3.1.2 transport in animals NOT ON MOCK

Question 1

Why do multicellular organisms require transport systems

Answer 1

They are large so have a small surface area to volume ratio and therefore have high metabolic rates. And the demand for oxygen is high, so need a specialised system to ensure a strong supply to all respiring tissues

Question 2

Summarise the different types of circulatory systems

Answer 2

Open: blood can diffuse out of vessels e.g. insects

Close to: blood confined to vessels e.g. fish, mammals

Single: blood passes through pump once per circuit of the body

Double: blood passes through heart twice per circuit of the body

Question 3

Relate the structure of arteries to their function

Answer 3

thick, muscular walls to handle high-pressure without tearing. Elastic tissue allows recoil to prevent pressure surges and narrow lumen to maintain pressure

Question 4

Relate the structure of veins to their function

Answer 4

Thin walls due to lower pressure. Valves to prevent back flow of blood. Have less muscular and elastic tissue as they don’t have to control blood flow

Question 5

Relate the structure of capillaries to their function

Answer 5

Was only one cell thick so they have a short diffusion pathway, very narrow so can permit tissues and red blood cells can lie flat against the wall, effectively delivering oxygen to tissues, also highly branched which means they have a large surface area

Question 6

Relate the structure of arterioles and venules to their function

Answer 6

They branch off arteries and veins in order to feed blood into capillaries. They are smaller than arteries and veins so that the change in pressure is more gradual

Question 7

What is tissue fluid

Answer 7

A watery substance containing glucose, amino acids, oxygen and other nutrients. It’s supplies these to the cells, while also removing any waste materials

Question 8

What types of pressure influence formation of tissue fluid

Answer 8

hydrostatic pressure: higher at arterial end of capillary than Venous end

Oncotic pressure: changing water potential of the capillaries as water moves out, induced by proteins in the plasma

Question 9

how is tissue fluid formed

Answer 9

As blood is pumped through increasingly small vessels, hydrostatic pressure is greater than oncotic pressure, so fluid moves out of the capillaries. It then exchanges substances with the cells

Question 10

How does tissue fluid differ from blood and lymph

Answer 10

Tissue fluid is formed from blood, but does not contain red blood cells, platelets and other various solutes usually present in blood. It contains less oxygen, nutrients and more products

Question 11

Describe what happens during cardiac diastole

Answer 11

The heart is relaxed. Blood enters the atria, increasing the pressure and pushing open the atrioventricular valves. This allows blood to flow into the ventricles. Pressure in the heart is lower than in the arteries, so semilunar valves remain closed

Question 12

Describe what happens during atrial systole

Answer 12

The atria contract, pushing any remaining blood into the ventricles

Question 13

Describe what happens during ventricular systole

Answer 13

The ventricles contract. Pressure increases, close in the atrioventricular valves to prevent back flow and opening the semilunar valves. Blood flows into the arteries

Question 14

How do you calculate cardiac output

Answer 14

Cardiac output is heart rate multiplied by stroke volume

Question 15

What does myogenic mean

Answer 15

The hearts contraction is initiated from within the muscle its self, rather than by nerve impulses

Question 16

Explain how the heart contracts

Answer 16

SAN Initiates and spreads impulse across the atria, so they contract. AVN Receives, delays and then conveys the impulse down the bundle of his. Impulse travels into the purkinye Fibres which branch across the ventricles so they contract from the bottom up

Question 17

Describe types of abnormal activity that may be seen on an ECG

Answer 17

tachycardia: fast heartbeat
bradycardia: slow heartbeat

fibrillation : irregular, fast heartbeat

ectopic: early or extra heartbeats

Question 18

Describe the role of haemoglobin

Answer 18

Present in red blood cells. Oxygen molecules bind to the haem groups and are carried around the body, then released where they are needed in respiring tissues

Question 19

How does partial pressure of oxygen affect oxygen haemoglobin binding

Answer 19

As partial pressure of oxygen increases, the affinity of haemoglobin for oxygen also increases, so oxygen binds tightly to haemoglobin. When partial pressure is low, oxygen is released from haemoglobin

Question 20

What do oxyhaemoglobin dissociation curve show

Answer 20

Saturation of haemoglobin with oxygen ( in percentage), plotted against partial pressure of oxygen in kilopascals. Curves further to the left show the haemoglobin has a higher affinity for oxygen

Question 21

describe the bohr effect

Answer 21

As partial pressure of carbon dioxide increases, the conditions become acidic causing haemoglobin to change shape. The affinity of haemoglobin for oxygen therefore decreases, so oxygen is released from haemoglobin

Question 22

Explain the role of carbonic anhydrase in the Bohr effect

Answer 22

Carbonic anhydrase is present in red blood cells. Convert carbon dioxide to carbonic acid, which dissociate to produce H + ions. these combine with a haemoglobin to form haemoglobinic acid. Encourages oxygen to dissociate from haemoglobin

Question 23

Explain the role of bicarbonate ions in gas exchange

Answer 23

Produced alongside carbonic acid. In the lungs, carbonate ions are converted back to carbon dioxide which we breathe out

Question 24

Describe the chloride shift

Answer 24

The intake of chloride ions across a red blood cells membrane. This repolarises the cell after bicarbonate ions have diffused out

Question 25

How does fetal haemoglobin differ from adult haemoglobin

Answer 25

The partial pressure of oxygen is low by the time it reaches the fetus, therefore fetal haemoglobin has a higher affinity for oxygen then adult

Question 26

ppq: Why is the delay between excitation of atria and ventricles essential

Answer 26

To allow time for the atria to fully contract/empty and the ventricles to fill so that ventricles don’t contract to early

Question 27

ppq: the purkyne tissue carries the Excitation wave down the septum to the apex of the heart. Explain why the excitation wave is carried to the apex

Answer 27

So that ventricular contraction starts at the apex, the bottom, to push blood upwards

Question 28

ppq: Describe and explain what happens to the blood plasma along the capillary

Answer 28

Plasma moves out of the capillary and forms tissue fluid. Plasma proteins remain in the capillary as they are too large to pass through capillary wall. The fluid moves down pressure gradient and hydrogen pressure is greater than water potential

Question 29

ppq: Describe how the action of the heart is initiated and coordinated

Answer 29

SAN Initiates excitation which spreads over atrial wall . Atrial systole Occurs and contraction is synchronised. There is a delay at AVN and excitation spreads down septum. Ventricular systole occurs from apex

Question 30

ppq: What is the name given to a trade show in the electrical activity of the

Answer 30

Electro cardiogram

Question 31

ppq: State to affects of digitalis on the activity of the heart

Answer 31

Heart rate is slower, diastole Longer, ventricle takes longer to contract

Question 32

ppq: describe the roles of SAN AND AVN In coordinating the cardiac cycle

Answer 32

SAN initiates heart beat and sends impulse over atria. AVN delays impulse and sends impulse down the septum

Question 33

ppq: How is hydrostatic pressure generated in the heart

Answer 33

Contraction of ventricle wall ventricular systole

Question 34

ppq: Explain why the hydrostatic pressure of the blood drops as blood moves away from the heart

Answer 34

There are more smaller vessels that have larger total surface area which reduces resistance to bloodflow as artery stretch and loss of plasma from capillaries

Question 35

ppq: Explain why it is important that the pressure changes as blood flows from the aorta to the capillaries

Answer 35

The capillary walls are thin and high-pressure would damage the capillary wall

Question 36

ppq: Suggest two advantages of keeping the blood inside vessels

Answer 36

It maintains high blood pressure and blood moves quicker

Question 37

ppq: Explain how pressure changes in the heart bring about the closure of the atrioventricular valve bicuspid

Answer 37

Tissue requires more oxygen for aerobic respiration and it produces more carbon dioxide. less haemoglobin available to combine of oxygen as involved in transport in carbon dioxide so bohr shift cause more oxygen to be released

Question 38

ppq: describe and explain how substances That are dissolved in the blood plasma into the tissue fluid from the capillaries

Answer 38

They enter by diffusion from an area of high concentration to low. Hydrostatic pressure in the capillary is higher than in tissue fluid and is more permeable and the fluid is forced out of the capillary

Question 39

ppq: Which to circulatory system is best described mammalian blood circulatory system

Answer 39

Close and double circulatory system

Question 40

ppq:Explain what causes the pressure to fluctuate as the blood flows along the aorta

Answer 40

systole Increases pressure, diastole decrease his pressure and ventricular systole increases pressure

Question 41

ppq: Explain why the fetal haemoglobin curve is to the left of the adult haemoglobin curve

Answer 41

The placenta has low partial pressure of oxygen an adult haemoglobin will release oxygen in the presenter. So fetal haemoglobin picks up more oxygen an adult as it has a high affinity for oxygen even when little is available

Question 42

ppq: State one difference between fetal haemoglobin an adult and give a reason why this difference is essential to the fetus

Answer 42

Fetal haemoglobin has a higher affinity for oxygen and this is essential because the fetal haemoglobin must be able to bind to oxygen in lower partial pressure in the placenta when the adult Oxy haemoglobin dissociates

Question 43

ppq:Explain why tissue fluid does not contain erythrocytes

Answer 43

The gaps are too small and erythrocytes are too large to fit between the gaps

Question 44

ppq:Describe the role of haemoglobin in transporting oxygen around the body

Answer 44

Haemoglobin has a high affinity for oxygen and the oxygen binds to haemoglobin in the lungs to make Oxy haemoglobin. Oxygen is then released in tissues when needed

Question 45

ppq: List the events that occurred during the cardiac cycle

Answer 45

Atrial walls start to relax, ventricle walls start to contract, S a node generates electrical signals, walls of atria contract, AV node receive electrical signals from SA node, electrical signals transmitted down septum, ventricle walls start to contract, AV valves close, ventricle walls relax, semilunar valves close

Question 46

ppq: Describe how the hydrogen carbonate ions are produced in the erythrocytes

Answer 46

Carbon dioxide enters into the white blood cells and combined with water to create carbonic anhydrase which catalyses and convert carbon dioxide to carbonic acid, which dissociates to produce H plus ions.

Question 47

ppq: Name the effect that high concentrations of carbon dioxide in the blood reduce the amount of oxygen transport to buy haemoglobin, and explain why occurs

Answer 47

bohr effect and it occurs to reduce the affinity of haemoglobin for oxygen and alter the shape of haemoglobin