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Control of Breathing
Elmo
16
Biology
Professional
11/01/2008

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Cards

Term
What are the three main groups of neurons in the brain stem?
Definition
  • Medullary respiratory center
  • Apneustic center
  • Pneumotaxic center
Term
Medullary respiratory center
Definition
  • Inspiratory center:(Dorsal) Regulates rhythm of breathing
  • Expiratory center:(Ventral) expiration
Term
Apneustic center
Definition
  • Normally inactive
  • Prolonged inspiration gasp followed by brief expiration.
  • Located in lower pons
Term
Pneumotaxic center
Definition
  • Can turn off Medullary Inspiratory center.
  • Located in upper pons.
Term
Cerebral cortex
Definition
  • Can temporarily override the automatic brain stem centers
  • Hyperventilation and Hypoventilation
Term
Central Chemoreceptors
Definition

Location: Near the Medullary inspiratory center(Dorsal)

Goal:

-Drive alveolar ventilation

-Control breathing rate

-Maintain arterial PCO2 in normal range

Mechanism: Direct effect of the change in the pH of the CSF and indirect effect to change in arterial PCO2.

↓pH of CSF→ Hypervetilation

↑pH of CSF→ Hypoventilation

Term
What is the main drive of alveolar ventilation at sea level?
Definition

The effect of the arterial PCO2 and CSF(H+) on the central chemoreceptors.

Term
Peripheral Chemoreceptors
Definition

Location: Carotid bodies and Aortic bodies. Always surrounded by arterial blood.

Goal:

-Control breathing rate and drive alveolar ventilation when PO2< 60mmHg

Mechanism:

-Detect changes in PO2, PCO2 and pH.

-Send information to inspiratory center.

-Aortic bodies use Vagus nerve(CN X)

-Carotid bodies use Glossopharyngeal nerve (CN IX)

Term
When PO2< 60mmHg the main drive of alveolar ventilation is:
Definition

The PO2 on peripheral chemoreceptors

Term
Why DONT you give a patient with chronic hypoventilation(COPD) 100% supplement O2?
Definition

Their main aveolar ventilation drive would have adapted to be Peripheral Chemoreceptors.

 

If PO2 increased they would lose their main drive.

Term
Lung stretch receptors
Definition
  • Mechanoreceptors located in the smooth muscle of airways
  • Distention(stretching) of lungs and airways leads decreased inspiration and ventilation.
  • (Hering-Breuer reflex= prolong expiratory period)
Term
Joint and Muscle receptors
Definition
  • Mechanoreceptors located in joints and muscles.
  • When limb movement is detected breathing rate is increased
Term
Irritant receptors
Definition
  • Located between epithlial lining of the airways.
  • Respond to noxious chemicals and particles.
  • Increase breathing rate and constirct bronchial smooth muscle.
Term
J receptors (juxtacapillary)
Definition
  • Located in aveolar wall(near pulmonary capillaries)
  • Sense when capillaries are filled with blood and increases breathing rate.
  • (e.g. left-side heart failure→ rapid shallow breathing and dysnea(shortness of breath)
Term
Cheyne-Stokes (Periodic) Breathing. Causes? Mechanism?
Definition

Periods or hyperventilation (10-20 sec) altering with similiar periods of apnea(not breathing)

Causes:

-Severe Hypoxemia (high altitude especially at night)

-Lesions in the CNS

-Cardiovascular diseases (e.g. heart failure)

Mechanism:

During apnea→↑brain PCO2→ stimulate ventilation maximally→ ↓alveolar PCO2 below the set point→ inhibiting respiration.

Thus, chemoreceptors recieve the information too late to regulate it properly

Term
Sleep Apnea Syndrome
Definition

A group of disorders in which breathing during sleep stops for more than 10 seconds and usually more than 20 times an hour. Causes measurable blood deoxygenation.

1. Central sleep apnea: due to decreased respiratory center output; longer intervals between breathing. Usually do to damage in the brain.

2. Obstructive sleep apnea: upper airway blockage despite normal airflow drive (most common).

3. Mixed central and obstructive sleep apnea.

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