3.4.1: Mass transport in animals

Question 1

Where are the coronary arteries?

Answer 1

Branch off from aorta

Question 2

Why is the left ventricle thicker than the right ventricle?

Answer 2

Right ventricle pumps blood through pulmonary arteries only and the left ventricle is pumping blood through a larger number of capillaries around the whole body

Question 3

Describe heart structure

Answer 3

• Deoxygenated blood returns from body in the vena cava and enters the right atrium
• Blood passes through atrio-ventricular valve in the right ventricle and out by the semi-lunar valve into the pulmonary artery.
• Blood passes through lungs and oxygenated blood returns into the left atrium by the pulmonary vein
• Blood passes through atrio-venticular valve into the left ventricle and through the semi-lunar valve into the aorta

Question 4

What is systole?

Answer 4

Contraction of heart muscle

Question 5

What is diastole?

Answer 5

Heart muscle relaxed

Question 6

Cardiac cycle:

Answer 6

1) Diastole - Blood enters atrium, blood volume increases in atrium. Pressure in atrium grater then in ventricle. AR valve opens.
2) Atrial systole - atrium muscles contract further increasing pressure, blood forced into ventricle from atrium.
3) Ventricular diastole - Ventricular muscle walls are relaxed. AV valve closes
4) Ventricular systole - ventricle muscles contract, increasing pressure until its greater than in artery. SL valve opens. Blood enters artery
5) diastole - Pressure in ventricle is less than artery. SL valve closes. Blood enters atrium

Question 7

Equation for cardiac output

Answer 7

cardiac output = stroke volume x heart rate

Question 8

Why do mammals require a double circulatory system?

Answer 8

• manage the pressure of blood flow

Question 9

What is the name for the blood vessels associated with the kidneys?

Answer 9

renal

Question 10

Artery outer layer

Answer 10

made of fibrous proteins, gives support and strength to resist damage due to high blood pressure

Question 11

Artery muscle middle layer

Answer 11

smooth - contractions construct vessel to reduce volume of blood passing through vessel to increase blood pressure.

Question 12

Artery elastic layer (3)

Answer 12

• thick
• Stretch as blood flows past to stop pressure rising too high
• Recoils one blood passes to maintain hydrostatic pressure

Question 13

Artery inner layer (2)

Answer 13

• smooth endothelial cells to reduce friction and give smooth flow
• One cell thick

Question 14

What is the function of an artery? (3)

Answer 14

• transports blood from heart to organ
• Blood under high pressure
• thick wall to withstand pressure

Question 15

Arteriole

Answer 15

• Smaller than arteries and connects them to capillaries

Question 16

Outer layer arteriole

Answer 16

made of fibrous proteins, gives support and strength to resist damage due to high blood pressure

Question 17

Arteriole muscle layer

Answer 17

• Thicker
• Contracted to constrict vessel to reduce flow to organ so more oxygen can be delivered to respiring muscle

Question 18

Arteriole elastic layer

Answer 18

Thinner - blood pressure is lower less elasticity needed for pulse of blood

Question 18

Arteriole inner layer

Answer 18

• one cell thick
• Smooth endothelial cells to reduce friction and a smooth flow

Question 19

Capillary function

Answer 19

Exchange of materials between blood and tissues
- Small diameter and a large number to create greater friction and larger surface area reducing blood pressure and flow

Question 20

Capillary inner layer (3)

Answer 20

• One cell thick
• Smooth endothelial cells to reduce friction and smooth flow
• Fenestrations (pores)

Question 21

Vein elastic layer

Answer 21

• Thin
• Low pressure walls don’t need to stretch and recoil

Question 22

Vein function (4)

Answer 22

• Carries blood back to heart from tissues
• Valves - blood flows in one direction
• Low blood pressure
• Blood moves along by squeezing of muscles

Question 23

Vein muscle layer

Answer 23

• Thinner - no need for vaco-constriction as blood is going back ti the heart

Question 24

Formula for saturation

Answer 24

(oxygenated haemoglobin / maximum saturation) x 100

Question 25

Why is the oxygen dissociation curve a sigmoid shape?

Answer 25

First O2 molecule alters the tertiary structure of haemoglobin. This exposes the second and third O2 binding sites which makes it easier for the second and third O2 molecules to bind and load

Question 26

What is the Bohr shift?

Answer 26

At higher partial pressure of CO2 haemoglobin affinity for oxygen is even lower. If partial pressure of CO2 increases the saturation of haemoglobin decreases. This causes the oxygen dissociation curve to shift to the right.

Question 27

Why does haemoglobin have a lower affinity to O2 at higher levels of CO2?

Answer 27

When CO2 dissolves in the blood it makes the blood more acidic, lowering the pH. Haemoglobin is a protein so this alters the terry structure.

Question 28

Describe haemoglobin when there is a lower partial pressure of o2?

Answer 28

• Dissociation curve shifts to the left
• Haemoglobin has a higher affinity for O2
• Become fully saturated at a lower partial pressure of O2
• Rapidly unloaded when haemoglobin passes through tissues

Question 29

Describe how tissue fluid is formed and how it’s returned to the circulatory system.

Answer 29

Formation:
- In arteriole end the blood has higher hydrostatic pressure
- Forces fluid out
- Large proteins remain in capillary

Return
- Lower water potential in capillary
- Due to plasma proteins
- Water enters capillary
- By osmosis
- Excess water is removed from tissues by lymph vessels