Circulation

Question 1

What are the three components of the circulatory system?

Answer 1

• blood ( 50-60% blood plasma, 40-50% red blood cells + white blood cells)
• blood vessels
• the heart

Question 2

How is rejection of organs prevented?

Answer 2

• a donor with a tissue type that closely matches the patient, based on similar antigens
• patient takes immunosuppressant drugs so that their immune system won’t attack the transplanted organ

Question 3

What are platelets?

Answer 3

• these are small fragments of cells with no nucleus
• help blood to clot a wound, by stopping blood pouring out and stoping microorganisms from getting in
• the reaction of clotting is controlled by enzymes
• fibrinogen (soluble protein) is changed into fibrin (insoluble solid fibres), the fibrin fibres tangle to form a mesh where platelets and red blood cells get trapped
• a lack of platelets may cause excessive bleeding and bruising

Question 4

What are the three different types of blood vessel?

Answer 4

• arteries: carry the blood away from the heart to the organs and tissues
• capillaries: these are involved in the exchange of matures in the organs and tissues
• veins: these carry the blood back to the heart

Question 5

What are stents?

Answer 5

• tubes inserted inside arteries

- keeping them open so blood can pass through

Question 6

What are the cons of artificial valves?

Answer 6

• major surgery

- blood clots

Question 7

Which blood type is universal donor?

Answer 7

• O type because it has no antigens on its surface

Question 8

Describe capillaries

Answer 8

• arteries branch into capillaries in the organs and tissues
• capillaries are very narrow and too small to see
• very close to the blood as it is the site of exchange
• thin, permeable walls so substance can diffuse in and out.
• very small lumen
• supply food and oxygen and take away CO2
• walls are one cell thick which increases the rate of diffusion by decreasing the distance over which it occurs

Question 9

What are antigens?

Answer 9

• proteins on the surface of cells

- they can trigger a response from a person’s immune system

Question 10

What do valves in the heart do?

Answer 10

• makes sure the blood flows in the right direction

- prevents it from flowing backwards

Question 11

What are the cons of stents?

Answer 11

• stents can irritate the artery, making scar tissue grow and so narrowing the artery
• have to take drugs to prevent blood clotting

Question 12

Why may a valve need to be replaced?

Answer 12

• valve tissue may have stiffened, so doesn’t open properly

- valve may have become leaky, so flows in both directions, not as effective circulaton

Question 13

What is blood?

Answer 13

• a tissue

Question 14

What are the disadvantages of artificial hearts?

Answer 14

• surgery to fit one may causes bleeding and infection
• doesn’t work as well as natural hearts. it may wear out or motor could fail
• blood doesn’t flow through artificial hearts as smoothly, may lead to blood clots and strokes
• they have to take blood thinners to stop clotting, but not good if they bleed

Question 15

What do the blood types represent?

Answer 15

• they refer to the type of antigens on the surface of the person’s red blood cells

Question 16

What is the double circulatory system?

Answer 16

• the first one pumps deoxygenated blood to the lungs to take in oxygen, then the blood returns to the heart
• the second one pumps oxygenated blood around all the other organs of the body. the blood gives up its oxygen at the body cells and the deoxygenated blood returns to the heart to be pumped out of the lungs again

Question 17

Describe veins

Answer 17

• capillaries eventually join up to form veins
• blood is at lower pressure, so walls are not as thick
• large lumen to help blood flow despite lower pressure
• valves to keep blood flowing in the right direction and prevents backflow

Question 18

Describe how the heart uses its four chambers to pump blood around

Answer 18

• blood flows into the two atria from the vena cava and the pulmonary vein
• the atria contract, pushing the blood into the ventricles
• the ventricles contract, forcing the blood into the pulmonary artery and the aorta and out of the heart
• blood then flows to the organs through arteries and returns through veins
• atria fill again and cycle repeats

Question 19

What are biological valves?

Answer 19

• valves taken from humans or other mammals

Question 20

What is an artificial pacemaker?

Answer 20

• it is used to control heartbeat if the natural pacemaker cells don’t work properly.
• it is implanted under the skin and has a wire going to the heart. it produces an electric current to keep the heart beating regularly

Question 21

What are red blood cells and its function?

Answer 21

• carries oxygen from the lungs to all the cells as haemoglobin binds to oxygen to form oxyhaemoglobin
• bi-concave shape to increase surface area for absorbing oxygen
• no nucleus allows more room to carry oxygen
• contains a red pigment called haemoglobin
• in the lungs, oxygen diffuses from the alveoli into the blood. haemoglobin binds with the oxygen to from oxyhemoglobin
• in the body tissues, oxyhemoglobin splits up into haemoglobin and oxygen, releasing oxygen which diffuses into the cells

Question 22

Why could a donor organ be rejected by the recipient’s immune system?

Answer 22

• foreign antigens on the donor organ are attacked by the patient’s antibodies

Question 23

What happens if an anti-A (or B) antibody meets and A (or B) antigen?

Answer 23

• blood clumps together, known as agglutination

Question 24

Why can AB receive blood from anyone?

Answer 24

• it has no antibodies

- it has A and B antigens

Question 25

How is your resting heart rate controlled?

Answer 25

• it is controlled by a group of cells in the right atrium wall that act as a pacemaker
• these cells produce a small electric impulse which spreads to the surrounding muscles cells, causing them to contract

Question 26

What is coronary heart disease?

Answer 26

• coronary arteries that supply the blood to the muscle of the heart gets blocked by fatty deposits
• this causes the arteries to become narrow, so blood flow is restricted and there is a lack of oxygen to the muscle
• may result in heart attack

Question 27

Describe arteries

Answer 27

• artery walls are strong and elastic because heart pumps blood out at high pressure
• thick walls, to prevent rupture due to pressure
• narrow lumen
• thick layers of muscles to make them strong
• elastic fibres to allow them to stretch and spring back

Question 28

What is plasma?

Answer 28

• carries everything in the blood
• red, white blood cells and platelets
• nutrients e.g. glucose and amino acids, absorbed from digestion
• CO2 from the organs to lungs
• urea from liver to the kidneys
• hormones
• antibodies and antitoxins produced by white blood cells

Question 29

What is the circulatory system?

Answer 29

• its main functions is to transport substances to every cell in the body and also removes substances from cells

Question 30

What is an artificial heart?

Answer 30

• mechanical device put into a person to pump blood
• usually temporary, used to keep a person alive whilst waiting for a donor heart, or for recovery to allow heart to heal itself
• artificial hearts are less likely to be rejected by the body’s immune system as they are made of metal or plastic, so they are not recognised as foreign

Question 31

What do white blood cells do?

Answer 31

• they can change shape to engulf microorganisms
• produce antibodies to fight microorganisms
• produce antitoxins to neutralise toxins produced by microorganisms

Question 32

What are mechanical valves?

Answer 32

• man made valves

Question 33

What is the heart and what is it made of?

Answer 33

• a pumping organ that keeps blood flowing around the body

- it is made of mostly muscle tissue