Exchange Surfaces

Question 1

Why do multicellular organisms need specialised exchange surfaces?

Answer 1

They have high metabolic activity so have a high demand for oxygen and produce lots of waste to be removed

Larger diffusion distances than unicellular so diffusion alone is too slow

Low surface area to volume ration so need for oxygen outgoes the supply

Question 2

What are 4 features of an efficient exchange surface?

Answer 2

Increased surface area

Thin layers

Good blood supply

Ventilation in mammals

Question 3

Describe the structure and components in the trachea?

Answer 3

C shaped rings of cartilage to prevent collapse and allow food down the oesophagus

Ciliates epithelial and goblet cells

Smooth muscle and elastic fibres to allow expansion and recoil

Question 4

Describe the structure and components in the bronchi?

Answer 4

Rings of cartilage to prevent collapse

Ciliates and goblet cells

Elastic fibres and muscle to allow expansion when need more oxyge and recoil

Question 5

Describe the structure and components in the bronchioles?

Answer 5

Smooth muscle to proved strength and support- keep open and control air flow

Elastic fibres to allow stretch and recoil

Ciliates and larger have goblet cells

Question 6

Describe the structure and components in the alveoli?

Answer 6

Squamous epithelium

Elastic fibres for stretch and recoil

Large surface area

Moist surface - lung surfactant

Question 7

Describe what happens in inspiration?

Answer 7

External intercostal and diaphragm contract

Rib cage moves up and out and diaphragm flattens

Increases volume and decreases pressure of thorax below atmospheric pressure

It is an active process

Question 8

What contracts in forced expiration?

Answer 8

Internal intercostal muscle

Question 9

Define vital capacity

Answer 9

The volume of air that can be breathed in when the strongest possible exhalation of air is followed by the deepest intake of breath

Question 10

Define tidal volume

Answer 10

The volume of air that moves in and out of the lungs with each resting breath

Question 11

Define breathing rate

Answer 11

The number of resting breaths taken per minute

Question 12

Define oxygen uptake

Answer 12

Amount of O2 consumed by an organism

Question 13

Describe a spirometer and how it works

Answer 13

Consists of an oxygen chamber with a movable lid

Person breaths into chamber through mouth peice, moving the lid up and down

The movements are recorded by a pen attached to the lid which writes on a roaring drum = spirometer trace

Or hooked to motion senser and data logger records movements

Soda line absorbs co2

Question 14

Ventilation in boney fish

1. Mouth of fish opens, so _______ ______ is lowered
   This increases the volume in the _______ ______ and lowers the pressure below the surrounding pressure
2. Water _____ __
3. Mouth closes and ______ _____ raises
   Decreasing volume and ________ pressure
4. Water moves into ____ _______ which increases its pressure
5. __________ is forced open and water moves out across gills

Answer 14

Buccal cavity
Buccal cavity
Flows in
Increasing 
Gill cavity
Operculum

Question 15

How does the gills have a large surface area?

Answer 15

They are divided into gill filaments which split into many gill lamellae

Question 16

How do fish make their exchange system very efficient?

Answer 16

Their countercurrent flow
Blood flows in the opposite direction to the water over the gills

This means oxygen concentration is higher in water than the blood across the full length of the lamellae

Question 17

Gas exchange in insects

1. Air moves into the insect via ________
2. Oxygen travels down concentration gradient towards cells via _____ and then smaller ________ to respiring tissues
3. Oxygen dissolves in the _________ _____in the tracheoles
4. _________ _________ ________ change the volume and pressure of the body to move air in and out of spiralled

Answer 17

Spiracles
Tracheae
Tracheaeoles
Tracheole fluid
Rhythmic abdominal movement

Question 18

How can you dissect fish gills?

Answer 18

Push back the operculum and cut off gills with scissors
Cut the gill arch at the top and bottom of the bone
Place in water to see gill filaments

Question 19

How to dissect an insect

Answer 19

Place dissecting puns in legs

Remove piece of exoskeleton from the abdomen

Fill abdomen with saline solution with a syringe

Tracheae should show up silvery as they are filled with air

Question 20

what is the average tidal volume?

Answer 20

0.4 dm^3

between 0.3 and 0.7

Question 21

what are the structures involved in mammalian gas exchange system? how do each increase efficiency o gas exhange?

Answer 21

nasal cavity
large surface area and good blood
supply , warms air
• mucus secreting cells , trap dust and
microbes
• moist surfaces , increase humidity
and reduce evaporation from surfaces
in lung

trachea
• cartilage rings , stop it from collapsing
• ciliated epithelium and goblet cells
secrete mucus , trap dust and
microbes and move them towards
stomach

bronchi/bronchioles
• smooth muscle , allows air to move in
and out and maintains high
concentration gradient of O2 / CO2
and to control airflow

alveoli
• thin (epithelial) wall , reduces diffusion
distance
• collagen / elastic fibres , elastic recoil
to help squeeze air out during
exhalation
• large number / provide large surface
area , to increase rate of diffusion
• good blood supply / capillaries ,
maintains high concentration gradient
• surfactant , allows gases to dissolve

diaphragm/ intercostal mucles
• contract to increase volume in lungs ,
reduce pressure and cause inspiration

Question 22

how do you calculate SA:V ratio?

Answer 22

SA/V

always x:1