8 - Control of Respiration

Question 1

What factors influence the ventilatory response to CO2?

Answer 1

• hypoxemia makes the response more sensitive to CO2
• narcotics decrease response to CO2
• sleep - response is the same, but at a higher CO2 level (more tolerant of CO2)
• anesthesia decrease response to CO2

Question 2

What does the pneumotaxic respiratory center do? What happens when it doesn’t work?

Answer 2

Regulates medullary respiratory output - switches off inspiration to regulate inspiratory volume

Dysfunction leads to deep, prolonged inspiration

Question 3

What does the apneustic respiratory center do? What happens when it doesn’t work?

Answer 3

Regulates medullary respiratory output - excitatory effect on DRG and VRG to prolong ramp action potential

Dysfunction leads to shortened inspiration

Question 4

What does the medullary respiratory center do? What happens when it doesn’t work?

Answer 4

Generates respiratory rhythm and is responsible for automatic control of respiration; dorsal respiratory group generates ramp action potentials and sends signals to diaphragm and other inspiratory muscles; ventral respiratory group generates rhythm and innervates the expiratory muscles (during quiet breathing, the VRG does not stimulate expiratory muscles)

Dysfunction leads to irregular breathing patterns and apnea (ataxic breathing)

Question 5

What are the factors that influence the ventilatory response to O2?

Answer 5

• hypercapnia - increases response to decreased PO2

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Question 6

What are the factors that influence peripheral and central chemoreceptors?

Answer 6

Peripheral chemoreceptors (aortic and carotid bodies) will stimulate breathing in the cases of low O2, high CO2, and low pH

Central chemoreceptors will stimulate breathing in the cases of high CO2 and low pH

Question 7

What is eupnea?

Answer 7

normal, quiet breathing

Question 8

What is tachypnea?

Answer 8

increased respiratory rate

Question 9

What is hyperpnea?

Answer 9

increased respiratory rate and depth

Question 10

What is dyspnea?

Answer 10

sensation of breathlessness; labored breathing

Question 11

What is orthopnea?

Answer 11

dyspnea at rest while recumbent

Question 12

What is Cheyne-Stokes respiration?

Answer 12

an abnormal pattern with waxing and waning tidal volume and periodic apnea due to a lack of coordination in central and local CO2 sensation; usually indicates a severe CNS disorder, causes central sleep apnea

Question 13

What is Kussmaul breathing?

Answer 13

a regular rapid rate with large tidal volume, usually caused by metabolic acidosis

Question 14

What is ataxic breathing?

Answer 14

highly irregular respirations, usually separated by long periods of apnea; usually seen with lesions to the medulla

Question 15

What is apneusis?

Answer 15

prolonged inspirations separated by brief expirations

Question 16

What is the Bötzinger Complex?

Answer 16

It is the rhythm generator in the ventral respiratory group of the medulla respiratory center (similar to pacemaker cells in the heart)

Question 17

Stretch receptors in the lungs [stimulate/inhibit] medullary respiratory action.

Answer 17

inhibit

Question 18

Irritant receptors in the lungs [stimulate/inhibit] medullary respiratory action.

Answer 18

inhibit

Question 19

Irritant receptors in the lungs [stimulate/inhibit] medullary respiratory action.

Answer 19

inhibit

Question 20

[Aortic/Carotid] bodies are more sensitive to hypoxia.

Answer 20

Carotid

Question 21

What happens to respiration when PaCO2 is above 100 mmHg?

Answer 21

Respiratory response is reduced, leading to CO2 narcosis

Question 22

What is the Hering-Breuer reflex?

Answer 22

Overinflation of lung stimulates slowly adapting stretch receptors to send signals to pneumotaxic center to terminate inspiration

Question 23

The sneeze and cough reflexes are activated by [slowly/rapidly]-adapting stretch receptor stimulation

Answer 23

Rapidly-adapting

Question 24

What is the function of J receptors?

Answer 24

Respond to interstitial edema and engorgement of pulmonary capillaries –> mediate closure of layrnx and apnea followed by rapid shallow breathing; also mediate tachypnea in response to pulmonary embolism

Question 25

What are the functions of chest wall mechanoreceptors?

Answer 25

• detect impediments to breathing in the chest wall and stimulate increased inspiratory activity
• provides conscious sensation of respiratory movements to the cortex, allowing for voluntary breathing