ABSTRACT
Study objectives Describe the morphological differences between skeletal muscle and smooth muscle Explain how contraction of smooth muscle occurs Explain how relaxation of smooth muscle occurs Explain why smooth muscle contraction is slow and prolonged Describe the latch state condition Distinguish between multiunit smooth muscle and single-unit smooth muscle Compare and contrast pacemaker potentials and slow-wave potentials List the factors that may alter smooth muscle contractile activity Explain how intracellular calcium concentration may be increased Describe the stress-relaxation response Describe the length-tension relationship in smooth muscle Discuss hyperplasia in smooth muscle
. Introduction Although skeletal muscle composes the bulk of the muscle tissue in the body, smooth muscle is far more important in terms of homeostasis. Most smooth muscle is found in layers or sheets in the walls of tubes and hollow organs. Contraction and relaxation of the smooth muscle in these tissues regulates the movement of substances within them. For example, contraction of the smooth muscle in the wall of a blood vessel narrows the diameter of the vessel and leads to a decrease in the ow of blood through it. Contraction of the smooth muscle in the wall of the stomach exerts pressure on its contents and pushes these substances forward into the small intestine.
