Peripheral Nervous System

Question 1

How many cranial nerves & where do they come from?

Answer 1

12 pairs of cranial nerves arise from the brain stem

Question 2

What sort of nerves are cranial nerves?

Answer 2

Mixed, sensory & motor

Question 3

How many spinal nerves?

Answer 3

31 pairs - 8 cervial, 12 thoracic, 5 lumbar, 5 sacral, 1 coccoygeal

Question 4

What types of nerves are spinal nerves?

Answer 4

Only mixed - posterior contain sensory - anterior contain motor

Question 5

What are the function of sympathetic fibers?

Answer 5

Fight or flight - increase alertness, metabolism and prepare for emergency

Question 6

Sympathetic examples?

Answer 6

Exercise, emergency, embarrassment, stall unnecessary functions - urination & defecation effects longer lasting

Question 7

What are the functions of parasympathetic fibers?

Answer 7

Rest & digest, energy conservation, control smooth muscle & replenish nutrients

Question 8

Parasympathetic examples?

Answer 8

Salivation, lacrimation, urination, defacation, digestion

Question 9

What is the autonomic tone?

Answer 9

The balance between sympathetic & parasympathetic fibers and controlled by hypothalamus

Question 10

Somatic nervous system?

Answer 10

Contain sensory and motor neurons, consciously perceived sensation and stimulate only skeletal muscle

Question 11

What are reflexes?

Answer 11

Fast, involuntary, planned sequence of events that occur in response to a stimulus that can be inborn, learnt or aquired

Question 12

Use of reflexes?

Answer 12

Diagnosing abnormalities in skeletal functioning

Question 13

What are somatic reflexes?

Answer 13

Involve skeletal muscle

Question 14

Autonomic reflex?

Answer 14

involuntary reflex

Question 15

Cranial reflex?

Answer 15

Involve brain stem

Question 16

Ipsilateral reflex?

Answer 16

Sensory nerves enter spinal cord same way motor neurons exit - change occurs on same side of stimulus

Question 17

Contralateral reflex?

Answer 17

nerves enter and exit the spinal cord through opposite sides - left responds to right

Question 18

What happens during a stretch reflex (patella reflex)?

Answer 18

Causes contractions of skeletal muscle in response to muscle stretch - monosynaptic reflex arc

Question 19

What is reciprocal innervation?

Answer 19

The contraction of a muscle results in the relaxation of its antagonistic muscle pair and prevents conflict between opposing muscles - polysynaptic

Question 20

What is the function of the tendon reflex?

Answer 20

Controls muscle tension by relaxing muscle before rupture and can override stretch reflex - ipsilateral reflex

Question 21

What is the Flexor & Crossed Extensor Reflex?

Answer 21

Reflexes that work together in response to dangerous stimuli and coordinate balance

Question 22

What happens during the flexor reflex?

Answer 22

Stepping on tack stimulates nocicereceptors which generate sensory impulses to the spine where they activate interneurons across levels of spinal segments which in turn synapse with motor neurons which result in the release of Acetylcholine which causes flexor muscles to contract and step back - intersegmental reflex

Question 23

What is an intersegmental reflex?

Answer 23

Stimulates more than one effector

Question 24

What else do flexor reflexes do?

Answer 24

Initiate crossed extensor reflex

Question 25

What happens during the crossed-extensor reflex?

Answer 25

When the right foot step on tack, sensory neurons activate multiple interneurons that synapse with motor neurons on the left side of spinal cord where incoming signals cross to the opposite side through interneurons which stimulate motor neurons across spinal segements, and cause extensor muscles in the left thigh to contract - contralateral reflex

Question 26

What happens during the receptory or sensory level?

Answer 26

Stimulation of sensory receptors result in the transmission of the impulse through sensory afferent nerves to spinal cord

Question 27

What happens during circuit level?

Answer 27

Stimulus converts energy into graded potentials which result in nerve impulses along sensory neurons that travel up the ascending tracts to spinal cord to the thalamus.

Question 28

What happens during the Perception level?

Answer 28

Thalamus directs impulses to specific region of somatosensory cerebral cortex responsible for interpreting the specific region of the sensation