Download Thibodeau: Anatomy and Physiology, 5/e Chapter 11

Thibodeau: Anatomy and Physiology, 5/e
Chapter 11 - Physiology of the Muscular System
Together, the skeletal and muscular systems produce most body movements. This chapter examines the
basic characteristics of skeletal muscle and, briefly, smooth and cardiac muscle tissues, contrasting them
with skeletal muscle tissue. Three generalized functions of skeletal muscle tissue are movement, heat
production, and posture. Skeletal muscle cell characteristics essential to movement and function include
excitability, contractility, and extensibility.
Skeletal muscle fibers have many of the same structural parts as other cells. Several of them,
however, bear different names in muscle fibers (e.g., sarcolemma, sarcoplasm, sarcoplasmic reticulum).
Certain structures not found in other cells include sarcomeres, T tubules, and myofibrils (each of which
contains thousands of thick and thin myofilaments).
This chapter describes the mechanisms of excitation, contraction, and relaxation, as well as
exploring energy sources for muscle contraction (e.g., ATP). Also discussed are the "all-or-none principle"
and the threshold stimulus (the minimal level of stimulation required to cause a fiber to contract).
The somatic motor neuron plus the muscle fibers that it innervates constitute a motor unit.
Myography is used to study muscle contractions such as the twitch contraction, treppe, and tetanic
contractions. A tonic contraction is a continual, partial contraction, whereas an isotonic contraction is one
in which the tone or tension within a muscle remains the same but the length of the muscle changes. An
isometric contraction is one in which muscle length remains the same but tension increases.
The graded strength principle is used to demonstrate that skeletal muscles contract with varying
degrees of strength at different times. Cardiac muscle (striated involuntary muscle) is found only in the
heart; smooth muscle is of two types: visceral (single-unit) and multiunit.
Objectives
After students have completed this chapter, they should be able to:
1.
List and discuss the three generalized functions of skeletal muscle tissue.
2.
Discuss the three characteristics of skeletal muscle cells that allow them to function as they do.
3.
cells.
List and discuss the structural parts of skeletal muscle fibers that are also found in other types of
4.
List and discuss the structural parts of skeletal muscle fibers that are not found in other cells.
5.
Discuss the structure and function of myofilaments.
6.
Explain the series of steps in muscle contraction.
7.
Describe the sliding filament theory.
8.
Explain the series of steps in muscle relaxation.
9.
Identify and explain the energy sources for muscle contraction.
10.
Discuss aerobic and anaerobic respiration.
11.
Define a motor unit.
12.
Describe the following types of skeletal muscle contractions: twitch, treppe, tetanic, tonic,
isotonic, isometric.
13.
Explain the graded strength principle.
14.
Describe the anatomical and functional characteristic of cardiac and smooth muscle.
Copyright © 2003 Mosby, Inc. All Rights Reserved.
Chapter 11 - Physiology of the Muscular System
Lecture Outline
I.
Introduction (p. 312)
A.
II.
III.
How the muscles move the skeleton and viscera
General Functions (p. 312)
A.
Movement
B.
Heat production
C.
Posture
Function of Skeletal Muscle Tissue (p. 312)
A.
B.
Overview of the muscle cell (Figs. 11-1, 11-2, 11-3)
1.
Sarcolemma
2.
Sarcoplasm
a.
Sarcoplasmic reticulum (SR)
b.
Myofibrils (Fig. 11-1, B)
1)
Myofilaments (Fig. 11-1, D)
2)
Sarcomere (Fig. 11-1, C)
3.
T tubules (transverse tubules) (Fig. 11-1, B)
4.
Triad (2 SR sacs and a T tubule) (Fig. 11-3)
Myofilaments (p. 315)
1.
Thick myofilaments
a.
Myosin (Fig. 11-4, B)
1)
2.
Thin myofilaments
a.
Actin (Fig. 11-4, A)
1)
C.
D.
E.
Cross bridges (Fig. 11-4, C)
Active sites covered by tropomyosin
b.
Tropomyosin (Fig. 11-4, A)
c.
Troponin (Fig. 11-4, A)
The mechanism of contraction (Box 11-1)
1.
Excitation of the sarcolemma (Fig. 11-6)
2.
Contraction (Figs. 11-6, 11-7, 11-8)
3.
Relaxation
Energy sources for muscle contraction (p. 318)
1.
ATP (Figs. 2-26; 11-7, A; 11-9)
2.
Glucose and oxygen
3.
Aerobic respiration
4.
Anaerobic respiration
5.
Heat production (Fig. 11-10)
Characteristics of Muscle Tissue (Table 11-1)
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Chapter 11 - Physiology of the Muscular System
IV.
V.
Function of Skeletal Muscle Organs (Fig. 11-1, A)
A.
Motor unit (Fig. 11-11)
B.
Myography
C.
The twitch contraction (Figs. 11-12; 11-13, A)
1.
Latent period
2.
Contraction phase
3.
Relaxation phase
D.
Treppe: the staircase phenomenon (Fig. 11-13, B)
E.
Tetanus (Figs. 11-13, C; 11-13, D)
F.
Muscle tone
G.
Isotonic and isometric contractions (Figs. 11-18, A; 11-18, B)
H.
The graded strength principle (Figs. 11-14, 11-17)
1.
Recruitment (Fig. 11-14)
2.
Length-tension relationship (Fig. 11-15)
3.
Load imposed on muscle (Fig. 11-16)
4.
Stretch Reflex and Strength of Muscle contraction (Fig. 11-16)
Function of Cardiac and Smooth Muscle Tissue (p. 328)
A.
Cardiac muscle (Fig. 11-19; also Chapters 18 and 19)
1.
B.
C.
VI.
Smooth muscle (Fig. 11-21)
1.
Visceral (single unit)
2.
Multiunit
Comparison of the three muscle types (Table 11-1)
The Big Picture: Muscle Tissue and the Whole Body (p. 331)
A.
VII.
Striated involuntary
Muscle contribution to homeostasis
1.
Movement
2.
Temperature
3.
Posture
Mechanisms of Disease (p. 332)
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