Chapter 9 Muscle and Muscle Tissue

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1

How much of the body's mass is muscle tissue?

nearly half

2

What are the three types of muscle?

skeletal

smooth

cardiac

3

Describe skeletal muscle?

voluntary

striated

contains elongated cells called muscle fibers

contracts rapidly

stimulated by nervous system

4

Describe cardiac muscle?

located only in the heart

striated

involuntary

can contract without nervous system stimulation

5

Describe smooth muscle?

in walls of hollow organs

no striations

can contract without nervous system stimulation

involuntary

6

What are the 4 characteristics of muscle tissue?

excitability

contractibility

extensibility

elasticity

7

What are 4 important functions of muscle?

move blood and fluid

maintain posture and body position

stabilize joints

heat generation

8

True/False: each muscle is served by one artery, one nerve, and one vein

true

9

What is the epimysium in skeletal muscle?

dense irregular connective tissue that surrounds the entire muscle, outter most layer, may blend with fascia

10

What is the perimysium in skeletal tissue?

fibrous connective tissue surrounding fascicles

11

What are fascicles?

groups of muscle fibers

12

What is the endomysium of skeletal muscle?

fine areolar connective tissue that surrounds each muscle fiber, inner most layer

13

What is the difference between direct and indirect attachment in skeletal muscle?

direct - epimysium is fused to the periosteum of bone or to the perichondrium of cartilage

indirect - connective tissue wrappings extend beyond muscles as either tendons (ropelike) or aponeurosis (sheetlike)

14

In the microscopic anatomy of a cell, what is the sarcolemma?

plasma membrane

15

In the microscopic anatomy of a cell, what is the sarcoplasm?

cytoplasm

16

In the microscopic anatomy of a cell, what are the contractile units?

sarcomeres

17

What re th type types of contractile myofilaments and how do they differ in shape?

actin - thin

myosin - thick

18

What is rigor mortis?

the stiffening of the joint and muscles in the body, usually a few hours after death

19

Contractions produces ____ ______ , force exerted on load or object to be moved.

muscle tension

20

What type of muscle contraction occurs when there is no muscle shortening, the muscle tension increases but does not exceed the load?

isometric contraction

21

What type of muscle contraction occurs when the muscle shortened because muscle tension exceeds load?

isotonic contraction

22

What are the 3 phases of muscle twitch?

latent period (no muscle tension)

period of contraction (cross bridge formation/tension increases)

period of relaxation (tension declines to zero)

23

What are the 2 type of isometric contractions and how do they differ?

concentric - muscle shortens and does work

eccentric - muscle generates force as it lengthens

24

What does the body produce in response to anaerobic exercise?

lactic acid

25

What does the body produce in response to aerobic exercise?

CO2 and H2O

26

What is defined as the inability of a muscle to contract, despite continued stimulation?

muscle fatigue

27

____% of energy released in muscle activity is useful as work, ____% of energy is given off as heat.

40% of energy released in muscle activity is useful as work, 60% of energy is given off as heat.

28

What is the result of muscle contractions to generate heat when cold?

shivering

29

Force of contraction depends on number of cross bridges attaches, which is effected by?

number of muscle fibers stimulated (recruitment)

relative size of fibers (hypertrophy)

frequency of stimulation

degree of muscle stretch

30

What is velocity and duration of contraction influenced by?

muscle fiber type (fast or slow fibers)

load

recruitment

31

What is muscle hypertrophy?

growth of the muscle due primarily to increases in fiber size (increased muscle size and strength)

32

What is muscle atrophy?

loss of muscle, a result of immobilization, muscle strength declines 5% per day

without neural stimulation, muscles atrophy to 1/4 initial size

33

Smooth muscles are found in the walls of hollow organs, what are the 2 layers?

longitudinal and circular

34

What is peristalsis in smooth muscle?

alternating contraction and relaxation of smooth muscle layers that mix and squeeze substances though lumen of hollow organs

35

What is hyperplasia and give an example?

smooth muscle cells can divide and increase in numbers

example. estrogen causes uterus to expand during pregnancy due to the increase in smooth muscle cells