Respiratory - Control of Ventilation

Question 1

Respiration demonstrates both:

Answer 1

Automaticity
Self - Modulation

Question 2

Respiration Automaticity

Answer 2

Begins at birth
automatic

Question 3

Respiration Self-modulation allows us to:

Answer 3

Voluntarily hyperventilate
Hold our breath
Change breathing patterns for speech and singing

We can override automaticity - voluntary

Question 4

Ventilatory Control System:

Answer 4

Sensors (chemoreceptors and mechanoreceptors, feedback)
Central Controller (respiratory control center, driver)
Effectors (respiratory muscles, carry out orders)

Question 5

Neural Control of Breathing: Voluntary

What controls it?

Answer 5

Cerebral Cortex

Question 6

Neural Control of Breathing: Autonomic

What controls it?

Answer 6

Medullary Centers
Pontine Centers

Respiratory Centers

Question 7

What makes up the medullary respiratory centers?

Answer 7

Dorsal Respiratory Group
Ventral Respiratory Group

Question 8

What makes up the Pontine Respiratory Centers?

Answer 8

Pneumotaxic Center
Apneustic Center

Question 9

Which respiratory control center does majority of the work?

Answer 9

Medullary centers

Question 10

Dorsal Respiratory Group (DRG)

What is it? What makes it up?

Answer 10

Comprised mainly of inspiratory neurons
responsible for inspiration
Influences Pre-Btzinger Complex

Question 11

Pre-Botzinger Complex

Answer 11

The anatomic location of the respiratory pattern generator
these neurons display pacemaker activity

Question 12

Ventral Respiratory Group (VRG)

Answer 12

Responsible for both expiration and inspiration, but inactive during quiet breathing
active during exercise

Question 13

Pontine Centers

What is it? What does it do?

Answer 13

Rhythm generated in the medulla can be modified by neurons in the pons

Fine tune breathing

Question 14

What happens if the spinal cord is cut between the medulla and the pons?

Answer 14

Fairly normal ventilation

Question 15

What happens if the spinal cord is cut below the medulla?

Answer 15

Ventilation ceases

Question 16

What is the major rhythm generator?

Answer 16

Medulla

Question 17

Neural Control

Sensors

What do they do?

Answer 17

Reflexes from the periphery provide feedback for fine-tuning

Question 18

Define

Mechanoreceptors

Type of Sensor

Answer 18

Detect distention and irritation

Airways, Lung parenchyma

Question 19

Define

Chemoreceptors

Type of Sensor

Answer 19

Chemical content of blood or CSF

Samples levels of PO2, PCO2, H+

Question 20

Where are central chemoreceptors located?

Answer 20

In brain
Located on surface of medulla; seperate from respiratory center

Question 21

What is the most important mechanism controlling ventilation at rest?

Answer 21

CO2-Induced H+ in CSF

Question 22

Does CO2 directly bind chemoeceptors?

Answer 22

No

Question 23

What causes a loss of sensitivity to elecated PaCO2 during prolonnged hypoventilation?

Chronic Lung Disease

Answer 23

Loss of sensnitivity to PaCO2
HCO3- gets actively transspirted to BBB
Central chemoreceptors no longer “aware” of elevated PCO2
Hypoxic drive becaomes primary respiratory stimulus

Question 24

Should we administer O2 when a patient’s primary respiratory stimulus relies on CO2?

Answer 24

No

Adapts

Question 25

Do central chemoreceptors respond to hypoxia?

Answer 25

No

Question 26

Peripheral Chemoreceptors

Outside brain

Answer 26

Glomus cells in the carotid and aortic bodies that detect O2, CO2, and H+

Question 27

Peripheral Chemoreceptors

Hypoxia

What does it do to PaO2?

Answer 27

Respond to PaO2 not oxygen content
Normal = no response
Inhibit K+ channels; depolrize cell

Stimulates chemoreceptors to increase ventilation; impt emergency mech

Question 28

Peripheral CHemoreceptors

Hypercapnia

Answer 28

Central receptors more sensitve
CO2 diffuses into glmus
H+ inhibits K+ Channel

Question 29

Peripheral Chemoreceptors

Acidosis

Answer 29

Arterial H+ inhibits K+ channel

Question 30

What is the effect of dangerously low PaO2 on peripheral chemoreceptors?

Answer 30

The activity of all other nervous tissue becomes reduced with O2 deprivation
If not for stimulatory effect on peripheral chemoreceptors, ventilation would cease

Question 31

Effect of Increased PaCO2 on Ventilation

Arterial PCO2

Answer 31

The most important regulator of ventilation
response primarily arises from central chemoreceptors with added input from peripheral chemoreceptors

Question 32

Effect of Increased PaO2 on Ventilation

Arterial PO2

What happens when it is low?

Answer 32

When PO2 is low, ventilation increases
response from peripheral chemorepectors (central do not directly sense PO2)

Question 33

Effect of increased H+ on ventilation

Arterial pH

Answer 33

As H+ increases, ventilation increases
H+ cannot diffuse into CSF as well as CO2

Question 34

Pulmonary Stretch Receptors

Answer 34

Mechanoreceptors in smooth muscle of conducting airways
Respond to lung distention
Excited inspiratory off switch
Shortend inspiration

Question 35

Point and Muscle Receptors

Answer 35

Mechanoreceptors in joints and muscles signal to DRG to increase breathing frequency
Activated during movement when O2 demand will remain high

Increase ventilation immediatly after, have yelling matdches at school

Question 36

Irritant Receptors

Answer 36

Mechanoreceptors in airway epithelium of larger conducting airways
Respond to irritation of the airways by touch, dust, and smokeo
Protects by inducing a cough and hypercapnea

Question 37

Juxtapulmonary Capillary Receptors (J receptors)

Answer 37

Stimulated by distortion
Increase ventilation

Question 38

Why is countercurrent multiplication important?

Answer 38

Brings water into system