Heart Rate

Table of Contents

Introduction

Normal heart rate is 72/min.It ranges between 60 and 80 per minute.

Tachycardia

Tachycardia is the increase in heart rate above 100/ min

Physiological Condition when Tachycardia Occurs

  • Childhood
  • Exercise
  • Pregnancy
  • Emotional conditions such as anxiety

Pathological condition when Tachycardic Occurs

  • Fever
  • Anemia
  • Hypoxia
  • Hyperthyroidism
  • Hypersecretion of catecholamines
  • Cardiomyopathy
  • Diseases of heart valves
Heart rate

Bradycardia

Bradycardia is a decrease in heart rate below 60/ min

Physiological condition when Bradycardia Occurs

  • Sleep
  • Athletes

Pathological Conditions When Bradycardic Occurs

  • Hypothermia
  • Hypothyroidism
  • Heart attack
  • Congenital heart disease
  • Degenerative process of aging
  • Obstructive jaundice
  • Increased intracranial pressure

Drugs that Induce Bradycardia

  • Beta-blockers
  • Channel blockers
  • Digitalis and other antiarrhythmic drugs.

Regulation of Heart rate

Heart rate is regulated by the nervous mechanism, which consists of three components:

  • Vasomotor center
  • Motor (efferent ) nerve fibers to the heart.
  • Sensory(afferent) nerve fibers from the heart.

Factor affecting vasomotor center – regulation of vagal tone

  • Impulses from higher centers
  • Impulses from respiratory centers
  • Impulse from baroreceptors marey reflex
  • Impulse from chemoreceptors
  • Impulses from right atrium – Bainbridge reflex
  • The impulse from other afferent nerves
  • Bezold – Jarisch Reflex

Recent Article post