Lab 8: Respiratory Physiology Flashcards
If the percent of Oxygen is the same everywhere, why might it be harder to breathe at higher altitudes?
As you ascend into higher altitudes, the total atmospheric pressure drops causing a drop in the partial pressure of the gases that make up the air.
What must happen for O2 to diffused from the alveoli into the blood?
The partial pressure of O2 in the blood must be lower than that in the in the alveoli.
Why do we need hemoglobin?
What is it’s structure?
O2 has a very low solubility in liquid and if the body tissues had to rely only on dissolved O2, there would not be a suffcient amount to meet the metabolic demands of the tissue. Hemoglobin allows blood to carry oxygen.
A hemoglobin molecule has four O2 binding sites.
What is percent saturation?
The number of binding sites occupied by oxygen in all red blood cells.
How does CO2 diffuse out of the body?
The partial pressure of CO2 is higher in peripheral tissues so it can leave the tissue and enter the blood. The pressure gradient between CO2 in the blood the alveoli also ensures that CO2 diffuses out.
What is the primary way that CO2 is carried in the blood?
What is the reaction?
As bicarbonate (HCO3-) which is made possible by the bicarbonate buffering reaction in the cytosol of a red blood cell.
CO2 + H2O <—–> HCO3- + H+
What controls breathing?
Contraction of the respiratory skeletal muscles must be intiated by somatic motor neurons, controlled by the CNS.
What is the pre-Botzinger area?
Contains spontaneously active neurons that may act as the basic pacemaker for the respiratory rhythm.
What can modify the rhythm of breathing?
Sensory inputs from central and peripheral chemoreceptors can modify the rhythm of breathing including the rate and/or depth, to help maintain blood gas homeostasis.
Describe peripheral chemoreceptors.
Located in the aorta and cartiod arteries and are sensitive to changes in PO2, PCO2, and H+ of the plasma.
Describe central chemoreceptors.
Located along the medulla and sensitive to changes in pH and PCO2 of CSF.
Plasma H+ cannot readily cross the brain-blood barrier,
Where does the change in pH of CSF come from?
CO2 can be converted into H+ and CO2 can diffuse across the blood-brain barrier into CSF.
What is minute ventilation?
What is the equation?
Represents the volume of air inhaled or exhaled in one minute.
Tidal Volume (volume of air that is inhaled or exhaled in one breath) x Breathing rate (# of breaths per minute) = Minute Ventilation
When should gases be collected?
Gases should be collected when a person has reached a steady state when O2 consumption remains constant (about 3-5 minutes at a particular condition).
