Exchange Surfaces And Breathing

Question 1

What are the 3 main factors that effect the need for an exchange system

Answer 1

Size
Surface area to volume ratio
Level of activity

Question 2

Describe how size effects the need for a transport system

Answer 2

In very small organisms, such as single-celled organisms, all the cytoplasm is very close to the
environment in which they live. Diffusion will supply enough oxygen and nutrients to keep the cells
alive and active. However, multicellular organisms may have several layers of cells. Here, any oxygen
or nutrients diffusing in from the outside have a longer diffusion pathway. Diffusion is too slow to
enable a sufficient supply to the innermost cells.

Question 3

Describe how surface area to volume ratio affects the need for a exchange rate

Answer 3

Surface area to volume ratio
Small organisms have a small surface area, but they also have a small volume. Their surface area is
relatively large compared with their volume. We say that they have a large surface area to volume ratio. This
means that their surface area is large enough to supply all their cells with sufficient oxygen (see Table 1).
Larger organisms have a larger surface area, but they also have a larger volume. As size increases,
the volume rises more quickly than the surface area. Therefore, their surface area is relatively small
compared with their volume. We say that they have a small surface area to volume ratio.
Some organisms increase their surface area by adopting a different shape. An animal such as a
atworm has a very thin, flat body. This gives it a larger surface area to volume ratio (SA V). But suc
body form limits the overall size that the animal can reach. Most large organisms need a range of
sues to give the body support and strength. Their volume increases as their body gets thicker, but
anism is relatively small.

Question 4

Describe how the level of activity affects the need for a exchange surface

Answer 4

Some organisms are more active than others , metabolic activity uses energy from food and requires oxygen to release the energy in aerobic respiration , the cells of an active organism need good supply of nutrients and oxygen to supply the energy for movement. This need for energy is increased in those animals such as mammals that keep themselves warm

Question 5

What are the features of a good exchange surface

Answer 5

Large surface area to provide more space for molecules to pass through , this is often achieved by folding the walls and membranes involves

A thin barrier to reduce the diffusion distance and that barrier must be permeable to the substance being exchanged

A good supply of blood , this can bring fresh supplies of molecules to one side , keeping the concentration high or it may remove molecules from the demand side to keep the concentration low , this is important to maintain a steep concentration gradient so that diffusion can occur rapidly

Question 6

Define alveoli

Answer 6

Tiny folds of the lung epithelium to increase the surface area

Question 7

Define bronchi and bronchioles

Answer 7

Smaller airways leading into the lungs

Question 8

Define diaphragm

Answer 8

A layer of muscle beneath the lungs

Question 9

Define intercostal muscles

Answer 9

Between the ribs , contraction of the external intercostal muscles raise the ribcage

Question 10

Define trachea

Answer 10

The main airway leading from the back of the mouth to the lungs

Question 11

Define ventilation

Answer 11

The refreshing of the air in the lungs , so that there is a higher oxygen concentration than in the blood , and lower carbon dioxide concentration

Question 12

Define lungs

Answer 12

A pair of inflatable sacs lying in the chest cavity

Air can pass into the lungs through the nose and along the trachea , bronchi and bronchioles - then reaches alveoli

Question 13

The lungs are protected by

Answer 13

The rib cage

Question 14

The ribs are held together by

Answer 14

The intercostal muscles

Question 15

Describe gaseous exchange in the lungs

Answer 15

Gases pass by diffusion through the thin walls of the alveoli. Oxygen passes from the air in the alveoli to the blood in the capillaries. Carbon dioxide passes from the blood to the air in the alveoli. The lungs must maintain a steep concentration gradient in each direction in order to ensure that diffusion can continue

Question 16

What are the adaptations to reduce the distance the gases have to diffuse in the gaseous exchange

Answer 16

• alveolus wall is one cell thick
• the capillary wall is 1 cell thick
• both consist of squamous cells
• the capillaries are in close contact with the alveolus walls

Question 17

How does a good blood supply help gaseous exchange

And how does the body do this

Answer 17

Maintains a steep concentration gradient

• the blood system transports carbon dioxide fro the tissues to the lungs . This ensures that the concentration of Veblen dioxide in the blood is higher than that in the air of the alveoli . Therefore carbon dioxide diffuses into the alveoli

The blood also transports oxygen away from the lungs , this ensure that the concentration of oxygen in the blood is kept lower than that in the alveoli - so that oxygen diffuser into the blood

Question 18

Ventilation ensures that

Answer 18

• the concentration of oxygen in the air of the alveolus remains higher than that in the blood
• the concentration of carbon dioxide in the alveoli remains lower than that in the blood

Therefore the concentration gradient necessary for diffusion is maintained

Question 19

Inspiration / inhaling process

Answer 19

The diaphragm contacts to move down and become flatter

The external intercostal muscles contract to raise the ribs

The volume of the chest cavity is increases

The pressure in the chest cavity drops below the atmospheric pressure

Air is moved into the lungs

Question 20

Expiration / exhaling process

Answer 20

The diaphragm relaxes and is pushed up by the displaced organs underneath

The external intercostal muscles relax and the ribs fall , the internal intercostal muscles can contract to help push air out more forcefully

The volume of the chest cavity is decreased

The pressure in the lungs increases and rises above the pressure in the surrounding atmosphere

Air is moved out of the lungs

Question 21

Define cartilage

Answer 21

A form of connective tissue

Question 22

Define ciliated epithelium

Answer 22

A layer of cells that have many hair like extensions called cilia

Question 23

Define elastic fibres

Answer 23

Protein fibres that can deform and then recoil to originals size

Question 24

Define goblet cells

Answer 24

Cells that secrete mucus

Question 25

Define smooth muscles

Answer 25

Involuntary muscles that contact without the need for conscious thoughts

Question 26

Describe lung tissues

Answer 26

Lin consists of large numbers of tiny air filled sacs called alveoli , these are comprised of squamous epithelium and are surrounded by blood capillaries so that the distance that gases must diffuse is very short. The alveolus walls contain elastic fibres that stretch during inspiration but then recoils to help push air out during expiration . The alveolus walls are so thin that it may not be possible to distinguish separate cells under a light microscope

Question 27

describe the airways and what theyre lined with

Answer 27

includes the trachea, bronchi and bronchioles allows the passage of air into the lungs and out again the airways are lined by ciliated epithelium which contributes to keeping lungs healthy . goblet cells in the epithelium release mucus which traps pathogens . the cilia then move the mucus up to the top of the airways where it is swallowed . the glandular tissue in the loose tissue also produces mucus

Question 28

to be effective , airways must meet certain requirements , which are ?

Answer 28

- to be large enough to allow sufficient air to flow without obstruction - to be supported to prevent collapse when the air pressure inside is low during inspiration - be flexible in order to allow movement

Question 29

describe the trachea and bronchi and what there made up of

Answer 29

bronchi are narrower than the trachea these airways are supported by rings of cartilage which prevent collapse during inspiration . the ring of cartilage in the trachea are c- shaped rather than a complete ring which allows flexibility and space for food to pass down the oesophagus

Question 30

describe the bronchioles and what there made up of

Answer 30

they are much narrower than the bronchi . the larger bronchioles may have some cartilage , but smaller ones have no cartilage. the wall is comprised of mostly smooth muscle and elastic fibres the smallest bronchioles end in clusters of alveoli

Question 31

describe smooth muscles and elastic tissue

Answer 31

the smooth muscles can contract . the action of the smooth muscles will constrict airways this makes the lumen of the airways narrower. Constrictions of the lumen can restrict the flow of air to add to and from the alveoli . controlling the flow of air to the alveoli might be important if there are harmful substances in the air . the contraction of smooth muscles and control of airflow is not a voluntary act and may occur as a result of an allergic reaction . once the smooth muscle has contracted it cannot reverse this effect on its own. the smooth muscles is elongated again by the elastic fibres . when the muscles contract , it deforms the elastic . as the muscles relax, the elastic fibres recoil to the original sixe and shape . this acts to dilate the airways

Question 32

define breathing rate

Answer 32

the number of breaths per minute

Question 33

define oxygen uptake

Answer 33

the volume of oxygen absorbed by the lungs in one minute

Question 34

define tidal volume

Answer 34

the volume of air inhaled or exhaled in one breath , usually measured at rest

Question 35

define spirometer

Answer 35

a device that can measure the movement of air into and out of the lungs

Question 36

define lung capacity

Answer 36

the greatest volume of air that can be expelled from the lungs after taking the deepest breath possible

Question 37

describe how a spirometer works

Answer 37

lung volumes can be measured by a spirometer .A float chamber spirometer consists of a chamber of air or medical oxygen floating on a tank of water. During inspiration , air is drawn from the chamber so that the lid moves down. During expiration the air returns to the chamber , raising the lid. these movements may be recorded on a datalogger. the carbon dioxide rich air is exhaled is passed through a chamber of soda lime which absorbs the carbon dioxide. This allows the measurement of oxygen consumption

Question 38

precautions that must be taken when using a spirometer

Answer 38

- the subject should be healthy and , in particular, free from asthma - the soda lime should be fresh and functioning - there should be no air leaks in the apparatus , as this would give invalid or inaccurate results - the mouthpiece should be sterilised - the water chamber must not be overfilled or water may enter air tubes

Question 39

what does total lung volume consist of and which one can be measured

Answer 39

vital capacity - which can be measured | residual volume- which cannot me measured using the spirometer

Question 40

what factors does vital capacity depend on

Answer 40

size of person age gender level of regular exercise

Question 41

what is the usual region of vital capacity

Answer 41

2.5-5.0 dm3

Question 42

a typical tidal volume at rest is

Answer 42

0.5 dm3

Question 43

describe how the oxygen uptake effects the spirometer trace

Answer 43

as a person breathes from the spirometer , oxygen is absorbed by the blood and replaced by carbon dioxide. this carbon dioxide is absorbed by the soda lime in the spirometer , so the volume of air in the chamber decreases . this decrease can be measured and observed on a spirometer trace we can assume that the volume of carbon dioxide released and absorbed by the soda lime equals the volume of oxygen absorbed by the blood. therefore measuring the gradient of the decrease in volume enables us to calculate the rate of oxygen uptake

Question 44

how to calculate oxygen uptake from a spirometer trace

Answer 44

on the start of the trace in the top left hand corner (A) draw a line from point A down to the horizontal axis , and another line from the end of the spirometer trace (B). measure the length of time between these points measure the difference in volume between points A and B divide by the time taken for this decrease the unit will be dm3s-1

Question 45

how to measure breathing rate

Answer 45

count the number of peaks in each minute

Question 46

a higher oxygen uptake will result from

Answer 46

increased demand such as during exercise when the muscles are respiring more

Question 47

increased oxygen uptake will result from

Answer 47

increased breathing rate | deeper breaths

Question 48

define buccal cavity

Answer 48

the mouth

Question 49

define filaments

Answer 49

slender branches of tissues that make up the gills , they are often called primary lamella

Question 50

define lamella

Answer 50

sometimes called secondary lamella | folds of the filament to increase surface area , they are also called gill plates

Question 51

define operculum

Answer 51

a bony flap that covers and protects the gills

Question 52

define spiracle

Answer 52

a external opening or pore that allows air in or out of the trachea in an insect

Question 53

define tracheal fluid

Answer 53

the fluid found at the ends of the tracheoles in the tracheal system

Question 54

define tracheal system

Answer 54

a system of air filled tubes in insects

Question 55

explain how bony fish exchange gases

Answer 55

bony fish must exchange gases with the water in which they live. they use gills in order to absorb oxygen dissolved in the water and release carbon dioxide into the water. the oxygen concentration will be typically much lower than found in air. most bony fish have five pairs of gills which are covered by a bony plate called the operculum each gill consists of two rows of gill filament (primary lamella) attached to a bony arch. the filaments are very thin and their surface is folded into many secondary lamellae (gill plates) this provides a very large surface area. blood capillaries carry deoxygenated blood close to the surface of the secondary lamellae where exchange takes place

Question 56

describe countercurrent flow

Answer 56

blood flows along the gill arch and out along the filaments to the secondary lamellae . the blood then flows through capillaries in the opposite direction to the flow of water over the lamellae. the arrangement creates a countercurrent flow that absorbs the maximum amount of oxygen from the water

Question 57

describe ventilation in bony fish

Answer 57

bony fish can keep water flowing through the gills by using a buccal opercular pump. the buccal cavity can change volume. the floor of the mouth moves downwards, drawing water into the buccal cavity. the mouth closes and the floor is raised again water through the gills. movements of the operculum are coordinated with the movement of the buccal cavity.as water is pushed from the buccal cavity, the operculum moves outwards . this movement reduces the pressure in the opercular cavity, helping water to flow though the gills

Question 58

describe ventilation in insects

Answer 58

insects do not transport oxygen in the blood . insects have an open circulatory system In which the body fluid acts as both blood and tissue fluid . circulation is slow and effected by body movements insects have an air filled tracheal system which supplied air directly to all respiring tissues. sir enters the system via a pore in each segment called a spiracle . the air is transported into thr body through a series of tubes called tracheae (singular trachea) . these divide into smaller and smaller tubes called thracheoles . the ends of the tracheoles are open and filled with tracheal fluid. gaseous exchange occurs between the air in the tracheoles and the tracheal fluid . some exchange can also occur across the thin walls of the tracheoles

Question 59

describe the tracheal fluid withdrawal

Answer 59

many insects are very active and need a good supply of oxygen .when tissues are active , the tracheal fluid can be withdrawn into the body fluid in order to increase the surface area of the tracheole wall exposed to air . this means that more oxygen can be absorbed when the insect is active

Question 60

larger insects can also ventilate their tracheal system by movements of the body . this can be achieved in a number of ways

Answer 60

- in many insects ,sections of the tracheal system are expanded and have flexible walls. these act as air sacs which can be squeezed by the action of the flight muscles . repetitive expansion and contractions of these sacs ventilate the tracheal system - in some insects , movements of the wings alter the volume of the thorax. as the thorax volume decreases , air in the tracheal system is put under pressure and is pushed out the tracheal system. when the thorax increases in volume, the pressure inside drop and air is pushed into the tracheal system from outside