The basics
Describe the difference between ventilation and respiration
Ventilation: Moving gas into and out of your lungs
Respiration: Exchange of gases
Describe the difference between minute ventilation and alveolar ventilation
Minute ventilation (VE)= frequency of breaths * Titovolume (how much air you are getting in and out of your lungs per minute)
Alveolar ventilation (Va)= frequency of breaths ( Titovolume - deadspace) (how much gas is actually reaching the alveoli)
Hemoglobin can carry how many oxygen molecules
4
Where is the respiratory center located?
Medulla--> Inspiratory and expiratory center
The visceral pleura is the ___________
The parietal pleura is the ___________
The space between the two is the _____________ and it is filled with ________________
Outer part of the lung
Inner part of the thorax
Pleural cavity; intraplural fluid (important for the lungs to adhere to the thorax for lung compliance)
Describe the V/Q at each zone of the lungs. How do we get all three zones to an optimal V/Q during exercise?
Upper zone: elevated ventilation, reduced perfusion, V/Q is high
Middle zone: ventilation≈ perfusion, V/Q is optimal
Lower zone: Reduced ventilation, elevated perfusion, V/Q is low
During exercise blood vessels in lower zone will vasoconstrict and vessels in upper zone will vasodilate
How does Hb go from relaxed to taut?
When the oxygenated RBC reaches the tissue the low PO2 and high CO2 conditions in the tissue trigger the Leubering- Rapoport Pathway (a deviation in the glycolitic pathway the RBC uses to make ATP) that makes 2,3 BPG which causes a conformational change of Hb to go from relaxed to taut.
What are the two centers in the Pons
Pneumotastic: responsible for rate and pattern of breathing
Apneustic: responsible for the intensity of breathing
According to boyles law what is happening during inspiration and expiration?
Inspiration: Diaphragm contracts (flattens bc its relaxed state is curved) which increases the volume that subsequently decreases pressure (boyles law). Gas moves from high to low pressure so air goes into lungs
Expiration: Diaphragm relaxes which decreases the volume that subsequently increases pressure (boyles law). Gas moves from high to low so pressure goes out of the lungs
How does the Shunt result in hypoxemia?
The faulty alveolus (maybe its filled with fluid) cannot oxygenate the blood flowing past it effectively therefore the amount of the oxygenated blood leaving the lungs is decreased= less oxygen in the blood=hypoxemia
What are the two ways CO2 can go once it has entered the RBC to return back to the lungs?
CO2 can bind to Hb
CO2 combines with H2O which forms H2CO3 (carbonic acid) that dissociates into H+ (proton) or HCO3- (bicarbonate ion). The HCO3- goes through the chloride shift and its the primary way CO2 is returned to the lungs
What does H+ have to do with respiration?
H+ is a powerful stimulator for ventilation in the medulla. When we are not breathing (we dont exhale CO2) CO2 will cross the Blood Brain Barrier. It will combine with H2O to form H2CO3 that dissociates into H+ and H2CO3-. H+ will stimulate ventilation
What is the law of La Place and how is it applicable in understanding lung compliance?
P= 2T/r
Because we have a alveoli that varying in size (r portion of the equation) the pressure differs. This is not good because it limits the air from reaching the alveoli for gas exchange. We can change the tension (T portion of the equation) with surfactant which will ensure the pressure is the same across all alveoli.
How does the VQ mismatch result in hypoxemia
The perfusion in the lungs is poor which affects how well our alveoli can oxygenate it. Too much blood can flow past one alveolus and it cannot keep up with oxygenating it all. This results in less oxygenated blood leaving the lungs= less oxygen in the blood= hypoxemia
Where in the pathway of oxygenation does the Bohr effect represent?
At the level of the tissue where there is decreased PO2, decreased PH, increased temp that causes the shift to the right (less O2 bound to Hb). The Oxygen is being used!
What do the carotid bodies and aortic bodies detect?
chemical changes in the blood: increase in temp, decrease in PO2, increase in PCO2, and a decrease in PH (exercise). They then send signals to elevate ventilation
Diaphragmatic paralysis is a condition where the innervation becomes damaged. What is the nerve and what symptoms would a patient likely experience? Describe the physiology behind it.
Phrenic nerve controls the diaphragm. If there is damage to the phrenic nerve, there is decreased ability for the diaphragm to contract. The volume in the lungs does not increase (as much), which limits how much the pressure drops therefore limiting how much air/oxygen we can flow into the lungs and how much we can oxygenate blood to deliver to our tissues: the patient would experience shortness of breath, fatigue
Altitude sickness increases the risk of hypoxia. How?
At altitude, the barometric pressure decreases (≈ 42mmHg). This results in a small pressure gradient between the oxygen in the lung and the red blood cell and therefore we cannot oxygenate as much blood. If there is reduced oxygenated blood then we can't deliver as much oxygen to our tissues
An individual with chronic high blood sugar levels report higher levels of HbA1c: Glycated hemoglobin (glucose bound to Hb). Glycayed Hb causes Hb to hold on to oxygen more tightly that it normally would. How would this lead to hypoxia?
This increase in oxygen affinity to Hb would make it more difficult to release the oxygen at the tissues that need it.
Congenital Central Hypoventilation Syndrome is caused by a mutation in PHOX2B gene that is essential for the development of the autonomic nervous system. With this condition, automatic breathing is severely compromised. Which structure does this primarily affect and how does it result in decreased ventilation?
The medulla, because it is responsible for automatic respiration.