Human Phys 6.9

Question 1

What are the main tasks of the respiratory control mechanism?

Answer 1

To establish automatic rhythm for contraction of respiratory muscles

To adjust this rhythm and accommodate changes in metabolic demand, mechanical conditions, and a wide range of episodic, non-ventilatory behaviors

Question 2

What are the main components of the control mechanism?

Answer 2

Control centers in the brain stem
(medulla and pons)

Chemoreceptors for O2 and CO2 (central and peripheral)

Mechanoreceptors in the lungs and joints

Respiratory muscles

Question 3

What 3 groups of neurons control breathing?

Answer 3

Medullary respiratory center

Apneustic center

Pneumotaxic center

Question 4

Where is the inspiratory center of the medullary respiratory center located?

Answer 4

Dorsal respiratory group

Question 5

What does the inspiratory center of the medullary respiratory control?

Answer 5

Basic rhythm by setting frequency

Question 6

What does the inspiratory center of the medullary respiratory send?

Answer 6

Motor output to the diaphragm via phrenic nerve

Question 7

How can inspiration be shortened in the inspiratory center of the medullary respiratory?

Answer 7

Inhibition via pneumotaxic center

Question 8

Apneusis

Answer 8

Prolonged inspirations separated by brief expirations

Question 9

What does stimulated of the apneustic center in the lower pons produce?

Answer 9

Breathing pattern (excites the inspiratory center in the medulla)

Question 10

What does the pneumotaxic center turn off?

Answer 10

Inspiration

Question 11

Where is the pneumotaxic center located?

Answer 11

Upper pons

Question 12

What does the pneumotaxic center limit?

Answer 12

Size of tidal volume and secondarily regulates RR

Question 13

What is respiration drive stimulated by?

Answer 13

Brainstem

Question 14

What inputs is the control of breathing modulated by?

Answer 14

Conscious inputs from the cortex

Influences from the limbic system and reticular activating system

Chemoreceptors

Metaboreceptors in muscle

Mechanoreceptors in lungs

Question 15

Chemoreceptors

Answer 15

Sense changes in the chemical constituents of blood (primarily PCO2 and H+)

Question 16

Hering-Breuer reflex

Answer 16

Reflex inhibition of inspiration triggered by pulmonary stretch receptors upon expansion of the lungs and mediated by the vagus nerve

Question 17

Where are central chemoreceptors located at?

Answer 17

Brainstem and are the most important for minute to minute control of breathing

Question 18

What do central chemoreceptors communicate with?

Answer 18

Inspiratory center

Question 19

What is the central chemoreceptors extremely sensitive to?

Answer 19

Changes in pH of the cerebrospinal fluid

Question 20

What do central chemoreceptors respond directly and indirectly to?

Answer 20

Directly to changes in pH

Indirectly to changes in PCO2

Question 21

What does a low pH result in?

Answer 21

Hyperventilation

Question 22

What does a high pH result in?

Answer 22

Hypoventilation

Question 23

What do changes in O2 have no direct effect on?

Answer 23

Respiratory center (indirect effect via peripheral chemoreceptors)

Question 24

Where are peripheral chemoreceptors for O2, CO2, and H+ found?

Answer 24

Carotid artery and aortic arch

Question 25

What is the information from the peripheral chemoreceptors about arterial PO2, PCO2, and pH relayed to?

Answer 25

DRG via central nerves 9 and 10

Question 26

When do peripheral chemoreceptors respond?

Answer 26

When PO2 < 60 mmHg

Question 27

What happens if PO2 decreases < 60 mmHg?

Answer 27

Breathing rate is increased in a steep and linear fashion

Question 28

What is the effect of decreased PCO2 less important than?

Answer 28

Response to decreased PO2

Question 29

What does detection of reduction in PO2 lead to?

Answer 29

Increased breathing rate

Question 30

What is decrease in arterial pH detected by?

Answer 30

On the carotid bodies

Question 31

Lung stretch receptors

Answer 31

Mechanoreceptors in airway smooth muscles are stimulated by the distention of the lungs and airway

This initiates a reflex decrease in breathing rate and is called hering-breuer reflex

Question 32

Joint and muscle receptors

Answer 32

Mechanoreceptors in the joints and muscles detect movement and stimulate the inspiratory center (they are important in the early ventilatory response to exercise)

Question 33

Juxtacapillary receptors

Answer 33

Located in the alveolar walls and when stimulated by engorgement of pulmonary capillaries increases breathing rate