The dynein arms then detach from the neighboring pair and return to start position so the process can repeat again and again. Muscle Muscle contraction is the most important effector mechanism that animals have for responding to their environments. Smooth muscle 2. Skeletal muscle 3. Smooth muscles associated with internal organs are under autonomic control.
Smooth muscles provide the contractile forces for most of our internal organs.
They move food through the digestive tract, controls the flow of blood through blood vessels, and empties the urinary bladder. Smooth muscles are usually long and spindle-shaped, and each cell has a nucleus. Smooth muscle cells in the wall of the digestive tract are in electrical contact with one another through gap junctions. The resting potential of a smooth muscle membrane is sensitive to being stretched. Membranes of the stretched cells depolarize and fire action potentials that cause the cells to contract.