Respiratory phys Flashcards
what is gases change dependent on (3)
ventilation- amount of gas delivered by the lungs
perfusion- amount of blood delivered to lungs
diffusion- amount of gas that passes thru air blood barrier
What is the air blood barier
Made up of capillary endothelium, basement membrane and type 1 pneumocytes
What do type II pneumocystis do
Produces surfactant which reduces surface tension of the alveoli
Rate of diffusion is determined by what
inversely proportional to tissue thiccness
Where is ventilation and perfusion greatest in lung
Ventilation- highest at apex
perfusion- greatest at base
What 4 factors cause a shift to right of oxygen saturation curve (decrease in Hb affinity for O2, causing more O2 to be released)
-Acidosis (decreased Ph)
-Carbon dioxide increase
-temp increase
-2,3 DPG
What are the 3 forms Co2 is transported in
bicarbonate (mc)
Carbaminohemoglobin
disolved plasma (least)
What is the haldane effect
binding of O2 to hemoglobin tends to displace CO2
What is the homeostasis of rate and depth of breathing
so that arterial Pco2= 40mmHg
What are the breathing centres in the brain
-Pneumotaxic center in upper pons turns off or inhibits inspiratory centre causing decrease in depth + increase in rate
- Apneustic center in lower pons- prevents turning off inspiratory centre
How does the brain sense increased CO2
CO2 crosses BBB and enters CO2 where it dissociates to form H+ and HCO
Medulla senses levels of H directly and co2 in blood indirectly
How are chemoreceptors stimed
first by raise in Pco2 and then by decreased arteriole Ph (acidosis) and finally by decreased PO2
What is cheyenne stokes breathing
periods of rapid breathing with increasing ten decreasing tidal volume with apnea– seen in CHF
What is Kissmaul breathing
Deep regular breathing
–seen in diabetic ketoacidosis
What is Biots respiration
bouts of irregularly irregular breathing and apnea
-breain stem compression
