In cardiac muscle tissue a Ca2 release from the sarcoplasmi

In cardiac muscle tissue, __________.
a) Ca2+ release from the sarcoplasmic reticulum initiates
contraction
b) Ca2+ enters the cell from the extracellular fluid, directly
initiating contraction
c) Ca2+ enters the cell from the extracellular fluid, which
causes more Ca2+ to be released from the sarcoplasmic
reticulum
d) A and B
e) A and C

Solution

Answer-e)A and C

Note-the release of Ca²⁺ from the sarcoplasmic reticulam is induced by Ca²⁺ influx into the cell through voltage gated calcium channel in sarcolema.

This phenomenon is caled cailcium induced calcium release and increases the mycoplasmic free Ca²⁺causing muscle contraction.