Lab Four Flashcards

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1
Q

What is skeletal muscle?

A

Excitable tissue where an action potential is generated along the plasma membrane of muscle cells, controlled by the motor neurons coming from the CNS.

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2
Q

What is a Neuromuscular Junction?

A

A specialized synapse in motor neurons that release a neurotransmitter (acetylcholine) that causes a muscle action potential that simulates the contraction of a muscle cell.

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3
Q

What do muscle neurons excite in vertebrates?

A

Muscle fibers (contractions).

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4
Q

What do muscle neurons do in invertebrates?

A

Both excitatory and inhibitory reactions, depending on the neurotransmitter released and receptor it binds to.

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5
Q

What do Antagonistic Muscle Groups do?

A

Cause movement of limbs due to the coordination of contraction and relaxation of the muscles, and can be responsible for changes in limb position.

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6
Q

What does an Electromyogram (EMG) do?

A

Records muscle activity by the electrical activity associated with skeletal muscle APs on the surface of the body. A non-invasive way to assess muscle function.

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7
Q

What do Skeletal Muscles contain?

A

Specialized receptors that convey information about muscle length, tension, and pressure to the CNS.

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8
Q

What are Muscle Spindles?

A

The mechanosensory receptors responsible for providing information about the length, or rate of change of length, of a muscle. Arranged in parallel with muscle fibres and are stretched when an external force stretches the muscle.

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9
Q

What is a Stretch (Myotatic) Reflex?

A

When the stretching of a muscle causes excitation of its muscle spindles and results in a reflex contraction of the muscle.

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10
Q

What do Stretch Reflexes contain?

A

Large diameter sensory axons and contain a small number of synapses to result in minimal time delay from stretching to contraction; a monosynaptic pathway.

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11
Q

What is the Patellar Reflex?

A

The thigh muscle group responsible for extension of the lower leg. The quadriceps muscles insert on the patellar tendon and act in concert to extend the lower leg.

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12
Q

What does the strength of a striated muscle contraction depend on?

A

The amount of electrical activity in the muscle.

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13
Q

What are Motor Neurons?

A

The innervate the groups of muscle fibres, a single motor neuron has a branched axon.

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14
Q

What is a Motor Unit?

A

The motor neuron and the nuscle fibres it innervates.

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15
Q

What happens when a motor unit undergoes an action potential?

A

All of the associated muscle fibres are stimulated and contract.

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16
Q

What is Moto Unit Recruitment?

A

Increasing the number of active motor units to increase the strength or force of the muscle contraction.

17
Q

What is the Maximal Level of muscle activity?

A

Since there are a finite number of action potentials in each muscle, once all the motor units have been recruited no additional force can be generated.