Control of Breathing

Question 1

Where does the rhythmic cycle of breathing originate?

Answer 1

brainstem (mainly from neurons in the medulla)

Question 2

What is the DRG?

Answer 2

dorsal respiratory group

Question 3

What does the DRG consist of?

Answer 3

inspiratory neurons

Question 4

What is the VRG?

Answer 4

ventral respiratory group

Question 5

What does the VRG consist of?

Answer 5

intermingled inspiratory and expiratory neurons

Question 6

Where do the DRG neurons send impulses and why?

Answer 6

phrenic and external intercostal nerves to provide the main stimulus for inspiration

Question 7

Where do the inspiratory VRG neurons send impulses?

Answer 7

• some to laryngeal and pharyngeal muscles

- others to diaphragm and external intercostal nerves

Question 8

Through what nerve do the inspiratory VRG neurons transmit impulses?

Answer 8

vagus

Question 9

Why do the inspiratory VRG neurons send impulses to the laryngeal and pharyngeal muscles?

Answer 9

to abduct the vocal cords and increase the diameter of the glottis

Question 10

Where do the expiratory VRG neurons send impulses?

Answer 10

internal intercostal and abdominal expiratory muscles

Question 11

What is the botzinger complex?

Answer 11

assumes that certain populations of inspiratory and expiratory neurons inhibit one another

Question 12

DRG and VRG neurons fire with rate ___ gradually after expiration ceases, leading to an increasing ramp signal

Answer 12

increasing

Question 13

What does an increasing ramp signal lead to?

Answer 13

stronger contraction of inspiratory muscles, smoothly and gradually inflating the lungs

Question 14

As expiration begins, the inspiratory neurons are ____ and switch off the ____ abruptly

Answer 14

inhibited; inspiratory signal

Question 15

What is the apneustic center?

Answer 15

a center in the lower pons that prevents inspiratory ramp signal from being switched off

Question 16

What is the pneumotaxic center?

Answer 16

a center in the upper pons that controls the length of inspiration

Question 17

What is the hering-breur inflation reflex?

Answer 17

stops further inspiration when receptors are stretched

Question 18

What tidal volumes are the hering-breur inflation reflex activated?

Answer 18

> or = to 800-1000

Question 19

What is the deflation reflex?

Answer 19

a sudden collapse of the lung stimulating inspiratory efforts and increases the RR

Question 20

What nerve is the pathway for the deflation reflex?

Answer 20

vagus

Question 21

What head’s reflex?

Answer 21

used to maintain large tidal volumes during exercise and is involved in periodic deep sighs during quiet breathing

Question 22

What is the purpose of periodic sighs?

Answer 22

help prevent alveolar collapse or atelectasis

Question 23

What reflex is used to stimulate the first breaths of a newborn infant?

Answer 23

head’s reflex

Question 24

What do inhaled irritants stimulate?

Answer 24

epithelium of large conducting airways that have vagal sensory nerve fibers

Question 25

What happens when the epithelium is stimulated?

Answer 25

reflexes of bronchoconstriction, coughing, sneezing, tachypnea and narrowing of glottis

Question 26

Stimulation of the reflexes in the epithelium causes what?

Answer 26

laryngospasm, bronchospasm, coughing and slowing of HR

Question 27

What are J receptors?

Answer 27

c-fibers in the lung parenchyma near pulmonary capillaries

Question 28

How are J receptors stimulated?

Answer 28

- pneumonia - CHF - edema

Question 29

Stimulation of the J receptors causes?

Answer 29

- rapid, shallow breathing - sensation of dyspnea - expiratory narrowing of the glottis

Question 30

What are proprioreceptors?

Answer 30

receptors that are found in muscles, tendons and joints. also pain receptors found in skin and muscle

Question 31

What are chemoreceptors?

Answer 31

receptors that are stimulated by an increase in H+ in the blood and transmit impulses to the medulla, increasing ventilation

Question 32

How are peripherally located chemoreceptors indirectly sensitive to CO2 and hypoxemia?

Answer 32

they are sensitive to H+

Question 33

Medullary located chemoreceptors are extremely sensitive to and why?

Answer 33

CO2. The H+ surrounding them is dependent on their reaction between CO2 and H2O in their local environment

Question 34

What is the BBB almost impermeable to?

Answer 34

H+ and HCO3-

Question 35

What is the BBB freely permeable to?

Answer 35

CO2

Question 36

What are peripheral chemoreceptors?

Answer 36

small, highly vascular tissues known as the carotid and aortic bodies which increase their firing rate when arterial H+ is increased

Question 37

What nerve do the carotid bodies send their impulses over?

Answer 37

glossopharyngeal

Question 38

What nerve do the aortic bodies send their impulses over?

Answer 38

vagus

Question 39

What is the ultimate effect of hypoxemia?

Answer 39

to increase the neural firing rate of the peripheral chemoreceptors, which increases minute ventilation

Question 40

T/F: increased PaCO2 increases blood H+, directly exciting the carotid bodies and stimulates ventilation

Answer 40

true

Question 41

When do the peripheral receptors respond 5 times faster?

Answer 41

a rise in arterial H+

Question 42

T/F: if PaCO2 gradually increases over years, the kidneys compensate and keep the pH within normal limits

Answer 42

true

Question 43

T/F: chronically hypercapnic patients' central chemoreceptors experience less stimulation than those of a health person for the same increase in PaCO2

Answer 43

true

Question 44

What is cheyne stokes breathing?

Answer 44

RR and VT gradually increase and then gradually decrease to complete apnea

Question 45

What is biot's breathing?

Answer 45

normal RR and VT with periods of apnea

Question 46

What does apneustic breathing indicate?

Answer 46

damage to the pons

Question 47

What is central reflex hyperpnea?

Answer 47

continuous deep breathing

Question 48

T/F: CO2 helps regulate cerbreal blood flow

Answer 48

true