L22: Respiratory System III Flashcards
CO2 is ___ soluble in body fluids than O2
more
in what ways is CO2 transported in the blood?
1) dissolved in the blood (7%)
2) as a bicarbonate ion (70%)
3) binds to hemoglobin - HbCO2 (23%)
the rapid conversion of CO2 into bicarbonate ion depends on the presence of __
carbonic anhydrase (CA)
carbonic anhydrase (CA) is found in __
in red blood cells
effects of O2 affinity changes upon __
Hb loading and unloading
conversion of CO2 to H+ and HCO3- continues until
equilibrium is reached
to keep the reaction going, the products __
must be removed from the cytoplasm
what are the ways of removing free H+ and HCO3- from RBCs?
1) an antiport protein exchanges HCO3- for Cl- in a process known as chloride shift
2) Deoxyhemoglobin within the RBC acts as a buffer and binds H+ in the reaction:
H+ + Hb -> HbH
how does CO2 bind to hemoglobin?
when O2 leaves its binding sites on the Hb molecule, CO2 binds with free Hb at exposed amino groups
what is formed when CO2 binds to Hb?
HbCO2 carbaminohemoglobin
most of the HCO3- __
moves out of the erythrocytes into the plasma in exchange for chloride ions
as venous blood flows through lung capillaries, __
blood P(CO2) decreases because of the diffusion of CO2 out of the blood into the alveoli, and the reactions are reversed
most of H+ generated in the erythrocytes from carbonic acid
binds to deoxyhemoglobin because deoxyhemoglobin formed as oxygen unloads from oxyhemoglobin, has a higher affinity for H+
as the blood flows through the lung capillaries
H+ bound to deoxyhemoglobin is released and combines with HCO3- to yield carbon dioxide and water
diaphragm and intercostal muscles are
skeletal muscles
skeletal muscles do not contract without
stimulation by motor neurons
breathing depends entirely upon
cyclical respiratory muscle excitation by the motor nerves
inhibition or destruction of motor nerves results from
paralysis of the respiratory muscles and death unless artificial respiration is instituted
when action potentials cease
the inspiratory muscles relax, and expiration occurs as the elastic lungs recoil