The smooth muscle type found in the walls of digestive and urinary system organs and that exhibits gap junctions and pacemaker cells is:
a. Multi unit
b. Unitary

Verified step by step guidance

Step 1: Understand the two types of smooth muscle: multi-unit and unitary (also called visceral). Multi-unit smooth muscle consists of individual fibers that operate independently, while unitary smooth muscle fibers are connected and function as a single unit.

Step 2: Recall that unitary smooth muscle is characterized by the presence of gap junctions, which allow electrical signals to pass directly between cells, enabling coordinated contractions.

Step 3: Recognize that unitary smooth muscle also contains pacemaker cells, which generate spontaneous action potentials to initiate rhythmic contractions without external stimuli.

Step 4: Note that unitary smooth muscle is typically found in the walls of hollow organs such as those in the digestive and urinary systems, where coordinated contractions are necessary for functions like peristalsis and urine flow.

Step 5: Conclude that the smooth muscle type described in the problem—found in digestive and urinary system walls, exhibiting gap junctions and pacemaker cells—is unitary smooth muscle.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Smooth Muscle Types

Smooth muscle is classified into two main types: multi-unit and unitary (single-unit). Multi-unit smooth muscle consists of individual fibers that contract independently, while unitary smooth muscle fibers are connected and contract as a single unit, commonly found in the walls of hollow organs.

Gap Junctions in Smooth Muscle

Gap junctions are specialized connections between smooth muscle cells that allow direct electrical communication. These junctions enable coordinated contraction by allowing ions and small molecules to pass between cells, which is characteristic of unitary smooth muscle.

Pacemaker Cells in Smooth Muscle

Pacemaker cells are specialized smooth muscle cells that generate spontaneous electrical impulses, initiating rhythmic contractions. These cells are typical in unitary smooth muscle, such as in the digestive and urinary systems, facilitating coordinated and automatic muscle activity.

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Textbook Question

Name and describe the four special functional abilities of muscle that are the basis for muscle response.

Distinguish between