Renal Physl 17 Flashcards
What is normal body pH?
7.4
What do we measure to asses the whole body pH?
The pH of the plasma
What happens to neurons if pH is too low?
Neurons are less excitable, and CNS depression occurs
What happens to neurons if pH is too high?
Neurons are highly excitable
What is the largest source of H+ ions?
Acid production from carbon dioxide during aerobic respiration
How is acid produced in aerobic respiration?
Carbon dioxide from respiration combines with water to form carbonic acid which then dissociates into hydrogen ion and bicarbonate ion
What are the three key process in pH homeostasis?
- Buffer systems
- Ventilation
- Renal regulation of hydrogen and bicarbonate ions
What do buffers do?
Prevent large fluctuations in pH
What is a buffer?
A molecule that can modulate pH in response to a disturbance
How do buffers tend to modulate pH?
By combining with hydrogen ions or releasing hydrogen ions
What is the first, second, and third line of defense in pH homeostasis?
1st - Buffer systems
2nd - Ventilation
3rd - Renal regulation
Where are buffers of the body located?
- In cells
* In circulating plasma
What kind of buffers are located in cells?
- Cellular proteins
- Phosphate ions
- Hemoglobin
What kind of buffers are located in plasma?
HCO3-
What happens to bicarbonate ions for every hydrogen ion?
For every hydrogen ion a bicarbonate remains in the RBC
How can a bicarbonate ion leave the RBC?
In exchange from a chloride ion
What is chloride shift?
When for every bicarbonate ion able to leave the RBC a chloride ion enters
What represents the most important extracellular buffer system in the body?
Large amounts of plasma bicarbonate produced from metabolic carbon dioxide
What are bicarbonate ions in the plasma able to buffer?
Hydrogen ions from non respiratory sources like metabolism
How would an increase in carbon dioxide affect the reaction?
It would cause an increase in hydrogen and bicarbonate ions decreasing pH
How would an increase in hydrogen ions shift the equation?
Bicarbonate ions bind with the H+ to form carbonic acid and both carbon dioxide and water increase
How does an increase in carbon dioxide affect ventilation?
It increases ventilation
What can acidosis induce in the lungs?
Respiratory compensation
What is ventilation?
A homeostatic approach for adjusting pH
What can stimulate respiratory compensation?
Hydrogen ions and carbon dioxide
What directly alters ventilation at the carotid and aortic chemoreceptors?
Plasma hydrogen ion levels
What stimulates chemoreceptors?
Increased hydrogen ions
What does stimulation of chemoreceptors by hydrogen ions do?
Sends information to medullary control centers which stimulates the muscles of ventilation and increase the rate and depth of breathing
What does increased ventilation permit?
Loss of carbon dioxide at the lungs and conversion of hydrogen ions to carbon dioxide and water in order to restore pH
Why don’t central chemoreceptors in the medulla oblongata respond directly to hydrogen ions?
Because H+ does not cross the blood brain barrier
What happens to the pH and carbon dioxide if ventilation is depressed in hypoventilation?
Carbon dioxide increases and causes an acidotic state
What happens to the pH and carbon dioxide if ventilation is increased in hyperventilation?
Carbon dioxide is decreased and pH increases
