Biology Chapter 11 - Gas exchange in humans

features of gas exchange surfaces

large surface area - more molecules can diffuse at once

thin surface - shoter diffuision distance

good blood supply - gas can be carried to/from cells that need/produce them

good air ventilation - keep up concentration gradients for oxygen and carbon dioxide

function of cartilage in the trachea

prevents trachea from collapsing during exhalation, keeps the airway open for uninterrupted airflow

inhalation

diaphragm contracts

external intercostal muscles contract

ribs goes upward and outward

volume increases, pressure decreases

exhalation

diaphragm relaxes

internal intercostal muscles contract

ribs goes downward and inward

volume decreases, pressure increase

breathing system

inspired air

Oxygen: 21%

Carbon dioxide: 0.04%

Nitrogen: 78%

Water vapour: lower

expired air

Oxygen: 16%

Carbon dioxide: 4%

Nitrogen: 78%

Water vapour: higher

reason for difference between inspired and expired air

oxygen: used by cells for respiration, thus reducing concentration in expired air

carbon dioxide: by product of respiration, expelled by lungs

water vapour: moisture is added from respiratory tract

nitrogen: not used or produced by body

physical activity and the rate and depth of breathing

Increased carbon dioxide concentration forms carbonic acid in the blood, lowering pH. Change is detected by the brain, which signals the diaphragm and intercostal muscles to contract faster and more forcefully. Leading to an increased rate and greater depth of breathing, helping to remove excess CO₂ and increase oxygen intake.

role of goblet cells, mucus and ciliated cells in protecting breathing system from pathogens and particles

goblet cells: produces mucus

mucus: forms a sticky layer lining the airways to trap harmful particles and microorganisms to prevent them from reach the lungs

ciliated cells: moves mucus up towards the throat, it is then swallowed or expelled