3.1 exchange surfaces and breathing

Question 1

what 3 factors affect the need for exchange surfaces

Answer 1

size
surface area to volume ratio
level of activity

Question 2

why can’t large organisms rely on diffusion only?

Answer 2

This is because they have a small surface area to volume ratio so cells in the center of the organism wouldn’t receive enough oxygen or nutrients due to the longer diffusion pathway.

Diffusion is too slow to enable a sufficient supply to the innermost cells

Question 3

how does surface area to volume ratio change as the organism gets larger?

Answer 3

As size increases volume rises more quickly than surface area so a small organism may have a small surface area but an even smaller volume whereas in a large organism the surface area is relatively small compared to the volume

Question 4

What does the surface area to volume ratio indicate?

Answer 4

A large SA:V means the surface area is large enough to supply all their cells with sufficient oxygen

Question 5

how does the need for exchange surfaces change with level of activity

Answer 5

Metabolic activity uses energy from food and requires oxygen to release energy in aerobic respiration.
The cells of an active organism require a good supply of nutrients and oxygens to supply energy for movement.

Question 6

What are the features of a good exchange system?

Answer 6

A large surface area to volume ratio
a thin barrier/ small diffusion distance
A good blood supply

Question 7

how do you calculate surface area and volume in a cylinder?

Answer 7

volume = πr2 * height
surface area = (2πr*height)+2πr

Question 8

How do you calculate the volume and surface area of a sphere

Answer 8

volume = 4/3πr3
surface area = 4πr2

Question 9

describe how air enters the lungs

Answer 9

Air passes along the trachea, bronchi, bronchioles and finally reaches the alveoli

Question 10

Describe what surrounds the lungs

Answer 10

The lungs are protected by the ribcage which are held together by the intercostal muscles.
The action of these muscles and the diaphragm helps to produce breathing motions

Question 11

Describe gaseous exchange in the lungs

Answer 11

Gasses pas by diffusion through the thin walls of the alveoli. Oxygen passes from the air in the alveoli to the blood capillaries and carbon dioxide passes from the blood to the alveoli.

Question 12

How are the lungs adapted for gas exchange?

Answer 12

barrier is permeable to O2 and CO2
thin barrier - short diffusion distance
A good blood supply
ventilation

Question 13

Describe the barriers in the lungs

Answer 13

alveolus wall is one cell thick
capillaries are one cell thick
both walls consist of squamous cells
capillaries are in close contact with the alveoli
narrow capillaries causes the red blood cells to squeeze against its wall making them closer to the air in the alveoli

Question 14

describe inspiration

Answer 14

Inhalation -
1- The diaphragm contracts to move down and become flatter
2- the external intercostal muscles contract to raise the ribs
3- the volume of the chest cavity is increased
4- the pressure in the chest cavity drops below atmospheric pressure
5- air is moved into the lungs

Question 15

Describe expiration

Answer 15

Exhalation
1- the diaphragm relaxes and is pushed up by the displaced organs underneath
2- the external intercostal muscles relax and the ribs fall
3- the volume of the chest cavity is decreased
4- the pressure in the lungs increases above the pressure in the surrounding atmosphere
4- air is moved out of the lungs

Question 16

What happens during coughing or sneezing

Answer 16

external intercostal muscles relax but internal intercostal muscles can contract to help push air out more forcefully

Question 17

What are the airways and what are the 4 things they require to be effective?

Answer 17

trachea, bronchi, bronchioles
Be large enough to allow sufficient air flow without obstruction
supportive to prevent collapse during inspiration wen pressure is low
flexible in order to allow movement
the airways are lined with ciliated epithelium and goblet cells to trap pathogens

Question 18

Describe the structure of the trachea and bronchi

Answer 18

They have a similar structure but the bronchi are narrower. These airways are supported by cartilage which prevent collapse

Cartilage in the trachea is C-shaped which allows flexibility and space for food to pass down the esophagus

Question 19

Describe the structure of the bronchioles

Answer 19

Much narrower than bronchi and larger bronchioles may contain cartilage but the smaller ones do not.

They’re composed of a wall of mostly smooth muscle and elastic fibers

Question 20

Describe the structure of the lung tissue

Answer 20

Comprised of alveoli with squamous epithelium and surrounded by blood capillaries

The alveolus walls contain elastic fibers to stretch during inspiration and recoil

Question 21

Describe the function of the smooth muscle

Answer 21

They can contract and constrict airways controlling flow of air if there are harmful substances in it.
however, it is not a voluntary act and can’t reverse on its own

Question 22

Describe the function of the elastic fibers.

Answer 22

Elastic fibers elongate the smooth muscle and dilate the airways.
When the muscle contracts it deforms the elastic fibers and as the fibers recoil it causes the muscle to relax

Question 23

What is a spirometer

Answer 23

It is used to measure lung volume

Question 24

What are the 4 precautions with using a spirometer

Answer 24

Subject should be healthy and asthma free
soda lime should be fresh and functioning
should be no air leaks in the machine
mouthpiece should be sterilised

Question 25

Define tidal volume

Answer 25

The volume of air that moves in and out of the lungs with each resting breath
avg= 0.5dm3 500cm3

Question 26

Define vital capacity

Answer 26

largest volume that can be inhaled and exhaled in one breath
inspiratory reserve volume + expiratory reserve volume
avg=5dm3

Question 27

Define residual volume

Answer 27

volume of air left in the lungs when you have exhaled as much as you can

Question 28

Define total lung capacity

Answer 28

sum of vital capacity and residual volume

Question 29

Explain why the air in the spirometer drops slowly

Answer 29

Because the CO2 being exhaled is being absorbed by the soda lime but the student continues to inhale and absorb oxygen

Question 30

what is the buccal cavity

Answer 30

The fish’s mouth

Question 31

What are filaments

Answer 31

Slender branches of issue that make up the gill and are often called primary lamellae

Question 32

What are the lamellae

Answer 32

folds of the filament to increase surface area

Question 33

What is the operculum

Answer 33

Bony flap that covers and protects the gills

Question 34

what is a spiracle

Answer 34

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

Question 35

What is tracheal fluid

Answer 35

Fluid found at the end of tracheoles in the tracheal system in insects

Question 36

What is the tracheal system

Answer 36

a system of air filled tubes in insects

Question 37

What is special about the blood and water flow in a fish relating to gas exchange

Answer 37

It has countercurrent flow to maximise absorption of oxygen from the water

Question 38

Describe the ventilation in bony fish

Answer 38

Bony fish keep water moving over the gills by changing pressure in the buccal cavity

When the fish opens it mouth the volume in the buccal cavity increases and pressure decreases so water is drawn in. The mouth closes and water is pushed through the gills

Movements of the operculum are co ordinated with movement of the buccal cavity
As water is pushed from the buccal cavity the operculum moves outwards reducing pressure in the opercular cavity helping water to flow through the gills

Question 39

How does an insect inspire and expire

Answer 39

air enters the system via a spore in each segment called a spiracle and is then transported into the body with trachea which then divide into smaller tubes called tracheoles which contain tracheal fluid where gas exchange occurs

Question 40

What happens to an insects tracheal fluid when more oxygen is required

Answer 40

The amount of tracheal fluid decreases in the tracheoles in order to increase the surface area of the tracheole wall exposed to air

Question 41

in terms of energy how do inspiration and expiration differ

Answer 41

inspiration is an active process but expiration is passive

Question 42

describe gaseous exchange at the alveoli

Answer 42

oxygen moves into the lungs and thus alveoli down a pressure gradient, red blood cells slow down as they move around the alveoli increasing diffusion time and oxygen will diffuse down it’s concentration gradient, from the alveolus cavity across two layers of epithelium and into the capillary, red blood cells are flattened against the capillary walls to reduce the diffusion distance and CO2 moves in the opposite direction, movement of air in and out of the lungs helps to maintain the concentration gradient

Question 43

what is the purpose of residual volume

Answer 43

prevents airway collapse

Question 44

what should tidal volume be able to do

Answer 44

should provide enough oxygen to tissues at rest

Question 45

what are the gas exchange tissues and what is their purpose

Answer 45

ciliated epithelial cells and goblet cells trap and waft pathogens
elastic fibres stretch to expand lungs and recoil to push air out
smooth muscle controls diameter of airways by contracting and relaxing
cartilage provide support and prevents airway collapse

Question 46

describe how to use a spirometer to find tidal volume

Answer 46

subject breathes normally and not through nose, measure amplitude of waves from the trace
(as you breathe in lid goes down and as you breathe out lid goes up )

measure at least three waves and calculate mean

Question 47

how does smoking lead to development of a smokers cough

Answer 47

tar causes singeing of ciliated cells and more mucus is produced which accumulates and cannot be removed

Question 48

How can excess coughing damage the lungs

Answer 48

it inflames alveoli and the elastic fibres, causing formation of scar tissue, airway walls thicken and the lumen narrows restricting air flow