TAMU BIOL 319 Lab Practical 2

EMG stands for ______________.

Electromyogram

Skeletal muscle comprises ______% of total body mass.

70%

Disease of muscle is _______ (rare/common).

Rare

Define: Upper motor neuron lesions

Loss of motor function due to damage of neurons in the brain

Individual muscle fibers are organized into ______.

Fascicles

Individual muscle fibers are innervated by ___________.

A branch of a motor axon

A neuronal action potential activates _________ (all/individual) muscle fibers that are innervated by that particular motor neuron.

All

Define: Motor unit

A motor neuron and all the individual muscle fibers it innervates

T/F: All motor units are about the same size

False: Motor unit sizes vary vastly

A single motor neuron can innervate _________ (only one/many) muscle fiber(s).

Many

A single motor neuron can innervate up to _________ of muscle fibers.

Thousands

Smaller motor units means ________ muscle control.

Finer

Define: Isotonic muscle contraction

Muscle fibers shorten or lengthen and a body part moves

Define: Isometric muscle contraction

Muscle contracts, but joints don't move and the muscle fibers maintains a constant length

_________ is released into the synaptic cleft after being triggered by an action potential.

Acetylcholine

What specific receptors does acetylcholine bind to?

Nicotinic acetylcholine receptor

Where are nicotinic acetylcholine receptors located?

Motor end plate

When acetylcholine binds to it's receptor, what happens next?

Cationic-selective ion channels open causing a depolarization of the muscle end plate

Depolarization of the motor neuron end plate causes the release of _______ from the _________.

Calcium; sarcoplasmic reticulum

________ hydrolyses acetylcholine.

Acetylcholine esterase

Acetylcholine is broken down by a process called _________.

Hydrolysis

CMP stands for _______.

Compound muscle potential

EMGs measure _____________.

Electrical activity of a whole muscle

The magnitude of a CMP is reflective of _________.

The number of active motor units

Define: Recuitment

The process by which the nervous system controls a muscle by controling the number of motor axons firing

WHO'S GONNA DO GREAT ON THIS LAB PRACTICAL?!

I AM!!!

Define: Summation

The additive effect by which increased frequency of action potentials cause stronger and stronger contractions

Define: Tetanic contraction

A smoother and stronger contraction than a twitch caused by summation

Define: Tendon

Strong bundles of collagen fibers

Define: Coactivation

Phenomenon by which contraction of a muscle leads to some minor activity in the antagonist muscle

What is the theorized purpose of coactivation?

Stabilization

What is the range for normal conduction velocities?

50-60 meters per second

In muscle groups that are resistant to fatigue, they have __________.

Greater capacity for oxidative metabolism

Define: Myotatic reflex

The knee jerk reflex that occurs when you tap the patellar ligament

In everyday life, the myotatic reflex aids in ______.

Standing upright

Sensory information from receptors in the body enters the spinal cord ___________ (dorsally/ventrally).

Dorsally

Effector information from the spinal cord leaves the spinal cord ___________ (dorsally/ventrally).

Ventrally

Relative to one another in a monosynaptic reflex, the motor and sensory neuron are located ___________.

In the same area of the body

Relative to one another in a polysynaptic reflex, the motor and sensory neuron are located ___________.

In different areas of the body

When compared to a monosynaptic reflex, a polysynaptic reflex contains an additional step involving ___________.

Interneurons

Define: Pupillary light reflex

When exposed to light, the pupil will constrict

Define: Consensual light reflex

When one eye is exposed to light, the pupils of both eyes will constrict

Pupilary constriction is known as ________.

Miosis

Pupillary dilation is known as ________.

Mydriasis

How many neurons are involved in the pupillary light reflex?

4

Another name for pain sensory receptors is ____________.

Nociceptive receptors

Auditory stimuli take _____ ms to reach the brain while visual stimuli take _____ ms.

8-10; 20-40

T/F: Auditory stimulus reaches the brain faster than visual stimulus

True

Fatigue in muscles is correlated to ______________.

- Depletion of ATP, nutrients, and oxygen in muscle tissue

- Perception of conditions in muscle by brain