bio ch 7
What is a muscle fascicle?
A bundle of muscle fibers surrounded by connective tissue
The endomysium is a layer of connective tissue that surrounds which of the following?
Individual muscle fibers
Which ion is released by the sarcoplasmic reticulum when skeletal muscle is activated?
calcium
Which ion is released from the sarcoplasmic reticulum during skeletal muscle excitation?
calcium
walls of the heart consist of __ muscle
cardiac
Which term refers to the connective tissue sheath that surrounds individual fascicles within skeletal muscles?
Perimysium
The smallest possible cycle of contraction and relaxation lasting as little as 7 milliseconds is called a muscle
twitch
True or false: Weight lifting stimulates mitosis and increases the number of muscle fibers in the exercised muscle.
false
A synapse is the point where a nerve fiber meets a target cell. When the target cell is a muscle fiber, this type of synapse is called the __ junction
moter / neuromuscular
A muscle fiber has
multiple nuclei
Movement, stability, heat generation, and glycemic control are all functions of which type of tissue?
muscle
A bundle of muscle fibers held together with perimysium is a _
muscle fascicle
What is the another name for the plasma membrane of a muscle cell?
sarcolemma
The portion of a myofibril from one Z disc to the next is called a(n
sarcomere
reticulum serves as a reservoir for calcium ions in skeletal muscle cells.
sarcoplasmic
The smooth endoplasmic reticulum of a muscle fiber is also called what?
sarcoplasmic reticulum
What triggers tropomyosin to change shape and move away from the myosin binding sites on the actin?
Binding of Ca2+ to troponin
The "cocking" of the myosin head, hydrolysis of ATP and the power stroke occur during which phase of skeletal muscle contraction?
Contraction
Muscle growth due to resistance training results from an increase in which of the following
Size of pre-existing muscle cells
Skeletal muscle is usually _
attached to bone
Myofibrils are
inside a muscle fiber
Each individual muscle fascicle is surrounded by a connective tissue sheath called the
perimysium
The plasma membrane of a skeletal muscle cell is called the
sarcolemma
Cells that are uninucleate, non-striated and fusiform shaped are found in
smooth muscle
The epimysium is a layer of connective tissue. What does it surround?
the entire muscle
Each tropomyosin molecule has a small calcium-binding protein called
troponin
put these events in oder to describe what happens at the neuromascular junction. start with an electrical signal arriving at the synapse
1 eletrical signal reaches the synapse 2 ach is released and diffused across the synaptic cleft 3 ach binds to receptors on the sarcolemma 4 ache breaks down the ach and stimulate ends
Arrange these events into the order in which they occur during muscle contraction. Begin with the hydrolysis of ATP.
1 hydrolysis of atp 2 cocking of myosin head 3 formation of cross bridge 4 power stroke 5 breaking of cross brigde
Put the following events in the order that they happen during muscle fiber excitation. Start with the release of ACh into the synaptic cleft.
1. ACH is released into the synaptic cleft 2. ACH diffuses across the cleft and binds to ACH receptors on the surface of the muscle cells 3. ion chemicals open in the activated ACH receptors 4. Na enters the msucle cell and K leaves the muscle cell through the open ion channels 5. the movement of the charged ions across the sarcolmma electrilly excites the muscle cell
Put these stages of muscle activity in order, starting with what happens first
1. electrical excitation of the muscle fiber 2. excitation- contraction coupling 3. contraction 4. relaxation
Which term refers to a wave of voltage changes that spreads rapidly across an electrically excited membrane?
Action potential
What is a motor neuron?
A nerve cell that stimulates skeletal muscle contraction
What is the neuromuscular junction?
A site where a motor neuron communicates with a muscle fiber
What is a muscle fiber?
A skeletal muscle cell
What is an action potential?
A specialized type of electrical signal that spreads rapidly across a membrane
In order to cause electrical excitation of the muscle fiber, ACh must do which of the following?
Bind to ACh receptors in the sarcolemma
Action potentials arriving at the transverse tubule cause the release of which of the following from the sarcoplasmic reticulum?
Calcium ions
What is the main function of the T-tubules?
Carry electrical current deep into the cell
Which of the following are functions of muscular tissue?
Glycemic control Heat generation Stability Movement
Which terms refers to neurons that activate skeletal muscle cells?
Motor neurons
At the neuromuscular junction, acetylcholine diffuses across the synaptic cleft and binds to ACh receptors. Where are these receptors located?
Sarcolemma
Which term refers to structure which extends from one Z disc to the next in a skeletal muscle fiber, and which constitutes one contractile unit?
Sarcomere
Which term refers to the tunnel-like infoldings of the plasma membrane that penetrate the muscle fiber and carry the electrical current to the interior of the cell?
T-tubules
The ACh receptor is a gated ion channel. When ACh molecules bind to the receptor, the channel opens. Which of the following are the two main ions that are able to pass through this channel once it opens? (Select two from the list below.)
Sodium (Na+) Potassium (K+)
Name the structures that store acetylcholine at the neuromuscular junction.
Synaptic vesicles
What is acetylcholine?
The neurotransmitter secreted at the neuromuscular junction
What causes the striations in skeletal muscle
The overlapping arrangement of contractile proteins
What is the sarcolemma?
The plasma membrane of a skeletal muscle cell
What happens after calcium binds to troponin?
The troponin-tropomyosin complex changes shape and exposes the myosin binding sites on actin
The stimulation of the muscle by acetylcholine is terminated by the enzyme called
acetylcholinesterase
The loose connective tissue layer that surrounds each individual muscle fiber is called the
endomysium
The connective tissue layer that covers the entire surface of the muscle is called the
epimysium
Which term describes the first stage of muscle contraction, in which electrical activity in the motor neuron triggers electrical activity in the muscle fiber?
excitation
Where is cardiac muscle found?
in the heart wall only
smooth muscle is
involuntary
The minimum contraction exhibited by a muscle is a _
muscle twitch
The minimum contraction exhibited by a muscle is a __
muscle twitch
Skeletal muscle cells may contain over a thousand thick bundles of contractile protein. These bundles, which take up most of the space deep inside the muscle cell, are called
myofibrils
The muscle protein composed of two protein chains intertwined together, forming a head and a tail, is called____ bundles of these protiens form thick filaments
myosin
Which protein makes up the thick filaments in a skeletal muscle cell?
myosin
Each muscle fiber is innervated by
one motor neuron
The overlapping arrangement of contractile proteins in skeletal muscles produces light and dark banding called
striation
Which of the following best describes a muscle twitch?
the smallest possible contraction
What are the characteristics of smooth muscle cells?
uninucleated nonstraited
A single motor neuron and all of the muscle fibers that it innervates make up a motor
unit
Which term is used to refer to skeletal muscle because it is subject to conscious control?
voluntary