Pathophysiology Neuro

central nervous system (cns)

brain and spinal cord

peripheral nervous system

carries messages to and from cns

somatic nervous system

controls voluntary muscles and transmits sensory information to cns

autonomic nervous system

controls involuntary body functions

sympathetic nervous system

arouses the body (EPI & NOREPI)

parasympathetic nervous system

relaxes the body (REST AND DIGEST)

cns supporting cells

1. oligodendroglia
2. astroglia
3. microglia
4. ependymal cells

oligodendroglia

myelinating cells (create the myelin sheaths that cover the NERVE and allows for very fast nerve transmission)

astroglia

provides support for brain structures and a mechanism for intercellular ion transport

microglia

phagocytic cells established in the brain that watch for specific invaders in order to protect the brain from inflammation and infection

ependymal cells

cells that line the cns and produce cerebrospinal fluid (csf)

neuron structure

dendrites receive the stimuli → stimuli passes down the axon → schwann cells increase speed of impulse transmission

pns supporting cells

schwann cells and satellite cells

schwann cells

wrap a layer of myelin around axons

satellite cells

separate nervous cells from supporting tissue

basics of cell firing

1. Stimulus opens Na+ gates
2. At threshold depolarization
3. action potential is produced
4. K+ gates open 
5. K+ diffuses out→ repolarization

salatory conduction

increases speed of electrical transmission and saves energy in the transfer of neurological information

3 substances secreted by neurons

1. neurotransmitters
2. neuromodulators
3. neurotrophic factors

neurotransmitters

substances sent out from neurons that produce responses in the body (ex: epi, norepi, dopamine)

neuromodulators

substances that change a cell's response to neurotransmitters (ex: change response to pain)

neurotrophic factors

serve as neuron survival signals and promote development of connections between neurons

sympathetic transmission-impulse one neuron to next

1. neurotransmitter is created/packaged/released from the cell
2. neurotransmitter binds to receptor site of the receiving cell (impulse is transferred to postsynaptic neuron upon binding)


1. neurotransmitter is released for REUPTAKE
2. neurotransmitter diffuses out of synaptic cleft and into the general circulation
3. neurotransmitter is broken down by enzymes (some parts can be taken up again/reused by presynaptic neuron)
3. Reuptake


1. neurotransmitter goes back into the presynaptic neuron after released and is packaged/released/used AGAIN

nervous system development

begins as a hollow tube, then the first segments of the tube become the brain

3 meninges (outer to inner)

1. dura mater: subdural space, bridging veins
2. arachnoid: subarachnoid space (cerebral arteries, CSF)
3. pia mater

3 meningeal spaces

1. epidural space: meningeal arteries
2. subdural space
3. subarachnoid space

2 layers of dura mater

\-first layer conforms to the skull \n -second layer conforms to the brain

falx cerebri

separates the brain hemispheres

tentorium

holds the cerebrum up off the cerebellum

arachnoid layer

\-CSF lies under arachnoid to cushion the brain 

\-Villi poke through the inner layer of the dura

\-Mater into the sinuses to let CSF drain in them

cerebrospinal fluid (csf)

cushions the brain while flowing in subarachnoid space

how is the amount of CSF flowing in the brain controlled?

extensions of the arachnoid (villi) poke through the inner layer of the dura mater into the sinuses that hold the CSF, where the CSF will drain, ensuring that old CSF will drain while new CSF is made

pia mater

holds the cerebral arteries in place and lies on surface of the brain

where is csf created

in the ventricles, via ependymal cells

how does CSF leave the ventricle

through an opening below the cerebellum

where does old CSF go once it has drained out through the Dural sinuses

returned to the heart in general circulation

blood brain barrier (how it works)

foot pods of astroglia wrap around the capillaries of the brain, and for these capillaries, we DON'T want them dropping off ALL of its contents; thus, we have tight junctions that overlap the endothelial cells on the capillary, making things not so easy to come in/out of brain (PREVENTS CAPILLARY PERMEABILITY)

anything that comes out of the capillary within the blood brain barrier must be ______ soluble

LIPID

cerebrum

outer layer of the brain that can override the automatic thinking of the brain

limbic system

system that deals with emotional experience and controls emotional behavior

3 things the limbic system structures are important in providing

1. memory
2. emotion
3. motivation

structures of the limbic system

1. limbic lobe
2. fornix
3. hippocampus
4. olfactory cortex
5. amygdala
6. portions of thalamus

basal ganglia function

1. initiation
2. coordination
3. execution of movement

basal ganglia structures

1. caudate nucleus
2. putamen
3. globus pallidus
4. subthalamic nuclei
5. substantia nigra

diencephalon

area where hypothalamus and thalamus live and wor

hypothalamus

continually monitor the needs of body

thalamus

rea of thinking, integrates information from the body and higher sources of the brain ACTUAL THINKING. WE EXPERIENCE WHAT IT IS TO BE HUMAN!!!!

cerebellum

coordinate movement, posture, and balance

brain stem

1. midbrain
2. pons
3. medulla oblongata

midbrain

coordinates head and eye movement through the use of motor tracts

pons

motor and respiratory tracts, chewing and speech

medulla oblongata

controls basic homeostatic functions; controls unconscious functions (cardiac/vascular and respiratory function); other voluntary/involuntary things such as swallowing, vomiting, coughing, and sneezing

decussation

the major sensory and motor tracts cross over in the medulla to connect with the opposite side of the cerebral cortex

organization of spinal cord

1. dorsal root
2. ventral root

where does information ENTER the spinal cord

dorsal root

dorsal root

afferent and sensory

ventral

efferent and motor

sensory and motor tract

where injury is based on deficit

reflex mechanisms

* Respond to environment 
* Info to the spinal cord via dorsal root
*  Does not consult the brain.

body responses from the stress response

1. increase HR
2. peripheral vasoconstriction
3. activation of sweat glands
4. bronchodilation
5. activates liver to produce more glucose
6. decreased GI/kidney function

parasympathetic nervous system is ran by what

\-CATECHOLAMINES (ex. are epi/norepi; dopamine)

\-ACETYLCHOLINE!! (Ach)

parasympathetic nervous system function

housekeeping (keeps heart rate at normal level, increases work of GI system, increases salivation, etc)

2 pain neurotransmitters

1. glutamate
2. substance P

glutamate

EXCITATORY; acts INSTANTLY; CONFINED to immediate area

substance P

acts SLOWLY; lasts longer; DIFFUSES TO OTHER AREAS; prolongs/enhances glutamate

chronic neuro disorders

1. Epilepsy
2. Headache
3. Pain

epilepsy

chronic neurological disorder characterized by recurrent seizures

seizures

sudden, abnormal, disorderly discharge of neurons within the brain

provoked seizures

can be caused by things like fever, electrolyte imbalance, hypoglycemia, CNS infection or damage

unprovoked seizures

unknown cause

4 epileptic syndromes

1. focal seizures
2. generalized seizures (grand mal)
3. absence (petit mal)
4. status epilepticus

focal seizures

localized in one cerebral hemisphere (one area is overactive and specific symptoms follow)

generalized seizures

involves both hemispheres

absence (petit mal)

disturbances in consciousness (person zones out; cannot interact with environment)

status epilepticus

continuous seizures that don’t stop (MEDICAL EMERGENCY)

ictal period

time of seizure (start to finish)

postictal

time after seizure (person is tired, confused, nauseated, may have amnesia)

interictal

if multiple seizures occur in short time, this is the time between seizures

aura

sensation before a seizure occurs

how to prevent injury during and after seizure

1. move objects out of the way
2. do not physically restrain
3. do not put anything in their mouth
4. afterwards, place patient on left side, turn head in case of vomiting, protect the airway, administer medication

primary motor cortex

programmed patterned, coordinated movement, posture, and positioning

supplementary

planning and initiation of complex, skillful movements

upper motor neuron

in the motor cortex; axons descend in the internal capsule through the white matter of spinal cord

upper motor neuron damage

1. Loss of voluntary motion
2. Spinal reflexes remain intact but cannot be modulated by the brain
3. Increased muscle tone 
4. Hyperreflexia 
5. Spasticity

lower motor neurons

found in SC; send axons through peripheral nerves to the muscles

lower motor neuron damage

people have spontaneous muscle contractions/movements (fasciculations)

death of neurons

Spinal reflexes are lost → Flaccid paralysis → Denervation atrophy of muscles

healthy motor unit

1. One lower motor neuron
2. Neuromuscular junction
3. The muscle fibers it innervates

motor function modulated by basal ganglia

•Upper motor neuron in the motor cortex

•Axons down through the internal capsule

•Basal ganglia inhibit and modulate movement patterns

•Initiation, coordination, and execution of movement

Parkinson’s Disease

progressive loss of dopamine producing neurons in the substantia negra within the basal ganglia, causing imbalance of dopamine and ACH, leading to disturbed movements

clinical manifestations of Parkinson’s

1. Rigidity cogwheel ratchet movements
2. Tremor 
3. Bradykinesia 
4. Dementia
5. Eventually ANS

treqtment of Parkinson’s

* Levodopa 
* Carbidopa 
* Drugs that activate dopamine receptors
* Surgical procedures

amyotrophic lateral sclerosis (ALS; Lou Gehrig’s Disease)

progressive loss of upper and lower motor neurons

symptoms of ALS

* Painless muscle weakness and atrophy
* Sensory neurons and cognitive function remain intact
* Eventually respiratory failure (mechanical venetian)

multiple sclerosis (MS)

chronic demyelinating disorder (loss of myelin sheaths) affecting brain, spinal cord, and optic nerves and is AUTOIMMUNE AND GENETIC IN ORIGIN

MS is characterized by

REMISSIONS and EXACERBATIONS **(**Myelin damage heals during remission)

MS risk factors

genetics, viral process, trauma, women, northern European, cooler climates

MS clinical manifestations

1. Weakness
2. Numbness
3. Balance 
4. Blurred vision 
5. Dysphagia 
6. Cognitive functioning 
7. Depression 

MS treatments

Immunomodulating agents, corticosteroids, immunosuppressants

Huntington’s disease

* Autosomal dominant disease
* Progressive neurological disorder of involuntary motor symptoms, cognitive and psychological decline

symptoms of HD

Symptoms appear between ages 30 to 50, progression to 10-30 yrs