circulatory system

Question 1

blood vessel names:

1. heart
2. lungs
3. liver
4. kidneys

Answer 1

1. coronary
2. pulmonary
3. hepatic
4. renal

Question 2

veins

Answer 2

• contains valves to prevent blood flowing backwards (not all veins have valves e.g. those in hands)
• wide lumen
• thinner walls with less muscle and elastic tissue than arteries
• carries blood at lower pressure.
• carries deoxygenated blood (except pulmonary vein)
• carries blood to heart

Question 3

arteries

Answer 3

• no valves
• narrow lumen
• thicker walls with more muscle and elastic tissue than veins to prevent bursting
• carries higher pressure blood
• carries oxygenated blood (except pulmonary artery)
• carries blood away from heart

Question 4

capillaries

Answer 4

• small vessels with walls made of a single layer of cells

- allow substances to pass easily from the blood into body cells

Question 5

electrocardiogram (ECG)

Answer 5

• the contraction of the heart muscle cells is coordinated using electrical impulses which pass between the different regions of the heart
• these impulses can be detected with an ECG which using electrodes placed on the skin to show the heart rate and rhythm
• the small bump shown on an ECG shows the electrical activity causing the atria to contract
• the large spike shows the electrical activity causing the ventricles to contract

Question 6

what factors can affect heart rate?

Answer 6

• exercise

- hormones e.g. adrenaline

Question 7

what effect does increased heart rate have on aerobic respiration?

Answer 7

blood can circulate faster and deliver more oxygen to muscle cells for aerobic respiration

Question 8

blood composition

Answer 8

• plasma 55%
• RBCs 44%
• WBCs and platelets 1%

Question 9

plasma

Answer 9

• watery liquid that the cells are transported in

- contains dissolved glucose, urea and amino acids, carbon dioxide and some proteins like hormones and antibodies

Question 10

RBC function and shape

Answer 10

• function: to transport oxygen around the body
• biconcave disc shape
• oxygen binds to the protein haemoglobin in the cytoplasm of the red blood cells

Question 11

mature red blood cell adaptations

Answer 11

• has a large surface area for diffusion of oxygen
• contains lots of haemoglobin protein in its cytoplasm
• has no nucleus or other structures to make more room for haemoglobin (so cannot replicate/ synthesise proteins)

Question 12

lymphocytes

Answer 12

• produce antibodies that target specific antigens on bacteria and viruses, destroying them
• some lymphocytes form memory cells which are involved in a secondary immune response (exposure to the same pathogen again)

Question 13

phagocytes

Answer 13

-engulf pathogens and digest them using enzymes to prevent damage to body cells

Question 14

platelets

Answer 14

• small fragments of cells
• contain no nucleus
• function: to help blood clot at a wound site, stopping blood loss and preventing microbes from entering the body
• clotting occurs when a series of enzymes convert the soluble protein fibrinogen into the insoluble fibrin, creating a mesh of fibres that traps platelets and RBCs to form the clot

Question 15

ABO system - blood groups

Answer 15

• the gene for the ABO system codes for the protein immunoglobulin (I) which is found on the cell surface membrane of RBCs
• the gene has three alleles but only two are present in any one person

Question 16

blood groups and genotype

Answer 16

• A: homozygous or heterozygous, IA allele is dominant to the IO allele.
• B: homozygous or heterozygous, IB allele is dominant to the IO allele.
• AB: IAIB, IA allele and IB allele are co-dominant so both are expressed
• O: homozygous recessive, IOIO

Question 17

blood group phenotype:

1. A
2. B
3. AB
4. O

Answer 17

antibodies present in blood plasma:

1. b
2. a
3. none
4. a and b

Question 18

blood transfusion donors and recipients

Answer 18

• A: donate=A and AB, receive=A and O
• B: donate=B and AB, receive=B and O
• AB: donate=AB, receive=universal recipient
• O: donate=universal donor, receive=O

Question 19

Why do we need gas exchange and transport systems?

Answer 19

• since we are large multicellular organisms we have a small SA:V ratio
• therefore, animals cannot rely on diffusion to provide oxygen to cells (this would take too long)
• thus, animals have a transport system which takes the oxygen close to a large number of cells throughout the body, ensuring that their cells are supplied with oxygen more rapidly

Question 20

hepatic portal vein

Answer 20

transports blood from small intestine to liver

Question 21

is blood an organ?

Answer 21

no it’s a tissue

Question 22

are skeletal muscles organs?

Answer 22

no they are tissues

Question 23

systole and diastole

Answer 23

• Systole is when the heart muscle contracts -> heart pushes the blood out of the heart and into the large blood vessels of the circulatory system -> blood pressure increases (systolic pressure)
• Diastole is when the heart muscle relaxes -> the chambers of the heart fill with blood -> blood pressure decreases (diastolic pressure)

Question 24

blood pressure

Answer 24

• blood pressure results consist of 2 numbers: 1st-systolic, 2nd-diastolic
• units: mm of mercury (mm Hg)
• normal: under 120/80

Question 25

heart valves

Answer 25

• Tricuspid valve = between RA and RV, open during diastole
• Bicuspid/mitral valve = between LA and LV, open during diastole
• Pulmonary valve = between RV and pulmonary artery, open during systole
• Aortic valve = between LV and aorta, open during systole