RESP 5

Question 1

The ultimate goal of respiration is to maintain proper concentrations of __________________ in the tissues.

Answer 1

O2
CO2
H+

Question 2

Excess CO2 or H+ activates respiratory centers to _________ alveolar ventilation.

Answer 2

increase

Question 3

Decreased O2 _________ alveolar ventilation.

Answer 3

increases

Question 4

What is detected by peripheral and central chemoreceptors?

Answer 4

high CO2
high H+

Question 5

What is detected by peripheral chemoreceptors?

Answer 5

low O2

Question 6

What are the two basic controls of breathing?

Answer 6

voluntary (corticospinal tract)
automatic (ventrolateral tract)

Question 7

What does the voluntary/corticospinal tract involve?

Answer 7

descending input from the thalamus and cerebral cortex, can bypass the respiratory control centers in pons & medulla

Question 8

When is the voluntary/corticospinal tract active?

Answer 8

talking, sneezing, singing, swallowing, coughing, defecation, anxiety, fear

Question 9

What is the automatic/ventrolateral tract controlled by?

Answer 9

– Primarily controlled by changes in PCO2
* Less sensitive to PO2 and H+
* Pulmonary mechanical receptors

Question 10

When is the automatic/ventrolateral tract activated?

Answer 10

Respiratory Centers in the pons & medulla (ex. DRG and VRG)

Question 11

What are the two areas of the brainstem that control respiration?

Answer 11

medullary respiratory center
pontine respiratoyr group

Question 12

What are the two sections of the medullary respiratory center?

Answer 12

– Dorsal Respiratory Group (DRG; inspiration)
– Ventral Respiratory Group (VRG; active expiration and inspiration)

Question 13

What are the two sections of the pontine respiratory group?

Answer 13

– Pneumotaxic Center
– Apneustic Center

Question 14

What is the dorsal respiratory group (DRG)?

Answer 14

• nucleus of the tractus solitarius
• inspiratory center
• one of the medullary respiration centers

Question 15

What does the DRG receive afferent input from?

Answer 15

CN IX (chemoreceptor)
CN X (chemoreceptor and mechanoreceptor)

Question 16

What does the DRG mirror the activity of?

Answer 16

the diaphragm

Question 17

How does the DRG provide excitatory inspiratory stimuli to phrenic motor neurons?

Answer 17

• Sets the basic rhythm for breathing by setting the frequency of inspiration—Central Pattern Generator
• Signal begins weakly, increases steadily for 2 seconds, then will abruptly cease for ~3 seconds before resuming the cycle (12-20 breaths per minute

Question 18

DRG contains opiate receptors (u receptors) that, when activated,
______ respiration

Answer 18

inhibit

Question 19

Which medullary respiratory center is mostly involved in expiration?

Answer 19

VRG

Question 20

VRG is the control for the motor neurons in the…

Answer 20

• Expiratory muscles (abdominals, internal intercostals)
• Accessory inspiratory muscles

Question 21

What is the pneumotaxic center?

Answer 21

• When activated, shortens the time of inspiration (possibly by inhibiting the Apneustic Center).
• Might inhibit the Apneustic Center.
• decrease tital volume

Question 22

What is the apneustic center?

Answer 22

• Its activation causes excitation of
  the DRG which results in prolonged
  inspiration with brief periods of
  expiration.
• Antagonist to Pneumotaxic Center
• increase tital volume

Question 23

What is the Hering-Breuer Reflex?

Answer 23

Stretch receptors in bronchi and bronchioles are activated when the lungs over-stretch

Question 24

How do you activate the Hering-Breuer reflex?

Answer 24

Stops further inspiration and decreases rate.

Question 25

What stimulates an irritant receptor?

Answer 25

noxious exogenous substances, endogenous agents, and mechanical stimulation

Question 26

What does the irritant receptor cause?

Answer 26

Promotes rapid, shallow breathing, coughing, sneezing

Question 27

Where are irritant receptors located?

Answer 27

between epithelial cells in conducting zone

Question 28

What do activation of J receptors do?

Answer 28

rapid, shallow breathing and a sensation of dyspnea

Question 29

What are the J receptors stimulated by?

Answer 29

In alveolar walls, “Juxtacapillary” and stimulated by alveolar inflammatory processes (pneumonia), pulmonary vascular congestion (congestive heart failure), and edema.

Question 30

What do joint and muscle proprioceptors do to DRG?

Answer 30

increase activity of DRG to increase rate of breathing

Question 31

Joint & Muscle Proprioceptors are sensitive to change in…

Answer 31

position and muscle movements - not metabolism

Question 32

Central Chemoreceptors are most effective within ___________ after a change in central CO2

Answer 32

1-2 days

Question 33

Where are peripheral chemoreceptors located?

Answer 33

aortic bodies = vagus
carotid bodies = glossopharyngeal

Question 34

Where are central receptors?

Answer 34

Located on ventral surface of medulla

Question 35

What are peripheral chemoreceptors sensitive to?

Answer 35

• Sensitive to (activated by) Low
  PaO2, High PaCO2, and Low pH
  – Only sensitive to dissolved gases

Question 36

What are central chemoreceptors sensitive to?

Answer 36

changes in pH in the CSF

Question 37

What leads to an enhanced response to PaCO2?

Answer 37

metabolic acidosis

Question 38

What leads to a depressed response to PaCO2?

Answer 38

sleep
opoids
narcotics
chronic obstruction
deep anesthesia

Question 39

Most inhaled anesthetics cause respiratory __________.

Answer 39

depression

Question 40

What anesthetic does not cause a respiratory depression?

Answer 40

nitrous oxide

Question 41

Hypoxic drive is _________ by nitrous oxide

Answer 41

decreased