lec 7

Question 1

what happens to the rate of oxygen consumption when at rest, exercising, and for elite athletes

Answer 1

-rest = cells use 200ml
-increases x15-20 times during exercise
-increases up to x30 for elite athletes

Question 2

explain the neg. feedback loop of the regulation of breathing

Answer 2

-chemoreceptors detect change in CO2, O2, pH, or mechanoreceptors detect stretch in lung, send info to control center (medulla, pons, cerebral cortex), send info to respiratory muscles (diaphragm, intercostals, abdominals)

Question 3

what are the 2 respiratory neurons medulla, 1 respiratory neuron in pons

Answer 3

-dorsal respiratory group (DRG)- inspiration
-ventral respiratory group (VRG)- active inspiration + expiration

-pontine respiratory group (PRG)- pneumotaxic + apneustic centres

Question 4

explain DRG

Answer 4

-in medulla
-inspirations
-determines timing of respiratory cycle
-intermitten signals- alternative contraction + relaxation

Question 5

explain the pre-botzinger complex

Answer 5

-pacemaker cells of medulla
-location of rhythmic pattern generations
-sends to DRG

Question 6

explain VRG

Answer 6

-located in medulla
-not active during rest
-active expiration + forceful inspirations
-input from chemoreceptors + brain centre

Question 7

f + Vt

explain pneumotaxic centre + apneustic centre

Answer 7

-turns DRG signals of early- limit inspiration
-increases f, decreases Vt

-keeps DRG signals on longer- prolongs inspiration
-increases Vt, decreases f

Question 8

explain central vs pheripheral chemoreceptors

Answer 8

-sensitive to H+ in CSF
-found in cerebrospinal fluid

-sensitive to O2, CO2, and pH
-found in arterial blood

Question 9

explain the strength of peripheral chemoreceptor firing

Answer 9

-80-100mmHg, weak firing
60-80mmHg, strong firing
-O2<60mmHg, decreased firing + decreased breathing, BAD

-less then 80, detected by recveptors, send to respiratory centre, increase ventilation + arterial PO2