Unit 4 Ch 14 lecture

Question 1

how is sensory info relayed to/from spinal cord by spinal nerves

Answer 1

spinal nerves bring sensory info INTO the spinal cord

Question 2

how are motor commands relayed to/from spinal cord by spinal nerves

Answer 2

the spinal cord processes the sensory info and can process it into a motor response (spinal reflex)

Question 3

what is a dermatome; why is it clinically significant

Answer 3

a dermatome is the area of the skin surface monitored by a pair of SPINAL NERVES
clinical significance: shingles form in a way that follows a dermatome on the skin

Question 4

what are the 3 characteristics most common to most nervous system pathways

Answer 4

1. travel through white matter of spinal cord
2. consist of paired tracts
3. composed of 2/3 neurons working together

Question 5

what does it mean to be contralateral

Answer 5

relationship to opposite side of the body (Most spinal cord pathways are decussate, cross over from one side of body to other)

Question 6

What are the locations and functions of the primary neuron

Answer 6

location: SENSORY PATHWAY CHAIN
functions:
-dendrites detect stimulus
-axon projecting to secondary neuron within CNS

Question 7

What are the locations and functions of the secondary neuron

Answer 7

location: extends from PRIMARY NEURON to TERTIARY NEURON/ CEREBELLUM, within POSTERIOR HORN of spinal cord or brainstem nucleus
function:
-projects to thalamus or cerebellum
-secondary neuron to thalamus projecting to tertiary neuron

Question 8

What are the locations and functions of the tertiary neuron

Answer 8

location: THALAMUS
extends from SECONDARY NEURON to CEREBRUM
function: axon projects to primary somatosensory cortex

Question 9

what are the characteristics of a motor pathway

Answer 9

formed from cerebral cortex, cerebral nuclei, cerebellum, descending projection tracts, and motor neurons

Question 10

What are the locations and functions of the upper motor neuron in a motor pathway chain

Answer 10

location: within CEREBRAL CORTEX or NUCLEI WITHIN BRAINSTEM
function:
- SYNAPSE directly on lower motor neurons or on interneurons
- EXCITES/INHIBITS activity of lower motor neuron

Question 11

What are the locations and functions of the lower motor neuron in a motor pathway chain

Answer 11

location: within ANTERIOR HORN of spinal cord or BRAINSTEM CRANIAL NUCLEUS
function: EXCITATORY

Question 12

what are the main properties of a reflex

Question 13

what are the 5 steps involved in the activation of a reflex

Answer 13

1. stimulus activates a sensory receptor
2. nerve signal travels through sensory neuron to CNS
3. info from nerve signals is processes by interneurons
4. motor neuron transmits a nerve signal to an effector
5. effector responds to the nerve signal from the motor neuron

Question 14

what is a monosynaptic reflex

Answer 14

has one synapse

Question 15

what is a polysynaptic reflex

Answer 15

has multiple synapses (2-hundreds)

Question 16

describe the characteristics of a stretch reflex

Answer 16

• MONOSYNAPTIC
• regulates skeletal muscle strength
• REFLEXIVE muscle contraction AFTER stretching of a muscle

Question 17

describe the characteristics of a Golgi tendon reflex

Answer 17

• Prevents muscles from contracting excessively
• detect excessive tension

Question 18

describe the characteristics of a withdrawal reflex

Answer 18

• Pulls a body part away from a painful stimulus
• Interneurons excite motor neurons of flexors so flexor muscles and limb is withdrawn
• other interneurons reciprocally inhibit motor neurons of extensors so that extensor muscles
  relax and withdrawal happens quickly

Question 19

describe the characteristics of a cross-extensor reflex

Answer 19

• excited by the nociceptor sensory neuron cross midline and excite extensor motor neurons on other side

Question 20

Explain the indication of a hypoactive reflex versus those of a hyperactive reflex

Answer 20

Hypoactive reflex- Reflex response is diminished or absent which indicates spinal cord damage, muscle disease
Hyperactive reflex- Abnormally strong reflex response which may indicate damage to the brain or spinal cord.