M3, C7 Exchange Surfaces and Breathing

Question 1

What does surface area to volume ratio mean?

Answer 1

This compares how big the surface area is compared to the volume inside

Question 2

Why can’t large and active animals rely on diffusion of substances across their body to survive?

Answer 2

They have a small SA:V
Long diffusion distance
High Metabolic rate
Diffusion too slow to rely on

Question 3

Explain why single celled organisms don’t need specialised exchange surfaces

Answer 3

Metabolic activity relatively low
So relatively low oxygen needed or co2 produced
SA:V is large
Diffusion distances are small

Question 4

What are all the features in the human gaseous exchange system?

Answer 4

nasal cavity
nostril
mouth
trachea
bronchus
bronchioles
intercostal muscles
ribs
diaphragm
abdominal cavity
alveoli

Question 5

what are the features of the nasal cavity?

Answer 5

Large surface area with a good blood supply, warms the air to body temperature
Hairy lining, secretes mucus to trap dust and bacteria, protecting delicate lung tissue from irritation and infection
Moist surface, increases humidity of incoming air, reducing evaporation

Question 6

what are the features of the trachea?

Answer 6

A wide tube supported by incomplete rings of strong, flexible cartilage –
Stops the trachea collapsing and allows food to move easily down the oesophagus
Lined by ciliated epithelium with goblet cells between them
Goblet cells – secrete mucus onto lining to trap dust and microorganisms
Cilia epithelium – cilia beat and move the mucus/trapped dirt and microorganisms away from lungs
Most of it goes into the throat is swallowed and digested

Question 7

what are the features of bronchus?

Answer 7

In the chest cavity the trachea divides to form the left and right bronchus, leading to left and right lung
CIliated Epithelial cells
Smaller complete rings of cartilage

Question 8

what are the features of bronchioles?

Answer 8

In the lungs the bronchi divides to form many smaller bronchioles. (less than 1mm diameter)
Contain no cartilage
Walls contain smooth muscle
-when contracts, causes the bronchioles to constrict (close up)
-when relax, causes the bronchioles to dilate (open up)
This controls the amount of air reaching lungs
Lined with squamous epithelium

Question 9

What are the adaptations in alveoli?

Answer 9

Made of squamous epithelium cells- one cell thick
Contains collagen and elastic fibres allowing them to stretch during inhalation and recoil during exhalation to force air out
Surrounded by many capillaires- good blood supply
Contain lung surfactant which keeps them inflated
Moist surfaces reduce evaporation of water

Question 10

what are some details in inspiration

Answer 10

energy using (active)
diaphragm contracts - flat and low
external intercostal muscles contract - ribs up and out
volume thorax increases, pressure decreases - below atmospheric pressure
air drawn through nasal passages, trachea, bronchi and bronchioles into lungs, down pressure gradient

Question 11

what are some details about expiration

Answer 11

passive process
diaphragm relaxes - domed and moves up
external intercostal muscles relax - ribs down and in
elastic fibres in alveoli return to normal length
volume of thorax decreases, pressure increases to above atmospheric pressure
air moves out of lungs until pressure it equals atmospheric pressure again

Question 12

what’s a peak flow meter

Answer 12

measures the rate air is expelled from the lungs

Question 13

what are vitalographs

Answer 13

A graph that shows the rate at which air can be expelled from the lungs

Question 14

define spirometer

Answer 14

A piece of equipment used to measure breathing patterns or lung volume

Question 15

how does a spirometer work

Answer 15

it has a oxygen-filled chamber with a movable lid
the person breathes through a tube connected to the oxygen chamber
as the person breathes in or out, the lid of the chamber moves up or down
these movements are recorded by a pen attached to the lid of the chamber, this writes on a rotary drum
the soda lime in the tube the subject breathes into absorbs carbon dioxide
the person wears a nose clip to ensure that air cannot enter or leave the body except via the apparatus

Question 16

what’s vital capacity

Answer 16

The maximum volume of air that can be inhaled or exhaled in one breath

Question 17

what’s tidal volume

Answer 17

The volume of air that is inhaled/exhaled during regular breathing

Question 18

what’s total lung capacity

Answer 18

total volume of the lungs

Question 19

what’s residual volume

Answer 19

Volume of air left in your lungs after the deepest possible exhalation

Question 20

what is inspiratory reserve volume

Answer 20

volume of air that can be inhaled over and above normal inhalation

Question 21

what is expiratory reserve volume

Answer 21

extra amount of air you can force out over and above normal exhalation

Question 22

what’s the equation for ventilation rate

Answer 22

VR = tidal volume X breathing rate

Question 23

on a spirometer trace, what does it mean when the line goes up

Answer 23

breath out - volume of gas in spirometer increases

Question 24

on a spirometer trace, what does it mean when the line goes down

Answer 24

breath in - volume of gas in spirometer decreases

Question 25

How do gills work in fish?

Answer 25

Water, containing oxygen, enters the fish through its mouth and passes out through the gills.

As water passes over of the gills, oxygen diffuses into the fish gills and into the blood, whilst carbon dioxide passes out of the fish blood in the gills back into the water.

Question 26

How are fish gills ventilated?

Answer 26

Open mouth = increase volume of buccal cavity (the space inside the mouth) and decreases pressure so water drawn in.
Closed mouth = decreases volume of buccal cavity and increases pressure so causes water to go back through the gills and so O2 diffuses out of the water into gills

Question 27

What is the structure of a gill?

Answer 27

The gill is supported by the gill arch

The gill arch branches out into many gill filaments stacked on top of one another

On top of the gill filaments are many gill lamellae which increase the SA of the gill

Question 28

What is the counter current system?

Answer 28

Blood in the gills flows in the opposite direction to water flow.
This means water with a high oxygen concentration always flows next to blood with a low oxygen concentration
Maintains steep conc gradient

Question 29

how do gases enter and leave an insect

Answer 29

Along the thorax and abdomen of insects are small openings, called spiracles.

Air and water can enter and leave through these

In order to minimise water loss, the spiracles can be closed, by the spiracle sphincter muscles contracting

When the animal is particularly active, more spiracles open to ensure sufficient oxygen enters the insect

Question 30

what body fluid do insects have instead of blood

Answer 30

haemolymph

which is yellowy-green and transports hormones, nutrients and waste around the body

Question 31

What type of insects needs more oxygen?

Answer 31

Larger and more active ones, such as bees, locusts and grasshoppers

Question 32

why can’t gases diffuse through an insect’s skin

Answer 32

because they have a tough exoskeleton

Question 33

how do insects limit water loss

Answer 33

they have spiracle sphincters which are kept closed for as much as possible

Question 34

what is the route for gases entering an insect

Answer 34

spiracle
tracheae
tracheoles
Tracheole fluid 
body cell

Question 35

what are tracheae (insects)

Answer 35

largest tubes of an insects respiratory system
carry air into the body
lined with spiral of chitin

Question 36

why do insects need chitin in their tracheae

Answer 36

keeps them open if they are bent or pressed

relatively impermeable to gases and so little gas exchange takes place in the trachea

Question 37

what are tracheoles

Answer 37

single, greatly elongated cell
no chitin lining so are freely permeable to gases
spread throughout the tissues of an insect
this is wear most gas exchange takes place between the air and respiring cells

Question 38

what is tracheal fluid

Answer 38

towards the end of the tracheoles

limits the penetration of air for diffusion

Question 39

what is mechanical ventilation of the tracheole system

Answer 39

air is actively pumped into the system by muscular pumping movements of the thorax and/or abdomen.
These movements change the volume of the body and this changes the pressure in the tracheae and tracheoles, so air is forced in or out depending on the pressure changes

Question 40

why do bigger insects need collapsible enlarged tracheae or air sacs

Answer 40

used to increase the amount of air moved through the gas exchange system. they are usually inflated and deflated by the ventilating movements of the thorax and abdomen

Question 41

What happens to the tracheal fluid in the trachea during times of high metabolic activity in an insect

Answer 41

During times of high metabolic activity the tracheal fluid diffuses into surrounding muscles from the tracheole, where oxygen can diffuse directly from the fluid into the cell and CO2 out of the cell

The removal of the tracheal fluid from the tracheole is advantageous as it increases the SA of the traceoles so more gas exchange can take place AND also increases the volume of the tracheoles, decreasing their pressure (to below atmospheric) so more air moves into the tracheoles down the pressure gradient