control of breathing

Question 1

respiratory system goal

Answer 1

regulate blood gas parameters (O2, CO2 and pH) within narrow range

Question 2

what regulates ventilation

Answer 2

peripheral and central chemoreceptors

Question 3

subgroups of peripheral chemoreceptor

Answer 3

carotid and aortic bodies

Question 4

Type 1 (glomus cell) senses..

Answer 4

senses decreased arterial pO2, increased pCO2, and decreased arterial pH changes

Question 5

stages of signalling to ventilatory response from peripheral chemoreceptor

Answer 5

signal to 9th cranial nerve- brain stem- medulla oblongata- ventilatory output changes

Question 6

peripheral chemoreceptor sensitivity to decreased pO2

Answer 6

isolated glomus cell under anoxia(no O2)= increased firing of signal to 9th cranial nerve

Question 7

acid base changes effect

Answer 7

modulate sensitivity of the peripheral chemoreceptor (increased firing rate = increased ventilatory response)

Question 8

peripheral chemoreceptors sensitivity to increased pCO2

Answer 8

responsive to changes in pCO2 and sensitivity of response modulated by pH

Question 9

CO2 not independent of pH

Answer 9

when CO2 increases so does H+, meaning pH decreases

Question 10

ventilation associated with pCO2

Answer 10

hypercapnia (increased pCO2)= increased ventilation

hypocapnia (decreased pCO2)= decreased pCO2

Question 11

ways O2 is sensed in hypoxia

Answer 11

• O2 dissociates from heme-containing protein (on cell membrane) near k+ channel
• low pO2 -> increase cyclic AMP (second messenger system
• low pO2 -> changes reduction/oxidation in mitochondrial content

Question 12

signalling mechanism in peripheral chemoreceptors with pCO2 and H+

Answer 12

hypercapnia leads to influx of CO2 into cell and production of H+ which leads to acidosis which leads to increased ventilation

Question 13

central chemoreceptors affected by

Answer 13

cerebral spinal fluid - mainly responds to pCO2 as it diffuses from arterial blood acutely but H+ ions diffuse as well more slowly

Question 14

central chemoreceptors stimulated by

Answer 14

pH (H+ ions) in cerebrospinal fluid (not directly CO2 which undergoes hydration - into bicarbonate and H+)

Question 15

effect of hydrogen on central chemoreceptors

Answer 15

hydrogen ions- stimulate central chemoreceptors- stimulate respiratory centre in medulla oblongata- increase ventilation

Question 16

central chemoreceptors sensitivity to increased paCO2

Answer 16

respond gradually to increase pCO2 and perfect linear relationship btw H+ (pH) in CSF and response by ventilation

Question 17

stimulation for increased ventilation though central chemoreceptors

Answer 17

results in change in CO2/H+

Question 18

ventilatory response emphasised by low O2

Answer 18

in respiratory acidosis - low pH and high C)2

Question 19

isocapnic hypoxia

Answer 19

artificially maintained hypoxia - keep CO2 level in tissues despite changing levels of ventilation

Question 20

Poikilocapnic

Answer 20

variety of resulting CO2 - natural hypoxia

Question 21

Va= (VCO2/paCO2) * K

Answer 21

basically for given metabolic rate doubling ventilation halves paCO2

Question 22

davenport diagram

Answer 22

acid-base disturbances with respiratory origin compensated by kidneys(renal) and metabolic origin compensated by respiration