Pathophysiology (neural function)

PNS is divided into

Somatic motor division and autonomic division

_____ controls the skeletal muscles

Somatic motor division

Autonomic nervous system is divided into

Sympathetic- Stimulatory

Parasympathetic- Inhibit branches that function to maintain homeostasis

Impulse transporting cell TO the spinal cord/brain

Afferent (sensory)

Impulse transporting cell AWAY from the spinal cord/brain

Efferent (motor)

-Myelinate neurons in the PNS

-A discontinuous wrapped protective covering around some axons of the PNS

Schwann cells

-Myelinated cells are separated by this

-Promotes salutatory propagation

-Because of the myelin, impulses move at greater speeds down the axon, jumping from one node to the next, much like stones skipping across water

Nodes of Ranvier

Carries impulse away from the cell body

Axon

Information gathering, carries impulse to the cell body

Dendrite

Cell body, perikaryon

Somite

Star shaped, aid in metabolism

Astrocytes

Form myelin in the brain and spinal cord, in CNS

Oligodendrocytes

Phagocytes dispose of debris

Microglia

Line the cavities of the brain/spinal cord and their cilia help to circulate CSF (also a source of neural stem cells)

Ependymal

-Point at which nerve meets the target (organ, muscle) to convey information

-Gaps between the neurons

Synapse

Presynaptic cell

Transmitting neuron/terminal button

Space between neurons

Synaptic cleft

Postsynaptic neuron

Neuron that receives the signal

Resting potential

-AKA "steady state"

-An equal number of + charge and - charged ions

Positive charge/resting states

Polarized

-More positive charge

-Sodium ion channels open

-Excitatory postsynaptic potential

Depolarized

-More negative charge

-Potassium ion channels open

-Inhibitory postsynaptic potential

Repolarized

Function of brain blood barrier

-Separate neurons from blood-borne substances

-Against fluctuations in hormones/neurotransmitters

-Protects against bacteria and plant toxins

What 3 things does the BBB not block?

Alcohol, nicotine, anesthetics

Chemical messengers

Neurotransmitters

-Located in CNS/PNS

-Learning and memory

-Controls skeletal muscle actions

Acetylcholine

Examples of catecholamines

Dopamine (Reward circuits)

Norepinephrine (Arousal)

Epinephrine (adrenaline)

T or F, Dopamine and norepinephrine are located in CNS and PNS

True

This is associated with Substantia Nigra (Parkinsons disease) and involved with fine motor movement

Dopamine

-Located in CNS

-Inhibitory, leads to sleepiness

Serotonin

-Located in CNS

-Release in hypothalamus and promotes alertness

Histamine

Anxiety disorders; epilepsy; major inhibitory neurotransmitter in the brain, located in CNS

GABA (Gamma aminobutyric acid)

Learning; major excitatory neurotransmitter in the brain, located in CNS

Glutamate

-Located in CNS

-Reduce pain

Enkephalins/endorphins

-Located in PNS

-Excitatory and associated with pain awareness

Substance P

-Class of metabotropic G protein receptors (GPCR) that are targets of the catecholamines

Adrenergic

A adrenergic excitation

Causes vasoconstriction (skin, kidneys, and splanchnic circulation)

B adrenergic excitation

Causes vasodilation (heart, kidneys, skeletal muscle)

-Sensors located in the blood vessels

-Type of mechanoreceptor that detects pressure of blood flow

-Can increase or decrease peripheral resistance and cardiac output

Baroreceptor

-Send signals to CNS

-Activate a G protein when bound to extracellular Ach

Cholinergic

-Cholinergic receptors that form ligand-gated ion channels in plasma membranes or neurons on the postsynaptic side of the neuromuscular junction

-Found in the autonomic ganglia and end-plates of skeletal muscle

Nicotinic-acetylcholine receptors nACHRs

Taste and smell

Chemoreceptors

Impaired sense of smell

Hyposmia

Loss of smell

Anosmia

Abnormal or perverted sense of smell

Parosmia

Decreased sense of taste

Hypogeusia

Absence of taste

Ageusia

Pressure, movement, hearing, and vibration

Mechanoreceptors

Associated with changes in body positioning

Proprioceptors

Unspecialized nerve cell endings that initiate the sensation of pain

Nociceptors

Organ, lining of body cavities (throbbing, gnawing pain)

Visceral

Deep muscle pain

Deep somatic

Continued stimulation causes pain

Hyperpathia

Spontaneous, unpleasant sensations, stabbing onset of pain

Paranesthesia

Distortions of somesthetic sensation

Dysesthesia

Reduced pain sensation

Hypalgesia

Pain after nonnoxious stimulus (not normally painful)

Allodynia

Open spine, vertebral arche doesn't fuse

Spina bifida occulta

If meninges come out _____ if both cord and meninges come out ____

Meningocele, myelomeningocele

-Herniation of cerebellum and medulla into spinal canal

-Occurs when skull is too small or abnormally shaped

-Effect of hydrocephalus

Arnold-Chiari Syndrome

-Degenerative disorder of the substantia nigra of the basal ganglia

-Tremor, rigidity, bradykinesia, and dopamine depletion

Parkinson disease

-Demyelination disorder characterized by inflammation selective destruction of the CNS myelin

-Autoimmune disorder/inherited

-Causing progressive and irreversible demyelination of brain, spinal cord, and cranial nerve neurons

-Unsteady gait, muscle weakness/spasm, paranesthesia, tremor, lack of coordination

Multiple Sclerosis

-Excess CSF accumulates, dilating the ventricles and compressing the brain and blood vessels

-Most common after the age of 60 and usually results from enlarged ventricles without increased cerebral pressure

-Common condition present at birth

Hydrocephalus

-Benign tumor of the choroid plexus

-Increase in CSF/pressure and leads to subarachnoid bleed or meningitis

Communicating hydrocephalus

-Prevention of CSF to reach subarachnoid space

-Most common cause is blockage of the sylvius in children

Non-communicating hydrocephalus

-Blood clot between the bone and dura

-Rapid bleeding of meninge arteries, unconsciousness, lucid periods

Epidural hematoma

-Is a complex cascade of events that results in increased blood pressure. When the mean arterial pressure drops below the ICP, the hypothalamus increases sympathetic stimulation

Cushing reflex

If unresolved, the increased ICP eventually leads to a trio of effects known as

Cushing triad

-Bradycardia, hypertension, and changes in RR

What is a feared complication of increased CSF?

Brain herniation

-Rupture of the bridging veins between the dura and arachnoid

-Onset is over days to weeks

-Fluctuating consciousness and dementia if left untreated

Subdural hematoma

-Inflammation of the subarachnoid space, usually resulting from an infection

-Most often caused by viral infections associated with enterovirus, West Nile virus, influenza, human immunodeficiency virus

Meningitis

-Inability to flex the neck forward due to rigidity of the neck muscles

-Associated with headache and fever

Nuchal rigidity

Bacterial infection which causes inflammation of the meninges and contains pus

Purulent

Usually a viral infection of the meninges and is aseptic

Lymphocytic

-Caused by a genetically programmed degeneration of neurons in the brain

-Autosomal dominant disorder that is inherited

-Leads to atrophy of the brain

-Defect on chromosome 4

-Antisocial behavior, hallucinations, paranoia, psychosis, irritable, apathetic, passive, depressed, or angry.

Huntington disease

-Acquired chronic autoimmune disease mediated by antibodies against the acetylcholine receptor at the postsynaptic membrane of neuron junctions

-Weakness of the voluntary skeletal muscles because of inadequate nerve stimulation

-Facial paralysis, drooping head, fatigue, dysphagia

Myasthenia Gravis

-Caused by herpes zoster virus affecting sensory ganglia and peripheral nerves

Shingles (postherpetic neuralgia)

-Acute inflammatory demyelinating disease involving the PNS

-Autoimmune etiology often preceded by a viral infection, immunization, or allergic reaction

-Life threatening polyneuropathy

Guillian Barre Syndrome

The PNS contains ____ cells that separate nervous cells form supporting tissue

Satellite cells

Regulate ion content in the ICF

Astroglia

Tracks of myelinating cells and damage to these cells will cause MS and interferes with transmission of nerve signals

Oligodendroglia

Stationary cells but use cilia to "sweep"

Ependymal

White matter =

Gray matter =

W- Myelinated

G- Unmyelinated

Catecholamines (sympathetic) attach to ____ receptors

Adrenergic

Acetylcholine (parasympathetic) attach to __ receptors

Cholinergic

Attach to receptors and change response to neurotransmitters

Neuromodulators

A1

A2

B1

B2

A1- Vasoconstriction

A2- Negative feedback, stop neurotransmitter release

B1- Speed/strength of heart (pump o2 to body)

B2- Bronchodilation

Slow heart, stimulate GI tract, and vasodilate

Muscarinic receptors

Dorsal

Afferent/sensory

Ventral

Efferent/motor

Large myelinated, fast pain, impulse travels quickly, and release glutamate

A-delta nerve fibers

Small, non-myelinated, slow impulse, and release sub P (pain awareness)

C Fibers

Ischemic stroke vs hemorrhagic stroke

I- Large vessl and impairs blood flow

H- Slow bleed

Sudden onset of headache with nausea, vomiting, and dizziness

Aneurysm

Sudden onset of severe headache, neck stiffness, photophobia, vision/motor problems

Hemorrhage

-Dysfunction of certain area of brain

-Seizures, hallucinations, weakness, sensory deficits

Focal disturbance brain tumor

-Increase intracranial pressure, headache, vomiting, and visual problems

Generalized disturbance brain tumor

Generalized epileptic syndrome vs partial

G- Involves both hemispheres

P- Being in 1 cerebral hemisphere

Secondary- Being in 1 hemispheres and spread

-Are short in duration, strictly unilateral, and associated with autonomic features

-Common in young males who smoke

Cluster headache

-Is a progressive disease that involves damage to the upper motor neurons of the cerebral cortex and lower motor neurons of the brainstem and spinal cord that control voluntary muscle movement

-The nerves lose their ability to trigger muscle movement, resulting in muscle weakness, disability, paralysis, and death usually as a result of respiratory failure

Amyotrophic lateral sclerosis (ALS)