NEUROPHYSIOLOGY Flashcards
set of tpatways to and from the CNS that innervates and regulates smooth muscle, cardiac muscle, and glands
Autonomic Nervous system
3 divisions of ANS
Sympathetic
Parasympathetic
Enteric
[ANS] synapses between neurons are made in the__________
autonomic ganglia
located in in or near the effector organs
Parasympathetic ganglia
Located in the paravertebral chain
Sympathetic ganglia
Have their cell bodies in the CNS adn synapse in the autonomic ganlia
Preganglionic neurons
Preganglionic neurons of the sympathetic nervous system originate in the spinal cord segments ________
T1-L3 or thoracolumbar region
Preganglionic neurons of the parasympathetic nervous system originate int he nuclei of cranial nerves and in the spinal cord segments ________
S2 to S4 or craniosacral region
_________ of both devisions of ANS have their cell bodies in the autonomic ganglia ans synapse on effector organs
Postganglionic neurons
specialized ganglion of the sympathetic nervous system
Adrenal medulla
- preganglionic fibers synapse directlt in chromaffin cells
- secretes epinephrine (80%) and norepinephrine (20%)
tumor of the adrenal medula that secretes excessive amount sof catecholamnes and is associated with increased excretion of 3 methoxy-4-hydroxy mandelic acid (VMA)
Pheochromocytoma
______release norepinephine as the neurotransmitter
Adrenergic neurons
________ release ACh weheter in the SNS or PNS as the neurotranmistter
Cholinergic neurons
includes some postganglionic parasympathetic neurons of the GIT, which releasse substance P, vasoactive intestinal peptide
Nonadrenergic, noncholinergic neurons
Organization of the autonomic Nervous system

Sympathetic or Parasympathetic
Short preganglionic nerve axon
Sympathetic
Sympathetic or Parasympathetic
long oreganglionic nerve axon
Parasympathetic
Sympathetic or Parasympathetic
Nicotinic receptors in ganglion
BOTH
Sympathetic or Parasympathetic
Muscarinic receptor in effector organs
Parasymapthetic
- alpha 1, alpha 2, B1 and B2 = Sympathetic
- nicotinic = somatic *
Signalling pathways and mechanisms forAutonomic receptors

Adrenergic receptors
alpha 1
alpha 2
Beta 1
Beta 2
Cholinergic receptors
NM (N1)
NN (N2)
M1
M2
M3
located on vascular smooth muscles of the skin and splanchic regions, the GI, and bladder sphincters, and the radial muscle of the iris
Alpha 1
- Produce excitation (contraction or constriction)
Mechanism of action of alpha 1 receptors
Gq protein, stimulation of phospholipase C and increase IP3 and intracellular calcium
Located on the sympathetic postganglionic nerve termnals (autoreceptors), platelets, fat cells, and the walls of the GI tract (heteroreceptors)
alpha 2
- often produce INHIBITION (relaxation or dilation)
Mechanism of action of alpha 2 receptors
Gi protein, inhibition of adenylate cyclase and decrease in cAMP
located in the SA node, AV node, and ventricular muscle of the heart
B1 receptors
- Produce EXCITATION (increased heart rate, increased conduction velocity, increased contractility)
- sensitive to both NE and E.
- more sensitive than alpha 1
Mechanism of action of B1 receptors
Gs protein, stimulation of adenyate cyclase and increase in cAMP
located on vascular smooth muscle of Skeletal muscle, bronchial smooth muscle, and the walls of GIT and bladder
B2 receptors
- Porduce RELAXATION (dilation of vascular smooth muscle, dilation of brochioles, relaxation of the bladder wall)
- More sensitive to EPINEPHRINE than NE
- more sensitive to EPINEPHRINE than alpha 1
Mechanism of Action of B2 receptors
Gs protein, stimulation of adenylate cyclase and increase in cAMP (similar to B1)
EXCITATION OR RELAXATION?
alpha 1
excitation
EXCITATION OR RELAXATION OR INHIBITION?
alpha 2
inhibition
EXCITATION OR RELAXATION OR INHIBITION
B1
Excitation
EXCITATION OR RELAXATION OR INHIBITION
B2
Relaxation
located in the automic ganglia of the sympathetic and parasympathetic nervous system, at the NM junction and in the Adrenal medulla
Nicotinic reeptors
- Activated by ACh or nicotine
- produce EXCITATION
Nicotinic receptors are blocked by _________ in the autonomic ganglia, but not in the NMJ
ganglionic blockers (hexxamethonium)
Mechanism of action of Nicotinic receptors
ACh binds to alpha subunits of the nicotinic ACh receptor.
The nicotinic receptors are also ion channels for ________
Na and K
Located in the heart, smooth muscle, and glands
Muscarinic
- M2 (heart)
- M3 (smooth muscle , glands)
- activated by ACh and muscarine
muscarinic receptors are _______ in the heart
inhibitor
muscarinic receptors are ______ in smooth muscles and glands
Excitatory
Muscarinic receptors are blocked by ________
atropine
Mechanism of action of muscarinic receptors
- Heart SA node: Gi protein, inhibition of adenylate cyclse, which leads to opening of K channels, slowing of the rate of spontaneous phase 4 depolarization and decreased heart rate
- Smooth muscle and glands: Gq, stimualtion of phospholipasee C, and in increase in IP3 and intracellular Calcium
Prototype of drugs that affect autnomic activity

alpha 1 agonists
Norepineehrine
Phenylephrine
Alpha 1 antagonists
Phenoxybenzamine
Phentolamine
Prazosin
Alpha 2 agonist
clonidine
Alpa 2 antagonists
Yohimbine
Beta 1 agonists
Norepinephrine
Isoproterenol
Dobutamine
Beta 1 antagonists
Propanolol
Metoprolol
Beta 2 agonist
Isoproterenol
Albuterol
B2 antagonist
Propanolol
Butoxamine
Nicotinic agonists
ACh
Nicotine
Carbachol
Nicotinic anatagnist
Curare (NMJ)
Hexamethonium (ganglionic N2 rceptors)
Muscarinic agonist
ACh
Muscarine
Carbachol
Muscarinic antagonist
Atropine
Effects of the autonomic nervous system on organ system

vasomotor center
respiatory center
swallowing, coughing, and vomiting center
Medulla
Pneumotaxic center
Pons
Micturition center
Midbrain
temperature regulaion center
thirst and food intake regulatory center
hypothalamus
Specialized epithelial cells or neurons that transduce environmental signals into neural signals
Sensory receptors
Types of sensory transducers
- Mechanoreceptors
- Photoreceptors
- Chemoreceptors
- Extreme of temperature and pain (nociceptors)
area of the body that, when stimualtd, changes, the firing rate of a sensory neuron.
Receptive field
Nerve fiber types

Steps in sensosry transduction
- Stimulus arrives at the sensory receptor
- Ion channels are opened in the sensory receptors
- usually inward. causing DEPOLARIZATION
- exception: Photoreceptors (HYPERPOLARIZTAION)
- The change in membrane potential produced by the stimulus is the receptor potential or genrator potential
Slowly adpating or tonic receptors
muscle spindle; pressure; slow pain
Rapidly adapting of phasic receptors
pacinian corpuscle; light touch
Sensory pathways from the receptor to the cerebral cortex
- Sensory receptors
- transduce the stimulus to electrial energy
- First order neurons
- Second order neurons
- third order neuron
- fourth order neurons
First order neuron of sensory pathway
primary afferent neurons.
dorsal root or spnal cord ganglia
Second order neuron of sensory pathway
relay nuclei and transmit to the thalamus
located in the SC or brain stem
May cross the midlone
Third order neuron of sensory pathway
located in the relay nuclei of the thalamus
from there, encoded sensory information ascends to the cerebral cortex.
fourth order neurons
located in the appropriate sensory area of the cerebral cortex. the information received results in a conscious perception of the stimulus
Includes the seantion of touch, movement, temperature,and pain
Somatosensory system
Pathways in the somatosensory system
Dorsal Column system
Anterolateral system
processes sensations of fine touch, pressure, two pint discrimination, vibration and proprioception
Dorsal column system
somatosensory system that is primary consists of group II fibers
Dorsal column system
Course of Dorsal column system
- Primary afferent neurons n the dorsal root
- ascends ipsilateral to the nucleus gracilis and nucleus cuneatus of the medulla
- cross the midline of medulla
- ascends to the thalamus
- ascends to the somatosensory cortex
processes sensations of temperature, pain, and light touch
anterolateral system
consists primarily of group III and IV fibers, which enter th SC and terminate in the dorsal horn
Anterolateral system
Course of anterlateral system
- Second order neurons cross the midle to the anterolateral quadrant of the SC
- ascends to th contralateral thalamus
- ascends to the somatosensory cortex
Onion like structures in the SC skin (surronding unmyelinated nerve endings)
pacinian corpuscles
- Detects vibration, tapping
- rapidly adapting
Present in nonhairy skin
Meissner corpuscle
- Detects velocity
- Rapidly adapting
Encapsulated, detects pressure, slowly adapting
Ruffini corpuscle
transducer is on the epithelial cells, detectslocation, slowly adapting
Merkel disc
information from different parts of the body is arranged somatotropically
thalamus
Destruction of the thalamic nuclei results in the loss of sensation on the___________side of the body
contralateral
The major soatosensory areas of the cerebral cortex are _______
SI and SII
has somatotropic representation similar that in the thalamus
SI
the largest areas in the homuculus represent the ___ , _____, ____ where precise localization is most important
Face, hands, and fingers
associated with the detection anf perception of noxious stimuli
Pain
The receptors for pain are ________
free nerv endings
Neurotransmitters for nociceptors _______
substance P
carried by group III fibers.
fast pain
carried by C fibers. Achinh, burning, or throbbing that is poor;y localized
slow pain
Pain of visceral origin is referred to sites on the skin and follows the dermatome rule.
Referred pain
Refractive power of a lens is measuredin _____
diopters
equals to the reciprocal of the focal distance in meters
diopters
Farsighted. Light focuses behind the retina
Hypertropia
- corrected by convex lens
Nearsighted. Light focuses in front of the retina
Myopia
- corrected with biconcave lens
curvature of the lens is not uniform
Astigmatism
- corrected with a cylindric lens
result of loss of the accomodation power of then lens
presbyopia
Corrected by convex lens
Layers of the retina
- Pigment layer
- photoreceptor layer
- External limiting membrane
- outer nuclear layer
- outer plexiform layer
- inner nuclear layer
- Inner plexiform layer
- ganglion cell layer
- optic nerve cell layer
- internal limiting membrane

Absorbs stray light and prevent scatter of light
converts 11-cis retinal to all-trans retinal
Pigment epithelial cells
Sensitive to low intesity light; night vision
Rods
Lower visual acuity
not present in fovea
rods
adpats later (dark adaptation)
rods
Color vision : NO
Rods
Sensitive to high intensity light; day vision
Cones
Higher visual acuity
Present in fovea
Cones
Color vision: YES
Cones
Rods and cone are not present on the _________
optic disk (blind spot)
form local circuits with the bipolar cells
Horizontal and amacrine cells
_____ are the output cells of the retina
ganglion cells
Optic pathway
- fibers from each nasal hemiretina cross the optic chiasm
- fibers from each nassal hemiretina remains ipsilateral
- fibers from the lateral geniculae body form the geniculocalcarine tract and pass to the occipital love of the cortex

cutting of the optic nerve
blindness in the ipsilateral eye
Cutting the optic chiasm
causes heteronymous bitemporal hemianopia
Cutting the optic tract
homonymous contralateral hemianopia
Cutting the geniculocalcarine tract
causes homonymous hemianopia with macular sparing
The photosensitive element is _____
rhodopsin
- composed of opsin and retinal
Steps in photoreception in the rods
- light converts 11 cis retinal to all trans retinal.
- Metarhodopsin II is formed
- Metarhodopsin II activates transducin (Gt) which in turns activate phosphodiesterase
- cGMP levels decrease
- Closure of sodiu channels - > hyperpolarization
- Decreased release of glutamate
- ionotoropic (excitatory)
- metabotropic (inhibitory)
Receptive visual fields
- Receptive fields of the ganglion and lateral geniculate cells
- Receptive fields of the visual cortex
Neurons in the visual cortex detects _____ and _____
shape and orientation
3 cortical fields of the visual cortex
- Simple cells
- respond best to bar of ligh that habe the correct position and orientation
- Compelx cells
- moving bars or edges of ligth with the correct orientation
- Hypercomplex cells
- particular length and to curves and angles
Frequency is measured in_____
hertz
Intensity is measured in ______
decibels , log scale
Directs the sound waves into the auditory canal
Outer ear
Air filled
contains the tympanic membrane and the auditory ossicles
Middle ear
fluid filled
consists of a bony labyrinth and a series of ducts called membranous labyrinth
Inner ear
The scanal vestibuli and scala tympani contains _____
perilymph
perilymph has a high ______
sodium concentration
Scala media contains _______
endolymph
Endolymph has ahigh _________
potassium concentration
The scala media is bordered by the __________
basilar membrane.
(site of the organ of corti)
_____ hair cells are arranged in single rows and are few in nubers
Inner
________ outer haircells are arranged in parallel rows and are greater in number
Outer
contains the cell bodies of the auditory nerve (CN VIII), which synapse on the hair cells
spiral ganglion
Steps in auditory transduction by the organ of corti
- sound waves causes vibration of the organ of corti
- hair cells bend by shearing force
- change in K conductance f the hair cell membrane
- the oscillating potential is the cochlear microphonic potential
- Intermittent firing of the cochlear nerves
the cilia of hair cells are embbed in the _____
tectorial membrane
more elastic
Basilar or tectorial membrane?
basilar
base of the basilar membrane responds to _____ frequencies
High
Apex of the basilar membrane (wide and compliant) responds to ___________ frequencies
low
Central auditory pathway
- Fibers ascend through the lateral lemniscus it the inferior colliculus
- medial geniculate nucleus of the thalamus
- auditory cortex
- Fibers may be crossed or uncrosssed
detects anguar and linear accelaration of the head
Vestibular system
The membranous labyrinth consists of _______ perpendicular semicircular canals, ____ and a _____
3
utricle
saccule
Detects angular accelaration or rotation
semicircular canals
Detects linear acceleration
Utricle and saccule
The canals are filled with ____________
endolymph
Cilia if the hair cells are embedded in a gelatinous structure calle the ______
cupula
If the stereocillia are bent toward the kinocillium, the hair ________
depolarizes (excitation)
If the sterocilia are bent away from the kinocilium teh hair cell _________
hyperpolarizes (inhiviton)
are tre neurons that conduct action potential into the CNS
receptor cells of the olfactor pathway
Only neurons in the adult human that repalce themselves
Olfactory neurons
The axons of the olfactory nerves are ___________ and are among the smallest and slowest
unmyelinated C fibers
the olfactory nerves pass through _______ on their way to the olfactory bulb
cribriform plate
second order neurons of the olfactory pathway
Mitral cells in the olfactory bulb.
output projects to the prepiriform cortex
Steps in transduction in the olfactory receptor neurons
- Odorant molecules bind to olfactory receptor proteins
- activate G proteins which activates adenylate cyclase
- increase in intracellular cAMP
- depolarizing receptor potential
- action potentals
Taste receptor cells line the taste buds that are located on specialized _______
papillae
in contrastt to olfactory cels, taste receptors are ________
not neurons
Has fungiform papillae
anterior 2/3 of the tongue
detects salty sweet and umami
anterior 2/3
the anterior 2/3 is innervated by
CN VII (chorda tympani)
has circumvallate and foliate papillae
detects sour and bitter sensations
Posterior 1/3 of the tongue
the posterior 1/3 is innervated by
CN IX
The back of the throat and the epiglottis are innervated by
CN X
CN VII, IX, an X enter the medulla, ascend in the _______
solitary tract
Consists of a single motorneuron and the muscle fibers that it innervates
Motor unit
group of motorneurons that innervates fibers within the same muscle
motorneuron pool
The force of muscle contraction is graded by ________
Recruitment of additional motor units
States that as additional motor units are recruited, the more motorneurons are involved and more tension is generated
Size principle
Innervate a few muscle fibers
lowest thresholds (fire first)
generate smallest forces
Small motorneurons
innervate many muscle fiers
highest threshold
generates the largest force
Large motorneurons
Types of muscle sensors
- muscle spindles
- golgi tendin organs
- pancinian corpuscles
- free nerve endings
Groups Ia and II afferents
detectsboth static and dynamic hanges in muscle length
Muscle spindles
Group Ib afferents
detects muscle tension
Golgi tendon organs
group II afferents
detects vibration
Pacinian
groups III and IV afferents
detects noxious stimuli
Free nerve endings
Types of muscle fibers
Extrafusal
Intrafusal
Make up the bulk of muscle
provide the force for muscle contraction
Extrafusal fibers
Innervated by alpha motorneurons
Extrafusal
smaller fibers
encapsualted to form muscle spindles
intrafusal fibers
Innervated by y-motorneurons
Intrafusal
consist of small encapsulated fibers connected in parallel with large force-genrating extrafusal fibers
Muscle spindles
The finer the movement required the ______ the number of muscle spindles in a muscle
greater
Types of Intafusal fibers
Nuclear bag
Nuclar chain
type of intrafusal fiber that detect teh rate of change in muscle length
innervated by group Ia afferents
Nuclear bag
type of intrafusal fiber that detects static changes in muscle length
innervated by group II afferents
more numerous
Nuclear chain
How muscle spindle works
- sensory information about muscle lenth received by group Ia (velocity) and group II (static)
- if muscle lethenes, muscle spindle is also stretch stimualting group Ia and II
- Stimulation of group Ia - > alpha motorneurons -> contractions and shortening
they innervate intrafusal muscle fibers
adjust the sensitivity of the muscle spindle
y-motorneurons
alpha and y motorneurons are ______ so that muscle spindles remain sensitive to chaines
coactivated
Summary of muscle reflexes

Stretch reflex is ______
monosynaptic
examples: knee jerk reflex
golgi tendon reflex (inverse myotactic) is _____
dysanptic
ane xaggerated form of the golgi tendon reflex, can occur with disease of the corticospinal tracts
Clasp-knife reflex
Flexor withdrawal reflex is ____________
polysynaptic
Occurs when a single alha motoneuron receives inout from many muscle spindle group Ia afferent in the homonymous muscle
Convergence
Occurs when the muscle spindle group Ia afferent fibers project to all of the alpha motoneurons that innervate the hmonumous muscle
Diveregence
inhibitory cells in the ventral horn of the spinal cord
they receive inout from collateral axons of motorneurons and , when simualtedm negatively feedback on the motorneuron
Renshaw cells
Examples of pyramidal tracts
corticospinal and corticobulbar
originates in the red nucleus and projects to interneurons in the lateral spinal cord
produces stimulation of flexors and inhibition of extensors
rubrospinal tract
originates in the nuclei of the pons and projects to the ventromedial spinal cords
stimulatory effect on both the extensors (predominant) and flexors
Pontine reticulospinal tracts
originates in the emdullar reticular formation and prohects to spinal cord interneurons in the intermediate gray area
general inhibitory effect on both extensors and flexors
Medulalry reticulospinal tract
Originates in Deiters nucleus and projects to ipsilateral motoneurons and interneurons
causes a powerul stimulation of extensors and inhibition of flexors
lateral vestibulospinal tract
Originate in the superior colliculus and projects to the cervical spinal cord
involved in the control of neck muscles
tectospinal tract
Immediately after transection, there is loss of the excitatory influence fro alpha and y motoneurons. Limbs become flaccid and reflexes are absent
Spinal shock
if the lesion is at _____, there will be loss of sympathetic tone to the heart.
C7
if the lesion is at ________, breathing will stop
c3
if the lesion is at ______, death occurs
c1
Lesions above the lateral vestibular nucleus
decerebrate rigidity
- removal of inhibition from higher centers
Lesions above the pontine reticular formation but below the midbrain
Decerebrate rigidity
Lesions above the red nucleus
decorticate
Control of balance and eye movement
Vestibulocerebellum
planning and initiation of movement
Pontocerebellum
Synergery, which is control of rate, force, range, and direction of movement
Spinocerebellum
innermost layer of the cerebelalr cortex
granular layer
- contains granule cells, golgi type II, and lomeruli
middle layer of the cerebellar cortex
Purkine cell layer
- purkinje cells
- output is always inhibitory
Outermost layer of the cerebellar cortex
molecular layer
- Contains stellate and basket cells, dendrites, of purkinje and Golgi type II cell and parallel fibers (axons of granule cells)
Input to the cereballar cortex
- Climbing fibers
- single region
- complex spikes
- motor learning
- Mossy fibers
- many centers
- simple spikes
- glomeruli
- parallel cells
Output of the cerebellar cortex
- Purkinje cells
- GABA
is the inability to stop a movement
rebound phenomenon
Consists of striatum, globus pallidus, subthalamic nuclei, and substantia nigra
GABA
plan and execute smooth movements
basal ganglia
Two pathways in the basal ganglia
- Indirect = inhibitory
- D2 receptors
- Direct = excitatory
- D1 receptors
Connections between the striatum and substantia nigra use _____ as their NT
dopamine
Lesions of the globus pallidus
inability to maintain postural support
Lesions of the subthalamic nucleus
wild, flinging movements
caused by release of inhibition on the contralaterl side
Lesion of the striatum
caused by release of inhibition
quick continuous and uncontrollable movements
Huntington
Lesions of the substantia nigra
destuction of dopaminergic neurons
parkinson disease
responsible for genrating a plan for movement
mental rehearsal
premotor cortex
Primary motor cortex is area ___
4
execution of movement
Epileptic evets in the primary motor cortex cause _______
jacksonian seizures
EEG change
it reflecrs synaptic potentials evoked in largenumber of neurons
Cortical evoked potential
In awake adults with eyes open ______ waves predominate
beta
In awake adults with eyes closed ____ waves predominate
alpha
During sleep ______ waves predominate
slow
the circardian periodicity is thought to be driven by the _______ of the hypothalamus
suprachiasmatic nucleus
Rapid eye movement occurs every _______ minutes
90
REM sleep is charcterized by ______________
eye movements, loss of muscle tone, pupilalry constricion, and penile erection
The ______ hemisphere is dominant in facial expression, intonation, body language and spatial tasks
Right
The _____ hemisphere is usually dominatn with respect to language
left
Damage to the ______area causes sensory aphasia
Wernicke
Damage to _____ area causes motor aphasia
broca
BBB consists of _______________
endothelial cells of the cerebral capilalries
choroid plexus epithelium
______ and _____ are excluded from CSF because of their large molecular size
Protein and Cholesterol
Functions of the BBB
- Maintains a constant environment
- prevents teh escape of NT
Comaprison of CSF and Blood concentraions

Cold temperatures active the _____________
sympathetic nervous system
Most important potent mechanusm for icnreasing heat production
Shivering
Response to heat loss is orchestrated by the _____ hypothalamus
anterior
heat generating mechanism are activated by the _________hypothalamus
posterior
Pyrigens increase the production of IL_____ in phagocytic cells
1
caused by excessive sweating, As a result, blood volume and arterial blood pressure decrease and syncope occurs
heat exhaustion
occurs when body temperature increases to the point of tissue damage.
heat stroke
characterized by massive increase in oxygen consumption and heat production by skeleal muscle
Malignant hyperthermia