Human bio nervous system terms

central nervous system

part of the nervous system made up of the brain and spinal cord

peripheral nervous system

part of the nervous system made up of nerves outside the cns

sensory (afferent) division

division of the pns composed of nerves that carry information to the cns

motor (efferent) division

division of the pns composed of nerves that carry information from the cns

somatic division

part of the motor division responsible for conscious or voluntary control of skeletal muscles and reflexes

autonomic division

part of the motor division responsible for automatic or involuntary responses

neuroglia

cells of the nervous system that insulate, support, and protect delicate neurons

neurons

nerve cells

dendrites

fibers that receive and convey message to the cell body of a neuron

cell body

the metabolic center of a neuron; contains the nucleus

axon

neuron fibers that conduct impulses away from the cell body

myelin

white, fatty material found in neuron coverings

myelin sheath

covering composed of Schwann cells that insulates nerve fibers and increases the rate of transmission

schwann cell

cells that are wrapped around axons; produce myelin

node of ranvier

gaps along the axon that are not covered by myelin sheath; impulses jump from node to node

axon terminal

branching end of an axon; responds to a nerve impulse by releasing neurotransmitters from vesicles

synapse

the space between an axon terminal and the membrane of the next cell

white matter

bundles of myelinated axons in the brain and spinal cord

gray matter

unmyelinated and tightly-packed neuron cell bodies

sensory neuron

type of neuron that carries impulses from receptors to the CNS

interneuron

type of neuron that connects sensory and motor neurons in the CNS

motor neuron

type of neuron that carries impulses from the CNS to a muscle or gland

proprioceptors

sensory receptors in muscles and tendons that detect stretch or tension in skeletal muscles, tendons, and joints; maintain balance and posture

irritability

functional property of a neuron that enables it to respond to a stimulus and convert it into a nerve impulse

conductivity

functional property of a neuron that enables it to transmit an impulse to other neurons, muscles, or glands

resting potential

the charge on a nerve cell membrane at rest that gives it the potential to react to a stimulus

polarized

the difference in charge across a nerve cell due to the presence of fewer positive ions along the inside of the membrane than along the outside of the membrane

depolarization

occurs when a stimulus temporarily changes the permeability of the neuron membrane and sodium ions rush into the cell; membrane polarity is changed

action potential

if the stimulus is strong enough to cause a large influx of sodium ions the depolarization will activate a nerve impulse or action potential

all-or-none response

an action potential will travel along the entire length of the neuron or it doesn't happen at all; there is no partial response

repolarization

the restoration of the negative charge on the inside of the membrane that occurs immediately after an action potential; membrane becomes impermeable to Na+ ions and K+ ions diffuse out

sodium-potassium pump

Membrane channel that uses atp to actively transport na+ and k+ ions to the original ionic state of the resting potential

neurotransmitters

chemicals released from vesicles at the axon terminal that diffuse across the synapse to carry the nerve impulse to the next cell

reflex

a rapid, predictable, involuntary response to a stimulus that protects the body

reflex arc

pathway of a reflex to the spinal cord where an immediate response is sent

cerebrum

the largest and most superior part of the brain; composed of two hemispheres

longitudinal fissure

the anterior-posterior division between the two hemispheres of the cerebrum

gyri

elevated ridges of tissue on the surface of the cerebrum

sulci

shallow grooves of on the surface of the cerebrum

cerebral cortex

outermost layer of the cerebrum composed of gray matter; responsible for thinking and processing information from the five senses

frontal lobe

most anterior section of the cerebrum; involved in motor function, problem solving, memory, language, etc.

parietal lobe

section of the cerebrum over the parietal bone; processes sensory information such as touch, temperature, and taste

temporal lobe

section of the cerebrum over the temporal bone, inferior to the frontal and parietal lobes; responsible for auditory and olfactory perception

occipital lobe

most posterior section of the cerebrum; responsible for visual processing

corpus callosum

large fiber tract that connects the two cerebral hemispheres; allows communication between the two sides of the cerebral cortex

diencephalon

area of the brain superior to the brainstem that includes the thalamus, hypothalamus, and epithalamus

brain stem

connects the brain to the spinal cord; 3 areas are midbrain, pons, and medulla oblongata; controls breathing, heart rate, and blood pressure

cerebellum

section of the brain with parallel surface grooves, inferior to the occipital and temporal lobes; responsible for balance, equilibrium, and coordination

meninges

protective connective tissue membranes around the brain and spinal cord; dura mater, arachnoid mater, and pia mater

cerebrospinal fluid

fluid formed from plasma in brain cavities called ventricles; provides a watery cushion for the CNS

blood-brain barrier

physical barrier formed by very impermeable capillaries in the brain; protects neurons from blood-borne substances

endoneurium

connective tissue around each neuron

perineurium

connective tissue around each group of neurons or fascicle

epineurium

connective tissue around each nerve

fascicle

bundle of nerve cells (or muscle cells)

spinal nerves

31 pairs of nerves exit from the vertebral column

plexus

complex networks of spinal nerves that serve motor and sensory needs of the limbs

cranial nerves

12 pairs of nerves that originate in the brain and serve primarily the head and neck

autonomic nervous system

motor subdivision of the pns that automatically controls body activities such as heart rate, digestion, perspiration, etc.

sympathetic nervous system

part of the ans that mobilizes the body during extreme situations; active during fear, exercise, rage, etc.

parasympathetic nervous system

part of ans that allows us to unwind and conserve energy; most active when the body is at rest

fight-or-flight

action of the sympathetic nervous system that prepares the body to either fight or run from a threat

traumatic brain injuries

occurs when an external force injures the brain; falls, auto accidents, and violence are most common causes

concussion

mild tbi caused by a jolt, bump, or blow to the head that causes the brain to move rapidly inside the skull

meningitis

acute inflammation of the meninges usually caused by viral or bacterial infection; most common symptoms are severe headache and neck stiffness

multiple sclerosis

autoimmune disease that occurs when the myelin sheath is destroyed and hardens into "scleroses" which distort and interrupt nerve impulses; no cure

alzheimer's disease

mental illness caused by progressive brain cell death that worsens over time; leads to problems with memory, thinking, and behavior

parkinson's disease

motor system disorder that leads to trembling of the hands, arms, legs, etc. and impaired balance and coordination; results from a loss of brain cells in an area the midbrain called the substantia nigra

paralysis

loss of ability to move or feel anything in all or part of the body; usually results from stroke or spinal cord injury

stroke

death of brain cells that occurs when an area of the brain is deprived of oxygen due to poor blood flow; may be ischemic (clot) or hemorrhagic (bleeding)