Resp - Ventilation Control

Question 1

Respiratory control centers in brainstem

Answer 1

pons

medullary resp center

Question 2

parts of medullary resp center

Answer 2

pattern generator
dorsal resp group (DRG)
ventral resp group (VRG)

Question 3

parts of pons resp center

Answer 3

integrator
pneumotaxic center
apneustic center

Question 4

dorsal resp group

Answer 4

pacemaker of inspiration

responsible for continuous (tonic) inspiratory drive

Question 5

DRG how it works

Answer 5

intrinsically oscillate
APs transmitted via phrenic nerve to diaphragm/inspiratory muscles to initiate inspiration
inspiratory neurons: fire –> inspire, cease fire –> expire

Question 6

VRG

Answer 6

quiescent during quiet breathing
Pre-botzinger complex
play a role in forced expiration

Question 7

Pre-Botzinger complex actions

Answer 7

expiratory neurons: inhibit inspiratory neurons in DRG

Question 8

inspiration/expiration control center responses

Answer 8

1. latent period
2. inspiration: up DRG firing, then stop at end
3. expiration: up DRG (brakes) in phase I, then cease in phase 2

Question 9

DRG neuron types

Answer 9

1 alpha
1 beta
both are inspiratory

Question 10

1 alpha actions

Answer 10

prevent over distension
inhibited by lung inflation (high V)
Hering Breuer inflation reflex

Question 11

1 beta actions

Answer 11

prevent extreme deflation
excited by lung deflation
Hering Breuer deflation reflex

Question 12

Hering Breuer inflation reflex

Answer 12

inhibits inspiring when lung volume is high
use pulmonary stretch receptors in SM of airway
inhibit DRG inspiratory neurons

Question 13

pneumotaxic center

Answer 13

tells DRG to turn off inspiratory neurons
downs TV
up RR
dominates pons

Question 14

apneustic center

Answer 14

stops inspiratory neurons from being turned off

Question 15

apneusis

Answer 15

no pneumotaxic brakes

prolonged inspiratory gasps w/ brief expirations

Question 16

central chemoreceptor

Answer 16

in CSF, respond to CO2 that comes in and dissociates into H+

tell respiratory control center to up ventilation to lower PCO2

Question 17

most important mech to control ventilation at rest

Answer 17

CO2-induced H+ in CSF

why we cant die by holding our breath

Question 18

central chemoreceptor change in sensitivity

Answer 18

prolonged hypoventilation
bicarb used to buffer H+
receptors cant tell theres more CO2
hypoxic drive becomes primary resp stim

Question 19

peripheral chemoreceptor sensitive to…

Answer 19

hypoxia (PaO2 >. 60)
hypercapnia (weakly)
acidosis

Question 20

PCO2 and PO2 (together) effects on ventilation

Answer 20

1. ventilation goes up as PCO2 goes up – BUT if PO2 is low also, ventilation goes up more quickly as PCO2 goes up (increases sensitivity to hypercapnia)
2. ventilation goes up as PO2 goes down – BUT if PCO2 is high also, ventilation will go up more quickly as PO2 goes down (increases sensitivity to hypoxia)

Question 21

submaximal exercise and ventilation

Answer 21

ventilation up in few seconds

then up slowly to plateau

Question 22

maximal exercise and ventilation

Answer 22

up ventilation disproportionately

due to lactic acid stim carotid bodies (peripheral chemo)

Question 23

why make lactic acid during exercise

Answer 23

increased ATP demand - glycolysis, glyconeogenesis
mitochondrial saturation –> goes to lactate
fast twitch units recruited (use more glycolysis)

Question 24

athletes and ventilation

Answer 24

lower ventilation
same lung structure
up oxidative capacity of muscles - less lactic acid made

Question 25

apnea - why?

Answer 25

sleep - central chemo less sensitive to PCO2

Question 26

SIDS - why?

Answer 26

immaturity of respiratory control mechanisms (brain stem or chemoreceptors - carotid*)