Cardiopulmonary Reflexes

Cardiopulmonary Reflexes


CARDIOPULMONARY REFLEXES

  • Important baroreceptors involved – 
  • Cardiac baroreceptors.
  • Pulmonary artery baroreceptors.

I. CARDIAC BARORECEPTORS:

  • Located in subendocardial heart walls.
  • Includes – 
  • Atrial stretch receptors
  • Ventricular receptors.
  • Both innervated by vagus nerve. 

Ia. ATRIAL STRETCH RECEPTORS:

  • Present in atrial walls.
  • Also referred as “Low-pressure” receptors.

Types:

  • Receptors with,
  • Large myelinated efferent fibers.
  • Non-myelinated afferent fibers.

1. Receptors with large myelinated efferent fibers:

  • Located at various venoatrial junction.

1a. Subtypes:

  • According to location –  
  • Atriocaval receptors:
  • Located in right atrium, at entrance of SVC & IVC.
  • Pulmonary venoatrial receptors:
  • Located in left atrium, at entrance of pulmonary artery. 

1b. Subtypes:

  • According to discharge pattern – 
  • Type A receptors –
  • Discharge during atrial systole.
  • Type B receptors – 
  • Discharge during later part of atrial diastole.

2. Receptors with non-myelinated afferent fibers:

  • Located throughout atria & interatrial septum.

ROLE OF ATRIAL RECEPTORS:

1. As low-pressure receptors:

  • Atrial receptors (especially type B receptors) along with pulmonary arterial receptors.
  • Minimize arterial pressure change in response to blood volume change.

2. Atrial reflex control of heart rate –

  • “Bain-bridge reflex”:
  • Increases venous return.
  • E.g., After rapid saline infusion leading to tachycardia.

3. Atrial control of blood volume –

  • “Volume reflex”:
  • Volume overload to atrial stretch receptors.
  • Causes diuresis.
  • By increasing atrial ANP secretion.
  • Inhibiting pituitary ADH secretion.

Ib. VENTRICULAR STRETCH RECEPTORS:

  • Scattered throughout left ventricle & interventricular septum.
  • Stimulated by injecting Serotonine, Veratibine, or Nicotine into left coronary artery.
  • Produces apnea, bradycardia & hypotension.
  • This is referred as “Bezold-Jarisch reflex” / “Coronary chemoreflex”.

II. PULMONARY ARTERY BARORECEPTORS:

  • “Low-pressure receptors” (similar to atrial low-pressure receptors).
  • Located in,
  • Walls of pulmonary trunk.
  • In right & left pulmonary artery.
  • Important role in minimizing arterial pressure changes in response to blood volume change.
  • Does along with atrial stretch receptors.
Exam Question
 

CARDIOPULMONARY REFLEXES

  • Atrial stretch receptors also referred as “Low-pressure” receptors – 
  • Especially type B receptors.
  • Functions along with pulmonary arterial receptors.
  • Minimize arterial pressure change in response to blood volume change.
  • Receptors with large myelinated efferent fibers include,
  • Atriocaval receptors:
  • Located in right atrium, at entrance of SVC & IVC.
  • Pulmonary venoatrial receptors:
  • Located in left atrium, at entrance of pulmonary artery. 
  • “Bain-bridge reflex” – Atrial reflex control of heart rate.
  • Ventricular stretch receptors are stimulated by injection Serotonine, Veratibine/Nicotine into left coronary artery.
  • Produces apnea, bradycardia & hypotension.
  • This is referred as “Bezold-Jarisch reflex” / “Coronary chemoreflex”.
  • Pulmonary artery baroreceptors are “Low-pressure receptors” (similar to atrial low-pressure receptors).
  • Important role in minimizing arterial pressure changes in response to blood volume change.
  • (Along with atrial stretch receptors).
Don’t Forget to Solve all the previous Year Question asked on Cardiopulmonary Reflexes

Leave a Reply

Free Mini Course on Stomach

Mini Course – Stomach

22 High Yield Topics in Stomach

in Just 2 Hours

Submission received, thank you!

Close Window
%d bloggers like this:
Malcare WordPress Security