What is the principal structures of the ventilatory system?
Nose, Mouth, Pharynx, Larynx, Trachea, Bronchi, Bronchioles, Lungs, Alveoli
What are the functions of the conducting airway?
- Low resistance pathway for airflow
- Defence against chemicals and other harmful substances that are inhaled
- Warming and moistening the air
What is the function of the Nose? (Conducting Airways)
Humidifies the air and filters particles
What is the function of Pharynx? (Conducting Airways)
Offers a low resistance pathway for airflow
What is the function of Larynx? (Conducting Airways)
Functions as the ‘voice box’ and protects the trachea from invasion of foods and fluids
Define Pulmonary Ventilation.
Movement of air in and out of the lungs (breathing)
Define Total Lung Capacity (TLC).
The amount of air in the lungs after a maximal inspiration
Define Vital Capacity (VC).
The amount of air an individual can inhale or exhale during normal quiet breathing (7-8% of total lung capacity)
Define Expiratory Reserve Volume (ERV).
The amount of air that an individual can inhale above a tidal inspiration (20% of the total lung capacity)
Define Inspiratory Reserve Volume (IRV).
The amount of air that an individual can inhale above a tidal inspiration (60% of total lung capacity)
Define Residual Volume (RV).
The amount of air remaining in the lungs after a maximal exhalation (makes up 20% of the total capacity)
What happens during inhalation? (Mechanics of Ventilation)
- Diaphragm contracts and lowers
- External intercostal muscles contract
- This causes the rib cage to move upwards and outwards
- The volume of the chest cavity increases
- The pressure inside the lungs drops below atmospheric pressure
- Air rushes into the lungs
What happens during Exhalation? (Mechanics of Ventilation)
- The diaphragm relaxes and turn to a dome shape
- Internal intercostal muscles contract
- This causes the ribcage to move downwards and inwards
- The volume of the chest cavity decreases
- The pressure inside the lungs increases above atmospheric pressure
- Air is forced out of the lungs and into the atmosphere
Describe how Ventilation differs during exercise. (Nervous & Chemical Control)
Ventilation increases as a direct result of increases in blood acidity levels due to increase in CO2 content in the blood, which is detected by the respiratory centre.
This results in an increase in the rate and depth of ventilation.
What receptors does the respiratory centre (Neural control) go through in order to send messages to the ventilatory muscles? (Nervous & Chemical Control)
Neural control of ventilation includes lung stretch receptors, muscle proprioceptors and chemoreceptors.
What is the role of hemoglobin in oxygen transportation?
98.5% of oxygen in the blood is transported by hemoglobin as oxyhemoglobin within red blood cells
What is Gaseous Exchange at the alveoli?
The delivery of oxygen from the lungs to the bloodstream, and the elimination of carbon dioxide from the bloodstream to the lungs. It occurs in the lungs between the alveoli and the capillaries which are located around the walls of the alveoli.
How do oxygen and carbon dioxide take place in the alveoli during gas exchange?
- Oxygen from the inhaled air diffuses through the walls of the alveoli and into the capillaries
- The red blood cells carry the oxygen to the body (oxygenated)
- Carbon dioxide which is produced by the body return to the lungs in the red blood cells (deoxygenated)
- The carbon dioxide then diffuses across the capillary and the alveolar walls into the air so that it can be removed from the body via expiration
What are the adaptations of Alveoli?
(These adaptations make the gaseous exchange more efficient)
- Walls of the alveoli are one cell thick
- They are folded, providing a larger surface area
- They are each surrounded by capillary which allows the good blood supply
