Transport in Animals

Question 1

State 5 reasons why most animals need specialised transport systems.

Answer 1

• Very small SA:Vol ratio if you have a big multicellular ogranism.
• Metabolic demands of most multicellular organisms is high so diffusion over long distances is not enough to provide sufficient nutrients.
• Molecules such as hormones or enzymes may be made in one place but needed in another.
• Food will be digested in one organ system but needs to be transported to every cell to be used in respiration.
• Waste products of metabolism need to be removed

Question 2

Describe how diffusion distance, SA, Volume and SA:Vol ratio vary with increasing organism size.

Answer 2

• The bigger the organism the longer the diffusion distance is likely to be as some cells in the centre of the organism will be very far from the outside environment.
• The SA and volume will both increase with the size of the organism.
• The SA:Vol ratio will get smaller with the increasing of the organism.

Question 3

Describe how the level of activity of an organism is related to demand for oxygen and glucose.

Answer 3

• The higher the level of activity, the higher the demand is for oxygen and glucose due to increases levels of respiration in order to produce ATP.

Question 4

Explain how volume is related to demand and surface area is related to supply. Also explain why supply
meeting demand requires adaptations as organisms increase in size.

Answer 4

• A larger volume of organism means a larger volume of cells. More cells means a higher metabolic demand.
• Surface area gives a surface for the exchange of nutrients and gases. Therefore, a larger surface area means a faster supply.
• When the SA:Vol ratio is so small that the organism cannot meet its metabolic demands adaptions are required to develop a more efficient transport system.

Question 5

Define the term “mass flow”.

Answer 5

When substances are transported in a mass of fluid with a mechanism for moving the fluid around the body.

Question 6

Define circulatory system.

Answer 6

The transport system of an animal.

Question 7

Define the term open circulatory system.

Answer 7

A circulatory system with a heart but few blood vessels. The blood vessels open out into a pool of blood called the haemoceol.
Blood is not necessarily in blood vessels at all times.

Question 8

Define the term closed circulatory system.

Answer 8

A circulatory system with a heart and many blood vessels. The blood is always enclosed in blood vessels and it does not come into direct contacts with the cells beyond the walls of the vessels.

Question 9

Define the haemolymph.

Answer 9

The transport medium of blood in insects.

Question 10

Define the term single circulatory system.

Answer 10

A circulatory system where blood only passes through the heart for each complete circuit of the body.

Question 11

Define the term double circulatory system.

Answer 11

A circulatory system where the blood travels twice through the heart for each complete circulation of the body. The first circulation oxygenated blood is pumped by the heart to the lungs. In the second circulation oxygenated blood is pumped by the heart to the brain and body to supply cells with oxygen.

Question 12

Define the term pulmonary circulation.

Answer 12

Flow of blood away from the heart through the lung where oxygenation occurs and then returns to the heart again.

Question 13

Define the term systemic circulation.

Answer 13

The flow of blood away from the heart to the brain, liver, kidney, stomach and other organs, the limbs and the muscles of the body and then the return of this blood to the heart.

Question 14

State some examples of organisms with each type of circulatory system.

Answer 14

• A fishy has a closed and single circulatory system
• An insect has an open circulatory system, single?
• A human has a closed and double circulatory system.

Question 15

Describe the general features of circulatory systems and explain why certain organisms need mass flow.

Answer 15

• They have a liquid transport medium that circulates around the system.
• They have vessels that carry the transport medium.
• They have a pumping mechanism to move the fluid around the system.

Question 16

Draw a table to show the similarities and differences between, and advantages and disadvantages of,
open and closed circulatory systems.

Answer 16

Open:
- supply and disposal of materials is very slow. 
- Blood flow can't be regulated. 
- Blood flows at a slow velocity.
Closed:
- supply and disposal of materials is very fast. 
- blood flow can be regulated.
- blood flow is quite fast.

Question 17

Draw a table to show the similarities and differences between, and advantages and disadvantages of,
single and double circulatory systems.

Answer 17

Double:
- Double circulatory systems are important because they ensure that we are giving our tissues and muscles blood full of oxygen, instead of a mixture of oxygenated and deoxygenated blood.
- The blood pressure can be high in the systemic circuit while remaining low and safe in the pulmonary circuit.
- Requires more energy.
Single:
- Can only stay at one pressure, so it must always stay at low pressure so it doesn’t damage the capillaries.
- Fish aren’t as active so the single circulation is sufficient for their needs.

Question 18

. Explain the differences between the pulmonary and systemic circulations.

Answer 18

Pulmonary circulation refers to the circulation of blood in which deoxygenated blood is pumped from the heart to the lungs and oxygenated blood is returned to back to the heart. Pulmonary circulation only occurs between the heart and the lungs.
Systemic circulation refers to the circulation of blood in which oxygenated blood is pumped from the heart to the body and deoxygenated blood is returned back to the heart. Systemic circulation occurs between the heart and the entire body.

Question 19

List, in order, the sequence of blood vessel types that blood passes through once it leaves the heart.

Answer 19

Arteries —> Aterioles —-> Veins —-> Venules —> Capillaries

Question 20

Define the term “lumen”.

Answer 20

The hole in the centre of the blood vessel.

Question 21

State the three anatomical layers in arteries and veins.

Answer 21

From outer to inner:

• The tunica externa, mostly made up of collagen. Collagen provides support to stop the vessel from collapsing.
• The tunica media, layer that contains elastic fibres which allows expansions and recoiling to respond to pressure surges. Also contains smooth muscle which contracts and relaxes to control the size of the lumen.
• The tunica intima, a single layer of cells called the endothelium. Comes into direct contact with the blood so is very smooth to allow blood to move without resistance.

Question 22

State the anatomical layers in the capillary.

Answer 22

• A one-cell think endothelium(tunica intima).
• very little elastic tissue
• no collagen

Question 23

Compare the relative proportions of elastin fibres, smooth muscle and collagen in the aorta, mediumsized
arteries and arterioles and relate these to their function.

Answer 23

1) Elastin fibres - aorta has the most, then medium sized artery, then arteriole.
2) Smooth muscle - Medium sized artery has the most, then arteriole, then aorta.
3) Collagen - Aorta has the most, then arteriole, then medium sized artery.
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