Chapter 9 WORK SHEET
The Muscular System: Skeletal Muscle Tissue
1. Fill in the characteristics of the three muscle types:
Muscle Type
Cardiac
Skeletal
Smooth
Shape of cell
BRANCHING
ELONGATED
ELONGATED
# of nuclei
ONE
MULTIPLE
ONE
Striations
YES
YES
NONE
Control
INVOLUNTARY
VOLUNTARY
INVOLUNTARY

2. What attaches muscles to bone? SKELETAL.
3. The whole muscle is composed of muscle cells (fibers) grouped in bundles called FASCICLES.
4. Name the connective tissue coverings surrounding the following:
Whole muscle: EPIMYSIUM
Fascicles: PERIMYSIUM
Muscle cell: ENDOMYSIUM
5. Match the following three terms with their definitions:
Sarcolemma: - plasma membrane of muscle cell
Sarcoplasmic reticulum: - endoplasmic reticulum in muscle cell
Cytosol:- intracellular fluid around organelles
6. Match the following three terms with their definitions:
Terminal cisternae: - part of sarcoplasmic reticulum—stores calcium T-tubules: - part of sarcolemma—carries action potential
Triad: - T-tubule + 2 terminal cisternae

7. Myofibrils consist of contractile proteins called SARCOMERES
Name the two types and what they’re composed of:
THICK FILAMENTS composed of MYOSIN
THIN FILAMENTS composed of ACTIN
8. Arrangement of myofilaments. Give the letter name of each band:
Dark band  A band
Light band  I band
Match two definitions with each band:
I BAND- contains only thin filaments
I BAND- contains both thick and thin filaments
A BAND- defined by length of thick filament
A BAND- defined as distance between two thick filaments
9. Define the following terms:
Z line (disc): MIDLINE INTERRUPTION IN THE LIGHT I BAND; DARKER AREA IN I BAND; COIN-SHAPED SHEET COMPOSED LARGELY OF THE PROTEIN ALPHA-ACTININ, ANCHORS THE THIN FILAMENTS
H zone: LIGHTER MIDSECTION IN A BAND
10. What happens to these areas during contraction?
Z line (disc): THE DISTANCE BETWEEN THE Z DISCS SHORTENS
H zone: THE H ZONES DISAPPEAR
11. Define these two terms:
M line: DARK LINE BI-SECTING THE H ZONE; FORMED BY MOLECULES OF THE PROTEIN MYOMESIN
Sarcomere: REGION OF MYOFIBRIL BETWEEN TWO SUCCESSIVE Z DISCS. SMALLEST CONTRACTILE UNIT OF MUSCLE FIBER. THE FUNCTIONAL UNIT OF SKELETAL MUSCLE.
12. Organization of muscle. Put the following components in order, from smallest to largest:
1) MYOFILAMENT
2) SARCOMERE
3) MYOFIBRIL
4) MUSCLE FIBER (CELL)
5) FASCICLE
6) MUSCLE (ORGAN)
The Muscular System: Neuromuscular Junction
1. What insulates each muscle cell? ENDOMYSIUM
2. Synaptic vesicles in the axon terminal of a motor neuron contain what neurotransmitter? ACETYLCHOLINE
3. An action potential in the axon terminal of a motor neuron opens what type of ion channels? CALCIUM CHANNELS
4. By what means of membrane transport does the neurotransmitter leave the axon terminal? EXOCYTOSIS
5. Binding of neurotransmitter to the receptors on the motor endplate open what type of ion channels? CHEMICALLY GATED
6. Opening of these channels leads to DEPOLARIZATION of the motor endplate.
7. How is the neurotransmitter removed from the synaptic cleft?
ACETYLCHOLINESTERASE IS RELEASED AND BREAKS DOWN ACh TO ITS BUILDING BLOCKS. THE REMOVAL OF ACh PREVENTS CONTINUED CONTRACTION

8. As a result of question 6, an action potential is propagated along the
SARCOLEMMA of the muscle cell and down the T-TUBULE into the cell.
9. The result of this action potential releases what ion from the terminal cisternae? Ca+
The Muscular System: Sliding Filament Theory
1. a. The thick filament is composed of what molecule?
MYOSIN
b. Flexing the head of this molecule provides what is known as the POWER STROKE
2. The myosin head contains binding sites for what two molecules?
a. ATP
b. ACTIN
3. Three molecules make up the thin filament.
a. Which molecule has a binding site for myosin heads? ACTIN
b. Which molecule covers this binding site? TROPOMYOSIN
c. Which molecule has a binding site for calcium ions? TROPONIN
4.