3.1.1 - exchange and transport

why does the surface area of an organism affect its ability to exchange substances

the larger the organism, the smaller the SA:V ratio which means there is a long diffusion distance

why do multicellular organisms need exchange surfaces

-to supply its’ cells with glucose

-to remove waste products

what are 3 reasons why multicellular organisms can’t rely on diffusion alone for exchange

-long diffusion distance

-small SA:V ratio

-higher metabolic rate

how are root hair cells specialised for exchange

the plant root cells grow into long ‘hairs’ which stick out into soil, there are millions of them which increases surface area

how are the alveoli specialised for exchange

-short diffusion distance: each alveolus made from a single cell of squamous epithelium which are thin

-O2 and CO2 diffuse in opposite directions

-rich blood supply: the alveoli are surrounded by a large capillary network

-lungs are ventilated: air in alveoli are constantly replaced

how are fish gills specialised for exchange

-covered in gill filaments and lamellae which increase the surface area

-countercurrent flow of water and blood to maintain a steep concentration gradient

-rich blood supply: large network of capillaries

what are the main structures of the lungs

-trachea

-bronchi → 2 bronchus

-bronchioles

-alveoli

-external and intercostal muscles

-ribcage

-diaphragm

what is the role of the pleural membrane

has fluid in the pleural cavity to prevent friction during ventilation

what is the structure and function of goblet cells

-lined with cilia

-secrete and waft mucus to remove bacteria

what is the function of elastic fibres

stretch while breathing and recoil after to prevent the lungs from bursting

what is the trachea lined with and what does it do

-c shaped rings of cartilage

-prevents collapsing and provides support

what is the role of smooth muscle in the lungs

contract to constrict the airways

which structures are found in the trachea

-large c shaped rings of cartilage

-smooth muscle

-elastic fibres

-goblet cells

-ciliated epithelium

which structures are found in the bronchi

-small c shaped rings of cartilage

-smooth muscle

-elastic fibres

-goblet cells

-ciliated epithelium

what structures are present in the bronchioles

-smooth muscle

-elastic fibres

-squamous epithelium

what structures are present in the alveoli

-elastic fibres 

-squamous epithelium

in inspiration:

the 1.______ intercostal muscles 2.______.

this causes the 3._____ to move 4._____ and 5._____ and the diaphragm to move 6.______ and 7.____ to increase the volume in the 8.______. when the volume 9._____ the pressure in the lungs 10.______, which causes air to flow into the 11.______. as this is an active process 12.______ is required.

1. external

2. contract

3. ribcage

4. upwards

5. outwards

6. downwards

7. flatten

8. thorax

9. increases

10. decreases

11. lungs

12. energy

in expiration:

the 1.______ intercostal muscles 2.______.

this causes the 3._____ to move 4._____ and 5._____ and the diaphragm to move 6.______ and 7.____ to decrease the volume in the 8.______. when the volume 9._____ the pressure in the lungs 10.______, which causes air to flow out of the 11.______. as this is a passive process 12.______ is not required.

1. external

2. relax

3. ribcage 

4. down

5. inwards

6. up

7. outwards

8. thorax

9. decreases

10. increases

11. lungs

12. not

what happens during forced expiration

what is tidal volume

the volume of air in each breath

what is vital capacity

the maximum volume of air that can be breathed in and out

what is breathing rate

how many breaths are taken

what is oxygen consumption rate

the rate at which an organism uses up oxygen

what device is used to measure breathing

a spirometer

how does a spirometer work

-the person breathes through a tube connected to the oxygen chamber

-with each breath the chamber lid moves up and down

-a pen which is attached to the chamber lid draws a spirometer trace

-the soda lime in the tube absorbs CO2

what are the structures of the gills

-gill filaments

-lamellae

-gill arch

-capillaries

is the concentration of oxygen higher in the water or in the blood for countercurrent flow in fish

the water

the process of ventilation in fish:

the fish opens its mouth which lowers the floor of the 1._____ ______. the volume of the 2._____ ______ increases which 3.______ the pressure inside the cavity. 4._____ moves in. when the fish closes its mouth, the floor of the buccal cavity raises which 5._____ the volume in the cavity and increases the pressure. water is forced out across the gill 6.______. the gills are covered by a flap called the 7.______which protects the gill.

1. buccal cavity

2. buccal cavity

3. decreases

4. water

5. decreases

6. filaments

7. operculum

where is the main site of gas exchange in insects

tracheae

gas exchange in insects:

air moves into the trachea through small openings on the insect’s surface called 1._____. oxygen travels down its 2.________ ________ towards the cells. carbon dioxide from the cells move towards the spiracles to be released. trachea branch off into 3._____ which have thin permeable walls. the tracheoles contain 4.______ _____ which oxygen dissolves in. this oxygen then diffuses into body cells. insects use rhythmic movements to change the volume of their bodies.

1. spiracles

2. concentration gradient

3. tracheoles

4. tracheal fluid