Physiology Flashcards
(124 cards)
What are the tissues/components that facilitate ventilation?
1) Chest Wall
- Skeleton (Ribs, sternum, clavicles)
- Muscles (Diaphragm, intercostal muscles)
2) Others (under certain conditions)
- Neck muscles (Scalene, Sternomastoids)
During quiet expiration, the chest cavity _____, thoracic volume (↑/↓). This (↑/↓) the pressure in the _____ and ______, allowing for air to flow out.
Chest cavity recoils (inspiratory muscles relax)
Thoracic volume ↓
Lung and pleural cavity ↑
During inspiration, inspiratory muscles: ___________contract, causing thoracic volume (↑/↓). This (↑/↓) the pressure in the _____ and ______, allowing for air to flow in.
Inspiratory muscles: diaphragm and EICM contract
Thoracic volume ↑
Lung and pleural cavity pressure ↓
Is quiet expiration an active or passive process?
Passive
Is inspiration an active or passive process?
Active
During stimulated ventilation, how are inspiratory and expiratory efforts strengthened?
Extra muscles are recruited in inspiration/expiration:
- neck
- Internal intercostal
- abdominal muscles
What are the changes to ventilation during excercise?
1) Extra muscles recruited (IICM, neck, abdominal)
2) ↑lung volume inhaled during inspiration/exhaled during expiration (↑TV)
3) ↑air drawn into lungs per unit time
What is the pressure in the pleural space?
Intrapleural pressure
Before inspiration, what are the intra-alveolar and intrapleural pressures?
Intra-alveolar=atmospheric @ sea level (760mmHg/ 0 relative pressure)
Intra-pleural<Intra-alveolar (757mmHg/ -3 relative)
Why is intrapleural pressure at rest subatmospheric?
Negative intrapleural pressure created by lung recoil against chest wall (tends to spring out)
What are the changes in the (i) intra-alveolar and (ii) intra-pleural pressure during ventilation?
Both negative relative pressure:
Intra-alveolar ↓ (759mmHg/ -1 relative)
Intra-pleural ↓ (754mmHg/ -6 relative)
What are the changes in the (i) intra-alveolar and (ii) intra-pleural pressure during quiet expiration?
Intra-alveolar ↑ (761mmHg/ 1 relative)
Intra-pleural ↑ back to normal (753mmHg/ -3 relative)
Why does intra-alveolar pressure increase to positive relative pressure during quiet expiration?
Due to the air taken in during inspiration
How does a pneumothorax (lung puncture → air entry) affect (i) intra-alveolar and (ii) intra-pleural pressure?
↑ Intrapleural pressure (to 0 relative)
No change to intra-alveolar (alr 0 relative)
How does pleural effusion, hemothorax, or a pneumothorax affect the pleural cavity?
Pleural cavity expands (air drawn in by negative relative pressure)
What are the 4 ventilation volumes in order of increasing volume?
1) RV (residual)
2) ERV (expiratory reserve)
3) TV (tidal)
4) IRV (inspiratory reserve)
What is Residual Volume (RV)?
Volume of air left after maximum expiration
What is Expiratory Reserve Volume (ERV)?
Volume of extra air expelled with maximum expiration (after passive expiration)
What is Inspiratory Reserve Volume (IRV)?
Volume of extra air entering with maximal inspiration (on top of TV)
What is Tidal Volume (TV)?
Volume of air entering @ each resting breath/volume expelled on passive expiration
How do the ventilation volumes in men compare to women?
Men on avg > Women
- men > muscular framework & chest wall
- > vol. during forceful inspiration/expiration
How does Tidal Volume change during exercise?
Resting VT < Exercising VT
- exercising recruits other lung volumes @ rest
(IRV increase, ERV decrease)
What are 5 factors that may impair the body’s ability to ventilate and thus ventilation volume?
1) Muscle power of chest wall
2) Skeletal deformities of chest wall
3) Resistance to air flow (lung pneumothorax, pleural effusion)
4) Stiffness in Lung (loss of elasticity)
5) Lung collapse
6) Restriction of diaphragm movement (eg. abdominal pain)
What is the term for increased ventilation?
Hyperventilation