MEDICAL PHYSIOLOGY

PHYSIOLOGY

SYNAPTIC PHYSIOLOGY

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Which body does Ca bind to during muscle contraction?
A
Actin
B
Myosin
C
Troponin
D
Tropomyosin
Explanation: 

Detailed explanation-1: -The calcium ions released from endoplasmic reticulum72) bind to the calcium-binding subunit of troponin (troponin-C (TnC), ∼18 kDa), and the inhibition by troponin is neutralized to trigger muscle contraction.

Detailed explanation-2: -Each heartbeat is triggered by a pulse of intracellular calcium ions which bind to troponin on the actin-containing thin filaments of heart muscle cells, initiating a change in filament structure that allows myosin to bind and generate force.

Detailed explanation-3: -1: Muscle contraction: Calcium remains in the sarcoplasmic reticulum until released by a stimulus. Calcium then binds to troponin, causing the troponin to change shape and remove the tropomyosin from the binding sites.

Detailed explanation-4: -Ca2+ binding to troponin initiates thin filament activation exposing myosin binding sites on actin. However, unlike in skeletal muscle, thin filament activation in cardiac muscle is not achieved primarily by Ca2+ binding alone (16, 17, 37).

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