Muscular Tissue

Types and Characteristics of Muscular Tissue 408

  • Universal Characteristics of Muscle 408
  • Skeletal Muscle 408

Microscopic Anatomy of Skeletal Muscle 409

  • The Muscle Fiber 409
  • Myofilaments 409
  • Striations 411

The Nerve-Muscle Relationship 412

  • Motor Neurons 412
  • The Motor Unit 412
  • The Neuromuscular Junction 413
  • Electrically Excitable Cells 415

Behavior of Skeletal Muscle Fibers 416

  • Excitation 417
  • Excitation-Contraction Coupling 417
  • Contraction 417
  • Relaxation 422
  • The Length-Tension Relationship and Muscle Tone 422

Behavior of Whole Muscles 423

• Threshold, Latent Period, and Twitch 423


Behavior of Whole Muscles 423

• Threshold, Latent Period, and Twitch 423

  • Contraction Strength of Twitches 424
  • Isometric and Isotonic Contraction 425

Neuromuscular Toxins and

Muscle Metabolism 427

Paralysis 414

• ATP Sources 427


Clinical Application: Rigor

• Fatigue and Endurance 428

Mortis 422

• Oxygen Debt 429


Medical History: Galvani, Volta,

• Physiological Classes of Muscle Fibers 429

and Animal Electricity 424

• Muscular Strength and Conditioning 431


Clinical Application: Muscular

Cardiac and Smooth Muscle 432

• Cardiac Muscle 432

Dystrophy and Myasthenia Gravis 437

• Smooth Muscle 433

Chapter Review 438

Brushing Up

To understand this chapter, it is important that you understand or brush up on the following concepts:

  • Aerobic and anaerobic metabolism (p. 86)
  • The functions of membrane proteins, especially receptors and ion gates (p. 100)
  • Structure of a neuron (p. 175)
  • General histology of the three types of muscle (p. 176)
  • Desmosomes and gap junctions (p. 179)
  • Connective tissues of a muscle (p. 326)

Saladin: Anatomy & I 11. Muscular Tissue I Text I © The McGraw-Hill

Physiology: The Unity of Companies, 2003 Form and Function, Third Edition

408 Part Two Support and Movement

Movement is a fundamental characteristic of all living things, but reaches its highest development in animals because of their muscular tissue. Muscular tissue is composed of elongated cells that contract when stimulated. A muscle cell is essentially a device for converting the chemical energy of ATP into the mechanical energy of contraction. This chapter discusses contraction at the cellular and molecular levels and explains the basis of such aspects of muscle performance as warm-up, strength, endurance, and fatigue. These phenomena have obvious relevance to athletic performance, and they become very important when old age or lack of physical conditioning interferes with a person's ability to carry out everyday motor tasks. The effects of old age on the muscular system are discussed in chapter 29.

The three types of muscle tissue—skeletal, cardiac, and smooth—were described and compared in chapter 5. The expression "muscular system" refers only to skeletal muscle. This chapter is concerned primarily with the microscopic anatomy and physiology of skeletal muscle. Cardiac and smooth muscle are discussed more briefly to compare their properties and functions with skeletal muscle. Cardiac muscle is discussed more extensively in chapter 19.

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