Chapter 9: Muscles And Muscle Tissue

Question 1

What are the 3 types of muscle tissue?

Answer 1

1. Skeletal
2. Cardiac
3. Smooth

Question 2

Describe Skeletal Muscle Tissue

Answer 2

• Striated
• Location: Attached to skin and bone
• Voluntary

Question 3

Describe Cardiac Muscle Tissue

Answer 3

• Striated
• Location: Heart
• Involuntary

Question 4

Describe Smooth Muscle Tissue

Answer 4

• No Striations
• Location: Walls of hollow organs
• Involuntary

Question 5

What are the 4 main characteristics of muscle tissue?

Answer 5

1) Excitability (responsiveness)
2) Contractibility
3) Extensibility
4) Elasticity

Question 6

Excitability (responsiveness)

Answer 6

Ability to receive and respond to stimuli

Question 7

Contractibility

Answer 7

Ability to shorten forcibly when stimulated

Question 8

Extensibility

Answer 8

Ability to be stretched

Question 9

Elasticity

Answer 9

Ability to recoil to resting length

Question 10

What are the 4 main functions of the muscle?

Answer 10

1. Produce movement
2. Maintain posture
3. Stabilize joints
4. Generate heat as they contract

Question 11

What are the 3 features of the Skeletal muscle anatomy?

Answer 11

1) Nerve and blood supply
2) CT sheaths
3) Attachments

Question 12

Nerve and Blood Supply

Answer 12

• Each muscle receives a nerve, artery, and veins–> cellular respiration
• Contracting muscle fibers require huge amounts of oxygen and nutrients

Question 13

CT Sheaths

Answer 13

• Every skeletal muscle (and muscle fiber) is covered in CT
• Support cells and reinforce whole muscle
• Sheaths from external to internal (3)

Question 14

What are the 3 Sheaths of CT?

Answer 14

1) Epimysium
2) Perimysium
3) Endomysium

Question 15

Epimysium

Answer 15

Dense irregular CT surrounding entire muscle

Question 16

Perimysium

Answer 16

Fibrous CT surrounding fascicles

Question 17

Endomysium

Answer 17

Fine areolar CT surrounding each muscle fiber (cell)

Question 18

Attachments

Answer 18

• Muscle spans joints and attach to bones

• Muscles attach to bone in a least (2) places:
  • Insertion
  • Origin

Question 19

Insertion

Answer 19

Attachment to movable bone

Question 20

Origin

Answer 20

Attachment to immovable or less movable bone

Question 21

Sarcolemma

Answer 21

Muscle fiber plasma membrane

Question 22

Sarcoplasm

Answer 22

Muscle fiber cytoplasm

Question 23

Myofibrils

Answer 23

Densely packed, rodlike elements

Question 24

Muscle tension

Answer 24

The force exerted on load or object to be moved; produced by contraction

Question 25

What are the 2 types of contractions?

Answer 25

1) Isometric | 2) Isotonic

Question 26

Isometric Contraction

Answer 26

No shortening; muscle tension increases but does not exceed load

Question 27

Isotonic Contraction

Answer 27

Muscle shortens because muscle tension exceeds load

Question 28

Why does the force and duration of a contraction vary?

Answer 28

In response to stimuli of different frequencies and intensities

Question 29

Motor Unit

Answer 29

Consists of the motor neuron and all muscle fibers it supplies

Question 30

Muscle twitch

Answer 30

Simplest contraction resulting from a muscle fiber's response to a single action potential from motor neuron

Question 31

Why do graded muscle responses vary?

Answer 31

The various strength of contractions are for different demands

Question 32

How do muscles graded in response to change change in stimulus frequency?

Answer 32

- Single stimuli= single contractile (i.e muscle twitch) | - Multiple stimuli= multiple contractiles from same fiber

Question 33

How does stimulus strength change to muscle response?

Answer 33

Recruitment (or multiple unit stimulation )

Question 34

Recruitment (or multiple unit stimulation )

Answer 34

Stimulus is sent to more muscle fibers, leading to more precise control

Question 35

What are the 3 types of stimulus in recruitment?

Answer 35

1) Sub threshold 2) Threshold 3) Maximal

Question 36

Sub Threshold stimulus

Answer 36

Stimulus not strong enough, so no contractions seen

Question 37

Threshold stimulus

Answer 37

Stimulus is strong enough to cause first observable contraction

Question 38

Maximal stimulus

Answer 38

Strongest stimulus that increases maximum contractile force

Question 39

Describe the asynchronous contraction of motor units in muscles?

Answer 39

Tag team back-and-forth, contracting and relaxing

Question 40

Muscle tone

Answer 40

Constant, slightly contracted state of all muscles

Question 41

ATP supplies the energy needed for the muscle fiber to:

Answer 41

- Move and detach cross bridges - Pump calcium back into SR - End the action potential moving through the muscle

Question 42

What are the 3 mechanisms in which ATP is regenerated quickly?

Answer 42

1. Direct phosphorylation of ADP by creatine phosphate (CP) 2. Anaerobic pathway; glycolysis and lactic acid formation 3. Aerobic respiration