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