GAS EXCHANGE OVERVIEW

Gas exchange insects:

Insects __________ by moving whole body.

This moved air into a network of tubes called __________.

These branch to make __________ to reach evert cell directly. The gases are not carried in a __________ __________

ventilate

trachea

tracheoles

blood stream

Tracheal system of an insect

Tracheoles end inside muscle fibres

Thoracic spiracles open __________ as abdomen expands (Inspiration)

first

Abdomen spiracles open __________ as the abdomen compresses (Expiration )

later

Insects ventilate through __________

spiracles

Air enters the spiracle allowing _________ to travel along among a network of tubes called __________ to reach the cells in the insect’s body

oxygen

tracheae

Terrestrial Adaptations

Air tubes branching through body

Gas exchanged by diffusion across moist cells lining terminal ends not through open circulatory system

Trachea kept open by circular bands of _______.

chitin

Branch to form ___________ that reach every cell

tracheoles

Ends of tracheoles are _______-

moist

Oxygen delivered directly to _________ cells. Insect blood does not carry ___________.

respiring

oxygen

How do the adaptations enhance efficiency?

Oxygen delivered directly to respiring cells

• can pump body to move air around in tracheal systems

But size of animal limited by slow _________ rate

diffusion

Alveoli adaptations for gas exchange:

Highly folded

Thin

Moist

Pleural membrane is a _____ fluid filled membrane that surrounds the ______ surface of the lungs and the ________ wall of the chest cavity.

thin

inner

Pleural membrane __________ and prevents friction between lungs and ________ walls

lubricates

friction

Internal lungs ___________ heat and water loss

minimise

Adaptations of lungs for efficient gas exchange

Capillaries and alveoli’s are one cell thick

Blood Circulation

Lung surfactant

Ventilation

Elastic tissue in lungs

Very large surface area

Why is it important for the alveoli and blood capillaries to be one cell think or squamous

To provide a short diffusion pathway

What is the significance of elastic tissue

It helps the lungs expand and contract during breathing

What is the significance of elastic recoil of alveoli?

It helps the alveoli return to their original shape after expanding

What is the significance of ventilation

fresh supply of molecules to maintain diffusion gradient

What is the significance of lung surfactant

reduces cohesive forces between water molecules so lowering water tension

What is the significance of blood circulation

maintains a steep diffusion gradient

What happens to the diaphragm position and muscle state during inhaling?

Diaphragm contracts flat and down, and muscle contracts

What happens to the ribs position during inhaling?

Ribs move up and out

What happens to the external intercostal muscles during inhaling

External intercostal muscles contract

What happens to the thorax volume during inhaling

The volume in thorax increases

What happens to the pressure in thorax compared to atmosphere

The pressure in thorax decreases

What happens to the air movement during inhaling?

Air moves in to lungs

What happens to the diaphragm position and muscle state during exhaling?

Diaphragm relaxes

What happens to the ribs position during exhaling?

Ribs move down and in

What happens to the intercostal muscles during exhaling?

external intercostal muscles relax

What happens to the volume in thorax during exhaling

Volume in thorax decreases

What happens to the pressure in thorax compared to atomospheric during exhaling

Increases

What happens to the air movement during exhaling

Air moves out of lungs

Organisms need to obtain resources from their _______________.

environment

How much they require depends upon their:

Volume (Bulk)

Activity levels

Metabolic rate of diffusion

Surface area

How does an organism’s size relate to it’s surface area to volume ratio?

The larger the organism, the lower the surface area to volume ratio.

How does surface area to volume ratio affect transport of molecules>

The lower the SA/V ratio, the further distance molecules must travel to reach all parts of the organism.

Why do larger organisms require mass transport and specialised gas exchange surfaces.

Small SA/V ratio

Diffusion insufficient to provide all cells with the required oxygen and remove all carbon dioxide

Large organisms are more active than smaller organisms

Four features of an efficient gas exchange surface.

Large surface area

Thin Barrier

Fresh supply of molecules

Ventilation mechanism

Why is a large surface area important for efficient gas exchange?

More space for molecules to pass through

Why is a thin barrier important for efficient gas exchange?

Short diffusion distances

Why is a fresh supply of molecules important for efficient gas exchange?

Maintains a steep diffusion gradient

Why is a ventilation mechanism important for efficient gas exchange?

maintains a steep diffusion gradient

Other features and why they’re important?

Moist — allows gases to dissolve

What type of organism is an amoeba?

Unicellular

Single cells have a very ________ surface area to volume ratio?

large

The cell membrane is _______ so diffusion into the cell is rapid

thin

A single cell is thin so ____________ _______________ inside the cell are short.

diffusion distance

Therefore _________ ______________ across the cell membrane is sufficient to meet the demands of the respiratory processes.

simple diffusion

What type of organisms are earthworms>

Multicellular organisms

What size is the SA/V ratio of an flatworm?

relatively small

However ____ structures provide a large ____________ _____ and reduces the diffusion distance

flat

surface area

__________ _______________ is sufficient to meet the demands of respiratory processes

Simple diffusion

What type of organisms are earthworms?

Cylindrical, multicellular organisms

How large is the SA/V ratio of earthworms?

relatively small

Earthworms are _____ _______________ and have a low ____________ _____ therefore require little oxygen

slow moving

low metabolic rate

Earthworms rely on ___________ ______________ for gas exchange

external surface

Earthworms require a ________________ _________ to transport oxygen to the tissues and remove carbon dioxide in order to ___________ a steep diffusion gradient

circulatory system

maintain

How do fish respire?

Through gills

Define ventilation

The movement of fresh air into a space and stale air out of a space to maintain a steep concentration gradient of oxygen and carbon dioxide.

What are the two main groups of fish

Cartilaginous Fish

Bony Fish

What ventilation system do cartilaginous fish have?

Parallel Flow

Parallel flow is ______ efficient than counter current flow

less

Define Parallel Flow

Blood and water flow in the same direction at the gill lamellae

maintaining the concentration gradient for oxygen to diffuse into the blood only up to the point where its concentration in the blood and water is equal

What are gill filaments

• Main site of gaseous exchange in fish over which water flows.

• They overlap to gain resistance to water flow

• Found in large stacks known as gill plates and have gill lamellae which provide a large surface area and good blood supply for exchange

What happens to the mouth during inspiration?

Mouth opens

What happens to the operculum in inspiration>

The operculum remains closed

What happens to the floor of the mouth during inspiration>

The floor of the mouth lowers

What happens to the volume in mouth cavity during inspiration?

The volume in mouth cavity increases

What happens to the pressure in the mouth cavity during inspiration?

Pressure in mouth cavity decreases

What happens to the water movement during inspiration?

Water movement in as external pressure is higher

What happens to the mouth during expiration?

Mouth remains closed

What happens to the operculum during expiration?

Operculum opens

What happens to the floor of the mouth

The floor of the mouth rises

What happens to the volume in mouth cavity?

Volume decreases in mouth cavity

What happens to the pressure in mouth cavity?

Pressure in mouth cavity increases

What happens to the water movement during expiration?

The water movement - out as external pressure is higher

Define counter current flow?

• Water and blood flow in opposite directions

• Maintains a concentration gradient

  • Oxygen diffuses into the blood along the entire length

How is the diffusion gradient maintained during counter current flow?

• Water is always next to blood of a lower oxygen concentration

• Keeps rate of diffusion constant and enables 80% of available oxygen to be absorbed

Compare counter current and parallel flow?