Control of Respiration

Question 1

What directly determines the respiratory rate?

Answer 1

The interval between the discharges of successive groups of respiratory neural and innervation of respiratory muscles

Question 2

What directly determines the depth of respiration?

Answer 2

The frequency of action potentials, duration of discharges and number of motor units activated

Question 3

Where are the centers that regulate breathing located?

Answer 3

Located in the reticular formation of the medulla beneath the floor of the 4th ventricle

Question 4

The dorsal respiratory neurons are located in what neural structure? What is the main functional type of neuron?

Answer 4

nucleus tractus solitaries; consists mainly of inspiratory neurons

Question 5

What is the primary target of dorsal respiratory neurons? What is the general speculated function of the DRG?

Answer 5

Contralateral diaphragm; The DRG is probably the initial integratin site for many cardiopulmonary reflexes that affect respiratory rhythm

Question 6

What are the components of the ventral respiratory groups?

Answer 6

The retrofacial nucleus, nucleus ambiguous, nucleus paraambigualis, and the nucleus retroambigualis

Question 7

What is contained in the retrofacial nucleus? What is its function?

Answer 7

It mainly contains expiratory neurons in a group of cells called the Botzinger complex; Shown to inhibit the DRG inspiratory neurons

Question 8

What are the targets of the nucleus ambiguous and nucleus para-ambigualis?

Answer 8

ambiguous- vagal motor neurons that innervate ipsilateral laryngeal, pharygeal, and tongue muscles; para- innervate contralateral inspiratory muscles

Question 9

What are the targets of the nucleus retroambigualis?

Answer 9

One group mainly projects contralaterally to external intercostal muscles and diaphragm; another group projects within the medulla to other inspiratory and expiratory cells

Question 10

What is the hypothesized location of the respiratory pacemaker? The “inspiratory cut-off switch”?

Answer 10

PreBotzinger complex in the ventral respiratory groups; apneustic center

Question 11

What is apneusis? How could it be reproduced?

Answer 11

A breathing pattern with prolonged inspiratory efforts interrupted by occasional expirations; occurs with transection through the pons and vagal nerves

Question 12

What is the function of the pontine respiratory groups

Answer 12

modulation of apneustic center activity— fine tuning of the breathing pattern

Question 13

What three reflexes can be elicited by stimulation of the pulmonary stretch receptors? What is their afferent pathway?

Answer 13

The Hering-Breuer inflation reflex, Hering-Breuer deflation reflex and paradoxical reflex of Head; Vagus

Question 14

What are the effects of the heuring-breuer inflation reflex?

Answer 14

Cessation of inspiratory effort, apnea or decreased breathing frequency; bronchodilation, Increased heart rate, slight vasoconstriction

Question 15

What are the effects of the heuring-breuer deflation reflex?

Answer 15

Hyperpnea

Question 16

What is the stimulus and effect of the paradoxical reflex of Head?

Answer 16

Lung inflation– inspiration

Question 17

What is the response to negative pressure in the upper airway?

Answer 17

Contraction of pharyngeal dilator muscles

Question 18

What is the response to mechanical or chemical irritation of airways?

Answer 18

Cough/sneeze; bronchoconstriction; increased blood pressure

Question 19

What is the respiratory response to a pulmonary embolus?

Answer 19

Apnea or tachypnea

Question 20

What is the respiratory response to pulmonary vascular congestion?

Answer 20

Tachypnea, possibly the sensation of dyspnea

Question 21

What is the response to low PaO2, high PaCO2, or low pHa?

Answer 21

Hyperpnea, bronchoconstriction, dilation of the upper airway, decreased HR, vasocontriction

Question 22

What is the respiratory response to increased systemic blood pressure?

Answer 22

Apnea, bronchodilation

Question 23

What is the effect of increasing CO2 on alveolar ventilation? how does hypoxia affect this?

Answer 23

Increases ventilation; hypoxia potentiates this response

Question 24

What is the stimulus that drives us to take the next breath?

Answer 24

High CO2

Question 25

Which of the following can easily diffuse through the BBB: CO2, H+, HCO3-?

Answer 25

CO2

Question 26

To what fluid are central chemoreceptors exposed?

Answer 26

CSF

Question 27

What is the typical pH and PCO2 of CSF?

Answer 27

7.32; 50 mmHg

Question 28

Why does arterial hypercapnia lead to greater changes in CSF [H+] than arterial blood?

Answer 28

Bicarbonate is the only buffer of consequence in the CSF

Question 29

To what stimuli do central chemoreceptors respond?

Answer 29

Local increases in H+ or PCO2

Question 30

Which chemoreceptors are responsible for establishing most of the resting ventilatory level?

Answer 30

Central

Question 31

Which chemoreceptors are resposible for eliciting min to min adjustments in ventilation due to CO2?

Answer 31

Peripheral

Question 32

How do arterial chemoreceptors monitor alveolar ventilation?

Answer 32

By detecting arterial PCO2, pH, and PO2

Question 33

How would initial acidosis affect central and peripheral chemoreceptor ventilatory drive?

Answer 33

Increased peripheral drive and normal central drive

Question 34

How does changes in plasma H+ concentration affect ventilation? What chemoreceptors are responding?

Answer 34

Ventilation increases almost linearly with increases in [H+]

Question 35

Which specific chemoreceptors are most important in the ventilatory response to hypoxia?

Answer 35

Carotid body peripheral