3.6 Respiratory System
2026-04-21 06:08
Status: #new
Tags: #biology #respiratory-system
Respiratory System
Primary Functions
- Allow for the exchange of gasses between the blood and the lungs
- Oxygen gas diffuses into the blood, CO2 diffuses out of it
- Diffusion occurs for any molecule and goes from high concentration to low concentration
- Osmosis is water only, across a semi-permeable (allows water) membrane. that goes from high concentration to low concentration
- Gasses enter by inspiration and exit expiration through the same set of organs
Upper Respiratory Tract
- Gasses enter the body through the nasal cavity and mouth
- (Higher surface area in the nose allows for increased smell capabilities)
- Turbinates
- Small curved bone structures in the nose that moisten and warm up air (Air is also warmed and moistened in the mouth)
- Air then passes through the pharynx before travelling into the larynx (voice-box)
- The epiglottis covers the larynx opening (glottis means the opening between vocal cords)
- A larger opening means a deeper pitch
- The Lateral and Anterior larynx's are made of cartilage
Lower Respiratory Tract
- Contained in the chest cavity (Thoracic Cavity)
- The Trachea divides into two branches known as bronchi (singular form is known as bronchus)
- Cilia:
- Small Hair-like projections help push mucus up into the throat to be swallowed.
- Cilia:
- Divides into further bronchioles that are made out of cartilage (for stability)
- This ends in a grape-like cluster called Alveoli (Alveolous)
- They are covered in capillaries and facilitate gas exchange to ensure gas is oxygenated
Alveolar cells
- Single celled in width
- Are covered in capillaries (to maximize surface area)
- Secrete surfactant to prevent air pocket collapse
- This is because this prevents Hydrogen bonds in the water from collapsing the alveolus structure due to waters sticky and reactive nature
Other Lung Features
- The lungs are surrounded by the pleural membrane (a double membrane that surrounds the lungs)
- The intrapleural space (space between pleura) is filled with a liquid to reduce friction as the lungs expand and contract
- The rib cage surrounds the pleura and protects the lungs and heart
- Between every rib is intercostal muscle that allows the rib cage to expand and contract during breathing
- Below the lungs is the diaphragm
Diaphragm
- When breathing:
- Diaphragm pulls down, rib cage expands up and out
- When breathing out:
- Diaphragm pushes outward
- Rib cage compresses down and inward
Lung Conditions
- Bronchitis
- A condition where it inflames the bronchi
- Emphysema
- This is deposition of the harmful particles
- Heart grows to pump harder
Spirometer
- Used to measure lung capacity
- Inspiratory Reserve Volume (IRV)
- Max volume of air that can be inhaled after a tidal breath
- Tidal Volume (TV)
- The volume of air inspired or expired during normal breath
- Expiratory Reserve Volume (ERV)
- Max volume of air that can be exhaled after a tidal breath
- Vital capacity
- The total amount of air that can be exhaled after maximum inhalation
- Residual volume
- The amount of air left in the lung after maximum exhalation