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52 terms

Ch. 48-49

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effector cells
the muscle cells or gland cells that actually carry out the body's responses to stimuli.
nerves
neural "cables" containing many axons. These bundled axons, which are part of the peripheral nervous system, connect the central nervous system with muscles, glands, and sense organs
neurons
cell that carries messages throughout the nervous system
cell body
largest part of a typical neuron; contains the nucleus and much of the cytoplasm
dendrites
branching extensions of neuron that receives messages from neighboring neurons
axons
a part of a neuron that carries impulses away from the cell body
myelin sheath
a layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next
schwann cells
Supporting cells of the peripheral nervous system responsible for the formation of myelin.
synapse
the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron
sensory neurons
neurons that carry incoming information from the sense receptors to the central nervous system
interneurons
Central nervous system neurons that internally communicate and intervene between the sensory inputs and motor outputs
reflex
a simple, automatic, inborn response to a sensory stimulus, such as the knee-jerk response
motor neurons
neurons that carry outgoing information from the central nervous system to the muscles and glands
glia
cells that support, nurture, and insulate neurons, remove debris when neurons die, enhance the formation and maintenance of neural connections, and modify neuronal functioning
excitable cells
Neurons and muscle fibers. These cells exhibit electrical excitability which is the ability to respond to certain stimuli by producing electrical signals such as action potentials. Action potenitals propagate along a nerve or muscle plasma membrane to cause a response. ( i.e. release of nuerotransmitters, muscle contraction)
resting potential
the potential difference between the two sides of the membrane of a nerve cell when the cell is not conducting an impulse
depolarization
sodium rushes into neuron through membrane, potassium ruses out; results in a change in charge
pons
part of the brain, works with the cerebellum in coordinating voluntary movement; neural stimulation studied in activation synthesis theory may originate here
action potential
a neural impulse; a brief electrical charge that travels down an axon. the action potential is generated by the movement of positively charged atoms in and out of channels in the axon's membrane
saltatory conduction
Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.
neurotransmitters
chemical messengers that traverse the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.
gray matter
Brain and spinal cord tissue that appears gray with the naked eye; consists mainly of neuronal cell bodies (nuclei) and lacks myelinated axons.
midbrain
the middle division of brain responsible for hearing and sight; location where pain is registered; includes temporal lobe, occipital lobe, and most of the parietal lobe
white matter
whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths
spinal nerves
the 31 pairs of nerves located along the spinal column
cranial nerves
12 pairs of nerves that carry messages to and from the brain
brain stem
the part of the brain continuous with the spinal cord and comprising the medulla oblongata and pons and midbrain and parts of the hypothalamus
medulla oblongata
contains centers that control several visceral functions, including breathing, heart and blood vessel activity, swallowing, vomiting, and digestion.
cerebellum
the "little brain" attached to the rear of the brainstem; its functions include processing sensory input and coordinating movement output and balance
thalamus
the brain's sensory switchboard, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla
hypothalamus
a neural structure lying below the thalamus; directs eating, drinking, body temperature; helps govern the endocrine system via the pituitary gland, and is linked to emotion
cerebrum
area of the brain responsible for all voluntary activities of the body; encompasses both hemispheres.
corpus callosum
the large band of neural fibers connecting the two brain hemispheres and carrying messages between them
short term memory
activated memory that holds a few items briefly, such as the seven digits of a phone number while dialing, before the information is stored or forgotten
nerve net
in cnidarians, a network of nerve cells that lacks a central control; impulses pass in any or all directions to produce a generalized response
long term memory
the relatively permanent and limitless storehouse of the memory system. Includes knowledge, skills, and experiences
sensation
the faculty through which the external world is apprehended
perception
becoming aware of something via the senses
sclera
whitish fibrous membrane (albuginea) that with the cornea forms the outer covering of the eyeball
choroid coat
" the middle layer of the eye"; it is the interlaced with many blood vessels, which nourish the eyes
conjunctiva
mucous membrane that lines the eyelids and outer surface of the eyeball
iris
muscular diaphragm that controls the size of the pupil
pupil
the adjustable opening in the center of the eye through which light enters
retina
the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information
lens
the transparent structure behind the pupil that changes shape to help focus images on the retina
aqueous humor
watery liquid secreted at the ciliary body that fills the anterior and posterior chambers of the eye and provides nourishment for the cornea, iris, and lens (humor = fluid)
vitreous humor
jellylike substance found behind the lens in the posterior cavity of the eye that maintains its shape
eustachian tube
A narrow tube between the middle ear and the throat that serves to equalize pressure on both sides of the eardrum
inner ear
the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs
cochlea
the snail-shaped tube (in the inner ear coiled around the modiolus) where sound vibrations are converted into nerve impulses by the Organ of Corti
myofibrils
Micorsopic, fiber-like structures that occupy most cytoplasm in skeletal muscle cells
microfilaments
the thinnest of the three types of fibers in cytoskeleton; two intertwined stands of actin