Breathing - Biology

Forced Expiration

  1. Internal intercostal muscles contract, diaphragm and external intercostal muscles relax.
  1. Ribs move further downwards and inwards.
  1. Volume in thorax becomes smaller
  1. Pressure is increased

Air is forced out against the pressure gradient

Gross Anatomy of the respiratory system

Trachea

Bronchi

Bronchioles

Alveoli

Inspiration

External Intercostal Muscles contract

Diaphragm contracts and flattens

Ribs move up and out

Volume increases so the pressure decreases below atmospheric pressure

Ribcage moves down and in

Why does ventilation rate increase when we excercise

Muscles contract - more energy

aerobic respiration needed

Oxygen Increases

Carbon Dioxide builds up so need to get rid

Lactic acid produced in anaerobic respiration