Mashour: Control of Breathing

Question 1

Reticular formation below the fourth ventricle

Answer 1

Medullary respiratory center

Question 2

Intrinsic respiratory rhythm generator, likened to the SA node

Answer 2

Pre-Botzinger complex

Question 3

2 regions of the medullary respiratory center

Answer 3

1. dorsal respiratory group = inspiration

2. ventral respiratory group = expiration

Question 4

Where is the pre-Botzinger complex located?

Answer 4

Caudal to the Botzinger complex
Rostral to the ventral respiratory group
Located in the Rostral ventrolateral medulla

Question 5

Discuss how the Pre-Botzinger Complex works?

Answer 5

starts with a latent period
crescendo of action potentials
stronger inspiratory muscle activity (ramp-type pattern)
action potentials then cease
inspiratory muscle tone falls to pre-inspiratory level

Question 6

Motor nucleus of CN IX and CN X

Answer 6

Nucleus ambiguus

Question 7

If this is destroyed, may cause respiratory failure

Answer 7

Nucleus ambiguus (seen in polio)

Question 8

Fasciculus solitarious

Answer 8

Smaller collection of neurons similar to nucleus ambiguus

Question 9

Inspiratory ramp can be turned off by this center. It can cause shortened inspiration and an increased breathing rate.

Answer 9

Pneumotaxic center

Question 10

Inspiration can also be modulated by these two nerves

Answer 10

Glossopharyngeal and vagal nerves

Question 11

The medulla is the (blank) area

Answer 11

Expiratory

Question 12

During quiescent breathing, ventilation is achieved by (blank) contraction of inspiratory muscles, followed by (blank) relaxation of chest wall

Answer 12

Active; passive

Question 13

This is found in the lower pons

Answer 13

Apneustic center

Question 14

Impulses from this center have an excitatory effect on the inspiratory center of the medulla

Answer 14

Apneustic center (sectioning in experiments above this area leads to prolonged inspiratory gasps interrupted by transient expiratory efforts

Question 15

This is found in the upper pons

Answer 15

Pneumotaxic center

Question 16

This inhibits inspiration and controls inspiratory volume. Involved in fine tuning of respiratory rhythm

Answer 16

Pneumotaxic center

Question 17

10-20 second periods of apnea followed by equal periods of hyperpnea. Seen with high altitude, severe heart disease, or neurological injury

Answer 17

Cheyne-Stokes respirations

Question 18

Describe apneustic breathing

Answer 18

Deep breath in, hold it, then exhale

Question 19

This structure can override the function of the brainstem within limits

Answer 19

Cortex

Question 20

Which is easier, voluntary hyperventilation or voluntary hypoventilation?

Answer 20

Voluntary hyperventilation, because when you hold your breath, it becomes very uncomfortable, and your midbrain will override your cortex and cause you to start breathing

Question 21

Involved in affective states such as fear and rage

Answer 21

Limbic system and hypothalamus

Question 22

Sensors for drive of breathing

Answer 22

Central chemoreceptors
Peripheral chemoreceptors
Lung receptors

Question 23

These receptors respond to changes in H+ concentration. Increase in [H+] stimulates ventilation

Answer 23

Central chemoreceptors

Question 24

How does CO2 levels in the blood regulate ventilation?

Answer 24

By its effect on pH in the CSF

Question 25

As arterial PCO2 rises, what occurs to ensure that the brain does not become too acidified?

Answer 25

Cerebral vasodilatation → increases CO2 washout in brain → results in reduced brain acidification → reduces increased ventilatory drive from central chemoreceptors

Question 26

The point at which rhythmic ventilation ceases at a given pCO2

Answer 26

Apneic threshold

Question 27

What is the normal pH of CSF?

Answer 27

7.32

Question 28

For a given increase in PCO2, is there a greater change in pH in the CSF or blood?

Answer 28

CSF

Question 29

If CSF pH is displaced for a prolonged period of time, there will be a compensatory change in (blank)

Answer 29

[HCO3-]

Question 30

With the high levels of CO2, does the CSF pH return all the way to 7.32?

Answer 30

No, but the response occurs more rapidly than in blood.

Question 31

Renal compensation for high pCO2 takes 2-3 days, while CSF pH is mitigated much more rapidly. What does the more rapid compensation for rising CO2 in the CSF mean?

Answer 31

The CSF is more important in its effect on changes in arterial pCO2 and level of ventilation

Question 32

Located in the bifurcation of the common carotid arteries (carotid bodies) and above and below the arch of the aorta (aortic bodies)

Answer 32

Peripheral chemoreceptors

Question 33

2 cell types in the carotid bodies that work hand in hand to modulate our response to pO2

Answer 33

``` Type I (large amount of dopamine) Type II (rich capillary supply) ```

Question 34

Three things peripheral chemoreceptors respond to

Answer 34

1. arterial pO2 (chief stimulant) 2. pH 3. arterial pCO2 increases

Question 35

When does sensitivity to changes in arterial pO2 begin? What level in mmHg?

Answer 35

Less than 50mmHg

Question 36

Responsible for all of the increase in ventilation in response to arterial hypoxemia

Answer 36

peripheral chemoreceptors

Question 37

Hypotension provides a clinical example of how the peripheral chemoreceptors work. Discuss.

Answer 37

With hypotension, there is decreased blood flow or O2 delivery to the carotid bodies, and this leads to an increase in ventilation.

Question 38

3 types of lung receptors

Answer 38

1. pulmonary stretch receptors 2. irritant receptors 3. J receptors

Question 39

lie within the airway smooth muscle discharge in response to distention of the lung activity is sustained with lung inflation

Answer 39

Pulmonary stretch receptors

Question 40

Stimulating these receptors will increase expiratory time and therefore reduce the respiratory rate

Answer 40

Pulmonary stretch receptors

Question 41

Important reflex in newborns, in which inflation of the lungs further prohibits inspiratory activity, while deflation initiates inspiratory activity.

Answer 41

Hering-Breuer inflation reflex

Question 42

lie between airway epithelial cells | stimulated by noxious gases, smoke, dust, and cold air

Answer 42

Irritant receptors

Question 43

When you have a stimulus like smoke, it may cause broncoconstriction, which can be especially problematic for what type of patients?

Answer 43

Patients with COPD

Question 44

Pulmonary edema is a classic example of activation of these receptors.

Answer 44

J receptors

Question 45

These are located in the alveolar walls near the capillaries

Answer 45

J receptors

Question 46

What’s the net effect of activation of the J-receptors?

Answer 46

Rapid, shallow breathing. When a patient comes in with pneumonia, this can be relevant.

Question 47

engorgement of the pulmonary capillaries and increases in the interstitial fluid volume of alveolar wall activates what type of receptors?

Answer 47

J receptors

Question 48

This system is located in the intercostal muscles and the diaphragm. Senses elongation and dyspnea (inability to breathe). Think of COPD, flattened diaphragm, so more work involved.

Answer 48

Gamma system

Question 49

Concerning the arterial baroreceptors, a decrease in BP causes

Answer 49

hyperventilation

Question 50

The most important factor in the control of ventilation under normal conditions is

Answer 50

Arterial pCO2

Question 51

You only need a slight change in (blank) to cause a response in ventilation rate, but a larger change in (blank) to cause a response in minute ventilation rate.

Answer 51

CO2, O2

Question 52

(blank) has little effect in day-to-day management of minute ventilation.

Answer 52

O2

Question 53

Does hypoxemia have an effect on central chemoreceptors?

Answer 53

No

Question 54

If no peripheral chemoreceptors, what would occur in the case of hypoxemia?

Answer 54

Respiratory depression

Question 55

If you reduce pH without an increase in pCO2, this can produce an increase in (blank)

Answer 55

Ve (minute volume)

Question 56

Minute volume (Ve)

Answer 56

Minute volume= tidal volume * respiratory rate