Exchange Surfaces and Breathing

Question 1

Why do organisms need exchange surfaces?

Answer 1

The sa:v ratio is too low to allow basic diffusion

Question 2

Why does level of activity affect if an organism needs an exchange surface or not?

Answer 2

More metabolically active organisms will require exchange surfaces so that they can perform more respiration to produce more ATP

Question 3

What are the 3 features of a good exchange system?

Answer 3

Large SA:V ratio

Short diffusion pathway

Good Blood supply

Question 4

Why is a good blood supply important for diffusion?

Answer 4

Provides working areas with Oxygen for respiration

Removes molecules that are being diffused to maintain a steep concentration gradient

Question 5

What are the parts features of the mammalian exchange system?

Answer 5

Mouth
Nose
Trachea
Bronchi
Bronchioles
Alveoli
Lungs

Question 6

What is the role of the intercostals?

Answer 6

Move the lungs up and down during breathing

To work with the diaphragm to create pressure gradients to cause breathing

Question 7

How are the alveoli specialised to perform their function?

Answer 7

Large SA:V ratio

Moist surface, allows gasses to diffuse easier and prevents pneumothorax

Short diffusion pathway (only 1 cell thick)

Good blood supply - transports CO2 to the lungs and O2 away from the lungs

Question 8

What do alveoli’s walls contain?

Answer 8

Elastic fibres

Stretch during inspiration and recoil in expiration to push air out

Question 9

How are the airways specialised to perform their function?

Answer 9

Have wide lumen to allow sufficient airflow without obstruction

Are lined with ciliated epithelium and goblet cells. Goblet cells release mucus to trap pathogens , epithelium move this up to the top of the airway where it is swallowed

Supported by rings of cartilage to prevent collapse during inspiration when pressure is low

Question 10

What is the role of smooth muscle and elastic fibres in the airways?

Answer 10

Smooth muscle can contract to restrict airflow, useful if there is something harmful in the air

Cannot relax on its own requires elastic fibres

Smooth muscle may over contract during anaphylaxis

Question 11

What device measures lung volumes?

Answer 11

Spirometer

Question 12

What are the 2 components of lung volume?

Answer 12

Vital capacity

Residual volume

Question 13

What is Vital capacity?

Answer 13

The maximum volume of air expelled from the lungs in one breath

Question 14

What are factors affecting the vital capacity of people?

Answer 14

Age
Gender
Height
How much they exercise

Question 15

What is the residual volume?

Answer 15

The amount of air that cant be expelled and remains in the lungs

Question 16

What is tidal volume?

Answer 16

The volume of air expelled in one breath at rest

Question 17

How does a spirometer measure oxygen uptake?

Answer 17

A person breaths in the oxygen and the body absorbs some of it

They breathe out carbon dioxide which is absorbed by the soda lime

The difference in volume is the amount of oxygen uptake

Question 18

How would you oxygen uptake from a spirometer trace?

Answer 18

Draw a line from one trough to another trough

Measure the gradient of the line

Question 19

How would you measure the breathing rate from a spirometer trace?

Answer 19

Count the number of peaks in a minute

Question 20

Describe the structure of the gaseous exchange system in bony fish

Answer 20

Gills covered by a bony plate called the operculum

Each gill consists of two rows of filaments which are very thin

Gill filament surface is folded into lamellae

Capillaries carry deoxygenated blood close to the surface of lamellae to perform gaseous exchange

Question 21

What is a countercurrent flow in the gills?

Answer 21

Blood flows in the opposite direction as the water

Maintains a steep concentration gradient and allows most oxygen to be removed

Question 22

What is the buccal cavity?

Answer 22

The mouth of the fish

Question 23

How does the buccal-opercular pump work?

Answer 23

Buccal cavity floor moves down drawing water into it

Mouth closes and floor is raised pushing water through the gills

simultaneously the operculum moves outwards to draw water over the gills also

Question 24

What is the name of the fluid circulated around insects?

Answer 24

Haemolymph

Question 25

Describe the gaseous exchange system in insects?

Answer 25

Have a respiratory cavity where gaseous exchange occurs

Air enters through a spiracle

transported via tracheae and tracheoles

The end of the tracheoles contain tracheal fluid where gaseous exchange occurs

Question 26

Give examples of how different insects may ventilate?

Answer 26

Sections of the tracheal system have flexible walls that can be contracted and relaxed by the flight muscles

Movement of the wings can alter the volume of the thorax causing pressure changes and thus ventilation

Some use valves over spiracles to create a ventilation system where air is drawn in at the front and out at the back