Nervous System Info. Pt 1

Afferent

Other name for sensory division

Efferent

Other name for motor division

Somatic

Division that transmits voluntary commands to skeletal muscles

Autonomic

Division that transmits involuntary commands to viscera

Soma or Perikaryon or Cell Body

Contains nucleus, cytoplasm, organelles, neurofilaments, Nissl bodies

Nissl Bodies

Another name for chromatophilic substance

Dendrites

Branches receptive surfaces, a neuron may have many

Axon

Neuron has only one, transmits impulses and releases neurotransmitters to effectors or neurons

Axon Hillock

Cone-shaped area of soma from which axon arises

Collateral

Branch of axon

Axon terminal

Specialized endings of extensions from axons

Synaptic Knob

Rounded ending of a synaptic terminal

Myelin

Mixture of fats and proteins that fill layers made by Schwann cell membranes

Myelin Sheath

A wrapped coating around some PNS axons; composed of layers of Schwann cell membranes and myelin; acts as electrical insulator

Nodes of Ranvier

Gaps in myelin sheath between Schwann Cells

Unmyelinated Axons

Make up gray matter in CNS

Myelinated Axons

Make up white matter in CNS

Multipolar Neurons

Make up 99% of neurons; most neurons of CNS, some in autonomic NS

Bipolar Neurons

Not common; found in eyes, ears, nose; type of neuron (structural classification)

Unipolar Neurons

Found mainly in ganglia of PNS (structural glassification)

Unipolar and bipolar

Types of neurons that afferent neurons could be (structural classification)

Multipolar

Type of neuron (structural) that interneurons are

Multipolar

Type of neuron that efferent neurons are (structural)

Neuroglia

Provide structural support for neurons, guide neurons into position and stimulate specialization

Neuroglia

Produce growth factors to nourish neurons and remove excess ions and neurotransmitters; aid in synapse creation

Astrocytes

Connect neurons to blood vessels, exchange nutrients and growth factors; form scar tissue; part of BBB; CNS

Astrocytes

Aid in metabolism of certain substances; regulate ion concentration (K+); CNS

Oligodendrocytes

Myelinate CNS axons; provide structural support

Microglia

Phagocytic cells; provide structural support; CNS

Ependymal Cells

Line central canal of spinal cord and ventricles of brain; cover choroid plexus; help regulate CSF composition; ciliated cuboidal or columnar cells

Schwann Cells

Produce myelin in PNS; speed up impulse transmission

Satellite Cells

Support clusters of neuron cell bodies (ganglia); nourish and balance ion concentrations; PNS

Astrocytes

Star-shaped cells between neurons and blood vessels

Oligodendrocytes

Shaped like astrocytes but with fewer processes; in rows along axons

Microglia

Small cells with few processes and found throughout CNS; aid in immune protection

Ependymal Cells

Form porous layer in which substances diffuse between interstitial fluid of brain and spinal cord and CSF

Satellite Cells

Small, cuboidal cells that surround cell bodies of neurons in ganglia

-70 mV

Resting potential inside a neuron (# and unit)

Potassium Ions

Type of ion in a higher concentration inside the neuron during rest

Sodium Ions

Type of ion in higher concentration outside of the neuron at rest

Negative proteins, phosphate, sulfur

3 particles inside neurons that contribute to the negative charge

3

Number of sodium ions that the Na+/K+ pump removes from the neuron

2

Number of potassium ions that the Na+/K+ pump brings into the neuron

Excitatory Stimulus

Opens chemical sodium channels in neuron

Absolute Refractory Period

Threshold stimulus cannot generate another AP; voltage-gated sodium channels briefly unresponsive

Relative Refractory Period

Time when only high intensity stimulus causes AP; repolarization is not yet complete

Saltatory Conduction

APs jump from node to node

Thick

Diameter of axon that conducts the fastest (thick vs thin)

EPSP

Membrane change in which NT opens Na channels

IPSP

Membrane change in which NT opens K+ channels

Summation

EPSP + IPSP

Vesicle trafficking

Membrane recycling of synaptic vesicles

Acetylcholine

CNS: controls skeletal muscle actions

Acetylcholine

PNS: stimulates skeletal muscle contraction at neuromuscular junctions; may excite or inhibit at autonomic NS synapses

Norepinephrine

CNS: creates sense of well-being; low levels cause depression; biogenic amine

Norepinephrine

PNS: may excite or inhibit autonomic NS activities depending on receptors; biogenic amine

Dopamine

CNS: creates sense of well being; biogenic amine

Dopamine

PNS: limited actions in autonomic NS; may excite or inhibit based on receptors; biogenic amine

Serotonin

CNS: Primarily inhibitory; causes sleepiness; action is blocked by LSD; biogenic amine

Histamine

CNS: release in hypothalamus promotes alertness; biogenic amine

GABA, glycine

2 of them; CNS: generally inhibitory; amino acids

Glutamate

CNS: most abundant excitatory neurotransmitter in CNS; amino acid

Enkephalins, endorphins

2 of them; CNS: generally inhibitory; reduce pain by inhibiting substance P release; neuropeptides

Substance P

PNS: excitatory, pain perception; neuropeptide

Nitric Oxide

CNS: may play role in memory; PNS: vasodilation

Clinical Depression

Debilitating, inexplicable sadness; deficient norepinephrine/serotonin

Epilepsy

Seizures, loss of consciousness; excess GABA leads to excess norepinephrine and dopamine

Huntington Disease

Cognitive and behavioral changes, loss of coordination, uncontrollable movements, death; deficient GABA

Hypersomnia

Excessive sleeping; too much serotonin

Insomnia

Inability to sleep; deficient serotonin

Mania

Elation, irritability, overtalkativeness, increased movements; excess norepinephrine

Parkinson’s Disease

Hand tremors, slowed movements, muscle rigidity; deficient dopamine

Schizophrenia

Inappropriate emotional responses, hallucinations; deficient GABA causes excess dopamine

Tardive Dyskinesia

Uncontrollable movements of facial muscles; deficient dopamine

Tryptophan

Stimulates serotonin synthesis; sleepiness

Reserpine

Decreases norepinephrine packaging into vesicles; decreases blood pressure

Curare

Blocks acetylcholine binding; muscle paralysis

Valium

Enhances GABA binding; decreases anxiety

Nicotine

Activates acetylcholine receptors and elevates dopamine; sense of pleasure and increased alertness

Cocaine

Blocks dopamine reuptake; euphoria

Tricyclic Antidepressants

Blocks norepinephrine and serotonin reuptake; antidepressant

Monoamine oxidase inhibitors

blocks enzymatic degradation of norepinephrine in presynaptic neuron; antidepressant

SSRI

blocks serotonin reuptake; antidepressant, anti-anxiety

Dual reuptake inhibitors

blocks serotonin and norepinephrine reuptake; mood elevation

neuromodulator

substance that alters a neuron’s response to a neurotransmitter or blocks the release of an NT

endorphins

Natural opitates

neuronal pools

Groups of interneurons that make synaptic connections with each other and are located within the CNS

Facilitation

Repeated impulses on an excitatory presynaptic neuron may cause that neuron to release more NT than usual

convergence

one neuron receives input from several neurons

divergence

one neuron sends impulses to several neurons via axon branches

antagonist

drug binds to receptor and blocks NT binding

Agonist

drug activates receptor and causes AP or helps NT bind