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
The distance from the gas supply to their cells is too large
Gases can’t diffuse fast enough for the animal to survive

Question 3

Explain why villi make good exchange surfaces

Answer 3

Large surface area to volume ratio
Thin layers - distance is small
Good blood supply - bigger the concentration, the faster the diffusion
Ventilation to maintain diffusion gradient

Question 4

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

Answer 4

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

Question 5

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

Answer 5

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

Question 6

what are the features of the nasal cavity?

Answer 6

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 7

what are the features of the trachea?

Answer 7

A wide tube supported by incomplete rings of strong, flexible cartilage –
stops the trachea collapsing
To allow 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 8

what are the features of bronchus?

Answer 8

In the chest cavity the trachea divides to form the left and right bronchus, leading to left and right lung
Similar in structure to trachea
Contain cartilage rings
-Smaller
-Complete rings

Question 9

what are the features of bronchioles?

Answer 9

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 changes the amount of air reaching lungs
Lined with thin flatterned epithelium, making gaseous exchange possible

Question 10

what are the features in alveoli?

Answer 10

Pulmonary capillary
Blood plasma
Red blood cell compressed against capillary wall
Endothelial cell of capillary
Cavity of alveolus
Alveolar duct
Epithelial cell of alveolus
Moist alveolar surface

Question 11

how are alveoli adapted for gas exchange?

Answer 11

large surface area
thin layers - diffusion distance is small
good blood supply - millions of capillaries surround the alveoli which makes a constant flow of blood which brings oxygen and takes away carbon dioxide
good ventilation - maintains steep diffusion gradients for oxygen and carbon dioxide
alveoli is covered in a solution of water, salts and lung surfactant which makes the alveoli remain inflated.

Question 12

what are some details in inspiration

Answer 12

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

Question 13

what are some details about expiration

Answer 13

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
air moves out of lungs until pressure in = pressure out

Question 14

what’s a peak flow meter

Answer 14

measures the rate air is expelled from the lungs

Question 15

what are vitalographs

Answer 15

more sophisticated than a PFM. patient breathes out as fast as possible, produces a graph of the amount of air they breathe out and how quickly.

Question 16

define spirometer

Answer 16

used to measure different aspects of the lung volume or breathing patterns

Question 17

how does a spirometer work

Answer 17

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 18

what’s vital capacity

Answer 18

the maximum volume of air that can be breathed in or out in 1 breath, about 5dm cubed but varies in men and women and fitness

Question 19

what’s tidal volume

Answer 19

the volume of gas that moves in and out of lungs in each resting breath, about 0.5dm cubed

Question 20

what’s total lung capacity

Answer 20

total volume of the lungs

Question 21

what’s residual volume

Answer 21

the volume of air that is left in the lungs, even after the biggest possible exhalation, about 1.5dm cubed

Question 22

what is inspiratory reserve volume

Answer 22

maximum volume of air breathed in over and above normal inhalation

Question 23

what is expiratory reserve volume

Answer 23

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

Question 24

what’s the equation for ventilation rate

Answer 24

VR = tidal volume X breathing rate

Question 25

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

Answer 25

breath out - volume of gas in spirometer increases

Question 26

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

Answer 26

breath in - volume of gas in spirometer decreases

this is because oxygen is used up in respiration, carbon dioxide is released in respiration and carbon dioxide is absorbed by soda lime

Question 27

How do gills work in fish?

Answer 27

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 28

How are fish gills ventilated?

Answer 28

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 29

What is the structure of a gill?

Answer 29

Each gill is made from lots of thin plates called gill filaments (primary lamellae)

Each gill filament is covered in lots of tiny structures called gill plates (secondary lamellae) which increase the surface area for exchange

The gill is supported by a gill arch which contains lots of capillaries.

Question 30

What is the counter current system?

Answer 30

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

Question 31

how do gases enter and leave an insect

Answer 31

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 32

what body fluid do insects have instead of blood

Answer 32

haemolymph

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

Question 33

What type of insects needs more oxygen?

Answer 33

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

Question 34

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

Answer 34

because they have a tough exoskeleton

Question 35

how do insects limit water loss

Answer 35

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

Question 36

what is the route for gases entering an insect

Answer 36

spiracle
tracheae
tracheoles
water in the tracheoles
muscles
body cell

Question 37

what are tracheae (insects)

Answer 37

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

Question 38

why do insects need chitin in their tracheae

Answer 38

keeps them open if they are bent or pressed

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

Question 39

what are tracheoles

Answer 39

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 40

what is tracheal fluid

Answer 40

towards the end of the tracheoles

limits the penetration of air for diffusion

Question 41

what is mechanical ventilation of the tracheole system

Answer 41

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, or forced out, as the pressure changes

Question 42

why do bigger insects need collapsible enlarged tracheae or air sacs

Answer 42

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