A progressive disease that begins in the central nervous system and involves the degeneration of motor neurons and the subsequent atrophy of volantary muscle. Also called Lou Gehrig disease.
Ascending tracts
Tracts that carry sensory information to the brain.
Axon
A single enlongated projection from the nerve cell body that transmits impulses away from the cell body.
Brain
The largest and most complex unit of the nervous system, the brain is responsible for preception, sensation, emotion, intellect, and action.
Brainstem
The primitive portion of the brain that contains centers for vital functions and reflex actions, such as vomiting, coughing, sneezing, posture, and basic movement patterns.
Central nervous system
The brain and spinal cord and their coverings.
Cerebellum
The second largest part of the brain, it is involved with balance, posture, coordination, and movement.
Cerebrospinal fluid
A clear, colorless fluid that flows throughout the brain and around the spinal cord, cushioning and protecting these structures and maintaining proper pH balance.
Cerebrum
The largest of the brain divisions, it consists of two hemispheres that occupy the uppermost region of the cranium. It receives, interprets, and associates incoming information with past memories and then trasmits the appropiate motor response.
Dendrites
Branching projections from the nerve cell body that carry signals to the cell body.
Descending tracts
Tracts that carry sensory information from the brain to the spinal cord.
Dorsal root
One of two roots that attaches a spinal nerve to the spinal cord.
Epilepticus
A continous seizure
Essential tremor
A chronic tremor that does not proceed from any other pathologic condition.
Gray matter
Unmyelinated nervous tissue, particularly that found in the central nervous system
Corpus Callosum
located underneath the gray matter and functions to connect the left and right hemispheres
Monoplegia
Paralysis of a single limb or a single group of muscles.
Myelin
A white, fatty, insulating substance formed by the Schwann cells that surrounds some axons. Also produced in the central nervous system by oligodendrocytes
Neurilemma
The outer cell membrane of a Schwann cell that is essential in the regeneration of injured axons.
Neurons
Nerve cells that cinduct impulses
Sensory neurons:
known as afferent neurons are neurons that are activated by sensory input and send projections into the central nervous system that convey sensory information to the brain or spinal cord. activated by physical modalities
Motor neurons
(or motoneuron) classically applies to neurons located in the CNS that project their axons outside the CNS and directly or indirectly control muscles. Motor neuron is often associated with efferent neuron, primary neuron, or alpha motor neurons.
Interneurons
(also called relay neuron, association neuron or local circuit neuron) is a multipolar neuron which connects afferent neurons and efferent neurons in neural pathways. Like motor neurons, interneuron cell bodies are always located in the CNS.
Neurotransmitters
Chemical compounds that generate action potentials when released in the synapses from presynaptic cells
Paraplegia
Paralysis of the lower portion of the body and of both legs.
Quadraplegia
Paralysis or loss of movement of all four limbs
Schwann cell
A specialized cell that forms myelin
Spinal cord
Portion of the central nervous system that exits the skull into the vertebral column. The two major functions of the spinal cord are to conduct nerve impulses and to be a center for spinal reflexes.
Synapse
Spaces between neurons or between a neuron and a effector organ.
Tracts
Collections of nerve fibers in the brain and spinal cord with a common function
Ventral root
One of two roots that attaches a spinal nerve to the spinal cord. One of two roots that attaches a spinal nerve to the spinal cord. One of two roots that attaches a spinal nerve to the spinal cord.
White matter
Myelinated nerve fibers, particularly those found in brain and spinal tissue.
Acetylcholine
Stimulates the skeletal muscles and primarily acts on the parasympathetic nervouse system. Plentiful in the brain, the chemical is involved in memory
Catecholamines
Neurotransmitters involved in sleep, motor funtion, mood, and pleasure.
Epinephrine
Involved in the fight or flight responses such as dilation of blood vessels to the skeletal muscles and is classified as a hormone when secreted by the adrenal gland.
Norephinephrine
Causes constriction of skeletal blood vessels, is considered a "feel good" neurotransmitters, and is involved in emotional repsonses
Dopamine
Generally excitatory, is found in the brain and ANS. A feel-good neurotransmitter. Is involved in emotions and moods and int the regulation of motor control and the executive funtioning of the brain. Release is enhanced by L-dopa and amphetamines.
Histamine
Considered a stimulant, it is released by the mast cells as part of the inflammatory process. It causes itching at a cellular level and also works as a vasodilator. It also stimulates pain receptors to sensitize agains further stimulation (sunburn)
Serotonin
Works as an inhibitor in the CNS and is synthesized into melatonin and affects our biologic cycles, sleep, and moods. Feel good neurotransmitter
Cholecystokinin
Found in the brain, retina, and gastrointestianl tract, the function in the nervous system is uncertain and may be related to feel good behavior. Is a gut-brain peptide
Endorphins & Enkephalins
These endogenous morphines block the brain from feeling pain. They inhibit pain by inhibiting substance P. Morphine and herion mimic their effects. They seem to play a part in mood regulation
Gamma-aminobutyric acid
Generally inhibitory and found in the brain, this acid is the most common inhibitory neurotransmitter in the brain.
Glutamate (glutamic acid)
Generally excitatroy an dfound in the CNS, is thought to be responsible for as much as 75% of the excitatory signals to the brain
Somatostatin
Generally inhibitory, it inhibits the release of growth hormone and is a gut-brain peptide
Substance P
Is excitatory and is found in the brain, spinal cord, sensory pain pathways, and gastroinstestinal tract. Transmits pain information Is excitatory and is found in the brain, spinal cord, sensory pain pathways, and gastroinstestinal tract.
Vasoactive Intestinal Petide
Found in the brainstem, some ANS and sensory fibers, retina, and gastrointestinal tract; the function of this peptide iin the nervous system is uncertain.
Depolarization
is a decrease in the absolute value of a cell's membrane potential. Thus, changes in membrane voltage in which the membrane potential becomes less positive or less negative are both depolarizations. In neurons and some other cells, a depolarization large
Membrane potential
when a neuron is positively charged on the outside of the cell membrane and negatively charged on the inside.
Refractory Period
the brief period after inhibition when the neuron recovers.
Parietal lobe
primary area of the brain that would process the pain/pleasure aspect of massage
Ventricles
Four pockets or spaces in the brain
Right hemisphere
Contains sensory and motor pathways for the left side of the body
Left hemisphere
Contains sensory and motor pathways for the right side of the body
Frontal lobe
Responsible for personality, judgment, planning, and speech; contains the motor cortex
Motor cortex
Initiates movement of skeletal muscles
Sensory cortex
Detects general sensory impulses from the skin
Temporal lobe
Contains auditory and olfactory areas, stores memories of auditory and visual experiences
Occipital lobe
Contains visual area for interpreting impulses from the eye
Insular lobe
Integrates cerebral activities, may also assist in memory
Integrative functions
activities that occur in the cerebrum after sensory signals are received and before motor responses are sent
Reticular Activating System
consists of centers in the brainstem that receive impulses from the spinal cord and relay them to the thalamus
Limbic system:
located on the interior of the cerebrum and is important in our emotional responses, including fear, rage and pleasure
Engrams:
structural traces in the cerebral cortex that involves protein synthesis and physical brain changes that support long term memory
Medulla oblongata
brain area that functions to regulate vital life functions such as heart rate, blood pressure and breathing
Peripheral nervous system
All of the nervous system except CNS
Somatic nervous system
Nerves that control skeletal muscle contractions
Autonomic nervous system
Nerves that control smooth muscle, cardiac muscle, internal organs, and glands
Sympathetic nervous system
Prepares the body for stress, the "fight or flight system"
Parasympathetic nervous system
Prepares the body for rest, the "rest and digest system"
Meninges
Three layers of tissue that surround the CNS
Dura mater
Thickest, most external layer of meninges
Arachnoid membrane
Delecate web-like middle layer of meninges
Pia matter
Thin, vascular, innermost layer of meninges
Thalamus
Sorts out incoming sensory impulses (except smell) and directs them to the proper areas of the cerebral cortex, also filters stimuli
Hypothalamus
Controls pituitary, regulates water and eletrolyte balance, hunger, temperature, sleep, sexual response, and emotions
Dorsal horns
Gray matter in the spinal cord that extends posteriorly
Ventral horns
Grey matter in the spinal cord that extends anteriorly
Reflex arc
Route followed by nerve impulses to provide protective response to potentially harmful stimulus
Receptor organ
Organ that contains dendrites and receives stimulus
Effector organ
Organ that produces or carries out a response
How many cranial nerves are there?
12
How many pairs of spinal nerves are there?
31
How many pairs of cervical nerves are there
8
How many pairs of thoracic nerves are there?
12
How many pairs of lumbar nerves are there
5
How many pairs of sacral nerves are there
5
How many pairs of coccygeal nerves are there?
1
Dorsal root
Nerve root that protrudes posteriorly from the spinal cord
Dorsal root ganglion
Collection of sensory nerve cell bodies outside of the dorsal
Ventral root
Nerve root that protrudes anteriorly from the spinal
Dermatome
Sensory area of the skin innervated by a particular spinal nerve
Nerve plexus
Network of interconnecting nerves
Cervical plexus
Nerve roots C1-C4 and part of C5; Provides sensory innervation for skin around the head, neck, and shoulders along with motor innervation for some of the muscles
Brachial plexus
C5-T1 and sometimes portions of C4 and/or T2; Provides sensory and motor innervation for the upper extremity and some neck muscles, gives rise to the axillary nerve, musculocutaneous nerve, radial nerve, median nerve, and ulnar nerve Lumbosacral plexus
Nerve roots L1-S4
Provides sensory and motor innervation for the lower extremities and gives rise to the obturator nerve, femoral nerve, and sciatic nerve Special sensory Smell, taste, vision
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