Respiratory Physiology Flashcards
What are the two types of respiration?
External (physically breathing) and internal (biochemistry)
What are the four steps of external respiration?
- Ventilation (bulk transfer of media to exchange surface)
- Respiratory Exchange (gas diffusion across a respiratory surface)
- Circulation (bulk transport of ECF)
- Cellular Exchange (exchange between ECF and ICF via diffusion)
What percentage of air is O2?
20.95%
What is the Partial Pressure of O2 in air?
159.22mmHg
What is the correlation between O2 levels in freshwater and saltwater?
O2 solubility in freshwater exceeds that of salt water by 20%
Where is the greatest amount of O2 in water?
at the surface
What contributes to the Partial Pressure of a solution?
only free gas molecules
What is Dalton’s Law?
total pressure of a mixture of gases is equal to the sum of the partial pressure of the individual gases in the mixture
What is Henry’s Law?
the amount of gas dissolved in a solution at equilibrium is effected by the pressure of the gas the solution is exposed to, as well as the solubility coefficient of the gas and is proportional to each
(Volume of dissolved gas = P of gas in exposed media x solubility coefficient)
What is Fick’s Law?
gases move down their partial pressure gradient across a permeable membrane
What is the Solubility Coefficient of CO2?
0.57
What is the Solubility Coefficient of O2?
0.024
What is the Solubility Coefficient of N2?
0.012
How much more soluble is CO2 than O2?
20 times more
What four factors affect the efficiency of gas diffusion across a membrane?
- Surface Area
- Thickness of membrane
- Pressure Gradient
- Diffusion Coefficient
What is Boyle’s Law?
For a fixed amount of an ideal gas (at room temp), Pressure and volume are inversely proportional
What are the type types of breathing?
Tidal breathing and flow through breathing
What are the cons of tidal breathing?
- air moves through the same opening.
- cannot completely empty lungs of old air
- incontinuous supply of fresh medium
What are the pros of flow through breathing?
- unidirectional flow of media
- completely fresh medium used
- constant flow of fresh medium
What are the three types of gas exchange?
- Concurrent
- Cross-current
- Counter-current
What is concurrent gas exchange?
- medium and blood from in same direction
- does not exist in nature
What is cross-current gas exchange?
- medium and blood travel at right angles
- constant diffusion
- more gas in blood than outgoing medium
- efficient gas exchange
What is counter-current gas exchange?
- medium and blood flow in opposite directions and parallel
- PP gradient remains the same and diffusion is constant
- more gas in blood than medium at the end
- most efficient
What gas exchange is seen in fish?
counter current gas exchange
What are the structure of gills?
- several large arches on each side, each with two rows of gill filaments, further divided into lamellae
- lamellae is gas exchange area
Explain how ventilation of gills is achieved?
- a dual pumping system:
Buccal pressure pump: opening and closing of mouth
Opercular suction pump: opening and closing of the opercula
what is the opercula?
flap on the outside of fish gills
What is included in the respiratory tree?
between trachea and alveoli
Describe the lining of the trachea, bronchi and bronchioles
smooth muscle and mucous
What is thew function of upper respiratory tract?
- condition inspired air
- filter air
- mucocilliary escalator
What does parasympathetic stimulus do to the bronchioles?
- airway constriction
- blood vessel dilation
- increased glandular secretions
What does sympathetic stimulus do to the bronchioles?
- airway relaxation
- blood vessel constriction
- inhibition of glandular secretions via beta2 receptors
What are Type I alveolar cells?
single thin layer of squamous epithelial cells (90-95% of surface)
What are Type 2 alveolar cells?
larger cuboidal cells, which produce the fluid layer that lines the alveoli as well as surfactant
What are Type 3 alveolar cells?
free ranging phagocytic alveolar macrophages that patrol the alveolar surface and phagocytise bacteria
What is the space between the visceral and parietal pleura?
intrapleural space filled with intrapleural fluid
What is Intrapleural pressure (Ppl)?
normally negative and holds the lungs open
What is Ppl during quiet inspiration and expiration?
becomes more negative during inspiration and less negative during expiration
What is Ppl during strong respiratory effort?
ranges from most positive to negative values
What are the values of Palv during breathing?
Inspiration: decreases to approx -1mmHg
expiration: increases to +1mmHg
What is Transpulmonary Pressure (Ptp)?
The difference between alveolar pressure and pleural pressure.
What does Transpulmonary pressure say about the lungs?
the more positive the pressure, the more the lungs are inflated
List the process of quiet inspiration in order
- Inspiratory muscles contract (diaphragm and ext. intercostals)
- rib cage expands
- Ppl becomes subatomic
- rise in Ptp
- lungs expand
- Palv becomes subatomic
- air flows into alveoli
List the process of quiet expiration in order
- diaphragm and ext. intercostals relax
- chest wall moves inward
- Ppl back to preinspo value
- Ptp back towards preinspo value
- lungs recoil to preinspo size
- air flows out of lungs
Describe the difference between breathing in normal mammals and horses
- horses have 2 inspiratory and 2 expiratory phases
- horses also have a totally active expiration
- collapse of upper airways during inspiration is prevented by contraction of abductor muscles attached to these structures
Define Eupnea
normal, quiet breathing
Define Hyperpnea
increased depth and frequency (as during exercise)
Define Tachypnea
excessive rapidity of breathing
Define Bradypnea
abnormal slowness of breathing