💙 3.3.4.1 Mass Transport In Animals

Question 2

There are three stages to the cardiac cycle, name them.

Answer 2

1) atrial systole
2) ventricular systole
3) atrial and ventricular diastole

Question 3

What happens during the stage atrial systole ?

Answer 3

The ventricles are relaxed and the atria contract. This increases the pressure and decreases the volume in the atria, pushing the blood into the ventricles. The atrioventricular valves are opened.

Question 4

Describe what happens during ventricular systole

Answer 4

The atria relax and the ventricles contract. There is now more pressure in the ventricles so the atrioventricular valves close to prevent backflow. The pressure is also higher in the ventricles than in the atria and the pulmonary artery which forces the semi-lunar valves open as blood is forced into the arteries.

Question 5

Describe what happens during atrial and ventricular diastole

Answer 5

The atria and ventricles are both relaxed. The pressure increases in both the aorta, and the pulmonary artery (from elastic recoil) this forces the semi lunar valves to close. Blood returns to the heart as the pressure in the pulmonary vein and vena cava is greater than in the atria. As the ventricles continue to relax, there is a higher pressure in the atria so the atrioventricular valves open and blood trickles into the ventricles.

Question 6

What muscle is the heart made out of?

Answer 6

Cardiac muscle

Question 7

What is the heart described as?

Answer 7

A double pump

Question 8

Where does the heart squeeze the blood to and around?

Answer 8

Around the body and to the lungs

Question 9

Why does the right side pump blood to the lungs?

Answer 9

To pick up oxygen

Question 10

What does the left side of the heart do?

Answer 10

It pumps blood around the rest of the body

Question 11

What is the order of atrioventricular valves and semi-lunar valves opening and closing during the cardiac cycle?

Answer 11

Atrial systole - av open and sl close
Ventricular systole - sl open and av close
Atrial and ventricular diastole - av open and sl close

Question 12

What does the Aorta do?

Answer 12

Carries blood from the heart to the rest of the body and it is an artery.

Question 13

What does the vena cava do?

Answer 13

Carries blood back to the heart from the body and it is a vein

Question 14

What does the pulmonary artery do?

Answer 14

Carries deoxygenated blood to the lungs

Question 15

What does the pulmonary vein do?

Answer 15

Carries oxygenated blood back from the lungs to the heart

Question 16

What does the coronary artery do?

Answer 16

Take blood into the heart to supply it with glucose/oxygen for respiration

Question 17

What does the coronary vein do?

Answer 17

Take blood away from the heart itself

Question 18

What does the renal artery do?

Answer 18

Carries blood from the heart to the kidneys

Question 19

What does the renal vein do?

Answer 19

Carries blood back from the kidneys to the heart

Question 20

The pressure of the blood returning to the heart is low, what is one mechanism to assist with this?

Answer 20

On mechanism is the contractions of leg muscles as a person walks about. The veins are massaged with the contractions causing blood to be pushed towards the heart (it cannot move away due to the valves preventing back flow)

Question 21

What is the equation to work out cardiac output ?

Answer 21

Cardiac output = stroke volume x heart rate

Question 22

What is the cardiac output ?

Answer 22

The cardiac output is the volume of blood pumped by a heart in one minute

Question 23

What is the stroke volume?

Answer 23

The stroke volume is the volume of blood pumped by a heart in a single heartbeat

Question 24

What is the heart rate ?

Answer 24

Heart rate is the number of heartbeats in 1 minute

Question 25

What does 60/cycle time convert from and to?

Answer 25

From per second to per minute

Question 26

Put the blood vessels in order of pressure with the left being highest pressure and the right being lowest pressure.

Answer 26

Arteries - Arterioles - Capillaries - Venules - Veins

Question 27

What do arterioles have which allow them to contract?

Answer 27

Rings of smooth muscle

Question 28

Why does pressure decrease in blood vessels ?

Answer 28

This is due to the permeability of the capillaries causing them to loose water/small substances

Question 29

What is another reason for the drop in pressure in blood vessels?

Answer 29

Due to the friction between the walls of the blood vessels and the blood itself.

Question 30

What reduces the friction between the walls of the blood vessels and the blood itself?

Answer 30

The lumen on the blood vessel which is smooth with endothelial cells

Question 31

What is the function of arteries and arterioles ?

Answer 31

To take blood away from the heart to the tissue

Question 32

How do arteries and arterioles resist high-pressure?

Answer 32

They have thick walls with elastic layers and a smooth muscle layer

Question 33

What size is the lumen of an artery and arterioles?

Answer 33

It is small

Question 34

Do arteries and arterioles have valves?

Answer 34

No (except in the heart)

Question 35

Does the blood in arteries and arterioles have a high or low pressure?

Answer 35

High pressure

Question 36

What type of blood do arteries and arterioles carry?

Answer 36

The blood is usually oxygenated (except in pulmonary circulation)

Question 37

What is the function of a capillary?

Answer 37

The function of a capillary is to allow exchange of materials between the blood and the tissues

Question 38

What is the structure of capillaries that enable it to allow exchange materials?

Answer 38

Very thin, permeable walls which are only one cell thick to allow exchange of material

Question 39

How is the lumen of a capillary described?

Answer 39

Very small lumen so blood cells must distort to pass through

Question 40

Do capillaries have valves ?

Answer 40

No valves

Question 41

What happens to the pressure of the blood in the capillaries?

Answer 41

It drops

Question 42

What does the blood change to and from in capillaries?

Answer 42

Changes from oxygenated to deoxygenated (except in pulmonary circulation)

Question 43

What is the function of veins and venules ?

Answer 43

Carries blood from tissues to the heart

Question 44

How thick are the walls (what are they made of) in veins and venules and what is this due to?

Answer 44

Thin walls, mainly collagen, since blood at low pressure

Question 45

What is the size of the lumen in veins and venules and what is this due to?

Answer 45

Large lumen to reduce resistance to flow

Question 46

Do veins and venules have valves?

Answer 46

Many valves to prevent backflow

Question 47

What is the pressure of blood in veins and venules?

Answer 47

The blood has low pressure

Question 48

Is the blood in veins and venules oxygenated or deoxygenated?

Answer 48

The blood is usually oxygenated (except in pulmonary circulation)

Question 49

What is the first step for the formation and reabsorption of tissue fluid?

Answer 49

At the atriole end of the capillary there is a high hydrostatic pressure on the blood due to contractions of the left ventricle. The walls of the capillaries are permeable so small soluble molecules including water, glucose and oxygen are forced out. This is sometimes called ultrafiltration.

Question 50

What is the second step in the formation and reabsorption of tissue fluid?

Answer 50

The water and other substances form tissue fluid which baths the cells and is an exchange medium.

Question 51

What is the third step in the formation and re-absorption of tissue fluid?

Answer 51

The hydrostatic pressure drops towards the venule end of the capillary due to water lost and friction between the blood and the capillary walls. Also, large, insoluble proteins become more concentrated with the loss of water – decreasing the water potential pressure of the blood. Because the tissue fluid is mainly water, it has a high water potential pressure – higher than the pressure in the blood. Water moves into the blood from the tissue fluid, by osmosis, down is water potential gradient.

Question 52

What is the fourth step in the formation and reabsorption of tissue fluid?

Answer 52

Any excess tissue fluid drains into the lymphatic system

Question 53

At a low partial pressure, what affinity does haemoglobin have for oxygen ?

Answer 53

Low affinity for oxygen

Question 54

At a low affinity for oxygen does haemoglobin load or unload oxygen more readily to the (aerobically) respiring tissues?

Answer 54

Unloads oxygen more readily to the respiring tissues.

Question 55

At a high partial pressure of oxygen, does haemoglobin have a high or low affinity for oxygen ?

Answer 55

High affinity for oxygen

Question 57

If haemoglobin has a high affinity for oxygen, does it load or unload oxygen more readily?

Answer 57

It loads oxygen more readily

Question 58

What kind of protein is haemoglobin?

Answer 58

A quaternary protein

Question 59

How many polypeptide chains does haemoglobin have?

Answer 59

Four polypeptide chains

Question 60

What is at the centre of each polypeptide chain?

Answer 60

A prosthetic group which is an iron ion (Fe3+)

Question 61

What is it called when haemoglobin is fully loaded with oxygen?

Answer 61

Oxyhaemoglobin

Question 62

What is it called when haemoglobin is fully unloaded with oxygen?

Answer 62

Deoxyhaemoglobin

Question 63

Can haemoglobin be partially loaded with oxygen and how?

Answer 63

It can be partially loaded with any 1,2 or 3 of its polypeptide chains bound to oxygen

Question 64

What shape are oxygen dissociation curves?

Answer 64

Sigmoid shaped (s shaped)

Question 65

What happens when the first oxygen molecule binds to haemoglobin?

Answer 65

It binds with difficulty and when it does so it causes a change in the shape of the tertiary structure of haemoglobin

Question 66

How easily do the next two oxygen molecules bind to haemoglobin?

Answer 66

They bind far more easily than the first due to the change in shape (cooperative binding)

Question 67

How easily does the last oxygen bind to haemoglobin?

Answer 67

It binds with difficulty as there is only one binding site remaining

Question 68

Is there only one type of haemoglobin?

Answer 68

No, there are many types

Question 69

What happens when the curve on a dissociation graph shift to the right?

Answer 69

The haemoglobin has a lower affinity for oxygen, at the same partial pressure. More oxygen is therefore unloaded to the respiring tissues. Small animals have a large surface area to volume ratio so need to respire more to maintain their body temperature.

Question 70

What happens when the curve is shifted to the left on a dissociation graph?

Answer 70

There is a low partial pressure of oxygen therefore haemoglobin has a higher affinity for oxygen at the low partial pressure so loads more oxygen readily