Unit 5 - PNS Spinal Cord Flashcards
3 connective tissue layers of spinal nerves
epineurium, perineurium, endoneurium
*same as you already learned
spinal nerves, where these two unite
“reunited and it feels so good!”
where dorsal and ventral roots unite!
“reunited and it feels so good (spinal nerves)”
what is a nerve plexus (spinal nerves)
complex, interwoven networks of nerve fibers
CONTROL SKELETAL MUSCLES OF NECK AND LIMBS
4 major plexuses are what
cervical plexus
brachial plexus
lumbar plexus
sacral plexus
automatic responses coordinated within spinal cord. these are known as what
REFLEXES
reflexes occur through
interconnected sensory neurons, motor neurons, and interneurons
describe a neural reflex
rapid, atomic responses to specific stimuli
basic building blocks of neural function
one neural reflex produces one motor response
describe a reflex arc
a reflex arc is the wiring of a single reflex
begins at the receptor
ends at the peripheral effector
generally opposes the original stimulus (negative feedback)
generally opposes the original stimulus (negative feedback)
reflex arc
5 steps in a neural reflex, describe. (beginning to end)
– Step 1: Arrival of stimulus, activation of receptor
* Physical or chemical changes
– Step 2: Activation of sensory neuron
* Graded depolarization
– Step 3: Information processing by postsynaptic cell
* Triggered by neurotransmitters (info processing in CNS, for example)
– Step 4: Activation of motor neuron
* Action potential
– Step 5: Response of peripheral effector
* Triggered by neurotransmitters
5 steps in a neural reflex, describe. (end to beginning, backwards)
step 5: response to peripheral effector
triggered by neurotransmitters
step 4: activation of motor neuron
action potential
step 3: information processing by postsynaptic cell
triggered by neurotransmitters (info processing in CNS, for example)
step 2: activation of sensory neuron
graded depolarization
step 1: arrival of stimulus, activation of receptor
physical or chemical changes
4 classifications of reflexes
1. by early ______. (clue: childhood, adulthood)
2. by type of ______.
3. by ______ of neural circuit.
4. by ______ of information processing. (where)
- by early development
- by type of motor response
- by complexity of neural circuit
- by site of information processing
development of reflexes, name the 2 types
classification #1 - from slide 12 (by early development)
innate and acquired reflexes…
innate are BEFORE YOU ARE BORN, THEY ARE FORMED
BABY THEY WERE BORN THAT WAY - genetically determined
motor response of reflexes, name the two types
classification #2 - from slide 12 (by type of motor response)
somatic reflexes - involuntary control of nervous system - superficial reflexes of skin, mucous membranes. stretch or deep tendon reflexes (patellar, knee jerk reflex) - to reiterate… include superficial and stretch reflexes
visceral reflexes (autonomic) - control systems other than muscular system such as smooth/cardiac muscles, glands, and adipose tissue
complexity of neural circuit, reflexes - name the two types
classification #3 - from slide 12 (by complexity of neural circuit)
monosynaptic reflex - sensory neuron synapses DIRECTLY onto motor neuron
polysynaptic reflex - at least one interneuron between sensory neuron and motor neuron…. from two to several hundred!
site of information processing, reflexes - name the two types
classification #4 - from slide 12 (site of info processing)
spinal reflexes - processing in spinal cord
cranial reflexes - processing in the brain
spinal reflexes, talk about them and talk about one key term
spinal reflexes range in increasing order of complexity. there are monosynaptic spinal reflexes and polysynaptic spinal reflexes…
key term here would be INTERSEGMENTAL REFLEX ARCS
what are those?
it’s where many segments interact -
produce a highly variable motor response
spinal reflexes - monosynaptic reflexes, talk about a mention two key terms
monosynaptic reflex, an example would be a stretch reflex. an example of a stretch reflex would be the patellar reflex.
these reflexes have the least delay! only 20-40 msec
receptor is the muscle spindle
what is the receptor for a stretch reflex
a muscle spindle!
spinal reflexes - postural reflexes, what they do?
they are stretch reflexes! believe it or not
they maintain normal uptight posture
the stretched muscles RESPOND by contracting
that’s how they automatically maintain balance
spinal reflexes - polysynaptic reflexes
they’re more COMPLICATED than the monosynaptic reflexes
interneurons control more than one muscle group - so interneurons can have be somewhat of a little control center
produce either EPSPs or IPSPs
spinal reflexes - the tendon reflex… talk about
prevents skeletal muscles from two things… developing too much tension (bad) and also prevents skeletal muscles from tearing or breaking tendons (really really bad)
instead of muscle spindles or proprioceptors THEY HAVE SENSORY RECEPTORS!
Spinal reflexes - withdrawal reflexes
move body part away from stimulus (pain or pressure)
FLEXOR REFLEX is a great example! pulls hand away from hot stove
strength and extent of response
- depend on intensity and location of stimulus
