Neurology terminology

Nerve

Bundles of cables, whiteish fibers of neuron cells- carry efferent and afferent to and from CNS. Composed of nerve fibers, blood vessels, lymphatics. Conducting zone for transporting signals.

Cranial nerves, spinal nerves, sensory nerves, motor nerves

Neuron

Functional Unit of the nervous system involved with transmitting impulses

Found in both PNS and CNS

Generates chemical and electrical signals

High requirement for oxygen, uses exclusively glucose for energy. Lack of reproductive ability can regenerate if the cell body is intact.

Sensory neurons, motor neurons, interneurons

Dendrite

"Satellite Dish" of the neuron, this is found growing from the soma.

cell body (soma)

Soma, Perikaryon, Body of the Neuron, this contained important structures that cannot fit elsewhere.

Perikaryon

Soma, Cell body, Body of the Neuron, this contained important structures that cannot fit elsewhere.

Axon

Longest portion of a neuron,

myelin sheath

Fatty Sheath, Cell membrane of oligodendrocytes (CNS), and Schwann (PNS). They function to enhance conductions of nerve impulses

myelinated axons

Allows the message to pass through the Axon much faster ( Leap Frog ). Prevents sodium from crossing the cell membrane,

non-myelinated axons

Continuous conduction across Axon, Slower than Myelinated

Nodes of Ranvier

Gaps in Myelin Sheath, Depolarized region

saltatory conduction

Depolarization can only occur at nodes of Ranvier, rapid conductions of the action potential

axon terminal

The endpoint of a neuron where neurotransmitters are stored

synaptic knob

Increase the surface area of the telodendrions

Synapse

Junction between two neurons ( or neuron and target cells)

pre-synaptic neuron

"Sending" Cell, Action potential moves through this pre synaptic cell and goes to the synapse. Ca influx, neurotransmitter release, receptors on post-synaptic neuron, synaptic transmission.

post-synaptic neuron

"receiving" Cell, Action Potential is obtained from the Synapse and continues the action

Interneurons

neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and motor outputs

Target cell

cell that has a receptor for a particular hormone

synaptic cleft

Gap in Synapse, electrical message cannot cross but a chemical message can ( neurotransmitters)

Action potential (AP)

Wave of depolarization down the cell membrane- conduction of the AP, nerve impulses.

All or nothing principle, it can not go backwards.

impluse

Firing

Nerve impulse conductions- Sudden change of nerve potential

Depolarization

Na channels open where the stimulus occurs on the neuron, passive diffusion. Na moves to the inside of the cell. This is caused by sudden influx of Na causing loss of membrane potential.

Repolarization

Na Channels Shut, K Channels open, passive diffusion- results in concentration gradient and electrical charge. K moves to the outside of the cell. Shift of membrane potential back toward the negative polarized state. At the end of repolarization, Na and K are concentrated at the wrong side of the cell membrane

Hyperpolarization

The movement of the membrane potential of a cell away from rest potential in a more negative direction.

resting state

Cell membrane working to maintain electrical polarization. Sodium-potassium pumps, ATP, 2K in Na out.

inside cell is more negatively charged

resting membrane potential

the electrical charge of a neuron when it is not active

Stimulus

threshold

The threshold must be reached in order for the neuron to fire.

absolute refractory period

time during which another action potential is impossible; limits maximal firing rate

Relative refractory period

the period of time following an action potential, when it is possible, but difficult, for the neuron to fire a second action potential, due to the fact that the membrane is further from threshold potential (hyperpolarized)

Neuroglia (glial cells)

Support the neuron, Glia=Glue

Astrocytes

CNS Maintain Blood Brain Barrier

Controlling levels of neurotransmitter around synapses, regulate ion, and providing metabolic support

ependymal cells

CNS Line spinal Cord & Ventricles of the brain. Involved in producing CSF.

Oligodendrocytes

CNS Myelinate CNS Axons, provide structural framework

Schwann cells

Myelinated Neurons in PNS, maintain and regeneration of neurons after injury.

central nervous system

CNS, Central axis of body, Brain and spinal cord

peripheral nervous system

PNS, Away from the central axis of the body, includes, cranial nerves, spinal nerves, and others

Sensory nerve

Afferent nerve, impulses from periphery to CNS

Motor nerve

Efferent Nerve, Impulses from CNS to Periphery

Mixed nerve

Most nerves of PNS Having both Motor and sensory nerves

afferent nerve fibers

axons that carry information inward to the central nervous system from the periphery of the body

Efferent nerve fibers

Axons that carry information outward from the central nervous system to the periphery of the body.

crainial nerves

12 pairs that attach to brain

spinal nerves

carry impulses to and from the spinal cord

nerve tracts

bundle of parallel axons within CNS, "white matter"

automatic nervous system

ANS, Automatic Contol of smooth muscle, cardiac muscle, glands. Afferent- Automatic sensory function (temp)

Efferent- Automatic motor function ( Hair standing )

( Internal environment effects )

Somatic nervous system

SNS, Conscious ( voluntary ) control of skeletal muscle.

Afferent- somatic sensory function, muscles, skin, eyes, ears- conscious perception

Efferent- Somatic Motor function

(External Environment effects)

repolaization

Potassium channels open, so K+ ions move out of the cell due to diffusional force. Inside is negative, and outside is positive.

Resting state

the state in which there is a negative electrical charge of about -70 millivolts within a neuron

resting membrane potential

An electrical potential established across the plasma membrane of all cells by the Na+/K+ ATPase and the K+ leak channels. IN most cells, the resting membrane potential is approximately -70 mV with respect to the outside of the cell.

sympathetic nervous system

a set of nerves that prepares the body for action in challenging or threatening situations

thoracolumbar system

alternate name for the sympathetic division of the autonomic nervous system that is based on the anatomical location of central neurons in the lateral horn of the thoracic and upper lumbar spinal cord

parasympathetic nervous system

a set of nerves that helps the body return to a normal resting state

Neurotransmitters

chemical messengers that cross the synaptic gaps between neurons

excitatory neurotransmitters

Open Na Channels, Goal is to depolarization of post-synaptic membrane- action potential

inhibitory neurotransmitters

Open Cl(into cell) and K Channel(out of cell). Goal hyperpolarize post synaptic membrane- no action potential

synaptic transmission

The relaying of information across the synapse by means of chemical neurotransmitters.

Acetylcholine

ACH- Both Excitatory and Inhibitory, Stimulates skeletal and smooth muscle contraction. Inhibits cardiac muscles via parasympathetic nerve

Catecholamines

hormones secreted by the adrenal medulla that affect the sympathetic nervous system in stress response

Epinephrine

EPI- Excitatory, fight of flight- sympathetic nervous system. " adrenaline"- from adrenal medulla

Norepinephrine

NOEPI- Excitatory arousal, fight or flight- sympathetic nervous system.

Dopamine

Both Excitatory and inhibitory, Stimulates growth hormone, inhibits unnecessary movements (e.g. Parkinsons disease with decreased # of dopamine neurons) and certain hormone secretion from pituitary gland

Gamma-aminobutyric acid (GABA)

Brain only- inhibitory Reduces neuronal excitability. Found in brain receptors activated by diazepam.

Glycine

Inhibitory- reduced neuronal excitablility, found in brain stem , spinal vord

Acetycholinesterase

AChE- breaks down acetylcholine, products reabsorbed by synaptic knob are reassembled and wait for next action potential in vesicles

What if acetylcholinesterase is inhibited, such as with organophosphate toxicity?

Persistent stimulation of receptors -> cholinergic crisis

SLUDGM- Salvation, Lacrimation, Urination, Diarrhea, GI pain/upset/nausea, emesis muscle twitching. the twitching leads to dyspnea, miosis muscle fasciculations, seizures.

Monoamine Oxidase Inhibitors (MAOIs)

antidepressant medications that increase the amount of monoamine neurotransmitter in synapses

Monoamine Oxidase

MAO- Breaks down Serotonin, NOREPI, Dopamine

White matter

Lots of Myelinated Fibers= Fat is light

Gray matter

Lots of neuron Cell bodies

Brain

Contains- Cerebrum, Cerebellum, Diencephalon, Brainstem, meninges, cerebrospinal fluid, blood brain barrier, Cranial nerves

Meninges

connective tissue layers surrounding brain/spinal cord. Nutrient and Oxygen supply, cushioning

Cerebrum

Largest part of the brain in domestic animals, area of learning, intelligence

Cerebellum

Second largest part, grey matter cortex with white matter underneath. Coordinates movement, balance, posture, complex reflexes

Diencephalon

Passageway between cerebrum and brainstem- contains Thalmus, Hypothalamus, and pituitary gland

Hypermetria

If Cerebellum damaged/disease- jerky, exaggerated movements

gyrus (gyri)

Grooves- separated by fissures and sulci

Longitudinal Fissure

Divides into left and right side of the brain.

Fissures

deep grooves in the brain

sulcus (sulci)

Divides hemispheres into lobes

corpus callosum

Communication between L& R side of brain

Lobes

4 lobes in the brain- Frontal- Parietal, Occipital, temporal lobes

hemisphere

Half of the brain, separated by longitudinal fissure

Left Hemispheres

Receives sensory information from the right side of the body. provides motor control to the right side of the body.

Right Hemispheres

Receives sensory information from left side of the body, Provides motor control to the left side of the body

Contralateral

on the opposite side of the body from another structure

Ipsilateral

on the same side of the body as another structure

cerebrospinal fluid

CSF- Fluid between layers of meninges in canals/ventricles of brain and spinal cord, Shock absorber (ponds of fluids) influences automatic functions- respiration, vomiting.

Blood-Brain Barrier

Tightly constructed capillary walls ( NO leaks, NO fenestrations) Gial cells add additional support and barrier. Prevents drugs, proteins, ion, ect, passing from blood to brain. Infection can happen if the barrier is weak.

Hypermetria (hypermetric gait)

Thalamus

Regulates sensory input to the cerebrum

Hypothalamus

Nervous system-endocrine system interface, Temp control, thirst, hunger, anger response

pituitary gland

(hypophysis) Endocrine system- "master Gland"

Brainstem

Connection between the spinal cord and the rest of the brain, most primitive part. - automatic control of the cardiovascular system, respiration, swallowing, vomiting. Origin of most cranial nerves

-Medulla oblongota, Pons, Midbrain

medulla oblongata

Part of the brainstem that controls vital life-sustaining functions such as heartbeat, breathing, blood pressure, and digestion.

Pons

A brain structure that relays information from the cerebellum to the rest of the brain

Midbrain

Region between the hindbrain and the forebrain; it is important for hearing and sight.

encephalitis

inflammation of the brain

dura mater

Tough fibrous, outside