Chapter 9 Review - Skeletal Muscle Flashcards
Name the 3 types of muscle tissue
Skeletal, Cardiac, Smooth
Where are the 3 types of muscle tissue found?
Skeletal = attached directly or indirectly to bones Cardiac = heart Smooth = walls of hollow organs, including digestive tract and arteries
What are the functions of SKELETAL muscle tissue?
- Produce body movement
- Maintain posture and body position
- Support soft tissues
- Guard body entrances and exits
- Maintain body temperature
- Store nutrients
What are the functions of CARDIAC muscle tissue?
pump blood thru the heart
What are the functions of SMOOTH muscle tissue?
digestive tract - move fluids and solids
arteries - regulate vessel diameter
Define TENDON and APONEUROSIS
Tendon = a BUNDLE of connective tissue that attaches a muscle to a specific point on a bone
Aponeurosis = a BROAD SHEET of connective tissue that provides attachment over a large area and may involve more than one bone
Describe the connective tissue layers associated with skeletal muscle tissue
Muscle, surrounded by epimysium. Made up of
Muscle fascicle, surrounded by perimysium. Made up of
Muscle fiber, surrounded by endomysium. Made up of
myofibrils
What special terms are used to describe the plasma membrane and cytoplasm of a skeletal muscle fiber?
plasma membrane = sarcolemma (flesh/husk)
cytoplasm = sarcoplasm
Define the FUNCTION of the layers surrounding each layer of muscular tissue
Epimysium - surrounds muscle; separates muscle from surrounding tissue
Perimysium - surrounds muscle fascicle; divides the skeletal muscle into a series of compartments
Endomysium - surrounds muscle fibers; loosely interconnects adjacent muscle fibers
Determine the correct structural hierarchy of skeletal muscles, from microscopic to gross levels.
myofibril - fiber - fascicle - muscle
How would severing a tendon affect the movement of that limb?
Movement requires attachment of the muscle to the tendon.
Skeletal muscle contractions pull on tendons to move our bones.
Describe the steps of the contraction cycle in the correct order
Step 1. Contraction cycle begins Step 2. Active Sites Exposed Step 3. Cross Bridges Form Step 4. Myosin Heads Pivot Step 5. Cross-bridges detach Step 6. Myosin Reactivates
The contraction cycle begins with the arrival of calcium ions to the zones of overlap via excitation-contraction coupling. Then, calcium ions bind to the troponin-tropomyosin complex, causing troponin to change position. Troponin’s movement rolls tropomyosin away from actin’s active sites, thus allowing them to form cross-bridges with energized myosin heads. After cross-bridge formation, the energy that was stored in the resting state is released as the myosin head pivots towards the M line (coincident with the release of bound ADP and P). This is known as the power stroke. Finally, to disengage cross-bridges following the power stroke, ATP binds to the myosin head, and the bond between myosin and actin is broken. Myosin is reactivated for further cycling when ATP is converted into ADP and P, and the myosin head returns to its original conformation.
The neuromuscular junction is a connection between a neuron and a __________.
myofibril
synaptic terminal
vesicle
* muscle fiber
The end of a neuron, where acetylcholine-filled vesicles are located, is called the __________.
motor end plate
synaptic cleft
* synaptic terminal
acetylcholine receptor
What is the synaptic cleft?
the space between the synaptic terminal and the motor end plate
Inside a neuron, acetylcholine is contained within __________.
vesicles
What causes the vesicles inside a neuron to fuse with the plasma membrane?
an action potential in the neuron
Acetylcholine receptors are primarily located __________.
on the motor end plate
An action potential in the muscle fiber causes __________.
the muscle fiber to contract
The role of acetylcholinesterase in the neuromuscular junction is to __________.
remove acetylcholine from the synaptic cleft
Inside a muscle, bundles of single muscle fibers form __________.
fascicles
The muscle action potentials that initiate contraction are transmitted from the sarcolemma into the interior of the muscle fiber by __________.
T tubules
T tubules and the terminal cisternae are clustered into structures called __________.
triads
The sarcoplasmic reticulum contains __________.
calcium
Which organelle completely surrounds each myofibril inside a muscle fiber?
sarcoplasmic reticulum
To what regulatory protein does calcium bind during the initiation of the contraction cycle in skeletal muscle fibers?
troponin
Which of the following causes the active site on actin to be exposed or uncovered?
tropomyosin shifting position
Which of the following most correctly describes excitation in the context of excitation-contraction coupling in skeletal muscle?
the generation of an action potential in the sarcolemma
Which of the following phrases best describes how excitation is coupled to contraction in skeletal muscle fibers?
through calcium release from the sarcoplasmic reticulum
Malignant hyperthermia (MH) is a rare genetic disease in which the sarcoplasmic reticulum leaks calcium when the patient is put under general anesthesia. Which of the following best describes how anesthesia would affect the skeletal muscles of a patient with MH?
The muscles would contract because of calcium binding to troponin.
Myofibrils are __________.
made of a series of sarcomeres
Z lines define the edges of which of the following?
sarcomeres
Myosin molecules form what part of the sarcomere?
thick filament
Which of the following is involved in the power stroke?
myosin
The myosin head pivots at the head after it binds to actin, causing the thin filament to be pulled towards the center of the sarcomere. This motion causes the muscle to shorten during contraction.
Which of the following proteins contains the active site involved in cross-bridge formation?
actin
Describe the structures of a sarcomere.
Sarcomeres run from Z line to Z line. Each sarcomere contains the I band and the A band. Within the A band are the H band and the M line.
I band = thin filaments only
A band = full length of thick filaments, including where they overlap with thin
H band = thick filaments only
M line = connects each thick filament; wraps around the myofibril
Describe the structures of a sarcomere.
Sarcomeres run from Z line to Z line. Each sarcomere contains the I band and the A band. Within the A band are the H band and the M line.
I band = thin filaments only
A band = full length of thick filaments, including where they overlap with thin
H band = thick filaments only
M line = connects each thick filament; wraps around the myofibril
Define transverse tubules
Narrow tubes that encircle and are tightly bound to the sarcoplasmic reticulum. T tubules form passageways through the muscle fiber that allow for transmission of an electrical impulse, or action potential, to the sarcomere. T tubules combine with the pair of terminal cistae to form the triad.
within a resting skeletal muscle fiber, where is the greatest concentration of Ca2+?
terminal cistae
Compare F-Actin with G-Actin
F-actin is a twisted strand of 2 rows of individual MOLECULES of G-actin.
Name the proteins that make up a thick filament
myosin
