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Ch. 9 Muscles and Muscle Tissue
Chapter 8, Problem 14

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.

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1
Identify the characteristics of smooth muscle types: multi-unit and unitary.
Understand that multi-unit smooth muscle cells function independently and are not connected by gap junctions.
Recognize that unitary smooth muscle cells are connected by gap junctions, allowing them to function as a single unit.
Recall that unitary smooth muscle often contains pacemaker cells, which help coordinate contractions.
Determine which type of smooth muscle is found in the walls of digestive and urinary system organs based on the presence of gap junctions and pacemaker cells.

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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. Multi-unit smooth muscle consists of individual muscle fibers that operate independently, while unitary smooth muscle fibers are connected by gap junctions, allowing them to function as a single unit. This distinction is crucial for understanding how different smooth muscle types respond to stimuli.
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Gap Junctions

Gap junctions are specialized intercellular connections that allow for direct communication between adjacent cells. In unitary smooth muscle, these junctions enable the rapid transmission of electrical signals, facilitating coordinated contractions across the muscle tissue. This feature is essential for the rhythmic contractions seen in organs like the intestines and bladder.
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Pacemaker Cells

Pacemaker cells are specialized cells that generate spontaneous electrical impulses, initiating contractions in smooth muscle. In the context of unitary smooth muscle, these cells help regulate the rhythmic activity of the muscle, ensuring that organs such as the digestive tract and urinary bladder contract in a coordinated manner to facilitate their functions.
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