7.3 Circulatory system of a mammal

Question 1

Why do large animals have a transport system?

Answer 1

• small organisms exchange over their body surface by diffusion
• with increased size, the surface area to volume ratio is too low so needs cannot be met by body surface diffusion
• specialist exchange surfaces are required in specific regions of the mammal
• also, as the animals have evolved tissues have become more dependent on each other

Question 2

What does the type of transport medium/ whether it uses a pump depend on?

Answer 2

• surface area to volume ratio

- how active the organism is

Question 3

What are the common features of transport systems?

Answer 3

• a suitable medium to carry materials
• a form of mass transport
• a closed system of tubular vessels
• a mechanism for moving the medium within vessels
• a mechanism to maintain mass flow movement in one direction
• a means of controlling the flow of the transport medium
• a mechanism for the flow of water and gases

Question 4

describe the suitable medium for carrying materials.

Answer 4

• generally liquid based on water so that substances can dissolve and be moved around easily. (EG: blood)
• can also be a gas and be breathed out.

Question 5

What is mass transport used for?

Answer 5

• moving around large quantities of the transport medium

- faster than diffusion

Question 6

What does the closed system of tubular vessels contain?

Answer 6

• the transport medium

- a branching network to reach all parts of the organism

Question 7

what is required for the mechanism for moving the transport system within vessels and how is this maintained?

Answer 7

A pressure difference is required, achieved by:

• muscular contraction of the body/organ
• plants rely on a passive process like the evaporation of water

Question 8

Why is a means of controlling the flow of the transport medium necessary?

Answer 8

to suit the changing needs of an organism.

Question 9

Describe the structure of the circulatory system in mammals.

Answer 9

• it is a closed double circulatory system- blood is confined to vessels and passes twice through the heart for every circuit of the body
• consists of veins, arteries, arterioles and capillaries

Question 10

Why is the mammalian circulatory system structured in the way it is?

Answer 10

• when blood is passed through the lungs, its pressure is low, so it is passed through the heart again to raise the pressure so that circulation doesn’t slow down
• this ensures that substances are delivered quickly and keeps the temperature high

Question 11

Which vessel takes blood away from the kidneys?

Answer 11

The renal vein

Question 12

Which vessel takes blood to the kidneys?

Answer 12

The renal artery

Question 13

Which vessel takes deoxygenated blood into the heart?

Answer 13

The vena cava

Question 14

Which vessel takes blood from the heart to the lungs?

Answer 14

the pulmonary artery

Question 15

Which vessel takes blood from the lungs to the heart?

Answer 15

the pulmonary vein

Question 16

Which vessel takes oxygenated blood away from the heart?

Answer 16

the aorta