Lungs as an organ of gas exchange

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

outer

Pleural membrane __________ and prevents friction between lungs and ________ walls

lubricates

cavity

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