Week 1 L2 Flashcards
Boyle’s law
Volume and presure are inversly related
Lung at rest position
diaphragm is relaxed so its high
Lung in expiration position
Diaphragm contracts and goes up
Volume of lung decrese
pressure increase
atmospheric pressure < alveolar pressure
Lung in inspiration position
Diaphragm contracts and goes down
Volume of lung increases
pressure decreses
atmospheric pressure > alveolar pressure
Intrapleural pressure
- sucks lungs to the ribs -3mmHg
- fluid lubricates outside of lung
2.negative pressure created by elastic recoil of ribcage (outward) and elastic recoil of lung (inward) - Allows lungs to fill thorax without anatomical attachment
What is Pneumothorax?
Pleural pressure is damaged
Treatment:
1. apply wet dressing
2. add positive pressure
Pressure changes during quiet breathing
- changes in volume = changes in pressure
- interapleural pressure goes from -3 to -6 when breath in
- Thoracic pressure changes more quickkly than alveolar pressure
- Alveolar pressure changes initially to due to chest volume change -1 or +1
- Alveolar pressure reverses due to air entering or leaving because u have resistance
what is lung compliance?
How much lung volume changes when interpleural pressure changes.
influenced by : 1. elastic fiber network
2. Surface tension in alveoli
Flexible balloon: less elastic and more compliant
Inflexible balloon: More elastic and less complaint
What influences elasticity in the lungs ?
elestic fibers stretch using cross link
eleasticity of the lungs decreases as we age
How is compliance measured ?
CL=Change in V / Change in P
line of compliance shows how much pressure u need to add to expand the lungs
slope negative
there is a elastic limit
Lung compliance curve change with diff diseases
Emphysems / normal/ fibrosis
Emphysema= very complaint so with a little pressure lung volume goes really high really bad when you want to breath out
Normal=
Fibrosis= you reduce pressure but volume doest change a lot
How does Syrface tension influence compliance?
- Surface tension shrinks the volume of alveoli
- pressur ein alveolus increses
- must overcome this pressure when inflating lungs
- the surface tension within alveoli increases elasticity
- Surfactants reduce surface tension/ elasticity
Law of LaPlace
P=2T/r
If two bubbles have the same T the smaller ball have higher pressure.
Pressure can be equal between teh big and small bubble if we add surfactant and reduce surface tension
Types of airflow
- Laminar
- Turbulent
- Intermediate
Laminar Flow’s resistance equation
Resistance= Ln/r^4
L=length of tube
n = viscosity a little change
r= radius
ONLY RADIUS CHANGES IN RESPIRATORY SYSTEM
How much airway resistance due to Trachea and bronchI?
90%
Explain air resistance in Bronchioles:
Bronchioles= large cross sectional are so low resistance, but can change in diameter:
* BRONCHIOCONSTRUCTION: diameter gets small HISTAMINE
* BRONCHIODILATION: diameter gets larger CO2, EPINEPHRIN BINDING TO B2 ADRENERGIC RECEPTORS
Explain air resistance in Bronchioles:
Bronchioles= large cross sectional are so low resistance, but can change in diameter:
* BRONCHIOCONSTRUCTION: diameter gets small HISTAMINE
* BRONCHIODILATION: diameter gets larger CO2, EPINEPHRIN BINDING TO B2 ADRENERGIC RECEPTORS
Resistance in asthma
in asthma air resistance increases therefore, swing of greater amount of pressure from -2 - +2
bronchodialeters can help
How much air is moved into and out of the lungs per minute ? Measurments
Normal Vt= 500mL/breath
Normal respiration rate= 12 breathes/min
Dead space volume= 150mL/breath
What is the total volume of air moving into and out of lungs per minute? calculations
Total pulmonary ventilation= Vt x respiratory rate
500mL/breath x 12 beaths/min= 600 mL/min
What i sthe volume of FRESH AIR reaching the gas exchnage area per minute ?
Alveolar ventilation= (Vt - dead space volume )x respiratory rate
less than pulmonary ventilation
some of the fresh air does not get to alveoli and stays in dead space
