Respiratory Reflexes

Respiratory Reflexes


RESPIRATORY REFLEXES

  • Respiratory rhythm is altered reflexly.
  • Occurs in response to metabolic signals & other stimuli.

MAJOR RESPIRATORY REFLEXES:

  • Hering-Breuer inflation reflex.
  • Hering-Breuer deflation reflex.
  • Irritant receptors.
  • J-reflex/J-receptors.
  • Head’s paradoxical reflex.
  • Afferent from proprioceptors.

1. HERING-BREUER INFLATION REFLEX:

  • Mediated by pulmonary stretch receptor.

Mechanism:

  • Lung inflation above particular volume results in,
  • Reflex inhibition of inspiration.
  • Initiation of expiration.

Major actions:

  • Limits tidal volume.
  • Increases respiratory frequency.
  • Prevents lung hyperinflation.

2. HERING-BREUER DEFLATION REFLEX:

  • Rapid lung deflation initiates prolonged inspiration (reflex hyperpnea).
3. IRRITANT RECEPTORS:
  • Respiratory tract mucosa contains rapidly adapting “Irritant receptors”.
  • Responds to noxious gases, cigarette smoke, inhaled dust, cold air, etc.
  • Information from irritant receptors conveyed to CNS by vagal afferent fibers.
  • Nerve stimulation causes reflex bronchoconstriction, cough & increased mucus secretion.
4. “J-REFLEX”/”J-RECEPTORS”:
  • J- receptors – 
  • Sensory nerve endings of non-myelinated (type – C) afferent fibers in vagus nerve.
  • “J” refers to “Juxtacapillary”.
  • Juxta-position to pulmonary capillaries,
  • In alveolar interstitium.
Stimulating factors:
  • Increased in alveolar interstitial fluid→Interstitial edema.
  • Alveolar capillaries engorged
  • As in CHF/pulmonary microemboli.
  • Stimulation reflexly causes,
  • Severe tachypnea
  • Bronchoconstriction
  • Hypotension.
  • Bradycardia.
Major stimulating factor:
  • Increased pulmonary capillary pressure.
  • Eg: Especially during exercise at high altitude.
Effect of stimulation:
  • Produces tachypnea → Leading to dyspnea.
  • Inhibits stretch reflex in skeletal muscles → Inhibits exercise.
  • Protecting from pulmonary edema precipitation.
5. HEAD’S PARADOXICAL REFLEX:
  • Lung inflation further induces inflation.

Functions:

  • Physiological role of Head’s reflex is uncertain.
  • Play a role in initiating respiration at birth.
  • Fetus is delivered with empty lungs.
  • First breath doesn’t fill lungs completely.
  • Each inflation promotes further inflation, facilitating lung filling.

6. AFFERENT FROM PROPRIOCEPTORS:

  • Proprioceptive afferent impulses from muscles & joints → Stimulate inspiratory neurons,
  • Hence, increase pulmonary ventilation during exercise.
Exam Question
 

RESPIRATORY REFLEXES

1. HERING-BREUER INFLATION REFLEX:

  • Limits tidal volume.
  • Prevents lung hyperinflation.
2. “J-REFLEX” (“J-RECEPTORS”):
  • “J” refers to “Juxtacapillary” 
  • Juxtaposition to pulmonary capillaries in alveolar interstitium.
Major stimulating factor:
  • Increased pulmonary capillary pressure.
  • During exercise, especially at high altitude.
3. HEAD’S PARADOXICAL REFLEX:
  • Lung inflation further induces inflation.

4. AFFERENT FROM PROPRIOCEPTORS:

  • Impulses from muscles & joints → Stimulate inspiratory neurons,
  • Hence, increased pulmonary ventilation during exercise.
Don’t Forget to Solve all the previous Year Question asked on Respiratory Reflexes

Leave a Reply

%d bloggers like this:
Malcare WordPress Security