The water vascular system of a sea star enables movement, digestion and respiration through the use of water to exert force on limbs known as tube feet. The vascular system is primarily water but also contains coelomocytes, protein and potassium salts.
The answer is immune system
Answer:
The correct answer will be option-D.
Explanation:
Calcium plays an important role in muscle contraction as they are released from the sarcoplasmic reticulum after they receive electric impulse.
Calcium triggers the muscle contraction cycle as these calcium ions bind to the troponin-tropomyosin complex. This binding exposes the myosin-binding site on the actin on which high energy myosin binds and cross-bridge is formed.
This cross-bridge formation causes the contraction of the sarcomere and therefore muscle contracts.
Thus, option-D is the correct answer.
A because it pertains the the ecosystem
<span>The muscle at the end of the esophagus is not able to close, which allows stomach acid and digested food to go back up into the esophagus. </span>
