respiratory control

Question 1

5 main respiratory centers in the brainstem

Answer 1

Dorsal respiratory group (DRG)

Ventral respiratory group (VRG)

Pontine respiratory group (PRG)

Botzinger complex (BotC)

Pre-Botzinger complex (Pre-BotC)

Question 2

Which respiratory centers are supposed to generate the timing (frequency) of respiratory rhythm?

Answer 2

Pre-Botzinger complex

PRG

Question 3

How was the PRG found to be associated w/ timing or frequency?

Answer 3

A lesion in the PRG caused apneusis (stuck in inspiration)

Transition from inspiration to expiration and vice versa is needed for rate/rhythm

SO, the PRG must play a role

Question 4

SO, the function of the PRG is what?

Answer 4

Turn off inspiration

Question 5

Function of DRG

Answer 5

Mostly pre-motor to phrenic nerve innervation

Lots of sensory information

Question 6

Function of VRG

Answer 6

Rostral - pre-motor to phrenic and other inspiration muscles

Caudal - pre-motor to upper airway and other expiration muscles

Question 7

SO, DRG and VRG control the what?

Answer 7

The depth (tidal volume) of breathing

Question 8

Apneusis vs. apnea

Damage that could cause each

Answer 8

Apneusis - maintained inspiration (no expiration) - Pons damage

Apnea - no respiratory effort - medullary/spinal damage

Question 9

Explain this equation:

VE = f x VT

Answer 9

f = timing/frequency of breaths

VT = tidal volume

VE =

Question 10

Explain the cycle of respiratory control (4 parts)

Answer 10

Medullary centers affect respiratory muscles (respiration), which then affect chemical balances (CO2, O2, pH), which affect chemoreceptors, which stimulate the medullary centers

Question 11

3 main chemoreceptor types (chemicals they respond to) in respiratory system

Increased or decreased causes receptor firing (for each)?

Answer 11

inc CO2 - increased
dec O2 - increased firing
increased H+ - increased

Question 12

Why are chemoreceptors so important? (What would happen w/o them?)

Answer 12

Normally, neurons would slow down w/ less O2 to not use up ATP for APs

BUT, this would cause decreased ventilation and further hypoxia

SO, the chemoreceptors cause INCREASED neuron activity when the system would otherwise want to slow down

Question 13

2 sets of chemoreceptors (w/ locations)

Answer 13

Central - brain

Peripheral - carotid (uses dopamine) and aorta

Question 14

Activation of central chemoreceptors

Specific location?

Answer 14

CO2 crosses BBB, reacts w/ water and is converted to HCO3 and H+, so the increased H+ triggers the chemoreceptors to increase breathing (“respiratory drive”)

Ventral medulla

Question 15

Peripheral chemoreceptor activation

Ultimate effect?

Answer 15

Direct activation by changes in O2, CO2, and/or H+ (pH)

Increased firing rate of afferents to brainstem

Increased frequency and tidal volume (controlled by centers in brainstem)

Question 16

Slowly-adapting mechanoreceptors in the lungs

Function?

Location?

Answer 16

Slow pulmonary stretch receptors - sensitive to airway stretch (i.e. lung volume increase)

Causes fibers in vagus n. firing to inhibit/terminate inspiration and prolong expiration

Located in airways

Question 17

So, explain the 4 parts of the respiratory control cycle

Answer 17

Medullary centers affect respiratory muscles (breathing), which changes lung volume, thus affecting pulmonary stretch receptors, which act on medullary centers

Question 18

When are pulmonary stretch receptors most important? (2)

Answer 18

Infants

Adults during exercise

Question 19

Rapidly-adapting mechanoreceptors in the lungs

Function?

Location?

Answer 19

Rapid stretch receptors

Irritation, foreign bodies, stretch cause vagus nerve fibers to innervate brain, causing COUGH

Located in airways

Question 20

J receptors

Effect?

Answer 20

Receptors near alveolar blood vessels that are sensitive to pulmonary edema

Again, vagus n. fibers

Cause cough, tachypnea

Question 21

When are J receptors and rapid-adapting receptors used?

Answer 21

ONLY when in need of immediate protection

Question 22

Explain cortical influences on breathing

Answer 22

When talking or holding your breath, the cortex bypasses the medullary centers and sends direct input to respiratory muscles

AGAIN, only when needed