Chemical Confrol Of Resp Flashcards
What is negative feedback
Primary type homeostasis
Opposes initial change
Components - sensor, control centre and effector
What are the controlled variables of RESP integrative feedback
Arterial Po2 (decreases) Arterial Pco2 (increases) Arterial hydrogen ion conc (increases)
What are the sensors for RESP negative feedback
Chemoreceptors (peripheral and central)
What is the conflict centre for RESP negative feedback
RESP centres
What are the effectors for RESP negative feedback
RESP muscles leading to changes in ventilation
What is chemical control of RESP
Example negative feedback
Controlled variables are blood gas tensions especially carbon dioxide
Chemo receps sense values of gas tensions
Where are peripheral chemoreceptors
Carotid and aortic bodies
What doe Peripheral chemoreceptors do
Sense tension of oxygen and carbon dioxide and hydrogen ion in the blood
Where are the central chemoreceptors
Near surface of medulla of brain stem
What DIT he central chemoreceps do
Respond to the hydrogen ion conc of the CSF
Hero is the Csf sep form blood
By blood brain barrier
Relatively Imperm to hydrogen ion conc and bicarbonate
Carbon dioxide diffuses readily
How does CSF differ to blood
CSF has less protiens than blood and hence less buffered than blood
What is hypercapnia
Increased arterial Pco2
Lead to co2 generated hydrogen ion through central chemoreceptors
What is hypoxia
Decreased arterial Po2 and ventilation
Effect via peripheral chemoreceps
Stim only when arterial po2 below 0.8 kPa
Imp at high altitudes and pt’s with chronic carbon dioxide retention
Hypoxia at high altitudes is caused by
Decreased partial pressure of inspired oxygen PiO2
What is the response to hypoxia at high altitudes
Hyperventilation and increased cardiac output
Symptoms - headache, sickness, dizzy, nausea, shortness breath
What are some chronic adaptations to high altitudes hypoxia
Increase RBC prod
Increase 2,3- BPG produced in RBC (increase oxygen offload)
Increase num caps
Increased num mito
Kidneys conserve acid (decrease arterial pH)
What sit he hydrogen ion drive of respiration
Effect via peripheral chemoreceps
H+ doesn’t readily cross blood Brian barrier but carbon dioxide does
Peripheral chemoreceps help control acidosis by add non carbonic acid h+ to blood
Stimulation of H+ causes hypervent and increased elim carbon dioxide
What are some neural and chemical factors that may increase ventilation during exercise
Reflexes originating form body movement Adrenaline release Impulses form cerebral cortex Increase body temp Accumulation carbon dioxide and hydrogen ion generated by active muscles
What is homeostasis
Maintain body internal enviro must be maintained in a morrow range Eg - ph - temp - conc of nutrients - conc of oxygen and carbon dioxide - conc waste prods
