Flashcards in Chemical control of respiration (7) Deck (15)
What is a stable internal environment and what components must be maintained within a narrow range?
-concentration of water and electrolytes within and outside the cells
-pressures and volumes
-conc of nutrients (glucose),O2 CO2 and waste products (urea)
What is the primary type of homeostatic control system?
What are the stages of negative feedback?
1)Sensor ( chemoreceptor)
2) integrating centre (medulla)
3)Effectors ( respiratory muscles)
4) Variable ( PO2/PCO2)
What are the arterial partial pressures of O2 and CO2 (set point)?
What are the venous partial pressures of O2 and CO2 (set point)?
What do peripheral chemoreceptors do and where are they situated?
Sense tension of oxygen and carbon dioxide and [H+] in the blood and are situated in the carotid and aortic bodies
What is normal ventilation?
What two values do you need to calculate inspired partial pressure(PO2)?
Atmospheric pressure and % of oxygen in inspired air (21%)
What happens when PO2 drops below 60mmHg?
What do chemoreceptors do?
Sense the values of gas tensions
What do peripheral chemoreceptors do?
Sense tension of oxygen and carbon dioxide and [H+] in the blood
What do central chemoreceptors do and where are they situated?
They respond to [H+] of the cerebrospinal fluid (CSF) and are situated near the surface of the medulla of the brainstem
What is Hypercapnia?
Increased arterial PCO2 and ventilation
What is Hypoxia?
Decreased arterial PO2 and ventilation (i.e. at high altitudes