3.4.1 Mass Transport in Animals

Question 1

Haemoglobin

Answer 1

Large protein with quaternary structure, made of four polypeptide chains. Each chain has a haem group with an iron ion. Each haemoglobin can carry four oxygen molecules

Question 2

Association/loading

Answer 2

Oxygen molecule joins to haemoglobin

Question 3

Dissociation/unloading

Answer 3

Oxygen leaves oxyhaemoglobin

Question 4

High partial pressure of oxygen

Answer 4

Haemoglobin affinity for oxygen increases. Oxygen loads onto haemoglobin to form oxyhaemoglobin where there’s a high pO2. Oxyhaemoglobin unloads its oxygen where there’s a lower pO2 (respiring tissues)

Question 5

Dissociation curve

Answer 5

Binding of first O2 molecule alters shape and makes it easier for other O2 molecules to join. As haemoglobin becomes saturated, harder for other molecules to join

Question 6

Carbon dioxide concentration

Answer 6

High CO2 concentration at respiring cells increases rate of oxygen unloading

Question 7

Bohr effect

Answer 7

Saturation of blood with oxygen lower, so more oxygen being released. Dissociation curve shifts due to pCO2

Question 8

Low oxygen environments

Answer 8

Organisms have haemoglobin with higher affinity for oxygen, good at loading oxygen

Question 9

High activity levels

Answer 9

Haemoglobin with lower affinity for oxygen, need to easily unload oxygen at respiring tissue

Question 10

Effects of size on haemoglobin

Answer 10

Small mammals have a higher surface area to volume ration, so high metabolic rate so high oxygen demand

Question 11

Function of circulatory system

Answer 11

Multicellular organisms have low surface area to volume ration, require specialised mass transport system to carry raw materials from specialised exchange organs to cells

Question 12

Pulmonary artery

Answer 12

Carries blood from the heart to the lungs

Question 13

Pulmonary vein

Answer 13

Carries blood from lungs to the heart

Question 14

Aorta

Answer 14

Carries blood from the heart to the body

Question 15

Vena cava

Answer 15

Carries blood from the body to the heart

Question 16

Renal artery

Answer 16

Carries blood from the body to the kidneys

Question 17

Renal vein

Answer 17

Carries blood from the kidneys to the vena cava

Question 18

Coronary arteries

Answer 18

The heart’s own blood supply, has a right and left one

Question 19

Arteries

Answer 19

Thick and muscular walls with elastic tissue to maintain high pressure. Inner lining (endothelium) is folded, allowing artery to stretch and maintain high pressure

Question 20

Arterioles

Answer 20

Arteries divide into smaller vessels called arterioles. Directs blood using muscles inside arteriole, contracts to restrict blood flow or relaxes

Question 21

Veins

Answer 21

Wider lumen with little elastic or muscle so blood under low pressure. Contain valves to prevent blood flowing backwards. Blood flow helped by contraction of body muscles

Question 22

Capillaries

Answer 22

Arterioles branch into capillaries, smallest blood vessels. Substances exchanged between cells so adapted for efficient diffusion. Always found near cells in exchange tissue and walls are one cell thick, short diffusion pathway. Large number of capillaries to increase surface area for exchange

Question 23

Capillary beds

Answer 23

Networks of capillaries in tissue

Question 24

Tissue fluid

Answer 24

Fluid which surrounds the cells in tissues. Doesn’t contain red blood cells or big proteins. Substances move out by pressure filtration

Question 25

Pressure filtration at arterioles

Answer 25

Nearer the arteries, higher hydrostatic pressure in capillaries from left ventricle contracting. Hydrostatic pressure in capillaries reduces lowers as tissue fluid forms

Question 26

Pressure filtration at venule end

Answer 26

Due to fluid loss and increasing concentration of plasma proteins, water potential at venule end is lower than tissue fluid. Some water re-enters at venule end by osmosis. Excess tissue fluid drained into lymphatic system which passes fluid back to circulatory system

Question 27

Left ventricle

Answer 27

Thicker, more muscular walls than right ventricle. Allows it to contract more powerfully and pump blood through whole body

Question 28

Ventricles

Answer 28

Thicker walls than atria to push blood out of heart, atria only push blood to ventricles

Question 29

Atrioventricular (AV) valves

Answer 29

Link atria to ventricles and stops blood flowing back to atria when ventricle contracts

Question 30

Semi-lunar (SL) valves

Answer 30

Link ventricles to pulmonary artery and aorta, stops blood flowing back into the heart after ventricles contract

Question 31

Cords

Answer 31

Attach atrioventricular valves to the ventricles to stop them being forced up into the atria when ventricles contract

Question 32

Heart valves

Answer 32

If pressure higher behind, forced open. If higher pressure in front, forced shut. Unidirectional flow of blood

Question 33

Cardiac cycle Step 1

Answer 33

Ventricle relaxes, atria contracts and decreases volume (increases pressure), pushes blood to ventricle

Question 34

Cardiac cycle Step 2

Answer 34

Ventricles contract, atria relaxes. Pressure higher in ventricles than atria which forces AV valves shut. Pressure forces SL valves open and blood forced out through arteries

Question 35

Cardiac cycle Step 3

Answer 35

Ventricles relax, atria relaxes. Higher pressure in pulmonary artery and aorta closes the SL valves. Blood returns to atria which increases pressure in atria but lower pressure in ventricle allows for blood to passively flow into the ventricle

Question 36

Cardiac output

Answer 36

Stroke volume * Heart rate

Question 37

Heart rate

Answer 37

The number of beats per minute

Question 38

Stroke volume

Answer 38

The volume of blood pumped during each heartbeat, measured in cm^3

Question 39

Coronary heart disease

Answer 39

Type of cardiovascular disease, occurs when coronary arteries have lots of atheromas which restricts blood flow. Leads to myocardial infarction

Question 40

Atheroma formation

Answer 40

If damage occurs to endothelium, white blood cells and lipids clump together under lining to form fatty streaks. Harden to form an atheroma which partially blocks the lumen and restricts blood flow, causing blood pressure to increase

Question 41

Aneurysm

Answer 41

Balloon-like swelling of the artery. After an atheroma, blood travelling at high pressures pushes the inner layers of the artery though the outer elastic layer. The aneurysm may burst and cause a haemorrhage

Question 42

Thrombosis

Answer 42

Formation of a blood clot. An atheroma may rupture the endothelium of the artery which damages the wall and leaves a rough surface where platelets and fibrin accumulate to form a blood clot. May cause complete blockage or becomes dislodged and blocks a blood vessel

Question 43

Myocardial infarction (heart attack)

Answer 43

If coronary artery is blocked, area of the heart doesn’t receive oxygen, causing a heart attack

Question 44

High blood pressure

Answer 44

Can be caused by not exercising or being overweight, increases risk of damage to the artery wall, causes atheroma formation which can lead to blood clots and myocardial infarction

Question 45

High blood cholesterol and poor diet

Answer 45

Cholesterol one of the main components of the fatty deposits that form atheromas. High salt increases risk of high blood pressure

Question 46

Cigarette smoking

Answer 46

Carbon monoxide combines with haemoglobin and reduces amount of oxygen available. Smoking reduces amounts of antioxidants (needed to protect cells from damage)