Respiratory System

6.4 Gas exchange• Distinguish between ventilation, gas exchange and cell

respiration.• Explain the need for a ventilation system.• Describe the features of alveoli that adapt them to gas

exchange.• Draw and label a diagram of the ventilation system,

including trachea, lungs, bronchi, bronchioles and alveoli.

• Explain the mechanism of ventilation of the lungs in terms of volume and pressure changes caused by theinternal and external intercostal muscles, the diaphragm and abdominal muscles.

What is the equation of respiration?

Cellular respiration is the controlled release of energy in the form of ATP from organic compounds in cells.

C6H12O6+6O26CO2+6H2O+energy(ATP)

What is gaseous exchange?

• It is the exchange of gases between on organism and its surroundings including the uptake and release of carbondioxide in animals and plants.

• It takes place by diffusion

Diffusion of gases depend on;

1. The size of the surface area

2. The difference in the concentration

3. The length of the diffusion path

Gaseous exchange in animals

• Aquatic animals versus land animals

• They need a ventilation pumping mechanism, which moves air into and out of the lungs efficiently, thereby maintaining concentration gradient for diffusion.

• They need blood supply

• Respiratory pigment

Gaseous Exchange in Humans

[animation]

Section 6.16 – The path taken by air to the lungs

Larynx

Tracheabronchibronchioles

alveoli

Features of alveoli;

Thin …

Folded

Moist

Have an excellent transport system …

Pleural Membranes

Efficiency of lungs

Large surface area …

Supply of blood …

Wall of alveoli

Surface film of moisture

Lungs volumeTidal volume: volume of the air normally

exchanged in breathing

Residual volume: volume of the air remaning in the lungs after maximum expiration

Vital volume (capacity): the total possible change in lung volume- the maximum volume of air that can be exhaled after a maximum inhalation.

BREATHING MECHANISM

Inhalation (Inspiration)

• Volume of chest cavity increases

• Diaphragm (dome shaped muscle at the bottom of the chest

cavity) moves downward

• Air pressure in lungs decreases (so air is pushed into lungs)

• The intercostal muscles contract, ribs and sternum move up & out

Exhalation(Expiration)

• Volume of chest decreases

• Diaphragm moves upward

• Air pressure in lungs increases (so air is pushed out lungs)

• The intercostal muscles relax, ribs and sternum move down&in