Cardiac Muscle-Unique features
1. Gap junctions
→ SINGLE NUCLEUS CENTRALLY placed – Seen in Intercalated disc region.
→ Protein subunit – CONNEXONS – 6 subunits of “Connexin”
functions:
→ Gap junctions causes “SYNCHRONIZED CONTRACTION” / “SYNCYTIAL CONTRACTION”.
→ Entire cardiac muscle unit contracts as single unit – FUCNTIONAL SYNCYTIUM.
2. Elasticity
→ Cardiac muscle ELASTICITY – Due to TITIN (Spring type protein) “Stretch Recoil”.
→ Titin mutation – Non-elastic cardiac muscle.
→ On stretching ↑ Stretch (Non-elastic nature) Dilated Cardiomyopathy (DCM).
3.CICR
→ Calcium Induced Calcium Release
→ EXTRACELLULAR calcium induces INTRACELLULAR calcium release (Stored in sarcoplasmic reticulum).
4.Sarcoplasmic reticulum
→ Presence of WELL-DEVELOPED sarcoplasmic reticulum (SR) & SERCA pump.
→ SERCA pump & SR – Aids calcium storage.
5.PHOSPHOLAMBAN
→ INHIBITS SERCA pump & interferes with calcium storage.
