TAMU BIOL 319 Lab Practical 2

Electromyogram

EMG stands for ______________.

70%

Skeletal muscle comprises ______% of total body mass.

Rare

Disease of muscle is _______ (rare/common).

upper motor neuron lesions

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

Fascicles

Individual muscle fibers are organized into ______.

A branch of a motor axon

Individual muscle fibers are innervated by ___________.

All

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

motor unit

A motor neuron and all the individual muscle fibers it innervates

False

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

Many

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

Thousands

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

Finer

Smaller motor units means ________ muscle control.

isotonic muscle contraction

Muscle fibers shorten or lengthen and a body part moves

isometric muscle contraction

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

Acetylcholine

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

Nicotinic acetylcholine receptor

What specific receptors does acetylcholine bind to?

Motor end plate

Where are nicotinic acetylcholine receptors located?

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

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

Calcium; sarcoplasmic reticulum

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

Acetylcholine esterase

________ hydrolyses acetylcholine.

Hydrolysis

Acetylcholine is broken down by a process called _________.

Compound muscle potential

CMP stands for _______.

Electrical activity of a whole muscle

EMGs measure _____________.

The number of active motor units

The magnitude of a CMP is reflective of _________.

recruitment

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

I AM!!!

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

summation

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

tetanic contraction

A smoother and stronger contraction than a twitch caused by summation

tendon

Strong bundles of collagen fibers

coactivation

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

Stabilization

What is the theorized purpose of coactivation?

50-60 meters per second

What is the range for normal conduction velocities?

Greater capacity for oxidative metabolism

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

myotatic reflex

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

Standing upright

In everyday life, the myotatic reflex aids in ______.

Dorsally

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

Ventrally

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

In the same area of the body

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

In different areas of the body

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

Interneurons

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

pupillary light reflex

When exposed to light, the pupil will constrict

consensual light reflex

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

Miosis

Pupilary constriction is known as ________.

Mydriasis

Pupillary dilation is known as ________.

4

How many neurons are involved in the pupillary light reflex?

Nociceptive receptors

Another name for pain sensory receptors is ____________.

8-10; 20-40

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

True

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

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

- Perception of conditions in muscle by brain

Fatigue in muscles is correlated to ______________.

latent period

period in which stimulus and action potential occurs

period of contraction

when the muscle actually receives the message and acts on it

fibers; neurons

muscle (fibers/neurons) are "controlled" by muscle (fibers/neurons)

acetylcholine

action potentials arriving at the axon terminal trigger the release of ____________ into the synaptic cleft of the neuromuscular junction.

synaptic cleft

action potentials arriving at the axon terminal trigger the release of acetylcholine into the _________ __________ of the neuromuscular junction

acetylcholine

the ____________ diffuses through the junctional cleft and binds to the nicotinic acetylcholine receptors on the motor end plate

nicotinic

the acetylcholine diffuses through the junctional cleft and binds to the ________ acetylcholine receptors on the motor end plate

motor

the acetylcholine diffuses through the junctional cleft and binds to the nicotinic acetylcholine receptors on the ______ end plate

cation selective

the bound receptors open __________ ___________ ion channels, which depolarizes the muscle end plate and leads to the release of calcium from the sarcoplasmic reticulum

depolarizes

the bound receptors open cation selective ion channels, which __________ the muscle end plate and leads to the release of calcium from the sarcoplasmic reticulum

calcium

the bound receptors open cation selective ion channels, which depolarizes the muscle end plate and leads to the release of _________ from the sarcoplasmic reticulum

one

a motor unit consists of ______ motor neuron (no matter how large it is) and all the muscle fibers it innervates

smaller

the (smaller/larger) the muscle unit, the finer the control of movement in that muscle

frequency modulation

goes along with recruitment; motor neurons are added from the lowest level up to a higher level

joints

act as pivot points for motion when skeletal muscle, either connected directly to bone or to tendons

antagonistically

two or more muscles usually work _______________; a contraction of one muscle stretches or elongates, the other contracts

stabilize

the physiological significance of coactivation is suggested that is helps ________ the joint

metabolic

skeletal muscle contraction requires ____________ energy

oxidative

some muscle fibers are more resistant to fatigue than others. these have a greater capacity for _________ metabolism

receptors

detect the change in the environment

sensory neurons

send the information to the central nervous system where it is processed

motor neurons

send the information to effectors that produce a muscle contractions and a movement of one or more parts of the body

is not

the brain (is/is not) necessary or required for many simple reflex functions

reflex

occurs quicker than a normal "response"

involuntary

is a reflex voluntary or involuntary

fewer

in a reflex, (fewer/more) synapses are required when compared to a voluntary response

efferent

travels away from the central nervous system

afferent

travels towards the central nervous system

same

neurons fire at (same/different) rates every time no matter what

crossed extension reflex

serves to enhance postural support during withdrawal of the affected limb from the painful stimulus

crossed extension reflex

reaction of the stimulated limb is accompanied by an opposite reaction in the opposite limb

spinal cord

most reflexes are confined to the (spinal cord/brain)

fatigue

this occurs when muscles are contracted for prolonged periods of time

fatigue

correlated with a depletion of ATP, nutrients, and oxygen in muscle fibers, but is also due to perception of conditions in the muscle by the brain

intrafusal fibers

specialized muscle fibers, connected to tendons/extrafusal fibers; don't do any work

extrafusal fibers

fibers that do the actual contracting of muscles

type ii

extrafusal fibers that are sensitive to the overall stretch of muscles

type ia

extrafusal fibers that are sensitive to the length of the muscle

alpha

nerve fibers that carry signals to your muscles (extrafusal)

gamma

nerve fibers that carry signals to the interfusal fibers (muscle spindle)

stretch reflex

response to changes in muscle length; helps keep balance/prevent injury

golgi tendon reflex

opposite from stretch reflex; when there is high tension in muscles, it relaxes it

withdrawal reflex

an example of this is a crossed extensor reflex; interneurons are present

lower

lower amplitudes on an EMG represent a (lower/higher) level motor unit

more

the stronger the stimulus, the (more/less) sensory neurons are activated