Exam 3: Control Of Respiration

Question 1

What is neurogenesis?

Answer 1

The growth and development of nervous tissue

Question 2

neurogenesis of respiratory drive is largely where?

Answer 2

The brain medulla but influenced by other areas and some peripheral factors

Question 3

neurons of the brain send impulses down the spinal cord to where?

Answer 3

Lower motor neurons which innervate the muscles

Question 4

What consists of neuron “pools” mostly in the
upper medulla oblongata, with some additional neurons in the
pons?

Answer 4

Respiratory control center

Question 5

What neuronal grouping receives information from chemoreceptors, baroreceptors and lung stretch receptors?

Answer 5

Dorsal respiratory group

Question 6

Where do afferent/sensory signals from vagus and glossopharyngeal enter the respiratory control center?

Answer 6

Dorsal respiratory group

Question 7

What is the main driver of respiratory control?

Answer 7

Dorsal respiratory group

Question 8

Where is the dorsal respiratory group located?

Answer 8

Tractus solitarius

Question 9

The dorsal respiratory group contains what kind of neurons?

Answer 9

Inspiratory neurons

Question 10

Ventral Respiratory Group contains what kind of neurons?

Answer 10

Inspiratory and expiratory

Question 11

Where is the pneumotaxic center located?

Answer 11

In the upper pons, within the nucleus parabrachialis

Question 12

What neuronal grouping of the respiratory control center is wired into the inspiratory neurons of the ventral and dorsal respiratory groups?

Answer 12

Pneumotaxic center

Question 13

Where is the chemosensitive area located?

Answer 13

At the ventral surface of the medulla

Question 14

Neurons of what respiratory control center grouping are responsive to chemistry of CSF?

Answer 14

Chemosensitive are

Question 15

What neuronal grouping of the respiratory control center is wired into the inspiratory neurons of the dorsal respiratory groups?

Answer 15

Chemosensitive area

Question 16

the many inspiratory neurons of the

dorsal respiratory group display rhythm signals called what?

Answer 16

inspiratory ramp signal

Question 17

The inspiratory neurons of the dorsal respiratory group primarily send signals where?

Answer 17

The diaphragm

NOTE: normal, restful breathing almost entirely an inspiratory/diaphragmatic
phenomenon (with expiration a passive recoil process)

Question 18

An increase in inspiratory ramp signal would result in what?

Answer 18

Increased contraction of the diaphragm

Question 19

the pontine pneumotaxic center inhibits the inspiratory neurons (mostly of dorsal respiratory
group) in order to affect breathing how?

Answer 19

limit the depth of breathing

Question 20

Increased pneumotaxic action will results in what?

Answer 20

Short inspiration (i.e. rapid breathing)

Question 21

Decreased pneumotaxic action will results in what?

Answer 21

Lengthened inspiration as seen in restful breathing

Question 22

The magnitude of the ramp signal can be modified/increased by the action of what medullary neuronal grouping?

Answer 22

Ventral respiratory group

Question 23

How does the ventral respiratory group increase ramp signal to make breathing more powerful?

Answer 23

It has both inspiratory and expiratory neurons that recruit muscles of the ribcage to assist in inspiration and expiration

Question 24

How does the ventilation cycle get voluntarily overridden by “higher center” of the brain?

Answer 24

by way of corticospinal and corticobulbar tracts directly to lower
motor neurons of thoracic musculature, bypassing respiratory control center

Question 25

How does the ventilation cycle get modified by pulmonary stretch (i.e. volume) receptors in the smooth muscle of airway?

Answer 25

pulmonary stretch receptors in the airways (smooth muscle)

send signals up the vagi (CN X) into the dorsal respiratory group to decrease activity of inspiratory neurons

Question 26

What is the Hering Breuer reflex?

Answer 26

is a reflex triggered to prevent over-inflation of the lung. Pulmonary stretch receptors present in the smooth muscle of the airways respond to excessive stretching of the lung during large inspirations

Question 27

What is the main control input from central and peripheral receptors?

Answer 27

central chemoreceptor in the form of the “chemosensitive area”
on the ventral surface of the medulla

Question 28

What is the primary purpose of the central chemoreceptor in the form of the “chemosensitive area”
on the ventral surface of the medulla?

Answer 28

to regulate the

amount of O2 and CO2 in the body

Question 29

The chemosensitive area on the ventral surface of the medulla is particularly sensitive to what?

Answer 29

H+ (↓ pH, and indirectly to ↑ CO2)

Question 30

Why is the chemosensitive area on the ventral surface of the medulla INDIRECTLY sensitive to carbon dioxide?

Answer 30

Because it is sensitive to H+ which is derived from the carbonic acid reaction that converts carbon dioxide and water to carbonic acid and ultimately dissociates to bicarbonate and H+

Question 31

What is tachypnea?

Answer 31

Increased ventilation depth and rate

Question 32

What do the central chemoreceptors in the form of the “chemosensitive area”
on the ventral surface of the medulla stimulate?

Answer 32

The dorsal respiratory group to increased ventilation rate and depth

Question 33

Why do small changes in the partial pressure of carbon dioxide cause significant changes in pH that affect the neurons of the central chemoreceptors?

Answer 33

because there is no hemoglobin or conventional buffers in the CSF to stabilize the acidity

Question 34

What are the three features of the carbon dioxide - ventilation relationship?

Answer 34

1) partial pressure of CO2 level dramatically affects
ventilation rate
2) even with high O2 levels, CO2 is the
prime determinant
3) as partial pressure of O2 falls, the reaction to the partial pressure of CO2 is even greater

Question 35

What are the peripheral chemoreceptors?

Answer 35

Aortic and carotid bodies

Question 36

What are peripheral chemoreceptors most sensitive to?

Answer 36

O2 (much less to H+ and CO2 as seen in central chemoreceptors)

Question 37

The peripheral chemoreceptors in the form of the aortic and carotid bodies (chemoreceptors) sample arterial blood and being firing when?

Answer 37

arterial partial pressure of O2 starts falling below 100 mmHg (and dramatically so below ~ 60 mmHg)

Question 38

What do peripheral chemoreceptor in the form of the aortic and carotid bodies stimulate?

Answer 38

these sensors stimulate the dorsal respiratory group

Question 39

Stimulation of the dorsal respiratory group by peripheral chemoreceptor in the form of the aortic and carotid
bodies will result in what?

Answer 39

Increased ventilation rate and depth

Question 40

What limits the depth of breathing by inhibiting inspiratory neurons?

Answer 40

Pneumotaxic center

Question 41

Increased pneumotaxic action results in

Answer 41

Short inspiration (rapid breathing)

Question 42

Decreased pneumotaxic action (no inhibition) leads to

Answer 42

Lengthened inspiration (restful breathing)

Question 43

Resting inspiratory neurons and increased ramp signal coincide with

Answer 43

Phrenic output and contraction of diaphragm and external intercostals

Question 44

Expiratory neurons and DEcreased ramp signal coincide with

Answer 44

Contraction of internal intercostal

Question 45

What neurons bypass respiratory control center?

Answer 45

Corticospinal and corticobulbar tracts