Mechanics Of Ventilation Flashcards
(21 cards)
What is the primary role of the respiratory system?
To meet the metabolic demands of the organism
What is functional residual capacity ?
The air in the lungs between breaths
What is the intrapleural space ?
A thin, fluid filled space between the two layers of pleura that surround each lung
What is the role of intrapleural space ?
Lubrication to reduce friction during breathing
Describe the intrapleural pressure at rest
The pressure is negative w.r.t atmospheric pressure
What is the only active process in breathing ?
Inspiration
What happens during inspiration?
The volume of the thorax is increased as:
- The diaphragm contracts and flattens
- External intercostal muscles contract, so move the ribcage up and out
What happens to intrapleural pressure as the volume of the thorax increases ?
Intrapleural pressure decreases
What happens to air flow as volume of the thorax increases ?
The alveoli expand.
Air flows into the lungs until alveolar pressure= atmospheric pressure
What is Boyles law ? How does it relate to breathing ?
P1V1=P2V2
The change in pressure and volume during inhalation and exhalation follows Boyles law.
What type of process is expiration ?
Passive
What happens during expiration ? What is the pressure difference ?
The volume of the thorax decreases.
The diagram relaxes.
Alveoli recoil.
Alveoli pressure > atmospheric pressure
What are the 2 points where there is no net air movement in or out ?
- Peak of inspiration
- Functional residual capacity
What is compliance ?
A measure of the elasticity of the tissues
How do we measure compliance?
C= change in volume / change in pressure
What effect does inspiration have on the pressure-volume curve ?
The curve bends to the right due to resistive forces which oppose airflow:
1. Airway resistance
2. Pulmonary tissue resistance- friction between lungs and chest wall
3. Inertia of the air and tissues
What effect does expiration have on the pressure-volume curve ?
The curve bends to the left due to resistive forces which assist airflow:
1. Elastic recoil of lungs and chest wall
2. Surface tension in alveoli
How would you describe mammalian airflow compared to avian ?
Mammalian is tidal
Avian is unidirectional
Describe ventilation in frogs
Air is forced into the lungs when they breathe in, air is circulated to promote gas exchange.
The lungs are emptied by abdominal contraction, which pushes the air out.
Describe the insect respiratory system
Airways penetrate each body segment, allowing diffusion.
Abdominal muscles ‘pump’ air through trachea, setting up convection currents.
Describe water movement across gills
Energy is needed to pump water across gills
Water is ‘pulled’ across gills when opercular cavity expands and opercular flaps open.
Water ‘pushed’ over gills when fish closes mouth.
