Nervous System

Question 1

Functions of the Nervous System

Answer 1

1. Control of internal environment
2. Control of movement
3. Programming of reflexes
4. Memory and learning

Question 2

Peripheral Nervous System

Answer 2

Motor (efferent)
(CNS > periphery; messages from the CNS to effector organs such as muscles, glands )

Sensory (afferent)
(periphery > CNS; touch, pain, pressure, force, heat, etc. )

Question 3

Synaptic Trasmission

Answer 3

t the neuromuscular junction is always excitatory
The action potential that is received at the neuromuscular junction is always sufficient to release adequate ACh to depolarize the motor endplate above threshold

Question 4

Voluntary Control of Muscle Movement

Answer 4

The brain initiates movement (1)
Information regarding the intended movement is then transmitted down the appropriate descending tract (2) (Descending tract: is an upper motor neuron which connects brain to spinal tract)

Question 5

Descending Tract

Answer 5

The neurons of the descending tract synapse with the motor neurons in the gray matter of the spinal cord
The efferent motor neuron then carries the impulse to the muscle, the effector organ (3)
The muscle then contracts and produces movement (4)
Changes in muscle length, tension, and position stimulate receptors in the muscles and joints (5)
This information is transmitted to the CNS through afferent sensory neurons (6)
The afferent neurons synapse with various association neurons in the gray matter of the spinal cord

Question 6

Components of Reflex Arc

Answer 6

Receptor
Afferent (sensory) Neuron
Integration Center
Efferent (motor) Neuron
Effector Organ

Question 7

Receptor

Answer 7

the organ that responds to the stimulus by converting it into a neural signal
These are all specialized to sense particular things

Question 8

Afferent (sensory) Neuron

Answer 8

carries the signal to the CNS

Question 9

Integration Center

Answer 9

Located in CNS, here the incoming signal is processed through the connection of incoming neural signals with association and/or efferent neurons

Question 10

Efferent (Motor) Neuron

Answer 10

carries the impulse from the CNS to the organ of the body that is to respond to the original stimulus

Question 11

Effector Organ

Answer 11

the organ of the body that responds to the original stimulation (usually a muscle or gland)

Question 12

Muscle Spindles

Answer 12

Encapsulated fibers within the muscle belly
Monitor changes in muscle length
Monitor the rate of change in muscle length
Respond by causing muscle contraction

Question 13

Golgi Tendon Organs

Answer 13

Encapsulated receptors
Located at the musculotendinous junction Monitor tension within the tendon Respond by causing the muscle to relax

Sensory Receptor (anatomy is much different than a muscle spindle)
They sense how much force or tension is being produce
When golgi is activated, it makes muscle relax (complete opposite of the muscle spindle)

Question 14

Muscle Spindles and the Myotatic Reflex (Stretch Reflex)

Answer 14

When you’re trying to stretch a muscle, you want to avoid activating the stretch reflex by slow movement
You wantt to make sure that the antagonist doesn’t release alpha motor neurson
(3B) You want to excite the inhibitory interneuron to release inhibitory chemicals
Excite quads / Inhibit hamstrings

Question 15

Myotatic Reflex

Answer 15

Stretch is initiated by tapping on the patellar tendon (ligament) (1)
Sudden stretching of the muscle spindle causes an impulse to be sent to the spinal cord by way of the annulospiral nerve fibers (2)
In the gray matter of the spinal cord this sensory fiber bifurcates, with one branch synapsing with an alpha motor neuron (3a). The other branch synapses with an association neuron (3b)
The alpha motor neuron exits the spinal cord and synapses with the skeletal muscle, which was originally stretched, resulting in a contraction that is roughly equal in force and distance to the original stretch (5)
The inhibitory association neuron synapses with another efferent neuron, which innervates the antagonist muscle (hamstring group) in this example, where it causes inhibition; this reflex relaxation of the antagonist muscle in response to the contraction of the agonist is called reciprocal inhibition. This response facilitates contraction of the agonist muscle that was stimulated; the inhibited antagonist cannot resist the contraction of the agonist (4b)
The muscle spindle is also supplied with a gamma efferent neuron (6)

Question 16

Golgi Tendon Organs and the Inverse Myotatic Reflex

Answer 16

This has nothing to do with stretch, but rather sensing force or tension
This one comes in to play when you’re doing maximal muscle contractions
This is also trainable, this becomes less sensitive with training

Turn off the muscle that was contraction and then Excite the inhibitory interneuron of the quads so that the quads are cut off from stimulation and then the excite excitatory interneurons to release to the hamstrings

Question 17

Inverse Myotatic Reflex

Answer 17

Contraction of a skeletal muscle (or stretching) results in tension that stimulates the Golgi tendon organs in the tendon attached to the skeletal muscle (1)
Stimulation of the Golgi tendon organ results in the transmission of impulses to the spinal cord by afferent neurons (2)
In the spinal cord, the afferent neuron synapses with an inhibitory association neuron and an excitatory motor neuron (3)
In turn, the inhibitory association neuron synapses with a motor neuron that innervates the muscle attached to the tendon; the inhibitory impulses lead to the relaxation of the contracted muscle (4a)
The excitatory association neuron synapses with a motor neuron that innervates the antagonist muscle (4b)
The end result is the activation of the antagonist muscle(s) (hamstrings), and inhibition of the muscle(s) producing the “excess” tension (quadriceps femoris) (5)