central nervous systerm, peripheral nervous systerm
Central nervous system
brain and spinal cord
Peripheral nervous systerm
nervous outside the brain and spinal cord
CNS composed of…
white matter and gray matter
Gray matter
nerve cell bodies
White matter
myelinated axons
Nerve tract
group of nerve fibers within the cns with a common origin and a common destination (ascending and descending)
Nucleus
cluster of nerve cell bodies within the CNS
Nerve
group of nerve fibers in the PNS with a common origin and common destination- afferent (sensory) and efferent (motor)
Ganglion
cluster of nerve cell bodies in the PNS
Structural components of nervous system
CNS and PNS
Fxnl components of nervous systerm
Autonomic Nervous systerm (ANS), Somatic nervous system
4 principal fxns of the nervous system
1. Orientation of body to internal and external environments. 2. Coordination and control of body activities. 3. Assimilation of experiences requisite to memory. 4. Programming of instinctual behavior (more important in vertebrates other than humans).
Cerebral palsy
pathology of the brain causing paralysis, lack of coordination, and other dysfunctions of motor and sensory mechanisms.
Coma
varying degrees of unconsciousness that may be the result of any one of a number of causes
Neurological examination
mental assessment following trauma to the CNS. 5 categories: 1. Mental status and speech 2. cranial nerves 3. motor system 4. sensory system 5. reflexes
Paraplegia
permanent paralysis of both legs due to injury or disease of the spinal cord.
Quadriplegia
permanent paralysis of arms and legs due to spinal cord injury or certain diseases.
Neuron
nerve cell; structural and functional unit of the nervous system
3 components of neuron
cell body, dendrites, axons
cell body
enlarged portion of the neuron containing the nucleus, Nissl bodies (layered rough ER), neurofibrils (strands of protein), and other organelles
dendrites
cytoplasmic extensions which receive stimuli and conduct impulses to the cell body
Axons
cylindrical processes that conduct impulses away from the cell body
Length of axons
few millimeters in the CNS to over a meter in the PNS
Schwann cells
long axons are generally myelinated with schwann cells in the pns
Oligodendrocytes
long axons are generally nyelinated with oligodendrocytes in the CNS
Nodes of Renvier
segments in the myelin sheath
Presynaptic terminals
where axon terminates
How are neurons classified?
direction of impulse conduction, the number of cytoplasmic processes, and the are of innervation
within the skin, muscles, and joints receive stimuli and convey impulses to the CNS
Somatic efferent neurons
convery impulses from the CNS to skeletal muscles
Visceral afferent neurons
convey impulses to the CNS from the internal organs
Visceral efferent neurons
convey impulses from the CNS to internal organs (cardiac muscle, glands, and smooth muscle within visceral organs)
Resting membrane potential
when a neuron is not conducting an impulse (resting), there is a difference in electrical charge between the inside and the outside of the cell membrane
Resting membrane charge difference
more positive ions outside the membrane and more negative ions on the inside
3 mechanisms responsible for the imbalance in particles across the membrane
Na-K pump moves Na+ outside and K+ inside; cell membrane is more permeable to K+ than Na+ so K+ moves out faster than Na+ moves in; membrane doesn’t allow negative proteins through and therefore keep more anions inside than outside
3 action potential synonyms
spike, nerve impulse, discharge
Do action potentials diminish as they are conducted down an axon?
no
What constitutes the code as well as the destination of the impulse?
the frequency and pattern of the action potential
Are action potentials similar in all organisms?
yes
Membrane potential
present in all cells
Current in membrane potential
-60 to -80 mV (inside cells)
Action potential recorded by…
oscilloscope
Time for action potential to occur
2 msec (1000 per sec)
5 Characteristics of action potential
rising phase, overshoot, falling phase, undershoot or hyperpolarization, gradual restoration of the resting potential
Sequence of action potential (first 5 steps)
1.Adequate stimulation 2.open sodium channels 3. Sodium ions move inward 4. Threshold level (all or none) 5. Depolarization of membrane
Sequence of action potential (steps 6-10)
6. Reverse polarization 7. Acts as a stimulus 8. Decreased sodium permeability and increased potassium perm 9. K+ moves out (repolarization) 10.prep for next impulse
Action potential 1
adequate stimulation of membrane-physical, chemical, temperature-different neurons/different stimuli
Action potential 2
Increased membrane permeability to sodium at site of stimulation (open sodium channels)-permeability favors sodium over potassium
Action potential 3
sodium ions move inward- inside of the membrane becomes less negative
Action potential 4
there is a critical level- threshold level- generator potential (-55 mV) that must be crossed in order to trigger an action potential- “all or none” (voltage gated sodium channels open)
Action potential 5
if the action potential is triggered the transmembrane potential reaches zero (depolarization of membrane)
Action potential 6
sodium ions continue to move inward and the inside of the membrane becomes positive (reverse polarization) relative to the outside
Action potential 7
reverse polarization acts as a stimulus to the adjacent regions
Action potential 8
decreased permeability of sodium channels and increased (continued) permeability of potassium channels – voltage-gated potassium channels are opened
Action potential 9
potassium ions move out, making the outside positive (repolarization)
Action potential 10
to prepare for the next impulse, pumps transport sodium back out of the neuron, and potassium back into the neuron
All or none
nerve and muscle fibers obey the al or none law, meaning that a threshold stimulus evokes an action potential, and that a subthreshold stimulus evokes no response
Absolute refractory period
during the interval from the onset of an action potential until repolarization is about 1/3 completed, a second stimulus cannot elicit another response because the channels are already open
Relative refractory period
following the absolute refractory period is an interval during which the neuron will not respond to a normal threshold stimulus, but a very strong stimulus can depolarize the membrane and produce a second action potential
Sodium Channel structure is formed by what?
a single, long polypeptide
How many domains are on the sodium channel structure?
4 distinct domains
each sodium channel domain constists of what?
6 transmembrane alpha helices
Tetrodotoxin (TTX)
sodium channel toxin which binds to and physically blocks the Na+ pores
Saxitoxin
sodium channel toxin that blocks Na+ pores
Batrachotoxin
sodium channel toxin that cuases the Na+ channels to open and stay open much longer than normal, thus altering the action potentials
delayer rectifier
movement of K+ during repolarization occurs about the same time the Na+ channels close (one msec later)
orthodromic conduction
impulses moving in the normal direction (natural)
antidromic conduction
backward propagation (experimentally) of impulse
average impulse travel time
10m/sec (vary from .5m/sec to 100m/sec
Mylinated speed vs. unmylinated
mylinated is much faster
Nodes of ranvier
interruptions in the myelin sheath that make it myelinated
Salutatory conduction
the leaping of action potentials on mylenated neuron (increases speed and conserves energy
Schwann cells
form the myelin sheath in the pns
Oligodendroglia
form the myelin sheath in the cns
Multiple sclerosis (MS)
2nd most common cns disease next to epilepsy. Autoimmune disease in which the body’s natural defenses attack the myelin in the CNS. Myelin sheath becomes damaged and this interferes with nerve conduction. More common in cold areas
Symptoms of MS
disturbances in speech, disturbances in vision, numbness, fatigue, depression, loss of coordination, uncontrollable tremors, loss of bladder control, memory problems, paralysis
Treatment of MS
ACTH, exercise, physical therapy
Tay-Sachs disease
an inherited disease in which the myelin sheaths are destroyed by excessive accumulation of lipids within the membrane layers
Local anesthesia
drugs (cocaine and lidocaine) that block the initiation of action potentials in neurons. They are injected into the are of the body to be anesthesized.
Lidocaine binding site
S6 alpha helix of domain IV
Synapse
anatomical junction between two neurons where the electrical impulse in one neuron initiates a series of events influencing the excitability of the 2nd
small rounded or oval knobs which are referred to as synaptic knobs, boutons, and end feet, or presynaptic terminals. Present within axon terminals are synaptic vesicles containing a neurotransmitter: Ach, Norepi
Synaptic cleft
microscopic space between the 2 neurons
Postsynaptic membrane
cell membrane of the postsynaptic neuron which contains specific receptors for the neurotransmitter
Synapse sequence of events (first 3)
impulse reaches the axon terminal of the presynaptic neuron, Ca+ enters the presynaptic neuron cuasing release of neruotransmitter into synaptic cleft, neurotransmitter diffuses across synaptic cleft and is detected by receptors on the postsynaptic neuron
Synapse sequence of events (#4 and #5)
the postsynaptic membrane is either stimulated or inhibited depending upon the types of neurotransmitter involved, the neurotransmitter either diffuses out of the cleft or is metabolized
Drugs may influence synaptic transmission by altering any of the following steps
synthesis of the neurotransmitter, release of the neurotransmitter, binding of the neurotransmitter with the receptor, destruction of the neurotransmitter
Deseases which affect synaptic transmission
parkinson’s disease-lack of neurotransmitter (dopamine), Myasthenia Gravis-block neurotransmitter (Ach) receptors, Botulism- inhibition of Ach release, Nerve Gas- anti cholinesterase
Synaptic Integration
an single neuron can be, and often is, simultaneously stimulated by excitatory and inhibitory transmissions from different presynaptic neurons.
Excitatory/inhibitory neurotransmitters
neurotransmitters may be excitatory, causin the postsynaptic neuron to become active, or inhibitory, preventing the post synaptic neuron from becoming active
Synaptic excitation
excitatory neurotransmitters increase the postsynaptic membrane’s permeability to sodium ions.
EPSP
excitatory postsynaptic potential- altered membrane potential said to be hypopolarized-two ways in which EPSP’s may combine to reach threshold and initiate an action potential: spatial summation, temporal summation
spatial summation
several p presynaptic neurons simultaneously release neurotransmitters to a single postsynaptic neuron; these EPSP’s produced at different synapses may summate in the postsynaptic dendrites and cell body
Temporal summation
the EPSP’s may summate as the result of the rapid successive discharge of neurotransmitter from the same presynaptic terminal
Synaptic inhibition
inhibitory neurotransmitters increase the postsynaptic membran’s permeability to Cl- and K+, resulting in a hyperpolarized membrane that exhibits an inhibitory postsynaptic potential (IPSP)
Glycine
amino acid that is a neurotransmitter known to be involved in the production of IPSP’s. It’s action is messed up by strychnine and tetanus toxin which produce convulsions and muscular hyperactivity.
GPSP
Grand postsynaptic potential-composite potential on the postsynaptic membrane due to the sum of all EPSP’s and IPSP’s occurring at the same time
derived from a single amino acid- Norepinephrine (noradrenaline), Epinephrine (adrenaline), Dopamine-made from tyrosine, Serotonin (5-hydroxtryptamine) made from tryptophan, histamine-made from histadine
Polypeptide neurotransmitters
substance P, endorphins and enkephalins
Gas neurotransmitters
Nitric Oxide (NO)-made from oxygen and arginine, freely diffuses into cells and binds to proteins, has a half-life of 2-30 seconds and is difficult to study
Cerebrum
largest and most prominent part of the brain (80% of total brain mass)
Grooves or valleys, called fissures or sulci in brain
Longitudinal fissure, Central fissure, Lateral fissure
Gyri
convolutions or folds in brain
Corpus callosum
two cerebral hemispheres are connected to each other by a thick band called corpus callosum, which is made up of 300 million neural axons allowing the 2 sides to communicate and cooperate
outer portion of cerebrum-3/16”-gray matter (six layers of neurons)
Functions of the cerebrum
all conscious fxns, interpretations of sensations, understanding of language, intelligence, memory, emotional feelings
Functions of the thalamus
recognition of crude sensations of pain, temp., touch; feelings of pleasantness and unpleasantness; production of complex reflex movements; relay center-receives all sensory input, except for smell, then relays it to the sensory cortex
Hypothalamus functions
controls the pituitary (hormones; thyroid, growth, reproduction, adrenal), water balance (ADH), appetite and food intake (glucostats-receptors for glucose), body temp., direct and indirect inputs to the autonomic nervous system
Hypothalamus blood brain barrier
not very well developed
Cerebellum functions
Control muscle action (planning and execution of voluntary movements), postural reflexes, equilibrium
center for the 5th, 6th, 7th, and 8th cranial nerves
Midbrain function
center for the 3rd and 4th cranial nerves
Brain stem consists of
medulla, pons, and midbrain
Reticular activating center
widespread network of interconnected neurons running throughout the entire brain stem and thalamus.
Function of reticular activating center
It controls the overall degree of alertness, wakefulness and sleep. General anesthetics suppress the neurons in this center and damage to these neurons may lead to a coma.
horse’s tail-thick bundle of elongated nerve roots at the lower vertebral canal
Cranial nerve I
olfactory-smell
Cranial nerve II
optic-sight
Cranial nerve III
oculomotor-movement of eyeball, focusing, and change in pupil size
Cranial nerve IV
Trochlear-movement of eyeball
Cranial nerve V
Trigeminal-Sensations from face, teeth, and tongue; movement of jaw, chewing muscles
Cranial nerve VI
Abducens-movement of eyeball
Cranail nerve VII
Facial-taste buds at the front of the tongue; movement of facial muscles, secretion of saliva and tears
Cranial nerve VIII
vestibulocochlear-hearing, balance, and posture
Cranial nerve IX
Glossopharyngeal-taste buds at the back of the tongue; swallowing and secretion of saliva
Cranial nerve X
Vagus-visceral sensations; visceral muscle movement (80% parasympathetic)
Cranial nerve XI
accessory-swallowing and head and neck movements
Cranial nerve XII
hypoglossal-speech and swallowing
Gray matter in spinal cord
neuron cell bodies
Central canal in spinal cord
cerebrospinal fluid (CSF)
White matter in spinal cord
myelinated axons
Anterior, posterior, and lateral columns of gray matter
divides the white matter into 3 areas called funiculi (posterior lateral, anterior)
Funiculi
nerve tracts are located in the 3 funiculi; tracts are either ascending or descending;name of most tracts indicates a. funiculus in which the tract is located b. location of its cells of origin c. level of destination
2 ascending funiculi tracts
anterior spinothalamic, lateral spinothalamic
anterior spinothalamic
ascending funiculi tract that conducts sensory impulses for crude touch and pressure
lateral spinothalamic
ascending funiculi tract that conducts pain and temp impulses
2 descending funiculi tracts
anterior corticospinal, lateral corticospinal
anterior corticospinal
descending funiculi tract that conducts motor impulses from the cerebrum to spinal nerves and outward through anterior horns for coordinated movements
lateral corticospinal
descending funiculi tract that conducts motor impulses from the cerebrum to spinal nerves through anterior horns for coordinated movements
Reflex arc
simplest type of sensory-to-motor nerve pathway
Reflex arc consists of
receptor (detect stimulus), sensory neuron (transmits a nerve impules to the CNS, and center (usually involving an interneuron)
Refex arc receptor and function
the portion of a dendrite or a specialized receptor cell in a sensory organ; sensitive to specific type of stimulus
Reflex arc Sensory (afferent) neuron and function
dendrite, cell body, and axon; transmits impulse from receptor to the CNS
Reflex arc interneurons description and function
dendrite, cell body, and axon of a neuron within the brain or spinal cord; serves as processing center; conducts impulse from sensory neuron to motor neuron
Reflex arc motor (efferent) neuron descritption and function
dendrite, cell body, and axon; transmits impulse from CNS out to an effector
Reflex arc effector description and function
a muscle or gland outside the nervous system; responds to stimulation by motor neuron and produces a reflex or physiological response
Blood brain barrier
tight jxn between endothelial cells lining the capillaries; cells surrounded by foot processes by the astrocytes
Electroencephalogram
graphic record of the evoked activity being emitted from neurons within the brain
4 EEG’s
alpha, beta, theta, delta
Alpha waves
8-12 waves/sec; parietal and occipital lobes; awake, relaxed, eyes closed. Increased blood sugar and corticoids and elevated body temperature increase the incidence of alpha waves
Beta waves
13-25 waves/sec; frontal lobes; visually orientating or thinking
Theta waves
5-8 waves/sec; temporal and occipital lobes; common in newborn infants and adults experiencing sever emotional stress
Delta waves
1-5 waves/sec; cerebrum; infants and sleeping adults; presence in awake adults is abnormal
Neurological assessment
deviation from normal EEG patterns are clinically significant in diagnosing trauma, mental depression, hematomas, and various diseases, such as tumors, infection, and epilepsy
Brain death (4 points)
unresponsive, absence of non-spontaneous unassisted respiration for three minutes, absence of CNS reflexes and fixed dilated pupils, a flat EEG for at least 10 minutes
Description of CSF
slightly alkaline solution containing more sodium, chloride, and magnesium ions than blood plasma, but less calcium, potassium, and glucose. In addition, CSF contains some proteins, urea, and leukoctyes.
Formation of CSF
CSF is continuously produced within the blood at specialized capillaries, called choroids plexuses, along the roofs of the ventricles of the brain. More CSF is formed by ependymal cells lining the ventricles and central canal.
Normal CSF fluid pressure
10 mm Hg
Pathway of flow of cerebrospinal fluid (CSF)
Lateral ventricles, interventricular forament (of Monro), Third ventricle, Cerebral aqueduct (of Sylvius), Fourth ventricle, subarachnoid space, reabsorption at the Arachnoid villi
Functions of CSF
Cushions the brain, allows for exchange of nutrients and wastes within nervous tissue, buoys the brain up
Hydrocephalus
abnormal accumulation of CSF in the ventricles and subarachnoid or subdural space. It may be caused by excessive production of or blocked flow of CSF. Hydrocephalus frequently cuases the cranial bones to thin and the cerebral cortex to atrophy.
Lumbar puncture
withdrawal of CSF from the subarachnoid space in the region of the lumbar vertebrae
Hydrocephalus
characterized by excess fluid in the cranial vault, subarachnoid space, or both. May occur at any stage of life.
Acute hydrocephalus
develops in a couple of hours in persons who hav sustained head injuries
Idiopathic or normal-pressure hydrocephalus
can occur where the CSF volume increases, but the pressure may or may not incease
Types of hydrocephalus
noncommunicating and communicating
Noncommunicating hydrocephalus
obstruction of CSF flow between ventricles; caused by congenital abnormality, aqueduct stenosis, compression by tumor
Communicating hydrocephalus
impaired absorption of CSF (caused by infection with adhesions, high venous pressure in sagittal sinus, head injury) or increased CSF secretion (caused by secreting tumor (choroid plexus)
Pathophysiology of hydrocephalus
obstructed CSF is under pressure, causing atrophy of the cerebral cortex and degeneration of the white matter tracts, there is selective preservation of gray matter.
Clinical manifestations of hydrocephalus
headache, vomiting, altered vital signs, deep coma. In congenital hydrocephalus in infants the cranial circumference is enlarged
Sleep stages
relaxation-alpha, non-REM, and REM
NonREM
Slow sleep, S state, quiet sleep
REM
active sleep, fast sleep, D state
Autonomic nervous system effector organs
cardiac muscle, smooth muscle, visceral organs and glands
thoracic and lumbar regions (T1 to T12 and L1 to L2 or 3)
Anatomical origin of parasympathetic division
cranial and sacral regions (cranial nerves 3,7,9,10 (80% comes from 10)
Three effector organs in sympathetic division that norepinephrine is not used as the neurotransmitter
sweat glands, smooth muscles in blood vessels going to skeletal muscles, and the adrenal medulla
Similarities between para/sympathetic divisions
1. Preganglionic neurons are myelinated; postganglionic are non-myelinated 2. Efferent outlow divided into pre and post ganglionic neurons 3. Pre ganglionic neurotransmitter is actylcholine
Differences between para/sympathetic divisions
sympathetic-short preganglionic neuron, long postganglionic neuron; parasympathetic- long preganglionic neuron and short postganglionic neuron
Cholingeric receptors
nicotinic and muscarinic- mumbrane receptor proteins located on autonomic postganglionic neurons or on effector organs that are regulated by acetylcholine or other molecules with similar activity
Nicotinic receptors
located at the ganglia in both sympathetic and parasympathetic divisions
Muscarinic receptors
located on all effector organs innervated by ostganglionic neurons of the parasympathetic division
Cholinergic
all preganglionic autonomic neurons and all postganglionic parasympathetic neurons are cholinergic- they use actetylcholine as a neurotransmitter
Nicotine derived from
tobacco
Muscarinie derived from
some poisonous mushrooms
Antimuscarinic agent
atropine
Muscarinic stimulants
acetylcholine, carbachol, methacholine, and bethanechol
Adrenergic receptors
membrane receptor proteins located on autonomic effector organs that are regulated by catecholamines (epi or norepi). Two types: alpha and beta
Alpha 1 tissue location
smooth muscles
Alpha 1 efect
stimulation of smooth muscle: vasoconstriction, uterine contraction, dilation of pupil, intestinal sphincter contraction, and pilomotor contraction
Beta 1 tissue
cardiac
Beta 1 effect
stimulation of cardiac muscle: increase in heart rate and force of contraction
Beta 2 location
smooth muscle
Beta 2 effect
inhibition of smooth muscle: vasodilation, uterine relaxation, intestinal relaxation, bronchodilation
Alpha 1 stimulants and degree
norepinephrine stimulates more than epinephrine
Beta 1 stimulants and degree
norepinephrine and epinephrine are about equal
Beta 2 stimulants and degree
epinephrine is much stronger than norep
Isoproterenol
a synthetic catecholamine stimulates mainly beta 2 receptors stronger than alpha 1 receptors.
G-proteins
all adrenergic receptors act via G-proteins
Alpha receptor stimulators cause
vasoconstriction and are used as decongestants
Alpha receptor blockers are used to
lower high blood pressure
Beta receptor stimulators are used to
stimulate the heart and cuase bronchodilation
Beta blockers are used to
slow the heart rate
Mechanoreceptors
detect mechanical defomation of the receptor or the cells adjacent to the receptor. Ex: touch, deep pressure, hearing, equilibrium, arterial pressure
Thermoreceptors
detect changes in temperature, some detecting cold and others detecting warmth. These receptors may be stimulated by changes in metabolic rate.
Nociceptors
pain receptors which detect damage in the tissues, whether it is physical or chemical damage
Electromagnetic or photoreceptors
detect light on the retina of the eye
Chemoreceptors
detect taste in mouth (sweet, salt, sour, and bitter), smell in the nose, oxygen and carbon dioxide levels in the blood
Sensory receptors adaption
adapt either partially or completely to their stimuli after a period of time
Tonic receptors
do not adapt at all or adapt slowly (muscle stretch receptors)
Phasic receptors
adapt rapidly-usually no longer responding to a maintained stimulus, but when the stimulus is removed, the receptor typically responds with a slight depolarization called the off response (watch, rings, clothing)
Pain threshold in people
there is a uniformity in the pain threshold for all people. People are not more or less sensitive to pain. People react differently to pain. Stoic people react far less intensely than do more emotional people.
Pain
protective mechanism that brings to conscious an awareness that tissue damage is occurring or is about to occur
Three types of pain
cutaneous, deep pain, visceral pain
Cutaneous pain
localized upon the surface of the body; pricking, sharp, burning—usually occurs first, short duration; can be localized or diffuse; referred to as fast pain (30m/s)—A-delta myelinated fibers
Deep pain
from muscles, tendons, and joints
Visceral pain
from visceral organs; both deep pain and visceral pain are usually poorly localized; dull, aching, nauseous, throbbing—occurs 2nd, persists longer; both are conducted by B neurons, which are unmyelinated and slow (1-12m/s)—C fibers
Damage cells
protaglandins, bradykinin, substance P, Glutamate
Prostaglandins
a special group of fatty acid derivaties that are cleaved from the lipid bilayers of plasma membranes
Bradykinin
activated by enzymes released from damaged cells
Substance P
pain neurotransmitter
Glutamate
pain neurotransmitter
analgesic system
CNS contains a neuronal system that suppresses pain.
endorphins and enkephalins
chemicals the body releases in resonse to outside stimuli like exercise or stress
2 locations where pain may be blocked
periaqueductal gray matter (surrounding the cerebral aqueduct) and in the reticular formation, where they block (via presynaptic inhibition) the release of substance P
Chronic pain
occurs in absence of tissue injury. May result from damage within the pain pathways in the peripheral nerves or in the CNS. Abnormal chronic pain is sometimes referred to as neuropathic pain
Action of Aspirin, acetaminophen, and ibuprofen
diminish pain by inhibiting prostaglandin production and release
function of opiate drugs such as codeine and morphine
act directly on pain centers in the brain
referred pain
not always felt over the organ from which it's derived (heart pain felt in left arm
2 mechanisms of referred pain
1)Embryonic origin of the organ 2)Cross over of first order neurons with second order neurons in the spinal cord
Epilepsy
a chronic disorder resulting from sudden, uncontrolled discharge of activity by neurons in the brain (seizure)
manifestations of seizure activity
loss of consciousness, tonic and/or clonic muscle contraction which can be either generalized or localized
trouble remembering recent events, loss of memories of the past, confusion, forgetfulness, hallucination, paranoia, vioent changes in mood
neural structural changes from alzheimer's disease
1)great loss of neurons in specific regions of the hippocampus and cerebral cortex 2)plaques of abnormal proteins deposited outside neurons 3)tangled protein filaments with neurons
mr. charles11
