QS Study

Catecholamines are the essences accountable for the fight-or-flight response to stressful situations. They are the chemicals that cause your heart to beat faster, sweat to coat your palms, and your emotions to change in an instant.

Functions of catecholamines (Epinephrine and Nor-epinephrine)

(A) Metabolic effects:

  1. (+) Glycogenolysis in the liver and skeletal muscle.
  2. ↑ Mobilization of FFA.
  3. ↑ Basal metabolic rate.

(B) Effects on the cardiovascular system:

  1. Increase the force and rate of contraction of the isolated heart (bi receptor)
  2. ↑ Cardiac output.
  3. On vessels – Vasoconstriction in skin and viscera (a) vasodilatation in skeletal muscle and liver.

(C) On Respiratory system:

  • Bronchodilatation (b2)
  • Muscle – Relaxation (Peristalsis)
  • Sphincter – Contraction

(E) Urinary bladder:

  • Detrusor muscle relaxation
  • Sphincter – Contraction.

(F) Eye:

  • Pupil dilation
  • Ciliary muscle relaxation