Chapter 10 Muscle Tissue

Question 1

Functions of Muscle Tissue:

Answer 1

A. Production of body movements.
B. Stabilize body position.
C. Storage and movement of substances through the body.
D. Generating Heat

Question 2

Properties of Muscle Tissue

Answer 2

A. Electrical Excitability - the ability to respond to stimuli
B. Contractility - the ability to contract (shorten) forcibly when
stimulated
C. Extensibility - the ability to stretch without being damaged
D. Elasticity - the ability to return to its original length and shape
after contraction or extension

Question 3

Myasthenia Gravis

Answer 3

• an autoimmune disorder
• antibodies bind to Acetylcholine receptors, inactivating them
• patient develops progressive muscle weakness
• initial symptoms often develop in the muscles of the face and
  neck
• if death occurs it is can be associated with paralysis of the
  respiratory muscles

Question 4

Muscular Dystrophy

Answer 4

• a group of genetic disorders associated with degeneration of
  skeletal muscle

Question 5

Effects of Aging

Answer 5

• the relative number of Slow Oxidative fibers increase
• inactivity leads to fibrosing of skeletal muscle
• overall decrease of skeletal muscle

Question 6

Smooth Muscle regeneration

Answer 6

• cells can enlarge to provide additional contraction strength
• certain smooth muscles retain the ability to undergo cell
  division, ex. Myometrium of the Uterus
• Pericytes = stem cells located in capillaries and small veins
• Limited regeneration capability, but much greater than Skeletal
  muscle

Question 7

Cardiac Muscle regeneration

Answer 7

• heals via fibrosis
• existing cells can enlarge to provide additional contraction
  strength
• recent studies have discovered stem cell that can differentiate
  to become healthy cardiac muscle cells, the extent of this
  regeneration remains to be discovered

Question 8

Skeletal Muscle regeneration

Answer 8

• most damaged muscle is replaced via fibrosis (scar tissue).
• undamaged cells will enlarge to attempt to make up for lost
  function
• Satellite Cells = cells located in Skeletal Muscle tissue that
  can differentiate to become new muscle cells (myofibers), not
  enough of these cells exist to replace damaged cells
• Limited regeneration

Question 9

Muscle tone

Answer 9

The tautness or tension that is constantly in a muscle due to
involuntary, weak stimulation of the motor units.
a. Flaccid - loss of muscle tone associated with damage to motor
neurons

Question 10

Types of Skeletal Muscle Fibers: Slow Oxidation fiber

Answer 10

• a red fiber
• high myoglobin content, an iron containing protein that binds
  oxygen
• smallest diameter
• contains many capillaries
• has many Mitochondria (aerobic respiration)
• fibers contract slower than the other two fiber types
• resist fatigue
• found in postural muscles and in muscles involved in endurance
  (i.e. prolonged contraction)

Question 11

Types of Skeletal Muscle Fibers: Fast Oxidative-Glycolytic

Answer 11

• a red fiber
• high myoglobin content
• intermediate in diameter
• contains many capillaries
• generate ATP by aerobic and anaerobic contraction
• uses ATP faster than Slow Oxidative fibers
• provides faster muscle contraction but fatigue quicker than Slow
  Oxidative fibers
• associated with activities like walking and sprinting

Question 12

Types of Skeletal Muscle: FibersFast Glycolytic fibers

Answer 12

• a white fiber
• low myoglobin content
• few capillaries
• few Mitochondria
• generate most ATP via glycolysis (anaerobically)
• provide strong, rapid contraction
• fatigue the quickest
• provide quick, short bursts of muscle contraction

Question 13

Control of Muscle Tension: The amount of stretch on the muscle fibers before
contraction.

Answer 13

B. Frequency of stimulation - the number of nerve impulses that
pass through a motor unit per second

(1) Wave Summation - The increased strength of a muscle
contraction that result when nerve impulses occur in
rapid succession.

c. The number of motor units that are stimulated.
(1) Motor Unit Recruitment - The process where an increasing
number of motor unit are activated in response to an
increased load.

d. The type of muscle fiber.
(1) Refractory Period - The period of time in which an
excitable cell (i.e. muscle or nerve cell) cannot
respond to a stimulus. Different types of muscle fibers
have different refractory periods

Question 14

Motor Unit Recruitment

Answer 14

The process where an increasing number of motor
units are activated in response to an increased load

Question 15

Recovery Oxygen Consumption

Answer 15

the elevated use of oxygen after exercise
to replace the lost energy stores and to facilitate tissue repair after
exertion

Question 16

Muscle fatigue

Answer 16

the inability of muscle to contract forcefully after
prolonged activity.

Question 17

Aerobic Respiration

Answer 17

occurs in the Mitochondria
- requires oxygen (oxygen is the limiting factor)
- produces up to 36 ATP
- can get energy from the breakdown of Pyruvic Acid, fatty acids
and amino acids
- provide energy for prolonged muscle use

Question 18

Anaerobic respiration - occurs in Sarcoplasm
- no oxygen is required

Answer 18

Glucose Glycolysis
or ——————-> 2 Pyruvic Acids + 2 ATP
Muscle glycogen
- provides energy for maximum muscle contraction for 30 to 40 seconds
- when plenty of oxygen is available Pyruvic Acid is transported to the
Mitochondria, where the Krebs cycle occurs
- when the muscle is short of oxygen, Pyruvic Acid is converted to Lactic
Acid which will diffuse into the blood, as the pH of muscle decreases the
ability of the muscle to function will also decrease.

Question 19

Creatine Phosphate

Answer 19

found in the Sarcoplasm
Creatine Kinase
ADP + Creatine Phosphate —————> ATP + Creatine
- provides energy for maximum muscle contraction for approx. 15 seconds

Question 20

ATP Production:

Answer 20

1. Creatine Phosphate
2. Anaerobic respiration - occurs in Sarcoplasm
   - no oxygen is required
3. Aerobic Respiration

Question 21

Termination of Muscle Contraction

Answer 21

1. Acetylcholinesterase- (an enzyme that deactivates ACh) in the
   Synaptic cleft continually breaks down ACh. If the signal to
   release ACh into the synaptic cleft ceases, the Action Potential in
   the muscle will cease.
   2.The Calcium pumps in the Sarcoplasmic Reticulum continuously pump
   the Ca++ around the myofibrils back into the Sarcoplasmic
   Reticulum.
   - With no Ca++ to bind to Troponin, the Tropomyosin slides over the
   Myosin binding sites. The Myosin head now has nowhere to bind,
   thus muscle contraction ceases

Question 22

Sliding Filament Mechanism

Answer 22

The process where the Thin filaments
are drawn towards the M line. This involves the repeating of
steps 9 through 12.