6. The circulatory system of mammals

Question 1

The mammalian cardiovascular system is designed to

Answer 1

meet the oxygen needs of all the cells in the body

If body cells are deprived of oxygen, they die

Question 2

The mammalian transport system is made up of

Answer 2

the heart and blood vessels

Question 3

Unlike plants, mammals require a transport system that moves oxygen and carbon dioxide around their bodies because

Answer 3

mammals are much more active than plants, which means that their cells require more energy and therefore respire more rapidly.

Cells therefore need constant deliveries of oxygen and must have the carbon dioxide produced in respiration taken away.

Moreover, mammals do not have branching bodies like those of plants, so their surface area : volume ratio is usually much smaller.

Many cells in a mammal are a long way from the gas exchange surface, so diffusion would not be sufficient to supply them with their needs

Question 4

what is the mass of the heart of an adult human

Answer 4

around 300 g and is about the size of your fist

It is a bag of muscle, filled with blood

Question 5

Figure 6.2 Diagram of the external structure of a

human heart, seen from the front

Answer 5

chegg

Question 6

The muscle of which the heart is made is called

Answer 6

cardiac muscle.

This muscle is able to contract and relax rhythmically, 24 hours a day, throughout your life.

Question 7

The heart is the pump that

Answer 7

keeps blood moving through the arteries

Question 8

The circulatory system of a mammal is

Answer 8

 a closed system

 a double circulation

Question 9

The circulatory system of a mammal is a closed system because

Answer 9

blood flows inside vessels in its journey around the body.

At no point does blood flow out of these vessels except where there is a cut; and blood clots quickly to seal external and internal wounds to limit blood loss.

Question 10

The heart is the pump that keeps

Answer 10

the blood flowing through the circulation

Question 11

the three main types of blood vessel in a closed system

Answer 11

arteries, capillaries and veins.

Question 12

blood is a

Answer 12

tissue composed of red and white blood cells, platelets and plasma

Question 13

An artery is

Answer 13

a vessel that carries blood away from the heart throughout the body

Question 14

A vein is

Answer 14

a vessel that carries blood towards the heart

Question 15

what are the smallest blood vessels

Answer 15

Capillaries

Question 16

what is primarily responsible for the movement of blood inside veins

Answer 16

The contraction of skeletal muscle pressing against veins

Question 17

benefits of cardiac muscle

Answer 17

Cardiac muscle is highly resistant to fatigue and its muscle cells have very large numbers of mitochondria

Cardiac muscle fibres contract involuntarily; they branch, interconnect, relay signals to each other and help to synchronize the heartbeat

Question 18

The major portion of the heart is called the

Answer 18

myocardium

Question 19

where is the heart located

Answer 19

the heart is located behind the breastbone between the left and right lungs

Question 20

what surrounds the heart

Answer 20

A thick membranous sac called the pericardium surrounds the heart

Question 21

Diffusion is fast enough for transport over

Answer 21

short distances

Question 22

The efficient supply of materials over larger distances requires a

Answer 22

mass transport system

Question 23

All organisms exchange materials between

Answer 23

themselves and their environment.

Question 24

Specialist exchange surfaces are required to absorb

Answer 24

nutrients and respiratory gases, and remove excretory products

Question 25

A transport system is required to take materials from

Answer 25

cells to exchange surfaces and from exchange surfaces to cells

Question 26

Whether or not there is a specialised transport medium, and whether or not it is circulated by a pump, depends on two factors:

Answer 26

the surface area to volume ratio,

and how active the organism is.

Question 27

The lower the surface area Lo volume ratio, and the more active the organism, the greater is the need for

Answer 27

a specialised transport system with a pump

Question 28

why multicellular organisms need transport systems

Answer 28

in multicellular organisms, oxygen obtained by the respiratory system and nutrients processed by the digestive system must be transported to cells throughout the body.

At the same time, carbon dioxide and other waste products produced within the cells must be returned to the respiratory, digestive, and urinary systems for elimination from the body

Question 29

Over large distances in organisms, efficient supply of

materials is provided by

Answer 29

mass transport

Question 30

the transport systems of many organisms have many common features:

Answer 30

• a suitable medium in which to carry materials (example blood)
  This is normally a liquid based on water because water readily dissolves substances and can be moved around easily, but can be a gas such as air breathed in and out of the lungs.
• A 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 pans of the organism.

-A mechanism for moving the transport medium within vessels.
This requires a pressure difference be tween one part of the system and another.