Compensatory & Counter-Regulatory Mechanisms

What are the Compensatory Mechanisms

1. SNS activation

2. RAAS

3. Ventricular Remodeling

4. Dilation

5. Hypertrophy

SNS Activation

• 1st and least effective

• Release catecholamines (epinephrine)

• Causes: increased HR, increased contractility, and peripheral vasoconstriction

SNS Activation Pathway

Weak heart→ body beats faster and harder → temporary help → leads to overworking the heart

RAAS Activation

• kidney’s not receiving enough blood causes release of renin which activates RAAS

• Lead to Vasoconstrictor and sodium/water retention

RAAS tip

RAAS= Retain Salt+ Retain Water+ Raise BP

RAAS Activation Pathway

When BP is low →body holds water and tightens the vessels→ RAAS activates→ heart already weak→ puts more resistance and fluids in the heart making it harder to work.

Ventricular Remodeling

• heart changes its structures → cells hypertrophy

• Ventricular enlarge→ pumps less effectively→ dysrhythmia risk increases

Dilation

• heart chamber enlargement

• caused by LV pressure elevated

Hypertrophy

• heart muscle becomes thicker

• overtime= poor contractility, increases oxygen requirements, poor coronary circulation, increased ventricular dysrhythmias

Counter-Regulatory

trying to reverse the too much fluid and squeezing

Counter-Regulatory Mechanisms

1. ANP & BNP

2. Nitric Oxide

ANP & BNP

• natriuretic peptides released when blood volume in heart increases

• Causes

  • Diuresis= pee out

  • vasodilation= opening blood vessels

  • decreased BP

Nitric Oxide

• released from vascular endothelium

• causes vasodilation

• less resistance to pump against