so water is a good temperature buffer
  • high latent heat of evaporation so organisms can cool down effectively as sweat evaporates without losing lots of water
  • high latent heat of fusion so organisms can survive in cold
  • water is liquid at room temp so good transport medium
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16
Q

Describe water’s density and significance

A

water has a higher density than ice so ice can form at the surface of water allowing organisms below to survive

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17
Q

Describe water’s hydrostatic property and significance

A

low compressibility allows buoyancy so organisms can survive in deep waters

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18
Q

Describe water’s attractive properties and significance

A
  • high cohesion (stick to one another) so water can travel up xylem vessels in unbroken columns
  • high adhesion so ware attracted to surfaces so water can travel up xylem due to capillary action
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19
Q

What is the function of arteries?

A

transport of blood & oxygen from heart to tissues

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20
Q

What is the function of veins?

A

transport of deoxygenated blood from tissues to heart

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21
Q

What is the function of capillaries?

A

exchange of materials between blood and tissues

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22
Q

Describe the structure of an artery

A
  • narrow lumen
  • thicker walls
  • more collagen, smooth muscle and elastic fibres to withstand pressure
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23
Q

Describe the structure of a vein

A
  • wide lumen
  • thinner walls
  • less collagen and smooth muscle, fewer muscle fibres
  • valves to prevent back-flow
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24
Q

Describe the structure of a capillary

A
  • no muscle

- narrow so one RBC can pass & blood can slow down due to friction to allow exchange between blood and tissues

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25
Q

Describe blood flow in veins

A
  • valves prevent backflow due to low pressure in veins

- veins pass between skeletal muscle which contract to squeeze vein

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26
Q

What are the steps in the cardiac cycle?

A

atrial systole, ventricular systole, cardiac diastole

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27
Q

What happens in atrial systole?

A
  1. Blood returns to the heart under low pressure due to skeletal muscle
  2. Atria fill without contraction due to higher pressure in veins
  3. As atria fill, pressure increases, forcing AV valves to open and blood leaks into ventricles
  4. Atria contract to force remaining blood into ventricles
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28
Q

What happens in ventricular systole?

A
  1. After a slight delay, ventricles contract from base upwards
  2. Pressure in ventricles increases so AV valves close to prevent blood from flowing back into aorta, and SL valves open
  3. Blood pushed out of arteries
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29
Q

What happens in cardiac diastole?

A
  1. Atria and ventricles relax due to elastic recoil (lower pressure results in back pull)
  2. SL valves close, preventing back flow into ventricles
  3. Coronary arteries fill
  4. Low pressure helps draw blood into atria from veins
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30
Q

Describe the route blood takes in the body

A

Body - Vena Cava - RA - (tricuspid valve) - RV - (pulp. semilunar valves) - Pulmonary Arteries - Lungs - Pulmonary Veins - LA - (bicuspid valve) - LV - (aortic semilunar valves) - Aorta - Body

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31
Q

What is the role of the pericardium? (2)

A
  • secretes lubricant to prevent friction

- connective tissue attaching heart to tissue

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32
Q

What is the role of the tendinous cords?

A

prevent valves from inverting

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33
Q

What is the pericardium?

A

outer layer of the heart

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34
Q

What is the role of the septum?

A

prevents oxygenated and deoxygenated blood from mixing

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35
Q

What is the role of the coronary arteries?

A

provide oxygen and glucose for aerobic respiration in cardiac muscle

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36
Q

What does the right side of the heart do?

A

receives deoxygenated blood and pumps it to the lungs

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37
Q

What does the left side of the heart do?

A

receives oxygenated blood from the lungs and pumps it to the body

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38
Q

What does the term myogenic mean, in terms of the heart?

A

can contract without external stimulation

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39
Q

How is heart rate controlled?

A
  1. Depolarisation at SAN, generating electrical impulse in wall of RA which spreads across atria, causing both to contract at the same time
  2. AVN node receives electrical impulse (0.13s delay before reaching ventricles)
  3. After delay, signal reaches Purkinje fibres and bundle of His
  4. First ventricular cells to be depolarised are at the apex of the heart so contraction is apex upwards
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40
Q

Why is there a 0.13s delay before the impulse from the AVN reaches the ventricles?

A

to ensure atria have fully contracted so ventricles are filled before they contract

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41
Q

What are contractions of cardiac muscle initiated by?

A

small changes in electric charge of cardiac muscle cells

slight negative = depolarisation

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42
Q

What does the P wave on an ECG represent?

A

atrial systole

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43
Q

What does the QRS complex on an ECG represent?

A

ventricular systole

44
Q

What does the T wave on an ECG represent?

A

diastole

45
Q

What does heart rate measure?

A

number of ventricle contractions per minute

46
Q

What is risk?

A

the probability of an unwanted event or outcome

47
Q

How can risk be calculated?

A

no. of people taking risk with unwanted outcome / total no. of people taking risk

48
Q

Why do people overestimate risk? (5)

A
  1. Undertaken involuntarily
  2. Unnatural/unfamiliar
  3. Unfair
  4. Rare
  5. Consequences are sudden
49
Q

Why do people underestimate risk? (5)

A
  1. Undertaken voluntarily
  2. Familiar
  3. Fair
  4. Common
  5. Consequences are long term
50
Q

What is a correlation?

A

a relationship between two variables

51
Q

What is a causation?

A

change in one variable is responsible for the change in the other

52
Q

How do you know if something is a causation?

A
  • controlled experiments to see if one variable has predicted effect
  • knowledge of mechanism for how one variable affects another
53
Q

What are the risk factors for CVD? (7)

A
  1. Age & gender
  2. High blood pressure
  3. Diet
  4. Blood cholesterol
  5. Genetic factors
  6. Obesity
  7. Smoking
54
Q

What is a cohort study?

A

prospective study where a group of people are followed over time to see who gets a disease

55
Q

What is a case-controlled study?

A

retrospective study where people with disease are compared to those without, to find risk factors

56
Q

What are the advantages of a cohort study?

A
  1. Determine causality of exposure to risk
  2. Minimises bias
  3. Measure disease incidence
57
Q

What are the disadvantages of a cohort study?

A
  1. More time & expensive
  2. Larger sample size needed
  3. Loss to follow-up bias
58
Q

What are the advantages of a case-control study?

A
  1. Less time & cheaper

2. Smaller sample size

59
Q

What are the disadvantages of a case-control study?

A
  1. Recall bias

2. Selection bias

60
Q

Define bias

A

introduction of a systematic error into a study by favouring one outcome over another

61
Q

What is selection bias?

A

choosing a group of participants that aren’t representative of the population

62
Q

What is recall bias?

A

systematic error caused by inaccurate recollection of past events

63
Q

What is loss to follow-up bias?

A

systematic error caused when study set-up increase likelihood of participants dropping out

64
Q

Why is age a risk factor for CVD?

A

arteries become less elastic, leading to high bp so likelihood of atherosclerosis increases

65
Q

Why is gender a risk factor for CVD?

A

women protected by oestrogen:

  • boosts HDL and decreases LDL
  • reduces likelihood of atherosclerosis
66
Q

What is blood pressure?

A

hydrostatic force of blood against vessel walls

67
Q

What does blood pressure depend on?

A
  1. Cardiac output (amount of blood)

2. Peripheral resistance (how much blood is in contact with the walls)

68
Q

What’s normal blood pressure?

A

120/80

69
Q

How is blood pressure controlled?

A
  1. Stretch receptors in carotid sinus detect increase in pressure
  2. Sensory nerves carries impulses to CVD centre in brain
  3. Inhibitory impulse sent via vagus nerve to SAN, slowing heart rate
  4. BP decreases
70
Q

Why is high blood pressure dangerous?

A

increases chance of damaging arteries and developing atherosclerosis

71
Q

What is atherosclerosis?

A

hardening of artery walls due to fatty deposits which can block the artery directly or increase the chance of it being blocked by a blood clot

72
Q

Describe how atherosclerosis develops

A

1 ENDOTHELIAL DYSFUNCTION: damage to endothelium due to high BP or toxins from cigs
2 INFLAMMATION: WBCs move to artery wall and deposit cholesterol so fatty deposit builds up
3 PLAQUE: calcium salts and fibrous tissues build up and artery wall loses elasticity
4 RAISED BP: lime becomes narrower, + feedback with further plaque formation

73
Q

When does blood clotting happen?

A

when platelets come into contact with damaged vessel walls and there are exposed collagen fibres

74
Q

Describe the process of blood clotting

A

1 - PLATELET ACTIVATION: platelets come into contact with vessel, releasing thromboplastin
2 - PLATELET PLUG: platelets stick to exposed collagen in wall
3 - BLOOD CLOTTING CASCADE
4 - FIBRIN MESH traps RBCs

75
Q

Describe the blood clotting cascade

A

1 - thromboplastin activates enzyme which convert prothrombin protein to thrombin enzyme (Via K & Ca ions)
2 - thrombin converts fibrinogen into fibrin

76
Q

What are the differences in structure of fibrinogen and fibrin?

A
  • fibrinogen is soluble and globular

- fibrin is insoluble and fibrous

77
Q

What is the estimated average requirement? (EAR)

A

energy intake which meets needs of 50% of people

78
Q

What is the lower reference nutrient intake (LRNI)?

A

energy intake which meets needs of only 2.5% of people

79
Q

What is the higher reference nutrient intake? (HRNI)

A

energy intake which meets needs of 97.5% of people (GDA)

80
Q

What is BMR?

A

energy expended when completely at rest for heartbeat, breathing and body temperature

81
Q

What is SDA (specific dynamic action)?

A

energy expended for metabolising food (eating, digestion and absorption)

82
Q

What is cholesterol?

A
  • water insoluble steroid
  • precursor for hormones
  • component of cell membranes
83
Q

Describe the structure of HDL

A
  • triglycerides with unsaturated fatty acids

- different apoproteins

84
Q

Describe the function of HDL

A

transports cholesterol to the liver for breakdown

85
Q

Describe the structure of LDL

A
  • triglycerides with saturated fatty acids

- apoprotein B only

86
Q

Describe the function of LDL

A

transports cholesterol from liver to cells

87
Q

How is cholesterol taken into cells?

A

1 - cells have LDL receptors on surface which bind to LDL
2 - LDL bound to receptor is taken up into cell by endocytosis
3 - LDL and receptor separated at low pH
4 - LDL receptors recycled back to cell surface
5 - LDL vesicle fuses with lysosome and is broken down

88
Q

What causes high cholesterol levels?

A
  • excess saturated fat from diet increases LDL

- not enough LDL receptors on cell surface so cholesterol remains in bloodstream

89
Q

Why is high blood cholesterol bad?

A

LDL can build up in artery walls leading to atheroma formation

90
Q

How can blood cholesterol levels be lowered?

A

unsaturated fat from diet increases HDL, which can scavenge cholesterol from atheroma and take it to the liver for breakdown

91
Q

How does smoking increase the risk of CVD?

A
  • CO reduces oxygen supply so heart rate increases to provide oxygen, increasing BP
  • nicotine constricts arteries, increasing BP
92
Q

What are free radicals?

A

highly reactive molecules with unpaired electrons (oxidising agents)

93
Q

How are free radicals formed?

A

UV light and ionising radiation

94
Q

Why are free radicals dangerous?

A

cause CVD by oxidising LDL and causing atherosclerosis

95
Q

How do antioxidants prevent CVD?

A

prevent oxidation of LDL by providing electrons for free radicals

96
Q

What are some sources of antioxidant?

A

vitamin C & E

97
Q

How do ACE inhibitors control blood pressure?

A

antihypertensive which reduces synthesis of angiotensin II, which causes vasoconstriction of vessels

98
Q

What are the side effects of ACE inhibitors?

A
  • dry cough
  • dizziness
  • reduction in kidney function
99
Q

How do calcium channel blockers control blood pressure?

A
  • antihypertensive
  • blocks calcium channels in muscle cells and artery lining
  • prevents contraction of muscle and constriction of blood vessel due to lack of calcium
100
Q

What are the side effects of calcium channel blockers?

A
  • fluid build up in legs

- worsens symptoms for people w/ heart failure

101
Q

How do diuretics control blood pressure?

A

increase urine volume so gets rid of excess fluids, reducing plasma volume and BP

102
Q

How do statins control blood pressure?

A

inhibit enzyme in production of LDL by liver, decreasing cholesterol and CVD risk

103
Q

How do anticoagulants control blood pressure?

A
  • interferes with production of Vit K and affects synthesis of clotting factors
  • reduced risk of thrombus blocking blood vessel
104
Q

How do platelet inhibitors control blood pressure?

A

reduces stickiness of platelets and likelihood of clot formaton

105
Q

What are the side effects if platelet inhibitors?

A

gastrointestinal bleeding

EDEXCEL BIOLOGY (14 decks)

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