Respiratory Phys I Flashcards
what are the 4 major steps to respiration
- Ventilation
- Gas exchange (bw alveoli + pulmonary capilaries)
- Transport of O2 + CO2 by blood bw lungs and tissues
- Gas exchange bw bloods + cells across systemic tissue capillaries
where does the conducting zone start and end
From trachea to the terminal bronchioles (cilliated for removal of debris)
Where is the respiratory zone
From respiratory bronchioles to alveoli
What is the alveolar PO2 and PCO2 are determined by
relationship bw alveolar ventilation and pulmonary capillary perfusion (VQ ratio)
What is henrys law
at a constant temp the amount of gas dissolved in a given liquid is directly proportional to the partial pressure of that gas
What is boyles law
At a constant temp, the pressure and volume of a gas in a system are invesly related
During inspiration how does the overall presure change
the diaphragm contracts and expanding the volume of the thoracic cavity (decrease pressure allowing air to come in)
During expiration how does the overall pressure change
the diaphragm relaxes and shrinks and the volume of the thoracic cavity increasing overall pressure, expelling air
Air pressure inside alveoli during quiet inspiration and quiet expiration
inspiration- less that atmospheric pressure
expiration- greater than atmospheric pressure
What is the trans pulmonary pressure gradient
the distending pressure of the alveoli that keeps them open
What is the trans thoracic pressure gradient
The pressure that pushes inward on the thoracic wall (neg pressure)
What occurs in a pneumothorax and what happens to the pressures
opening to the pleural cavity the allows air to flow into the pleural cavity
-intrapleural, intraalveolar and atmospheric pressure all become equal
Transplural pressure gradient is abolished which leads to collapse of lung
What are the steps on inhilation
transpulmonary pressure incrreases = more lung expansion-> decreases intra alveolar pressure
=air pressure in lung is lower than air and air rushes in
What are the steps of expiration
transpulmonary pressure decreases - lung volume decreases= air pressure in lungs increases
-The air pressure in lung is higher than atmospheric pressure and air is forced out
What does deep inspiration cause/ is caused by
strong contraction of the diaphram + external intercostals + accessory mm
-further increase in thoracic cavity dimensions, more of a drop in intra alveolar pressure
What does deep expiration cause/is caused by
active process done by contraction of expiratory mm
-causes decrease in thoracic cavity dimensions and increase intra alveolar pressure
What is complience and how does it cause
measure of distensibility of the lungs
-higher complience the easier the lung is to expand at a given transpulmonary pressure gradient (less work required)
What is elastance and what are 2 forces that modulate it
opposite of complience (how easily the lungs rebound after being stretched)
- tissue forces
- surface tension forces
what is lung elastic forces
arises from the elastin and collagen fibres in the alveolar walls and surrounding the bronchioles (once the distending force is released the tissue springs back
What 2 things/diseases impact lung elastic forces
Emphysema- destruction of alveolar walls (reduction of surface area w/ air trapped in lungs)
Pulmonary fibrosis- chronic inflammation leading to scar tissue replacing normal lung tissue
what is Surface tension forces
atractive forces between thin liquid molecules lining each alveolus, causes alveoli to collapse
What is surfactant and what is it made of
Type II alveolar epithelium (secretes lipid agent that reduces surface tension)
Why does infant respiratory distress syndrome due to
production of surfactant is absent or insufficient causing alveoli to collapse
How does sympathetic/parasympathetic cause to airway resistance (what does each release + cause)
Symp- adrenaline release-> broncholialation
Para- acH release-> bronchoconstriction
What does increased and decreased alveolar CO2 cause
increased CO2-> bronchodialation
Decreased Co2-> bronchoconstriction
What is radial traction
traction on the bronchial wall by recoil of alveolar septa
What is broncial asthma
imflamatorry disease of airway
-characterized by reversible airflow obstruction and bronchospasm
What is chonic bronchitis
inhaled irratants lead to prod of excess mucus
-obstruct airflow
What does COPD cause
A chronic inflammatory lung disease that causes obstructed airflow (due to emphysema + chronic bronchitis)
What is the importance of neg intraplueral pressure (3)
- keeps lungs streched
- Helps respiratory movement
- Helps venous and lymphatic return against gravity
