topic 1 - lifestyle, health, and risk Flashcards
(93 cards)
1
Q
what is a single circulatory system
A
the blood only passes through the heart once
2
Q
what types of animals may have a single circulatory system
A
fish/animals with gills to oxygenate the blood
3
Q
what is a double circulatory system
A
the blood passes through the heart twice
4
Q
what is a closed circulatory system
A
blood flows through vessels (arteries, veins, capillaries, etc)
5
Q
what is an open circulatory system
A
blood pumped through cavities surrounding the animals organs
6
Q
which side of the heart receives deoxygenated blood, and pumps it to the lungs
A
right
7
Q
where do the pulmonary veins pump blood
A
from the lungs to the left side of the heart
7
Q
which side of the heart receives oxygenated blood and pumps it to the body
A
left
8
Q
where does the vena cava pump blood
A
from the body into the right side of the heart
9
Q
where does the aorta pump blood
A
from the left side of the heart to the body
10
Q
where does the pulmonary artery pump blood
A
from the right side of the heart to the lungs
11
Q
what’s the bottom of the heart called
A
apex
12
Q
what are the valves called at the entrance to the pulmonary artery and aorta
A
semilunar valves
13
Q
what is the difference between the superior and inferior vena cava
A
superior vena cava brings in deoxygenated blood from the head and arms, but the inferior vena cava bring deoxygenated blood from the lower body
14
Q
what are the differences between arteries and veins?
A
arteries have a more narrow lumen, thicker walls, more collagen, more smooth muscle, and more elastic fibres (has thicker walls as more of this), and no valves, whereas veins have valves
16
Q
what is a small artery called?
A
arteriole
17
Q
what is a small vein called?
A
venule
18
Q
what is systole?
A
the contraction of the heart
19
Q
what is diastole?
A
the relaxation of the heart
20
Q
how are artery walls well adapted for the cardiac cycle?
A
when blood is forced into arteries during systole, their elastic walls can stretch to accommodate the blood. they can withstand the high pressure generated. during diastole, the elasticity of the artery walls causes them to recoil behind the blood, pushing it forward
21
Q
why are capillaries good for gas exchange?
A
walls one cell thick - short diffusion pathway
narrow lumen - blood flows slower due to friction if the blood against capillary walls allows for more gas exchange
22
Q
how is blood drawn into the heart from the veins?
A
low pressure in the thorax when breathing
23
Q
how is blood flow through the veins assisted?
A
contraction of skeletal muscles (during movement and breathing) pushes blood forward
24
Q
what are the three phases of the cardiac cycle?
A
atrial systole, ventricular systole, and cardiac diastole
25
what happens during atrial systole?
blood returns to the heart. blood under low pressure flows into the atria, from the pulmonary veins and vena cava. as the atria fill, pressure increases, and the blood pushes open the atrioventricular valves, and blood begins to leak into the ventricles. the atria walls then contract to force more blood into the ventricles.
26
what happens during ventricular systole?
after a slight delay, the ventricles contract from the base of the heart upwards, which increases ventricular pressure. this forces open the semilunar valves, pushing blood up and out through the pulmonary arteries and aorta. the pressure of blood against the atrioventricular valves closes them and prevents backflow into the atria.
27
what happens during cardiac diastole?
the atria and ventricles relax. elastic recoil of the relaxing heart walls lowers pressure. blood under high pressure in the pulmonary arteries and aorta is drawn back towards the ventricles, closing the semilunar valves and preventing backflow into the ventricles. the coronary arteries fill. low pressure in the atria helps draw blood into the heart from the veins.
28
what happens in atherosclerosis?
the endothelium becomes damaged (maybe due to high blood pressure or toxins from cigarettes), which causes an inflammatory response. white blood cells move into the artery wall, and accumulate chemicals from the blood, particularly cholesterol, and build up a fatty deposit called atheroma. calcium salts and fibrous tissue also build up, resulting in a hard plaque on the inner wall. the fibrous tissue build up causes the artery wall to lose some elasticity. plaques cause the lumen to narrow, which will increase blood pressure. this could lead to a positive feedback loop
29
what could atherosclerosis lead to?
stroke, myocardial infarction (heart attack), or tissue death
30
what is the purpose of a blood clot?
seals the break in the blood vessel, limits blood loss, prevents entry of pathogens
31
how do platelets change during blood clotting?
they change from flattened discs to spheres with long thin projections when they come into contact with the damaged vessel wall
32
what happens during the clotting cascade?
platelets stick to damaged wall and each other, forming a platelet plug. platelets and damaged tissue release a protein called thromboplastin. thromboplastin activates an enzyme which catalyses the conversion of the protein prothrombin into an enzyme called thrombin (vitamin K and calcium ions must also be present). thrombin catalyses the conversion of soluble fibrinogen into insoluble fibrin. a mesh of fibrin forms that traps more platelets and red blood cells, causing a clot
33
what is the role of thromboplastin in the clotting cascade?
released from damaged tissue and platelets. when calcium ions and vitamin K present, activates an enzyme that catalyses the conversion of prothrombin into thrombin
34
what is the role of thrombin in the clotting cascade?
converted from prothrombin. enzyme which catalyses conversion of soluble fibrinogen into insoluble fibrin, which is used to form the mesh for the clot
35
how does atherosclerosis lead to myocardial infarction?
narrow arteries limit amount of oxygen-rich blood reaching the heart. this may result in chest pain (angina), as the cardiac muscle is working harder and needs to respire more. lack of oxygen means the heart muscle must respire anaerobically.
if a plaque in the coronary arteries rupture, collagen is exposed, leading to rapid clot formation, potentially blocking blood supply to the heart (heart is now ischaemic (without blood)). this is a heart attack. if muscle cells starved of oxygen for long, could cause permanent damage
36
how does a stroke occur?
if a blood clot blocks one of the arteries leading to the brain, a full stroke will occur. if brain cells starved of oxygen for more than a few minutes, they will be permanently damaged, and it can be fatal.
if blood supply to the brain only briefly interrupted, mini-stoke will occur. same symptoms but just shorter
37
what are the symptoms of coronary heart disease?
shortness of breath, angina, heaviness, burning, fatigue
38
what are the symptoms of a stroke?
numbness, dizziness, confusion, slurred speech, blurred/lost vision, paralysis on one side of the body
39
what is the definition of risk?
the probability of occurrence of some unwanted event or outcome
40
what features build a good study?
clear aim, representative sample, valid/reliable results, large sample size, and controlling variables well
41
what are the risk factors for CVD?
high blood pressure, obesity, high blood cholesterol, poor diet, smoking, inactivity, genetic predisposition, age
42
what is high blood pressure called?
hypertension
43
how is blood pressure reported?
systolic pressure over diastolic pressure
44
what is an average healthy blood pressure?
100-140mmHg (systolic pressure) over 60-90mmHg (diastolic pressure)
45
what is peripheral resistance?
contact between blood and the blood vessel walls, causing friction, and impeding the flow of blood
46
how is an oedema formed?
at the arterial end of a capillary, blood is under pressure, which forces fluid and small molecules (normally found in plasma) out through tiny gaps between the cells of the capillary wall, into intercellular space, forming tissue fluid (or interstitial fluid). larger molecules/cells cannot pass through the gaps. the tissue fluid drains into a network of lymph capillaries, which returns the fluid to the blood via a lymph vessel, emptying into the vena cava. if blood pressure rises above normal, more fluid may be forced out, fluid accumulates within the tissues, causing an oedema
47
how is a disaccharide formed?
two monosaccharides joining together via a condensation reaction
48
what is the general formula of a monosaccharide?
(CH2O)n
- n is the number of carbon atoms in the molecule
49
what are the three main heroes monosaccharides?
glucose, galactose, and fructose
50
what bond joins two monosaccharides to form a disaccharide?
glycosidic bond
51
what are the three main disaccharides?
sucrose, maltose, and lactose
52
which two monosaccharides form sucrose?
a-glucose and fructose
53
which two monosaccharides form maltose?
two a-glucose molecules
54
which two monosaccharides form lactose?
galactose and a-glucose
55
how are monosaccharides and poly/disaccharides absorbed differently?
monosaccharides are rapidly absorbed into the blood, causing a sharp rise in blood sugar. complex carbohydrates (poly/disaccharides)have to be digested into monosaccharides before being absorbed, so it is released more slowly
56
what are the three main types of polysaccharide?
starch and cellulose in plants, and glycogen in animals
57
how is the structure of starch suited for its function?
- compact - good for storage
- insoluble - do not affect water concentration cytoplasm, or movement of water via osmosis
58
what is the structure of amylose?
- unbranched/straight chain
- 1,4-glycosidic bonds
- forms spiral shape
- more compact
- digested slower than amylopectin, so gives gradual energy release
59
what is the the structure of amylopectin?
- 1,4 and 1,6 glycosidic bonds
- branched
- larger surface area than amylose, so digested more quickly
- faster energy release
- more easily digestible than amylose
60
what is the function of glycogen?
used by bacteria/fungi/animals instead of starch as an energy store
61
how is the structure of glycogen suited for its function?
- numerous side branches - can be rapidly hydrolysed, giving easy access to stored energy
62
what is a triglyceride?
a lipid used as energy stores in plants and animals. they are made up of 3 fatty acids and 1 glycerol linked by condensation reactions. the bond between the fatty acid and the glycerol is an ester bond (3 ester bonds in a triglyceride)
63
what is a saturated fat?
no carbon-carbon double bonds, contains the maximum amount of hydrogens
64
what are the features of a saturated fat?
- can pack closely together
- strong intermolecular bonds between triglycerides made up of saturated fatty acids make them solid at room temperature
65
what is a monounsaturated fat?
they have one double bond between two of the carbon atoms in each fatty acid chain
66
what is a polyunsaturated fat?
have a larger number of carbon-carbon double bonds
67
what are the features of an unsaturated fat?
- double bonds cause kink in the hydrocarbon chain, which prevents them from being able to pack closely together
- increased distance between molecules weakens he intermolecular forces between the unsaturated triglycerides, meaning they are liquid at room temperature
68
what is basal metabolic rate (BMR)?
the energy needed for essential processes, e.g. pumping of the heart, breathing, and maintaining a constant body temperature
69
how is BMI calculated?
body mass (in kg) is divided by height (in metres) squared
70
what is a lipoprotein?
insoluble cholesterol combined with proteins
71
why is cholesterol bad?
the higher your blood cholesterol level, the greater your risk of coronary heart disease
72
what are the two types of lipoprotein?
low-density (LDL) and high-density (HDL)
73
what do LDLs do?
transport the cholesterol to body cells. LDLs circulate in the bloodstream and bind to receptor sites on cell membranes before being taken up by the cells, where the cholesterol is used in the synthesis and maintenance of cell membranes. excess LDLs overload these membrane receptors, resulting in high blood cholesterol levels. this LDL cholesterol may be deposited in the artery walls, forming atheromas
74
what do HDLs do?
HDLs have a higher percentage of protein and less cholesterol. they are made wen triglycerides from fats combine with cholesterol and protein. HDLs transport cholesterol from body tissues to the liver, where it is broken down. this lowers blood cholesterol levels and helps remove fatty plaques of atherosclerosis
75
how does saturated fat in the diet affect HDL/LDL levels?
- increased saturated fat = increased LDL and HDL cholesterol, however greater increase in LDL
76
what is a trans-fat?
when hydrogen is added to the double bonds of unsaturated fats, making them saturated. these are sometimes produced by the food industry and used in processed food
77
how does smoking affect the circulatory system?
- carbon monoxide in the smoke binds to the haemoglobin instead of oxygen
- reduces supply of oxygen to cells
- results in increased heart rate as the body reacts to provide enough oxygen for the cells
- nicotine stimulates adrenaline production
- causes increased heart rate, an causes arteries and arterioles to constrict
- raises blood pressure
- chemicals in smoke can cause damage to artery lining
- triggers atherosclerosis
78
how does exercise affect the risk of developing CHD?
moderate exercise helps lower blood pressure, and raises HDL cholesterol without affecting LDL cholesterol levels
79
what genes increase the likelihood of CHD?
- FH mutations - cause LDL receptors (remove LDL from the blood) to not form or be less efficient
- APO mutations
80
what is an apolipoprotein?
the protein component of lipoproteins. have an important role in stabilising the structure of the lipoprotein recognising receptors involved in lipoprotein uptake on the plasma membrane of most cells
81
what are three types of apolipoprotein?
APOA, APOB, and APOE
82
what are unstable radicals and why are they bad?
- unstable radicals result when and atom has an unpaired electron
- radicals are highly reactive and can damage many cell components, including enzymes and genetic material
- this type of damage has been linked to the development of cancer, heart disease, and re mature ageing
83
why are antioxidants good?
they provide hydrogen atoms that stabilise radicals by pairing up with its unpaired electron, preventing them from doing any damage
84
why is a high-salt diet bad?
a high-salt diet causes the kidneys to retain water. higher fluid levels in the blood results in elevated blood pressure
85
why is alcohol a risk factor for CHD?
- heavy drinking raises blood pressure, contributes to obesity, and can cause irregular heartbeat
- excess alcohol consumption can result in direct tissue damage
- high levels of alcohol can damage liver cells, which impairs the ability of the liver to remove glucose and lipids from the blood
86
how can the risk of cardiovascular disease be reduces?
- stop smoking
- maintain resting blood pressure below 140/85 mmHg
- maintain lo blood cholesterol levels
- regular physical exercise
- maintain normal BMI/low waist-to-hip ratio
- moderate alcohol consumption
87
what are ACE inhibitors and how do they work?
ACE inhibitors are antihypertensive drugs which reduce the synthesis of a hormone which causes vasoconstriction. by preventing the hormone from being produced, vasoconstriction is reduced, and blood pressure is lowered
88
what are calcium channel blockers and how do they work?
calcium channel blockers are antihypertensive drugs that block the calcium channels in the muscle cells in the lining of arteries. for muscles to contract, calcium must pass through these channels into the muscle cells. failure of calcium to enter the cell prevents muscle contraction, the blood vessels do not constrict, and blood pressure is lowered
89
what are diuretics and how do they work?
diuretics increase the volume of urine produced by the kidney and therefore rid the body of excess fluids and salt. this leads to a decrease in blood plasma volume and cardiac output, which lowers blood pressure
90
what are statins and how do they work?
statins work by inhibiting an enzyme involved in the production of LDL cholesterol by the liver
91
what are the features of a diet which offers protection against cardiovascular disease?
- energy balanced
- reduced saturated fat
- more polyunsaturated fats
- reduced cholesterol
- reduced salt
- more non-starch polysaccharides
- includes oily fish
- more ruins and vegetables
92
how do anticoagulant drugs reduce blood clotting?
interferes with production of vitamin K, which reduces the conversion of prothrombin to thrombin, slowing the clotting cascade
93
what do platelet inhibitory drugs do?
reduce the stickiness of platelets, to reduce clotting
