Synapse, Neuronal connection, and muscle contraction

The model that describes the contraction of the muscle is called the

Sliding filament model

In which of the following situations does a resting membrane potential exist?

A relaxed muscle fiber

A muscle fiber will respond to a stimulus when that stimulus reaches the________ level.

Threshold

Synaptic vesicles in the neuromuscular junction contain

Acetylcholine

The sites where a chemical substance is transmitted from the presynaptic terminal of an axon to the postsynaptic membrane of a muscle fiber are called

Neuromuscular junction

Acetylcholine is released from the presynaptic terminal by the process of

Exocytosis

The sarcoplasmic reticulum

Stores Ca2+

T tubules are invaginations of the

Sarcolemma

If Na+ cannot enter a muscle fiber in response to a stimulus,

Contraction can’t occur

In a contracted muscle, the A bands narrow because the length of the myosin myofilaments changes.

False

Which of the following individuals would have more mitochondria in her skeletal muscle?

22 year old soccer player

Due to the pattern of innervation of skeletal muscle, one would expect that

there are fewer motor neurons than skeletal muscle fibers.

Substance A is found to be a competitor with acetylcholine. Which step of muscle contraction physiology would be directly affected by this substance?

Generation of sarcolemma at action potential

A stimulus either causes an action potential or it doesn't. This is called

All or none response

During the absolute refractory period, the cell

Is insensitive to further stimulation

A series of local potentials causes the membrane potential to move to -80 mV. Predict the result.

The neuron is hyperpolarized

Saltatory conduction of an action potential means that

an action potential is conducted from one node of Ranvier to the next node.

Local hyperpolarization in a synapse is called a/an

Inhibitory postsynaptic terminal

Arrange the events of synaptic transmission in correct sequence.

1. Na+ diffuses into the cell and cause a local potential

2. Neurotransmitter binds with receptor on postsynaptic cell

3. Neurotransmitter diffuses across the synaptic cleft

4. Membrane permeability to Na+ on postsynaptic cell increases

5. Action potential causes release of neurotransmitter

5, 3, 2, 4, 1

Neurotransmitters are released from the

Presynaptic terminal

Neurotransmitters

cause the production of action potentials in the postsynaptic membrane.

Rapid removal or destruction of neurotransmitter in the synaptic cleft

may affect the ability of the postsynaptic membrane to generate action potentials.

List the following structures in order from smallest to largest.

1. Muscle fiber

2. Myofilament

3. Myofibril

4. Muscle fascicle

2, 3, 1, 4

Hypertrophy of skeletal muscles from weight lifting is caused by an increase in the

Size of muscle fibers

What type of muscle is under voluntary neural control

Skeletal muscle

What isn’t a function of skeletal muscle

Constriction of an organ

What is excitability

The ability to respond to a stimulus by nervous system

A fascicle is

Surrounded by perimysium

What connective tissue layer is outside all of the others

Epimysium

What is true about skeletal muscle

Every muscle fiber receives a branch of a axon from a motor neuron

Myosin is also known as

Thick myofilament

Muscle myofibrils

Contain myosin and actin filaments

The active sites to which cross-bridges attach are found on the

Actin myofilaments

Gap junctions are functionally

Electrical synapses

A

Depolarization - ligand-gated channels

B

Depolarization - voltage-gated channels (rapid Na influx)

C

Repolarization phase (K+ out)

D

Threshold

A

Actin

B

Myosin

D

Z disc

E

Sarcomere

At rest, the inside of the sarcolemma is _____ to the outside

Negatively charged