1
Q
Why do large animals need a circulatory system?
A
They have a large SA:V so could not depend on diffusion alone to transport vital molecules around the body
2
Q
What are the 3 types of circulatory system?
A
- Open
- Single closed
- Double closed
3
Q
Characteristics of an open circulatory system
A
- Large open spaces
- Heart pumps
- Diffusion between blood and cells
- Diffusion is less efficient
4
Q
Characteristics of a single closed circulatory system
A
- Enclosed in vessels
- Can maintain pressure
- More efficient
5
Q
Characteristics of a double closed circulatory system
A
- Enclosed in vessels
- Transports to lungs and body
- High metabolic rate
6
Q
Describe the structure of the heart
A
- Double pump
- Made up of cardiac muscle
7
Q
What is special about the cardiac muscles?
A
They don’t fatigue
8
Q
What type of contraction is used by the cardiac muscles?
A
Myogenic: rate controlled by autonomic nervous system
9
Q
Which side of the heart receives deoxygenated blood?
A
The right side receives deoxygenated blood from the body and pumps it to the lungs
10
Q
Which side of the heart receives oxygenated blood?
A
The left sided receives oxygenated blood from the lungs and pumps it round the body
11
Q
Name the 3 blood vessels
A
- Arteries
- Veins
- Capillaries
12
Q
What are the three layers of a blood vessel from outside inwards?
A
- connective tissue with collagen fibres
- Muscle and elastic tissue
- Endothelium cells
13
Q
What are the differences between arteries and veins?
A
Arteries have a:
- A narrower lumen
- Thicker walls
- More collagen, smooth tissue and elastic fibres
- No valves
14
Q
What is the function of a valve?
A
To prevent backflow
15
Q
Name the 3 phases of the cardiac cycle
A
- Atrial systole
- Ventricular systole
- Diastole
16
Q
Describe phase 1 of the cardiac cycle
A
Atrial systole:
- Low pressure blood flows into the atria from the pulmonary veins and vena cava
- As the atria fill, the increasing blood pressure against the atrioventricular valves forces blood into the ventricles
- The atria walls contract, forcing more blood into the ventrices
17
Q
Describe phase 2 of the cardiac cycle
A
Ventricular systole
- The ventricles contract from the bottom upwards, increasing pressure
- The pressure forces open the semilunar valves and pushes blood out of the pulmonary arteries and aorta
- The pressure against the atrioventricular valves closes them and prevents back flow into the aorta
18
Q
Describe phase 3 of the cardiac cycle
A
Diastole
- Elastic recoil lowers the pressure in the atria and ventricles
- Blood under high pressure in the pulmonary arteries and aorta is drawn back towards the ventricles, closing the semilunar valves
- The coronary arteries fill during diastole; low pressure in the atria helps draw blood into the heart from the veins
19
Q
Describe atherosclerosis
A
- Damage to the endothelium cells
- An inflammatory response of wbc and lipids causing an atheroma
- Calcium and fibrous tissues harden the atheroma
- The atheroma makes the lumen becomes narrower which increases blood pressure = positive feedback
20
Q
What type of feedback is atherosclerosis?
A
Positive
21
Q
Name 3 effects of atherosclerosis
A
- Myocardial infarction (heart attack)
- Thrombosis
- Stroke (caused by thrombosis)
22
Q
Describe the clotting cascade
A
- Damage to the endothelium cells causes a platelet plug
- Releases thromboplastin
- Thromboplastin triggers the release of prothrombin. Prothrombin is then converted into thrombin.
- Thrombin triggers the release of soluble fibrinogen with triggers insoluble fibrin
- Clotting occurs
23
Q
What is high blood pressure also known as?
A
Hypertension
24
Q
What is systolic pressure?
A
Pressure in an artery when the ventricles have contracted and forced blood into the arteries
25
What is diastolic pressure?
Pressure in the artery when the ventricles are relaxed
26
What unit is blood pressure measured in?
mmHg
27
In blood pressure, it is one number over the top of another. What is the top number?
Systolic pressure
28
What should the average blood pressure be?
120/80
29
What is odema?
A sign of high blood pressure and is the build up of fluid in tissues, causing swelling
30
Describe the formation of odema
1. Blood is under pressure at the end of a capillary
2. Fluid and small molecules found in plasma are forced out of gaps between cells in the capillary wall into intercellular space
3. The tissue drains into a network of lymph capillaries which returns to the body via the vena cava
31
Sugars are either ... or ... or ...
Monosaccharides ... disaccharides ... polysaccharides
32
How many types of glucose are there?
2: alpha and beta
33
What type of sugar is glucose and how many carbon atoms does it have?
It is an example of a monosaccaride and is a hexose sugar with 6 carbon atoms
34
What is the difference between alpha and beta glucose?
In an alpha glucose, the H is above C1
35
True or false: disaccharides are formed with peptide bonds.
False: disaccharides are formed with glycosidic bonds (either 1-4 or 1-6)
36
Disaccharides are formed when 2 monosaccharides bond together in a condensation reaction. What do condensation reactions produce?
Water
37
Which 2 monosaccharides are found in maltose and what is maltose found in?
Glucose + glucose = mainly found in seeds
38
Which 2 monosaccharides are found in sucrose and what is it found in?
Glucose + fructose = carbohydrates
39
Which 2 monosaccharides are found in lactose and what is it found in?
Glucose + galactose = milk
40
Why are polysaccharides used as storage molecules?
they have a low solubility so don't affect movement of water
41
Give 3 examples of polysaccharides
- starch
- cellulose
- glycogen
42
Compare the 2 forms of starch
Amylopectin has 1-4 bonds and side branches formed by 1-6 bonds. Branching means it has more terminal ends for rapid hydrolysis
Amylose only has 1-4 bonds, creating straight, coiled chains
43
What are lipids insoluble and soluble in?
Lipids are soluble in organic solvents such as ethanol and insoluble in water
44
True or false: Most of the lipids we eat are triglycerides.
True
45
What are triglycerides made of?
3 fatty acids and glycerol which are bonded by ester bonds
46
What reaction removes water?
Condensation reactions move water from between the glycerol and fatty acids to form ester bonds
47
Describe the characteristics of a saturated fat
- no double carbon bonds
- long and straight
- solid at room temp
48
Describe the characteristics of a unsaturated fat
- have one double carbon bond between 2 carbon atoms
- contain kinks
- liquid at room temp
49
Is cholesterol a long or short lipid?
short
50
Where is cholesterol made and what is it made from?
It is made in the liver from saturated fats
51
What is the basal metabolic rate?
the rate at which the body uses energy while at rest to maintain vital functions such as breathing and keeping warm
52
In which 4 types of people is the BMR higher
-younger people
-heavier people
-more active people
males
53
What is the equation for body mass index?
body mass(kg) / height^2(m^2)
54
Describe what LDLs do
- They circulate in the blood and bind to receptor sites on cells before being taken into cells where cholesterol is
- excess LDLs overload the receptors, resulting in high blood cholesterol levels
55
Describe the structure of LDLs
Triglycerides combined with cholesterol and protein
56
Describe what HDLs do
- They transport cholesterol from the body tissues to the liver where it’s broken down
- this lowers cholesterol levels and helps remove fatty plaques
57
Describe the structure of HDLs
They have a higher percentage of protein and less cholesterol
58
Why are women less likely to get coronary heart disease?
Oestrogen increases the amount of HDL in the blood, meaning there is less LDL and therefore a lower chance of an atheroma forming
59
How can CVD be hereditary?
There can be a mutation in the LDL receptor gene which causes the receptor to be misshaped, meaning that if the LDL receptors can't remove some of the LDL, there is a higher risk of CHD
60
What are apolipoproteins, what is their structure and where are they found?
- They are the proteins component of lipoproteins
- a gene cluster
- mainly found in the liver and intestine
61
What are the 3 types of apolipoproteins?
- APOA = major protein in HDL
- APOB = main protein in LDL
- APOE = main component in HDLs and VLDLs (very low density lipoproteins
62
What are ACE inhibitors and how do they work?
- they are antihypertensives
- they reduce the production of angiotensin 2 (a hormone which causes vasoconstriction)
- side effects include: dizziness, dry cough
63
What are calcium channel blockers and how do they work?
- they are antihypertensives
- they block calcium channels in muscle cells lining arteries and lack of calcium prevents constriction, lowering BP
- side effects: swollen ankles, uneven heart rhythms
64
What are diuretics and how do they work?
- they are antihypertensives
- they increase the volume of urine produced and decrease blood plasma volume which lowers BP
- side effects: nausea, muscle cramps
65
What are anticoagulants and how do they work?
- they thin the blood which reduces the chance of clotting
- they are often give to people at high risk
- examples include aspirin and warfrin
- side effects: excessive bleeding, jaundice
SNAB A level Biology
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