Exam 2: Neurophysiology (Topic 3)

Terms/Vocab.

Why is white matter white?

because it is comprised of myelinated axons

What is white matter called in the CNS?

tract

What are the glial cells that are responsible for myelination?

oligodendrocytes

what is white matter called in the PNS?

nerve (example vagus nerve)

what are the responsible glial cells for schwan cells

neurolemmocytes

when we see white matter think????

information highway

Why is gray matter gray?

bbecause it is comprised of cell bodies (full or organalles) and synapses

what is gray matter called in the CNS?

nuclei

in the PNS what is gray matter called

ganglion

when you see gray matter think???

synaptic transmission and integration 

what does the CNS consist of?

brain and spinal cord

what consists of the PNS?

afferent division (somatic, visceral and special sensory)

efferent division (somatic motor and autonomic motor like sympathetic, parasympathetic, and enteric)

higher areas of the CNS are more???? and lower areas of the CNS

voluntary (higher), reflexive (lower)

whats the function of the cortex?

interprets sensory information, generates voluntary movement and perform cognition (learning, memory and reasoning)

whats the function of the subcortical nuclei (basal nuclei)?

essential for regulation of movement

whats the function of the thalamus?

its a relay station for both sensory and motor information

whats the function of the hypothalamus?

source of lots of homestatic mechanisms (ex. hormone regulation, temperture regulation, water balence, etc)

whats the function of the limbic system?

emotions, emotional behavior, learning

whats the function of the cerebellum?

it is an error corrector for motor and sensory information, responsilbe for procedural memory (riding a bike)

whats the function of the brainstem?

it is the most reflexive part of the brain and is the control center for autonomic reflexes for breathing and heart function. reticular activating system helps us pay attention to important stimuli

what is CSF?

clear liquid surrounding and protecting the brain and spinal cord, it acts as a shock absorber, carries nutrients and oxygen to brain and spinal cord and remove waste, keep CSF low in proteins because it indicates that the blood CSF barrier is intact

what is the blood brain barrier?

it is a functional layer between the vessels and the neurons

Can Na+ ions cross the BBB

No, they only go through sodium channels

Can oxygen cross the BBB

crosses via passive diffusion, small, and diffuses

can glucose cross the BBB

no, they go through facilltated diffusion

can ethyl alcohol cross the BBB

yes, it can pass through the lipid membrane because its small and fat loving

can penicillin cross the BBB

no its not gonna be able to 

can H+ ions cross the BBB

no no no they can’t they are very slow and largely impermeable

what does the EEG monitor?

graded potentials from the pyramidal cells in the cortex

what are the two aspects of the signals in a EEG?

frequency (waves per time)

amplitude (magnitude of the waves)

what does beta waves measure?

measure the rapid electrial activity associated with active concentration, alertness and focused mental stress (low amplitude and high frequency)

what does alpha waves measure?

indicates a state of relaxed alertness and mediation

what does delta waves measure?

measure deep sleep, unconsciouness, and restoration (high amplitude and low frequency)

what are somatic modalities?

touch, temperture, pain and proprioception

what are receptors?

they are tranducers they convert one kind of stimulus energy to a different kind of stimulus energy. mechanical to electrical

when does a transduction occur?

occurs when a receptor signal is converted to a graded potential by a transduction channel

what is receptive fields?

area of skin that is monitored by a receptor, they vary in size and they are important because smaller receptor fields allow higher resolution

whats the labeled line theory?

receptive field in periphery connected to an area in the brain

what is 2 point discrimination related to?

size and density of receptive field

what are dermatomes?

how the body is organized into layers and each is innervated by a pair of spinal nervous

whats the function of the frontal lobe?

thinking, problem solving, decision making, planning, etc

whats the function of the auditory cortex?

hearing, sound and language comprehension 

whats the function of the temporal lobe?

hearing and memory

whats the function of the occipital lobe?

vision (occipatal lobe)

whats the function of the taste cortex?

process and integrate taste, texture (parietal lobe)

whats the function of the somatosensory cortex?

responsible for processing sensory information from the body such as pressure, pain, temperture, etc and sending it to the brain

what is lateral inhibition?

improves the ration between center and surround stimulus via inhibitory interneurons

where is lateral inhibition found and what does it improve?

found in the CNS and NOT the receptor level, improves the detection of edges if stimulli by reinforcing the center stimulus and inhibiting the lateral stimuli, it helps with 2 point discrimanation and loclizing stimuli by the cortex

whats CNS’s role in sensory?

complexity of sensation not a property of receptor but of CNS neurons

whats is pain?

nociception is sensation of noxious stimulus, and is impacted by emotions and mobility

whats the acute pain comparison in fast

fast, mechanical or temperture (receptors/stimuli), (primary afferents) A delta fibers (mylinated), pathway neospinothalamic, well localized (perception), and (neurotransmitter) glutamate

whats the acute pain comparison in slow

receptors/stimuli (polymodal-chemical), primary afferent (c-fibers), neurotransmitters (substance P), pathway (paleospinothalamic), perception (poor localized)

what is referred pain?

it is visceral pain that is felt superficially, the receptors synapse on same neaurons in spinal cord that skin receptors synapse on

what is chronic pain?

synaptic changes in spinal cord permit the transmission of pain signals and the perception of pain when tissue damage is no longer present, poor management of acute pain can lead to chronic pain and addiction

what are the parts of the motor system

upper level- primary motor cortex, pre motor cortex

middle level- brainstem, addtional structures (cerebellum and basal nuclei)

lower level- spinal cord

which cortex is the higher level

motor cortex

which consists of the middle level?

basal nuclei, thalamus and cerebellum

what do all parts of the motor system have in common?

each motor area contains a map of the body (somatotopic organization)

each level receives information from the periphery

higher levels can control input from periphery

all areas highly connected

where is the gating/walking behavior found?

spinal cord- complex circuitry in spinal cord

pattern generators- groups of neurons producing a movement with no input

stepping reflexes- observed in infants who cannot walk

arm and leg movement with walking

what are the general parts of the reflex arc?

receptor

afferent neuron

integrator

efferent neuron

effector

what are muscle spindles?

type of encapsulated stretch receptor that depolarize in response to stretch

what are proioceptors?

are muscle tendon, joint receptors that tell the brain where the body is in space

what is passive stretch?

activates the spindle such that the freq. of AP in the afferent neuron increases

whats the importance of the stretch reflex (tendon tap)

this tap does not stimulate tendon, it stretches the muscle, the control center is one synapse in the spinal cord

what is the GTO (golgi tendon organ)

is a stretch receptor in the tendon and it sets off a different reflex that is inhibitory

what does the primary afferent synapses on?

it synapses on an inhibitory interneuron that inhibits the same contracting muscle

whats the withdrawal reflex?

can be expanded to the cross extensor reflex through the activation of more interneurons and also activate some higher centers to maintain balance

where do most motor tracts that control the body start?

brainstem

define the vestibulospinal

equilibrium reflex control from the vestibular labyrinth

define the tectospinal

control of head and eye movements directed toward visual targets, tracking reflexes use the superior colliculus as a control center

define reticulospinal 

activation and inhibition of flexors and extensors, anti-gravity and weight bearing

define the rubrospinal fibers

red nucleus, works closely with corticospinal tract for discrete movements

the corticospinal tract is the exception….

projects from the motor cortex to the spinal cord

also called the pyramidal tract

only seen in higher mammal

allows for precise control of motor units called fractionation

the cerellum is an error corrector…..

motor cortex sends an intended motor command

the proprioceptros sends feedback to brain and cerebellum as to what is happening in the periphery

the cerebellum compares the 2 and makes corrections

more recent evidence indicates the cerebellum corrects sensory and cognitive functions

sypmtoms of cerebellar disease

dysetria-overshooting

ataxia- uncoordinated movements

intention tremor

cerebellar nystagmus-tremor of eyeballs

balence problems- with changing directions

hypotonia- loss of tone (low muscle tone)

gait problems-wide stance

whats parkinson disease and its symptoms 

is the loss of dopaminergic neurons projecting from the substantia nigra

rigidity

shuffling gate “walking statues”

difficulty initiation movement (eye movement, hand to target, speaking)

resting tremor “pill rolling”

depression

dementia

lewy body disease

huntingtions disease and its symptoms

motor defects

behavioral problems

AD inheritance

dementia and eventual insanity

what cranial nerve is important for physiology

Vagus nerve (10)

thoracic and lumbar levels carry….

sympathetic information

sacral levels carry….

parasympathetic information

nerves of the parasympathetic

cranial and sacral nerves

nerves of the sympathetic

thoracic and lumbar nerves

parasympathetic system

rest and digest

ganglia on or near target

ACH released in ganglion binds to nicotinic

post releases ACH binds muscarinic

muscle type: smooth, cardiac and glands

long pre-ganglionic, short post-ganglionic

sympathetic system

fight or flight response

location of ganglia: along the pre-vertebral ganglia trunk

ACH released in ganglion binds nicotinic

post ganglionic releases NE bind adrengic (alpha or beta)

muscle type: smooth muscle

short pre-ganglionic and long post-ganglionic

what is dual innervation?

sympathetic NS increase heart and blood pressure, raise blood glucose, dilate pupils inhibit digestive function

parasympathetic NS decreased heart rate, lower blood glucose, constrict pupil, stimulate digestive function

what does tone mean?

means baseline activity

what is the vagal tone?

the pacemaker rate is faster than the heart rate the vagus decreases the heart rate at rest

what is the sympathetic tone?

sympathetics cause some constriction of the blood vessels even at rest, the vagus has no direct effect on the blood vessels