Exam #3: Control of Breathing Flashcards Preview

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Flashcards in Exam #3: Control of Breathing Deck (34):
1

How is spontaneous respiration produced?

Rhythmic discharge of motor neurons that innervate respiratory muscles

2

What controls the discharge of the motor neurons responsible for respiration?

Chemical control:
- PCO2
- PO2
- H+

3

Where is the automatic control of respiration located?

Pons & medulla

4

Where is the voluntary control system of respiration located?

Cerebral cortex

5

What are the key controlling factors of respiration?

Increased PCO2*
Decreased PO2
Decreased pH

6

Draw the pathways that control breathing.

N/A

7

What are the non-chemical influences that control breathing?

Chest wall
Diaphragm
Conducting airway

Changes here sends signals directly to the spinal cord to alter breathing e.g. during exercise

8

What is the most important controlling factor of respiration?

Changes in PCO2

*Stronger effect than changes in pH

9

Can the partial pressure of oxygen change the respiratory rate independent of CO2?

Yes

10

In what range is the chemoreceptor system the most sensitive to changes in PO2?

30 - 60 mmHg

11

How does the effect of PCO2 & H+ compare in the control of respiration?

Changes in blood H+ have considerably less effect in stimulating chemosensitive neurons

12

Where are the peripheral chemoreceptors that detect changes in PO2?

Aorctic bodies
Carotid bodies

*Note that these respond to changes in CO2 & H+ to a lesser extent than oxygen

13

Where are the central respiratory chemoreceptors located?

In a "chemosensitive area" that lies just beneath the medulla

3 regions:
1) Rostral (Mitchell)
2) Intermediate (Schlafke)
3) Caudal (Loeschcke)

14

Where is the sensory integration center for impulses from peripheral chemoreceptors, baroreceptors, & other pulmonary receptors.

NTS

15

What are the four nuclei of the respiratory center?

1) DRG= Dorsal Respiratory Group
2) VRG= Ventral Respiratory Group
3) PRG= Pneumotaxic Respiratory Group
4) Pre-Botzinger complex

16

What is the function of the Pre-Botzinger complex?

Rhythmic respiration

*Note this is like the SA node in the heart.

17

Where do signals from the Pre-Botzinger complex go?

DRG

18

What is the function of the DRG?

Sends out repetitive bursts of inspiratory neuronal action potentials

19

What is the function of the PRG?

- Transmits signals to the inspiratory area (DRG)
- Switches off the DRG

*Primarily controls rate & depth of breathing

20

What is the function of the VRG?

- Inactive during normal respiration
- Increased stimulation results in spill over from the DRG
- DRG spillover recruits the VRG for active breathing (both inspiration & expiration)

21

How is respiration regulated during exercise?

Voluntary component added to the automatic component

22

What are irritant receptors?

Receptors that are stimulated to edema, toxic substances, smoking...etc.

23

What is the function of irritant receptors?

Causing coughing & sneezing

Note that these may also cause bronchial constriction in asthma & emphysema

24

What are J receptors?

Sensory nerves located in the alveolar walls, in juxtaposition to the pulmonary capillaries

25

What stimulates J receptors?

- Pulmonary capillary engorgement or pulmonary edema
- Gives a feeling of dyspnea

26

What is the effect of brain edema on respiration? How is it treated?

- Depressed respiration
- Hypertonic solutions e.g. mannitol

27

What reflex is initiated by the stretch receptors?

Hering-Breuer inflation reflex
- Located in the muscular portions of the bronchi & bronchioles
- Transmits signals to the DRG when the lungs are overstretched
- Switch off inspiratory ramp & increases the rate of respiration

Note that this normally does not happen until VT= 3x normal

28

What is the Hering-Breuer inflation reflex?

- Switch off inspiratory ramp in cases of overstretching of the lung parenchyma

29

What are Kussmaul's respiration's an indication of?

Metabolic acidosis

- Relentless, rapid, & deep breathing

30

What are Cheyne-Stoke's respiration's an indication of?

Stroke
Encephalopathies
Heart Failure

Ventilatory oscillations with long cycle times

31

What is Biot's breathing an indication of?

Medullary trauma
Stroke

- Quick, shallow inspirations followed by regular or irregular periods of apnea

32

Draw the diagrams of Kussmaul's, Cheyne-Stokes, & Biot breathing patterns.

N/A

33

Describe the reciprocal innervation of the respiratory muscles.

Active inspiratory muscles= inhibited expiratory muscles & vice versa

34

What do the central chemoreceptors respond most to? What do the peripheral chemoreceptors respond most to?

PCO2 & PO2 respectively

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