Unit 2.1: Ventilatory System
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What is Homeostasis?
The maintenance of internal environment between a specific and constant range
How do Pulmonary & Cardiovascular System Work Together?
To maintain oxygen content in blood
What are principal structures of ventilatory System?
Conducting Airways: - Nose, Mouth, Pharynx, Larynx, Trachea, Bronchi, Bronchioles Gas Exchange: - Lungs & Alveoli
Functions of Conducting Airways
• Low resistance pathways for airflow • Defence against harmful substances (cilia, macrophage cells, Mucus) • Warms and moistens air through lining of airways
What is cilia and what does it do?
Tiny hairs which filter air and traps present particles, stopping them from entering lungs and causing infection.
What are macrophage cells and what do they do?
Cells lining conducting airways which serve as defense against foreign bodies.
What are the two functions of mucus?
Trap particles & pathogens but also improves gas exchange
What is Pulmonary Ventilation and its Acronym?
PV = Inflow and outflow of air between atmosphere & lungs (breathing)
What is Total Lung Capacity and its acronym?
TLC = Volume of air in lungs after a maximum inhalation
What is average TLC in adults (male & female)?
6L for males & 4.2L for females
What is TLC = to?
Vital Capacity (VC) + Residual Volume (RV) = TLC
What is Vital Capacity and its acronym?
VC= Maximum volume of air that can be exhaled after maximum inhalation (Taking deep breath in & blowing it all the way out)
What is Residual Volume and its Acronym?
RV = Volume of air still contained in lungs after maximum exhalation (Blowing out as hard as you can: remaining air is RV)
Why is RV important? What percentage of lung capacity does it represent?
Prevents lungs from collapsing during forced breathing Is 20% of Total Lung Capacity
What is Tidal Volume and its acronym?
TV = Volume of air breathed in & out in one breath during normal breathing
What is the normal range of TV? What percentage of the TLC does it make up?
Normal range is 500ml Makes up 7-8% of TLC
What is Expiratory Reserve Volume and its acronym? What percentage of the TLC does it make up?
ERV = Additional air over tidal volume that can be exhaled forcibly (Exhale forcibly & push all air out that you possibly can) Makes up 20% of TLC
What is Inspiratory Reserve Volume and its acronym? What percentage of the TLC does it make up?
IRV = Additional inspired air over tidal volume (Make normal tidal inspiration, take a deep breath all the way in) Makes up 60% of TLC
What is vital capacity equal to? VC = … + … + …
TV + IRV + ERV = VC
How does ventilation work when at rest?
• Constant & predictable • Rate & Depth of breathing are automatic (no conscious imput required) • Breathing takes place place thanks to pressure gradients (air moves from areas of high pressure to regions of lower pressure)
Describe process of inhalation when at rest
• Diaphragm contraction most responsible for creating pressure imbalance • Diaphragm pulls downwards • External intercostal muscles contract • Rib cage moves upwards and outwards. • Thoracic cavity increases volume and decreases pressure, allowing oxygen rich air from the atmosphere (high pressure) to flow into the lungs (lower pressure)
Describe process of exhalation when at rest
• No energy required • Diaphragm relaxes • External intercostal muscles relax Rib cage pulled inwards and downwards • Volume reduced and pressure increases to higher than atmosphere’s allowing air to flow back out again
What is Breathing Frequency & Acronym?
BR = Number of breaths per minute
What is Minute Ventilation & Acronym?
VE = Tidal Volume x Breathing Frequency Product size of each breath