Resp Phisiology Mechanism Flashcards
Name the gas laws involved in respiratory system
Dalton’s law-
Fick law of diffusion
Boyle’s law
Ideal gas law
Explain Dalton’s law
Each gas in a mixture of gases will exert a pressure independentof other gases present
partial pressure of oxygen 760mm hg x21% = 160 mm Hg
Fick’s law of diffusion
The flus or diffusion of gases is directly proportion to partial p gradient
Factors affecting diffusion
- surface area
- partial pressure gradient - most important
- membrane permeability and thickness- diffusion distance
- capillary transmit time - amount of time for the interaction
- ventilation perfusion ratio
Gradient factor (partial pressure gradient)
Particles move from a High partial pressure in the lungs to a low partial pressure in the capillaries
Asthma- gradient
Partial pressure decreases
Membrane thickness
The thicker the lung the slower the diffusion eg silicosis, fibrotic lung disease
Fluid in interstitial space
Decreased diffusion eg pulmonary edema due to heart attack
Membrane surface
Low surface area low diffusion e.g smokers
Solubility of gases
02 much less soluble than carbon dioxide
Capillary transit time
When decrease - diffusion decrease
Ventilation to perfusion ratio
High v/q =higher oxygen and Carbon dioxicel diffusion PE
Low v/q- lower diffusion ASTHMA
What is alveolar ventilation
Air main in and out of the lungs 4L/ min
Alveolar perfusion
Pulmonary blood flow 5L/min
V/q average
0.8 L/min
V/Q apex and base ratio
Apex-0.25
Base-0.8
Boyle’s law
The relationship between gas pressure and volume is inversely related when increasing volume (alveoli) decrease pressure, increasing pressure (bronchi) decrease volume
Inspiration (inhalation)
- Inspiratory muscles contract (diaphragm) descends and rib cage rises
- Thoracic cavity volume increases
- Lungs stretches intrapulmonary-volume increase
- Intrapulmonary pressure drops to 1 mm Hg
- Air moves down pressure gradient until intrapulmonary pressure is 0 (equal to atmospheric pressure)
Muscles involved during primary respiratory muscles during inspirations
- External intercostal muscles and diaphragm
Accessory muscles during inhalation
SCM, scalene, pectoralis minor, serratus anterior.
Expiration
- Inspiration muscles relax and rib cage descends ( diaphragm rises)
- Thoracic cavity volume decreases
- Intrapalmonary pressure rises to above 1mm hg
- Air flows out following pressure gradient
Quiet breathing (eupnea)
Active inhalation and passive exhalation
- diaphragmatic breathing or deep breathing = dominated by diaphragm
- costal breathing or shallow breathing = dominated by rib cog movements
Elastic rebound
When muscles of inhalation relax
- elastic components of tissues recoil
- diaphragm and rib cage turn to original position
Forced breathing (hyperpnea)
- involve active inhalation and exhalation
* Assisted by accessory muscles
