Lecture 33: Control of Respiration and Chemoreceptors Flashcards

1
Q

Breathing occurs in what pattern

A
  • Continuous, cyclical pattern
  • Inspiratory muscles rhythmically contract
  • Activities are accomplished automatically without conscious effort
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2
Q

Respiratory muscles require what to bring about contraction

A

nervous stimulation

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3
Q

Respiratory control centers are housed where and are responsible for what

A

in the brain stem

generating the rhythmic pattern of breathing

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4
Q

Three respiratory centers in the brain stem

A
  1. Medullary
  2. Apneustic
  3. Pneumotaxic
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5
Q

What is the primary control center for respiration in the brain

A

Medullary

Consists of cell bodies

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6
Q

Two clusters that the medullary respiratory center are composed of

A
  1. Dorsal
    - inspiratory
  2. Ventral respiratory
    - expiratory
    - Also composed of inspiratory neurons
    - Dorsal respiratory group has connections to it
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7
Q

Inspiratory center of medullary purpose

A

-Controls basic rhythm for breathing by setting the frequency of breathing

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8
Q

Inspiratory center of medullary receives sensory input from

A
  • Peripheral chemoreceptos via glossopharyngeal (CN IX) and vagus (CN X) nerves
  • Mechanoreceptors in the lungs via vagus nerves
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9
Q

Inspiratory center sends motor output to…

and as a result…

A
  1. The diaphragm via the phrenic nerve, external intercostal muscles via the intercostal nerves
  2. As a result, respiration occurs because these muscles produce an increase in intrathoracic pressure and initiates the flows of air into the lungs
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10
Q

What muscles may be used for more vigorous respiration

A

Those connecting the sternum and the head

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11
Q

Ventral respiratory group is composed of inspiratory and expiratory neurons which remain inactive during

A

normal quiet breathing

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12
Q

Air is driven out of the lungs by

A

the reverse pressure gradient between the lungs and the atmosphere until the system reaches its equilibrium point again

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13
Q

Purpose of the ventral respiratory group

A
  • Called into play as an overdrive mechanism when demands for ventilation are increased
  • Esp important in active expiration
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14
Q

Pneumotaxic and apneustic centers are located

A

in the pons

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15
Q

Pneumotaxic and apneustic purpose

A

Exerts fine-tuning influences over medullary center to help produce normal, smooth, insp and exp

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16
Q

Pneumotaxic

A

Transmits inhibitory impulses to DRG that help turn off insp neurons, limiting duration of inspiration

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17
Q

Apneustic center

A

-Prevents inspiratory neurons from being switched off, providing extra boost to inspiratory drive

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18
Q

Pneumotaxic vs apneustic

A

Pneumotaxic is dominant over apneustic, helping to bring inspiration to a halt and allowing expiration to occur normally

19
Q

Arterial blood gases are maintained within a normal range by

A

varying the magnitude of ventilation to match the needs of the body for O2 uptake and CO2 removal

20
Q

Three chemical factors that increase ventilation

A
  1. An decrease in arterial PO2
  2. An increase in arterial PCO2
  3. An increase in H+ concentration
21
Q

Two types of chemoreceptor that monitors ventilation

A
  1. Peripheral

2. Central

22
Q

Where are peripheral chemoreceptors located

A

Carotid bodies and aortic bodies

23
Q

What do peripheral chemoreceptors respond to

A
  • Primarily to decreases in blood O2

- Less sensitive to increases in CO2 and decreases in blood pH

24
Q

Peripheral chemoreceptors relay info about

A

Arterial PO2, PCO2, and H+ to medullary inspiratory center via cranial nerves IX and X

25
Most important responsibility for peripheral chemoreceptors
-Detect changes in arterial O2
26
Arterial PO2 must fall below ___ mm HG before peripheral chemoreceptors are activated
60
27
Central chemoreceptors link
changes in arterial PCO2 to compensatory adjustments in ventilation
28
Do central chemoreceptors monitor CO2 itself
Nope
29
What do central chemoreceptors monitor?
Changes in CO2-induced H+ concentration in the ECF of the brain that bathes them
30
Central chemoreceptors monitor what breathing
minute to minute
31
Central chemoreceptors are very sensitive to what?
Changes in the pH of the brain ECF
32
A decrease in pH of ECF leads to
increased breathing rate (hyperventilation)
33
A increase in pH of ECF leads to
a decrease in the breathing rate (hypoventilation)
34
Diabetes mellitus
-Excess of H+ keto acids in the circulation
35
Four "other" respiratory receptors
1. Lung stretch receptors 2. Joint and muscle receptors 3. Irritant receptors 4. J receptors
36
Lung stretch receptors
- Located in smooth muscle of airways - When stimulated by lung distension, action potentials travel through afferent fibers to the medullary center and inhibit the inspiratory neurons
37
Hering-Breuer reflex
Negative feedback from highly stretched lungs prevents over-inflation
38
Proprioceptors (muscle and joint receptors)
-Increase breathing rate
39
Where are irritant (nocioreceptors) located
- Between epithelial cells lining airways | - Info travels to medulla and causes reflex constriction of bronchial smooth muscle and increase in breathing rate
40
J receptors are called
Juxtacapillary receptors
41
J receptors are located
In alveolar walls of near the capillaries
42
J receptor purpose
Engorgement of pulmonary capillaries with blood and increases in interstitial fluid volume activates these receptors to produce an increase in rate of breathing
43
Example of J receptor activation
In left-sided heart failure, blood backs up in pulmonary circulation. J receptors mediate change in breathing pattern, including rapid shallow breathing