Chapter 41 - Regulation of Respiration

Question 1

Where is the respiratory center located at?

Answer 1

Composed of several groups of neurons located bilaterally in the medulla oblongata and pons of the brain stem dived into 3 major collections of neurons.

Question 2

What are 3 major collections of neurons that make up the respiratory center?

Answer 2

1. Dorsal respiratory group – located in the dorsal portion of the medulla.
2. Ventral respiratory group – in the ventrolateral part of the medulla.
3. Pneumotaxic center – Dorsally in the superior portion of the pons.

Question 3

What does the Dorsal respiratory group control?

Answer 3

Breathing.

Question 4

What does the Ventral respiratory group control?

Answer 4

Expiration.

Question 5

What does the Pneumotoxic center control?

Answer 5

Controls rate and depth of breathing by primarily limiting inspiration.

Question 6

What does the nucleus of the tractus solitaruis do?

Answer 6

Sensory termination of both the vagal and glossopharyngeal nerves, which transmit sensory signals into the respiratory center from peripheral chemoreceptors, baroreceptors, and several receptors in the lungs.

Question 7

Describe the Ventral respiratory group control.

Answer 7

Functions more like an overdrive mechanism when high levels of pulmonary ventilation are required, especially during heavy exercise. Normally do not participate in respiration cycle.

Question 8

What is the Hering-Breuer Inflation reflex?

Answer 8

When lung gets overstretched, the stretch receptors in the lungs activate an appropriate feedback response that “switches off” the inspiratory ramp and thus stops further inflation.

Question 9

Describe Oxygen’s role in the chemical control of respiration.

Answer 9

Does not have a significant direct control of the respiratory centers of the brain. Instead acts on peripheral chemoreceptors located in the carotid and aortic bodies.

Question 10

Which area of the respiratory centers is sensitive to the blood concentrations of carbon dioxide or hydrogen ions?

Answer 10

The chemosensitive area, located bilaterally, lying only 0.2 millimeters beneath the ventral surface of the medulla.

Question 11

How can hydrogen ions influence the chemeosensitive area when it isn’t very permeable to the blood brain barrier?

Answer 11

CO2 crosses instead, immediately reacting with water to form new hydrogen ions.

Question 12

Describe the stimulatory effect of CO2 after the first 1 to 2 days.

Answer 12

Acute effect on controlling respiratory drive but only a weak chronic effect after a few day’s adaption.

Question 13

What is the major controller of respiration in terms of chemical control?

Answer 13

Carbon Dioxide.

Question 14

At what PO2 do peripheral chemeoreceptors for oxygen begin to respond?

Answer 14

When it falls below 70 mm Hg.

Question 15

Where are the carotid bodies located and thru what nerve do they reach the medulla?

Answer 15

In the bifurcation of the common carotid arteries; the glossopharyngeal nerves

Question 16

Where are the aortic bodies located thru what nerve do they reach the medulla?

Answer 16

Along the arch of the aorta; the vagus nerves.

Question 17

Describe the difference of CO2 stimulation thru peripheral chemoreceptors vs. the respiratory centers.

Answer 17

Stimulation of the respiratory centers is 7x stronger but peripheral is 5x faster.

Question 18

Describe acclimatization in terms of respiration.

Answer 18

The ability to withstand far lower atmospheric oxygen concentrations. This is achieved by mountain climbers when they ascend a mountain over a period of days rather than a few hours; they breathe much more deeply.

Question 19

What causes intense ventilation during exercise?

Answer 19

The brain, on transmitting motor impulses to the exercising muscle, is believed to transmit at the same time collateral impulses into the brain stem to excite the respiratory center.

Question 20

What are the pulmonary irritant receptors located and what do they cause?

Answer 20

In the epithelium of the trachea, bronchi, and bronchioles. Causes coughing and sneezing. They may also cause bronchial constriction in asthma and emphysema.

Question 21

What are the J receptors located and what do they cause?

Answer 21

In the alveolar walls in the juxtapositions to the pulmonary capillaries. They are stimulated especially when the pulmonary capillaries become engorged with blood or when pulmonary edema occurs in such conditions such as congestive heart failure. Their excitation may give the person a feeling of dyspnea.

Question 22

What effect can brain edema have on the respiratory center?

Answer 22

Can depress it to even inactivate it.

Question 23

What effect can anesthesia have on the respiratory center?

Answer 23

Depression to arrest of respiration.

Question 24

What is periodic breathing?

Answer 24

An abnormality of respiration, the person breathes deeply for a short interval and then breathes slightly or not at all for an additional interval, with the cycle repeating over and over.

Question 25

What is Cheyne-Stokes breathing?

Answer 25

A periodic breathing abnormality, characterized by slowly waxing and waning respiration occurring about every 40 to 60 seconds.

Question 26

What is sleep apnea?

Answer 26

Apnea that last for about 10 seconds or more during sleep, occurring 300 to 500 each night; can be caused by obstruction of upper airways, especially pharynx (called obstructive sleep apnea) or by impaired central nervous system respiratory drive (central sleep apnea).