7.3 - Circulatory system of a mammal

Question 1

why is a specialist exchange surfaces required to absorb the necessary amount of nutrients and respiratory gases in larger organisms

Answer 1

• as the size of an organism increases
• SA grows disproportionately to volume
• resulting in a lower SA:Vol, and therefore the organism can’t rely on their body surface alone for efficient exchange.

Question 2

what determines if an organism’s exchange system is specialised

Answer 2

• the SA:vol
• how active the organism is (metabolic rate)

Question 3

what are some of the common features of any organism’s transport system

Answer 3

• A suitable medium in which materials are carried (e.g. blood).
• form of mass transport in which the transport medium is moved around in bulk over large distances – more rapid than diffusion
• A closed system of tubular vessels that contains the transport medium and forms a branching network to distribute it to all parts of the organism
• A mechanism for moving the transport medium within vessels. This requires a pressure difference between 1 part of the system and another.
• a mechanism to maintain the mass flow movement in one direction (e.g. valves)
• A means of controlling the flow of the transport medium to suit the changing needs of different parts of an organism
• A mechanism for the mass flow of water or gases (e.g. intercostal muscles and diaphragm during breathing in mammals)

Question 4

describe the composition of most transport mediums

Answer 4

• It’s normally liquid based on water because water readily dissolves substances and can be moved around the body easily
• but can be a gas such as air breathed in/out of long

Question 5

what are the ways that a mechanism for moving the transport medium achieved

Answer 5

• animals use muscular contractions of body muscles or a specialised pumping organ (e.g. heart)
• Plants rely on natural, passive processes such as evaporation

Question 6

what type of circulatory system do mammals have

Answer 6

• a closed, double circulatory system
• in which blood is confined to vessels and passes x2 through the heart for each complete circuit of the body

Question 7

why does blood pass through the heart x2 for each complete circuit of the body

Answer 7

• when blood passes through the lungs, its pressure is reduced
• if it were to pass immediately to the rest of the body, its low pressure would make circulation very slow
• therefore it returns back to the heart in order to boost its pressure, before being returned to the tissues
• this is important because animals have a high body temp and hence a high rate of metabolism

Question 8

what are the 3 vessels that make up the circulatory system of a mammal

Answer 8

• arteries
• veins
• capillaries

Question 9

Name the blood vessel that joins the right ventricle of the heart to the capillaries of the lungs

Answer 9

pulmonary artery

Question 10

Name the blood vessel that carries oxygenated blood away from the heart

Answer 10

aorta

Question 11

Name the blood vessel that carries deoxygenated blood away from the kidney

Answer 11

renal vein

Question 12

Name the blood vessel that is the 1st main blood vessel that an oxygen molecule reaches after being absorbed from an alveolus

Answer 12

pulmonary artery

Question 13

Name the blood vessel that has the highest blood pressure

Answer 13

aorta

Question 14

State 2 factors that make it more likely that an organism will have a circulatory pump such as the heart

Answer 14

• low surface area to volume ratio
• a high metabolic rate

Question 15

state the main advantage of the double circulation found in mammals

Answer 15

it increases blood pressure and therefore the rate of blood flow to tissues

Question 16

Label the parts highlighted in yellow

Answer 16