Ch. 13 PNS and Reflex Activity Flashcards
These are receptors within the PNS that if stimulated they will generate graded potentials that can activate an action potential.
Sensory receptors.
This is any change in environment that activates a receptor.
Stimulus
Sensory receptors are classified in what 3 ways?
- Stimulus Type
- Stimulus Location
- Stimulus Structure
What are the 5 types of stimulus?
- Mechanoreceptor
- Thermoreceptor
- Photoreceptor
- Chemoreceptor
- Nociceptor
This stimulus type generates nerve impulses when a mechanical force is applied.
Mechanoreceptor
This stimulus type senses temperature changes.
Thermoreceptor
This stimulus type responds to light energy.
Photoreceptor
This stimulus type responds to chemicals in solution (smell, tastes, changed to internal fluid chemistry.
Chemoreceptor
This stimulus type responds to damaging stimulus and can be interpreted as painful.
Nociceptors
These sensory receptors respond to stimuli from outside the body.
Exteroceptors
These sensory receptors respond to stimuli from inside the body.
Interoceptors
These sensory receptors respond to stimuli inn the muscles and joints.
Proprioceptors
These sensory receptors are modified dendrites of sensory neurons. There are uncapsulated and encapsulated.
Simple
The structure of these sensory neurons are localized collections of cells associated with special senses and sense organs such as the eyes, ears, gates and olfactory bulbs.
Complex
This simple structure of sensory neurons are free nerve endings (temperature and pain) associated with skin sensory such as Merkel discs and hair follicle receptors.
Unencapsulated
This simple structure of sensory neurons are usually more sensitive and are wrapped around these and contain meissners corpuscles (discriminative touch), pacinian corpuscles (vibration), Ruffini endings (constant pressure), muscle spindles (muscle stretch), golgi tendon organs (muscles stretch), joint kinesthetic receptors (joint stretch).
Encapsulated
This is awareness of changes in the environment- activated receptor (PNS)
Sensation
This is conscious interpretation of stimuli. Turns change in environment into meaning (CNS)
Perception
What are the two types of nerves (axons) that carry into and from the CNS?
Mixed nerves
Ganglia
What are the 3 connective tissue structures that help protect the nerves (axons)?
- Endoneurium
- Perineurium
- Epineurium
This is a delicate layer of connective tissue that surrounds each Myelin sheath. Most deep.
Endoneurium
This is a group of axons (fascicles) wrapped by a coarser connective tissue layer. It wraps around bundles of nerve fibers within a single nerve.
Perineurium
This is a tough fibrous connective tissue surrounding all fascicles of a nerve. Outermost layer.
Epineurium
This type of nerve contains axons carrying sensory and motor impulses. This is all spinal nerves.
Mixed nerves
This is group of neuron cell bodies outside of the CNS. It is mostly sensory neurons.
Ganglia
This is the regrowth or repair of nerves. Typically only occurs in the PNS because there are no astrocytes. Damage is usually due to a crushing injury.
Regeneration of nerves.
Which end of the axon is able to regenerate?
The proximal end that is still attached to the cell body.
This part of the axon degenerated when damaged. The macrophages clean out the dead axon distal to the injury.
Distal axon
What happens when the axon regrows?
Axon sprouts or filaments grow through a regeneration tube formed by Schwann cells.
What happens when the myelin sheath is repaired?
The axon regenerates and a new myelin sheath forms.
How many pairs of cranial nerves are there?
12
2 cranial nerves originate in the ______.
10 cranial nerves originate in the _______.
Forebrain- telencephalon/cerebrum
Brainstem- midbrain, pons, medulla
What is the pneumonic to remember the 12 cranial nerves?
On Occasion Our Trusty Truck Acts Funny. Very Good Vehicle Any How.
Name the 12 cranial nerves.
Olfactory Optic Oculomotor Trochlear Trigeminal Abducens Facial Vestibulocochlear Glossopharyngeal Vagus Accessory Hypoglossal
Name the pneumonic that gives the cranial nerves functions.
Some Say Marry Money But My Brother Says Big Boobs Matter More
What do the first letters in the functions pneumonic mean?
S- sensory function
M- motor function- no sensory
B- both motor and sensory
How many pairs of spinal nerves are there?
31 pairs
Spinal nerves are mixed nerves meaning what?
They both have sensory and motor
What are the spinal nerves named for? And how many are there of each?
For their corresponding spinal cord level 8 cervical 12 lumbar 5 sacral 1 coccygeal
Spinal nerves are short and divide into what?
C, L and sacrum go to Dorsal Ramus- back muscles
T goes to Ventral ramus- front and limbs
Meningeal branch
Ventral rami join to for nerve plexuses in order to do what?
Innervate the arms and legs.
All nerves innervate the limbs except for which spinal nerves?
T2-T12
How many plexuses are there?
4
2 for upper body
2 for lower body
The neck contains which plexus? And what does it innervate?
Cervical plexus
Phrenic nerve innervates the diaphragm. (C3-5)
This connects rami together so that individual fibers can come off.
Plexuses
What are the 4 plexus?
- Cervical plexus and upper limb
- Brachial plexus
- Lumbosacral plexus and lower limb
- Sacral plexus
The brachial plexus is formed by which ventral rami?
C5 C6 C7 C8 T1
What does the brachial plexus innervate?
From shoulder to fingers
What are the 5 nerves of the brachial plexus?
- Axillary nerve
- Musculocutaneous nerve
- Median nerve
- Ulnar nerve
- Radial nerve
This brachial nerve serves the rotator cuff, the deltoid and teres muscle, skin and joint capsule of shoulder
Axillary nerve
This brachial nerve serves the upper flexor at the elbow including biceps brachii and brachialis muscles, cutaneous sensation of lateral forearm.
Musculocutaneous nerve
This brachial nerve serves the flexor muscles and lateral muscles of the palm and wrist (middle, pointer and thumb).
Median nerve
This brachial nerve serves the hand muscles and skin of the hand
Ulnar nerve
This brachial nerve serves the extensor muscles of upper limb.
Radial nerve
These plexuses overlap extensively and are often considered together.
Lumbar and sacral
The lumbar plexus is L1-L4 and has what two major nerves?
- Femoral nerve
2. Obturator nerve
This lumbosacral nerve innervates the quadriceps (thigh flexors and knee extensors)
Femoral nerve
This lumbosacral nerve innervates the adductor muscles of the thigh.
Obturator nerve
The sacral plexus is L4-S4 and contains which 4 nerves?
- Sciatic nerve
- Tibial nerve
- Superior and inferior gluteal nerves
- Pudendal nerve
This sacral nerve innervates the muscles of the entire lower limb except for the anterolateral leg. It is the largest nerve of the body.
Sciatic nerve
This sacral nerve innervates the knee joint, skin of the lateral calf, dorsum of foot and anterolateral muscles of the leg.
Tibial nerve
This sacral nerve innervates the gluteal muscles.
Superior and inferior gluteal nerves
This sacral nerve innervates voluntary control of urination, muscles and skin of perineum and erections.
Pudendal nerve
These are segments of skin innervates by each spinal nerve except for C1 which is for internal sensory information only.
Dermatomes
These are synaptic connections between neurons and muscles.
Neuromuscular junctions
These are varicosities (swelling of axons) along axons over visceral muscles and glands.
En passant synapses
What are the 3 levels of motor control?
- Segmental level
- Projection level
- Precommand level
This motor integration level is the spinal cord circuits and contains central patter generators (CPGs).
Segmental level
This motor integration level is the upper motor neurons ( primary motor cortex and brain stem nuclei). It conveys instructions to spinal cord motor neurons and sends a copy of that information to higher levels.
Projection level
This motor integration level is the cerebellum and basal nuclei. It programs and instructs and is modified by feedback
Precommand level
This is the nerve pathway involved in a reflex action including at its simplest a sensory nerve and a motor nerve with a synapse between. It requires no conscious control.
Reflex arc
These are reflexes mediated by the spinal cord. The brain is informed of these reflexes.
Spinal reflexes
This is 3-10 intrafusal muscle fibers enclosed in a connective tissue capsule. It’s job is to detect the stretch of muscle.
Muscle spindle
The muscle spindle is innervates by what motor neurons?
Gamma
There are 2 types of sensory fibers that wrap the muscle spindle. What are they?
Type Ia fibers
Type II fibers
These are primary sensory fiber endings that respond to rage and degree of stretch.
Type Ia
These are secondary sensory fiber endings that’s respond only to the degree of stretch.
Type II
These are skeletal muscle fibers that aren’t found in muscle spindle and are innervates my alpha motor neurons.
Extrafusal fibers
The most common stretch reflex is what?
Patellar or knee jerk reflex
These fibers transmit the stretch in a stretch reflex which activates motor neurons of the muscles and inhibits motor neurons of antagonistic muscles.
Afferent
These are small bundles of tendon surrounded by a capsule and innervated by sensory fibers and are located in tendons of the muscles.
Golgi tendon organs
The golgi tendon is the opposite from stretch reflexes is what way?
It relaxes muscles in response to stretch by inhibiting motor neurons and activating antagonistic muscles
This type of reflex is usually accompanied by crossed- extensor reflex. It occurs because noxious stimulus causes flexion of the limb (ipsilateral) and to maintain balance the crosses- extensor reflexes (contralateral).
Withdrawal reflex or crossed-extensor reflex
At the site of stimulus of a crossed extensor reflex, a noxious stimulus causes a flexor reflex on the same side withdrawing the limb. At the same time what happens on the opposite side?
The extensor muscles on the opposite side are activated.
This type of reflex are responses to gentle cutaneous stimulation.
Superficial reflexes
This type of superficial reflex tests integrity of spinal cord from L4-S2. Curling of the toes when a blunt object brushes downward in the bottom of the foot.
Plantar reflex
This is dorsi flexion of the great toe and smaller toes fan out. Occurs in infants under one year because the axons from the brain haven’t finished growing to the feet yet.
Babinski’s sign
This type of superficial reflex induces contraction of the abdominal muscles of stroking of the skin around the umbilicus occurs. Often a response to tickling.
Abdominal reflexes