Transport in Animals

Question 1

What are the left and right sides of the heart separated by?

Answer 1

a wall of muscular tissue called the septum

Question 2

How does the heart receive its blood supply?

Answer 2

through arteries on its surface called coronary arteries

Question 3

Why is it important that the coronary arteries remain clear of plaques?

Answer 3

as this could lead to angina or a heart attack

Question 4

Why does the heart require its own blood supply?

Answer 4

it is a muscle and so requires its own blood supply for aerobic respiration

Question 5

Why are valves important?

Answer 5

• they keep blood flowing forward in the right direction and stop it flowing backwards
• they also maintain the correct pressure in the chambers of the heart

Question 6

What are the names of the two blood vessels taking blood away from the heart?

Answer 6

pulmonary artery and aorta

Question 7

What is the name of the two blood vessels bringing blood to the heart?

Answer 7

vena cava and pulmonary vein

Question 8

What valve separates the left ventricle and aorta?

Answer 8

aortic valve

Question 9

What valve separates the left atrium and the left ventricle?

Answer 9

the mitral valve - the bicuspid valve

Question 10

What valve separates the right ventricle and the pulmonary artery?

Answer 10

pulmonary valve

Question 11

What valve separates the right atrium and right ventricle?

Answer 11

the atrioventricular valve - the tricuspid valve

Question 12

When do valves close?

Answer 12

when the pressure of blood in front of them is greater than the pressure behind them

Question 13

When do valves open?

Answer 13

when the pressure of blood behind them is greater than the pressure in front of them

Question 14

Why is the septum important?

Answer 14

it ensures blood doesn’t mix between the left and right sides of the heart

Question 15

Arteries

Answer 15

transport blood away from the heart (usually at high pressure) to tissues

Question 16

Arterioles

Answer 16

arteries branch into narrower blood vessels called arterioles which transport blood into capillaries

Question 17

Veins

Answer 17

transport blood to the heart (usually at low pressure)

Question 18

Venules

Answer 18

these narrower blood vessels transport blood from the capillaries to the veins

Question 19

What are the three layers of the artery wall?

Answer 19

tunica adventitia/externa, tunica media and tunica intima

Question 20

What is the tunica intima made up of?

Answer 20

an endothelial layer, a layer of connective tissue and a layer of elastic fibres

Question 21

What is the structure of the endothelium?

Answer 21

the endothelium is one cell thick and lines the lumen of all blood vessels - it is very smooth and reduces friction for free blood flow

Question 22

What is the tunica media made up of?

Answer 22

smooth muscle cells and a thick layer of elastic tissue

Question 23

Why do arteries have a thick tunica media?

Answer 23

• the layer of muscle cells strengthen the arteries so they can withstand high pressure; it also enables them to contract and narrow the lumen for reduced blood flow
• the elastic tissue helps to maintain blood pressure in the arteries; it stretches and recoils to even out any fluctuations in pressure

Question 24

Describe the type of circulatory system of a bird

Answer 24

double and closed circulatory system

Question 25

Describe how oncotic pressure is established

Answer 25

- large plasma proteins are too large to fit through fenestrations in capillary endothelial wall - so remain in blood, lowering water potential and generating a high hydrostatic pressure - water moves into blood by osmosis

Question 26

Explain how haemoglobin acts as a buffer

Answer 26

- CO2 and water form carbonic acid - carbonic acid dissociates giving H+ - H+ binds to haemoglobin - so CO2 can be carries as HCO3 -

Question 27

What does atrial fibrillation look like on an ECG?

Answer 27

- no visible P waves - irregular QRS complexes - a lot more additional smaller waves of differing sizes

Question 28

What do the walls of arteries contain so that they can stretch and recoil to maintain blood pressure?

Answer 28

a lot of elastic fibres

Question 29

How much muscle is in the walls of the venules?

Answer 29

little muscle

Question 30

Do the walls of arteries contain a lot of muscle fibres to contract and generate pressure in the blood?

Answer 30

No

Question 31

What is an ectopic heartbeat?

Answer 31

extra heartbeats outside of the normal rhythm

Question 32

Why do multicellular organisms require transport systems?

Answer 32

- large size (small surface area to volume ratio), subsequently high metabolic rates - demand for oxygen is high, so need a specialised system to ensure a strong supply to all respiring tissues

Question 33

Summarise the different types of circulatory system

Answer 33

- Open: blood can diffuse out of vessels e.g. insects - Closed: 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 34

Relate the structure of arteries to their function

Answer 34

Thick, muscular walls to handle high pressure without tearing. Elastic tissue allows recoil to prevent pressure surges. Narrow lumen to maintain pressure.

Question 35

Relate the structure of veins to their function

Answer 35

Thin walls due to lower pressure. Require valves to ensure blood doesn't flow backwards. Have less muscular and elastic tissue as they don't have to control blood flow.

Question 36

Relate the structure of capillaries to their function

Answer 36

- walls only one cell thick; short diffusion pathway - very narrow, so can permeate tissues and red blood cells can lie flat against the wall, effectively delivering oxygen to tissues - numerous and highly branched, providing a large surface area

Question 37

Relate the structure of arterioles and venules to their function

Answer 37

- branch off arteries and veins in order to feed blood into capillaries - smaller than arteries and veins so that the change in pressure is more gradual as blood passes through increasingly small vessels

Question 38

What is tissue fluid?

Answer 38

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

Question 39

What types of pressure influence formation of tissue fluid?

Answer 39

- 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.