S3_L6: Control of Respiration

Question 1

The basic rhythm of breathing is controlled by respiratory centers located in the ___.

Answer 1

brainstem

Question 2

The expiratory center (VRG) in the ___ appears to
function during forced expiration (labored, difficulty in breathing), stimulating the internal intercostal and abdominal muscles.

Answer 2

medulla oblongata

Question 3

Located at the superior border of pons, it controls the switch off point of the dorsal respiratory group (DRG). It tells when the train of impulses stop.

Answer 3

Pneumotaxic center

Question 4

The basic rhythm of breathing is modified by input
from the central and peripheral ____. They respond to changes in the PCO2, pH, and PO2 of arterial blood, the most important factors altering ventilation.

Answer 4

Chemoreceptors

Question 5

Determine the corresponding descriptions of hyper- and hypoventilation

1. High PCO2, Low pH of the blood results
2. To counteract, ↑ in PCO2 ↓ in pH (alkaline blood) will stimulate peripheral chemoreceptors to activate the respiratory centers to decrease the activity of pneumotaxic center
3. Low PO2 results
4. Breathing rate and depth is too low to maintain normal blood gas levels
5. Low PCO2, High pH of the blood results

A. Hyperventilation
B. Hypoventilation

Answer 5

1. B
2. A
3. B
4. B
5. A

Question 6

The basic rhythm of breathing is set by the ___, located in the medulla. Other respiratory centers, located in the medulla and pons, also control breathing.

Answer 6

inspiratory center

Question 7

____ monitor the PCO2, pH, and PO2 of arterial blood and alter the basic rhythm of breathing

Answer 7

Chemoreceptors

Question 8

____, reflected by changes in pH, is the most important stimulus controlling ventilation (rate
and depth of breathing)

Answer 8

Carbon dioxide / CO2

Question 9

What has an acute response to an increase in CO2?

Answer 9

Central chemoreceptors

Question 10

Found in the aortic bodies (aortic arch) and carotid bodies (bifurcation of carotids)

Answer 10

Peripheral Chemoreceptors

Question 11

Efferent information from the peripheral chemoreceptors travels to the respiratory centers via what two nerves?

Answer 11

vagus and glossopharyngeal nerves / CN IX & CN X

Question 12

Found in the CNS, specifically the medulla. It monitors the pH associated with CO2 levels in the CSF in the floor of 4th ventricle.

Answer 12

Central Chemoreceptors

Question 13

Found outside the CNS and monitors the PCO2, pH, and PO2 of arterial blood

Answer 13

Peripheral Chemoreceptors

Question 14

The ultrafiltrate of blood which protects brain from
traumatic injury and is rich in nutrients and O2.

Answer 14

Cerebrospinal fluid

Question 15

The ___ sets the basic rhythm of breathing by automatically initiating inspiration

Answer 15

inspiratory center (dorsal respiratory group)

Question 16

Which respiratory center has both I and E neurons; for inspiration and expiration which will be called upon
during labored breathing?

Answer 16

Ventral respiratory group

Question 17

The normal resting breathing rate is between ___
breaths per minute

Answer 17

12-15

Question 18

Contains I neurons for inspiration. Located at the medulla, bilaterally. Its function is for normal tidal inspiration

Answer 18

inspiratory center (dorsal respiratory group)

Question 19

The inspiratory center sends a train of impulses that will travel through the phrenic nerve, going to which two muscles?

Answer 19

diaphragm and external intercostal muscles

Question 20

For inspiration, the inspiratory center sends nerve impulses for (1)___ seconds, causing the diaphragm and external intercostal muscles to (2)___.

Answer 20

1. 2
2. contract

Question 21

For expiration, the inspiratory center stops sending nerve impulses for (1)___ seconds, causing the diaphragm and external intercostal muscles to relax, allowing for (2)___.

Answer 21

1. 3
2. elastic recoil

Question 22

What sends tetanic impulses for the respiratory muscles to fire and contract fully, allowing us to inspire completely?

Answer 22

Dorsal respiratory group

Question 23

TRUE OR FALSE: Voluntary control can influence ventilation by sending signals from the cerebral cortex to respiratory muscles, so we can voluntarily change our breathing rate and depth when holding our breath, speaking, or singing. However, chemoreceptors input to the respiratory centers will eventually override conscious control and
force you to breathe.

Answer 23

True

Question 24

What reflex is described wherein stretch receptors in the visceral pleura and large airways send inhibitory signals to the inspiratory center during very deep inspirations, protecting against excessive stretching of the lungs?

Answer 24

Hering-Breuer (Inflation) reflex

Question 25

This reflex prevents superinflation and bursting of the alveolus

Answer 25

Hering-Breuer (inflation) reflex

Question 26

Pain and strong emotions, such as fear and anxiety, can also influence ventilation. They act by way of the ____ to stimulate or inhibit
the respiratory centers.

Answer 26

hypothalamus

Question 27

What two protective reflexes can remove pulmonary irritants from the airways, such as dust, smoke, noxious fumes, and excessive mucus?

Answer 27

1. Coughing
2. Sneezing

Question 28

TRUE OR FALSE: Ventilation increases during strenuous exercise, with depth increasing more than the rate.

Answer 28

True

Question 29

During exercise, ___ in moving muscles and joints stimulate
the respiratory centers, as does an increase in body temperature. As muscles and joints move, the brain responds by giving a motor outflow, as a result of an anticipatory response.

Answer 29

Proprioceptors

Question 30

Other factors which increase ventilation during exercise are circulating epinephrine and norepinephrine secreted by the (1)___ stimulate the respiratory centers, as well as (2)___ produced by exercising muscles, which activate the peripheral chemoreceptors.

Answer 30

1. adrenal medulla
2. lactic acid

Question 31

TRUE OR FALSE: Ventilation increases within seconds of the beginning of the exercise, probably in anticipation of exercise, a learned response. It also increases because the motor areas of the cerebral cortex which stimulate the muscles also stimulate the respiratory centers.

Answer 31

True

Question 32

The peripheral chemoreceptors also monitor arterial PO2. However, the arterial PO2 must drop below ___ before chemoreceptors respond

Answer 32

60 mmHg

Additional: 60 mmHg is 90% O2 saturation

Question 33

At very high altitudes, the alveolar PO2 may fall to ___ and increased ventilation will make a dramatic difference in the amount of O2 loaded into the blood. The decreased PO2 will activate the peripheral chemoreceptors, DRG, VRG, and ventilation muscles to normalize the gas.

Answer 33

40 mmHg

Question 34

Carotid and aortic bodies are always exposed to
(1)___ blood; thus, any deviation of the blood
gases will immediately stimulate peripheral receptors to adjust respiration. (2)___ hemoglobin saturation will activate the peripheral chemoreceptors.

Answer 34

1. oxygenated
2. 75%

Question 35

The peripheral chemoreceptors are sensitive to blood pH and the ___ that is in plasma, which is produced during strenuous exercise.

Answer 35

lactic acid

Question 36

When there is an imbalance of the gas concentrations in the blood, the peripheral chemoreceptors increase ___ that will be exhaled to normalize

Answer 36

Carbon dioxide / CO2

Question 37

When there is increased PCO2 in fourth ventricle, there is an increased (1)___ and decreased (2)___ in fourth ventricle.

Answer 37

1. Hydrogen
2. pH

Question 38

TRUE OR FALSE: H+ ions cannot penetrate blood brain barrier formed by fibrous astrocytes

Answer 38

True

Question 39

CO2 diffuses and combines with water results to carbonic acid. However, carbonic acid is unstable and will dissociate to (1)__ and (2)__.

Answer 39

1-2. Hydrogen & bicarbonate

Question 40

Through hydrogen’s dissociation from carbonic acid, H+ will (1)___ stimulate the chemosensitive area. It depolarizes the nerve fibers, so more hydrogen means more action potentials. This results in the increased activity of (2)___ to increase the rate and depth of ventilation.

Answer 40

1. directly
2. phrenic nerve