Lesson 10 - Other Tissues: Muscular and Nervous
Student Performance Objectives1. List and state the locations of the 3 types of muscular tissue found in the human body.2. Explain the basic functions of muscular tissue.3. State the two major characteristics of nervous tissue. 4. List the 4 basic functions of nervous tissue.Lesson OutlineA. Other Tissues: to be examined more closely in subsequent lessons. 1. Muscular Tissue - tissue capable of contraction and relaxation that brings about movement. There are three types of muscular tissue. a. Skeletal (striated) muscle - generally considered to be under voluntary, conscious control, although many reflex activities involving these muscles occur automatically (unconsciously). The tissue is composed of elongated muscle fibers possessing many nuclei per fiber (multinucleate). This tissue forms much of the bulk of a human body, composing the muscles that are attached to and which move the skeleton, generally at the joints. The contractile filaments within each fiber are arranged in a regular, repeating pattern which presents the characteristic striated appearance under the light microscope. b. Smooth muscle - involuntary muscle found in the walls of the body's hollow organs like the stomach and other digestive organs, the urinary bladder and the blood vessels. Smooth muscle cells are mostly uninucleate; some are multinucleate. The contractile filaments within this muscle type do not occur in the regular arrangement that would produce striations so that the muscle, when viewed under the light microscope, appears non-striated, or smooth. c. Cardiac - the involuntary muscle tissue composing the heart's myocardium. Its rhythmic contractions propel the blood through the cardiovascular system under pressure. Cardiac muscle fibers are striated, are "welded" to each other through desmosomes (part of intercalated discs), and possess gap junctions that facilitate electrical signaling from one fiber to the next. 2. Nervous Tissue - tissue possessing the properties of irritability (the ability to be stimulated and to respond to such stimulation) and conductivity (the ability to transmit electrochemical signals over long distances along specialized cellular extensions - the axons and dendrites. Its signals help to regulate and coordinate bodily functions. The major organized regions of nervous tissue (brain, spinal cord, peripheral nerves, and sensory receptors) carry out the following functions: a. Conduct sensory signals (information) from receptors into the central nervous system (CNS - which consists of the brain and spinal cord working as an integrated unit). b. Analysis of incoming signals. c. Store incoming signal patterns as memory. d. Conduct motor signals from the CNS to muscle and glands.