the organ system that forms a communication and coordination network between all parts of an animal's body
a nerve cell; the fundamental structural and functional unit of the nervous system, specialized for carrying signals from one location in the body to another
Central Nervous System (CNS)
The integration and command center of the nervous system; the brain and, in vertebrates, the spinal chord
peripheral nervous system (PNS)
The network of nerves and ganglia carrying signals into and out of the central nervous system
A cable-like bundle of neuron fibers (axons and dendrites) tightly wrapped in connective tissue
A cluster (functional group) of nerve cell bodies in a centralized nervous system
The conduction of signals from sensory receptors to processing centers in the central nervous system
The interpretation of sensory signals within neural processing centers of the (CNS)
The conduction of signals from a processing center in a central nervous system to effector cells
A cell capable of carrying out some action in response to a command from the nervous system
An automatic reaction to a stimulus, mediated by the spinal cord or lower brain.
a nerve cell that receives information from sensory receptors and conveys signals into the central nervous system
a nerve cell, entirely within the central nervous system, that integrates sensory signals and may relay command signals to the motor neurons
a nerve cell that conveys command signals from the central nervous system to effector cells, such as muscle cells or gland cells
The part of a cell, such as a neuron, that houses the nucleus
a neuron fiber that conveys signals from its tip inward, toward the rest of the neuron; in a motor neuron, one of several short, branched extension that convey nerve signals toward the cell body
a neuron fiber that conducts signals to another neuron or to an effector cell
A supporting cell that is essential for the structural integrity and normal functioning of the nervous system.
a series of cells, each wound around, and thus insulating, the axon of a nerve cell in vertebrates. Each pair of cells in the sheath is separated by a space called a node of Raniver
nodes of Ranvier
an unmyelinated region on a myelinated axon of a nerve cell, where signal transmission occurs
The tip of a transmitting neuron's axon, where signals are sent to another neuron or to an effector cell.
a junction between two neurons, or between a neuron and an effector cell. Electrical or chemical signals are relayed from one cell to another at one of these.
The charge difference between a cell's cytoplasm and the extracellular fluid, due to the differential distribution of ions.
voltage across the plasma membrane of a resting neuron
Sodium Potassium (Na+ -K+) pumps
A membrane protein that transports sodium ions out of, and potassium ions into, a cell against their concentration gradients. The process is powered by ATP
A factor that triggers sensory transduction.
A self-propagating change in the voltage across the plasma membrane of a neuron; a nerve signal.
The minimum change in a membrane's voltage that must occur to generate a nerve signal (action potential)
In a chemical synapse; a narrow gap separating the synaptic terminal of a transmitting neuron from a receiving neuron or an effector cell.
a chemical messenger that carries information from a transmitting neuron to a receiving cell, either another neuron or an effector cell
a membranous sac containing neurotransmitter molecules at the tip of a presynaptic axon
A nitrogen-containing neurotransmitter. Among other effects, it slows the heart rate and makes skeletal muscles contract.
A neurotransmitter derived from an amino acid.
A weblike system of neurons, characteristic of radially symmetrical animals, such as hydra.
The concentration of a nervous system at the anterior end
The presence of a central nervous system (CNS) distinct from a peripheral nervous system.
an elongated bundle of axons and dendrites, usually extending longitudinally from the brain or anterior ganglia; one or more of these and the brain make up the central nervous system in many animals.
the dorsal hollow nerve cord in vertebrates, located within the vertebral column; with the brain, makes up the central nervous system
the part of the central nervous system involved in regulating and controlling bodily activity and interpretting information from the senses transmitted through the nervous system
a system of capillaries in the brain that restricts passage of most substances into the brain, thereby preventing large fluctuations in the brain's environment
(1) A heart chamber that pumps blood out of a heart. (2) A space in the vertebrate brain, filled with cerebrospinal fluid.
The narrow cavity in the center of the spinal cord that is continuous with the fluid-filled ventricles of the brain.
blood-derived fluid that surrounds, protects against infection, nourishes, and cushions the brain and spinal cord
layers of connective tissue that enwrap and protect the brain and spinal cord
Tracts of axons within the central nervous system
regions of dendrites and clusters of nerve cell bodies within the CNS
A nerve that leaves the brain and innervates an organ of the head or upper body.
In the vertebrate peripheral nervous system, a nerve that carries signals to or from the spinal cord.
somatic nervous system
The component of the vertebrate peripheral nervous system that carries signals to and from skeletal muscles
autonomic nervous system
The component of the vertebrate peripheral nervous system that regulates the internal enviroment; made up of sympathetic and parasympathetic subdivisions.
A set of neurons in the autonomic nervous system that generally promotes body activities that gain and conserve energy, such as digestion and reduced heart rate
A set of neurons in the autonomic nervous system that generally prepares the body for energy-consuming activities, such as fleeing or fighting.
Part of the autonomic nervous system consisting of complex networks of neurons in the digestive tract, pancreas, and gallbladder.
One of three ancestral and embryonic regions of the vertebrate brain; develops into the thalamus, hypothalamus, and cerebrum.
One of three ancestral and embryonic regions of the vertebrate brain; develops into sensory integrating and relay centers that send sensory information to the cerebrum
One of three ancestral and embryonic regions of the vertebrate brain; develops into the medulla oblongata, pons, and cerebellum
The largest, most sophisticated, and most dominant part of the vertebrate forebrain, made up of right and left cerebral hemispheres.
Part of the vertebrate hindbrain continuous with the spinal cord; passes datat between the spinal cord and forebrain and controls autonomic, homeostatic functions, including breathing, heart rate, swallowing, and digestion
Part of the vertebrate hindbrain that functions with the medulla oblongata in passing data between the spinal cord and forebrain and in controlling autonomic, homeostatic functions
A functional unit of the vertebrate brain, composed of the midbrain, the medulla oblongata, and the pons; serves mainly as a sensory filter selecting which information reaches higher brain centers.
part of the vertebrate hindbrain; mainly a planning center that interacts closely with the cerebrum in coordinating body movement.
An integrating and relay center of the vertebrate forebrain; sorts and relays selected information to specific areas in the cerebral cortex
An internal timekeeper that controls an organism's biological rhythms; marks time with or without environmental cues, but often requires signals from the environment to remain tuned to an appropriate period.
In an organism, a biological cycle of about 24 hours that is controlled by a biological clock, usually under the influence of enviromental cues; a pattern of activity that is repeated daily.
The right or left half of the vertebrate cerebrum.
the thick band of nerve fibers that connect the right and left cerebral hemispheres in placental mammals, enabling the hemispheres to process information together
clusters of nerve cell bodies located deep within the cerebrum that are important in motor coordination.
a folded sheet of gray matter forming the surface of the cerebrum. In humans, it contains integrating centers for high brain functions such as reasoning, speech, language, and imagination
The phenomenon in which the two hemispheres of the brain become specialized for different functions.
A system of neurons, containing over 90 separate nuclei, that passes through the core of the brain stem
A graph that shows the patterns of electrical activity in the brain during arousal sleep.
Rapid-eye-movement sleep. A period of sleep when the brain is highly active, brain waves are fairly rapid and regular, and the eyes move rapidly under the closed eyelids. This is when most dreams occur.
A functional unit of several integrating and relay centers located deep in the human forebrain; interacts with the cerebral cortex in creating emotions and storing memories
The ability to store and retrieve information.
An integrative center of the cerebrum; functionally the part of the limbic system that seems to label information to be remembered
An integrative center of the cerebrum; functionally, the part of the limbic system that plays a central role in memory and learning.
The ability to hold information, anticipations, or goals for a time and then release them if they become irrelevant
The ability to hold, associate, and recall information over one's life.
Severe mental disturbance characterized by psychotic episodes in which patients lose the ability to distinguish reality from hallucination.
Depressive mental illness characterized by experiencing a low mood most of the time
Depressive mental illness characterized by swings of mood from high to low; also called manic-depressive disorder.
Alzheimer's disease (AD)
An age-related dementia (mental deterioration) characterized by confusion, memory loss, and other symptoms.
A motor disorder caused by a progessive brain disease and characterized by difficulty in initiating movements, slowness of movement, and rigidity.
A feeling, or general awareness, of stimuli resulting from sensory information reaching the central nervous system
The brain's meaningful interpretation, or conscious understanding, of sensory information
a specialized cell or neuron that detects stimuli and sends information to the central nervous system
The conversion of a stimulus signal to an electrical signal by a sensory receptor.
The electrical signal produced by sensory transduction
The tendency of sensory neurons to become less sensitive when they are stimulated repeatedly.
Sensory receptor that detects pain
A sensor (sensory receptor) that detects heat or cold
A sensory receptor that detects physical deformations in the body's environment associated with pressure, touch, stretch, motion, and sound.
A type of mechanoreceptor sensitive to changes in muscle length; detects the position of body parts.
A type of mechanoreceptor that detects sound waves and other forms of movement in air or water.
A sensor (sensory receptor) that detects chemical changes within the body or a specific kind of molecule in the external environment.
A sensor (sensory receptor) that detects energy of different wavelengths, such as electricity, magnetism, and light.
A type of electromagnetic receptor that detects light
the simplest type of photoreceptor, a cluster of photoreceptor cells shaded by a cuplike cluster of pigmented cells; detects light intensity and direction
The photoreceptor in many invertebrates; made up of many light detectors, each of which detects light from a tiny portion of the field of view.
The camera-like eye found in some jellies, polychaetes, spiders, many molluscs, and in vertebrates.
A layer of connective tissue forming the outer surface of the vertebrate eye. The cornea is the frontal part of this
The transparent frontal portion of the sclera, which admits light into the vertebrate eye.
a thin, pigmented inner layer in the vertebrate eye, surrounded by the sclera. The iris is a part of this
The colored part of the vertebrate eye, formed by the anterior portion of the choroid
the opening in the iris that admits light into the interior of the vertebrate eye. Muscles in the iris regulates its size
The structure in an eye that focuses light rays onto the retina
The light-sensitive layer in an eye, made up of photoreceptor cells and sensory meurons
An eye's center of focus and the place on the retina where photoreceptors are highly concentrated
The place on the retina of the vertebrate eye where the optic nerve passes through the eyeball and where there are no photoreceptor cells.
A jellylike substance filling the space behind the lens in the vertebrate eye; helps maintain the shape of the eye
Plasma-like liquid in the space between the lens and the cornea in the vertebrate eye; helps maintain the shape of the eye, supplies nutrients and oxygen to its tissues, and disposes of its wastes.
A portion of the vertebrate eye associated with the lens. It produces the clear, watery aqueous humor that fills the anterior cavity of the eye.
The Automatic changes made by the eye as it focuses on nearby objects.
The ability of the eyes to distinguish fine detail.
An inability to focus on distant objects; occus when the eyeball is longer than normal and the lens focuses distant objects in front of the retina also called myopia.
An inability to focus on close objects; occurs when the eyeball is shorter than normal and the focal point of the lens is behind the retina also called hyperopia
Blurred vision caused by a misshapen lens or cornea
(1) In vertebrates a photoreceptor cell in the retina stimulated by bright light and enabling color vision (2) In conifers a reproductive structure bearing polen or ovules.
A photoreceptor cell in the vertebrate retina enabling vision in dim light.
A visual pigment that is located in the rods of the vertebrate eye and that absorbs dim light.
One of a family of visual pigments in the cones of the vertebrate eye that absorb bright, colored light
One of three main regions of the ear in reptiles, birds, and mammals; made up of the auditory canal and, in many birds and mammals, the pinna.
the flap like part of the outer ear, projecting from the body surface of many birds and mammals collects sound waves and channels them to the auditory canal
part of the vertebrate outer ear that channels sound waves from the pinna or outer body surface to the eardrum.
sheet of connective tissue separating the outer ear from the middle ear that vibrates in response to auditory stimuli and transmits sound waves to the middle ear
One of three main regions of the vertebrate ear; a chamber containing three small bones (the hammer, anvil, and stirrup) that convey vibrations from the eardrum to the oval window.
In the vertebrate ear, a membrane-covered gap in the skull bone, through which sound waves pass from the middle ear to the inner ear.
An air passage vetween the middle ear and throat of vertebrates that equalizes air pressure on either side of the eardrum.
One of three main regions of the vertebrate ear; includes the cochlea, organ of Corti, and semicircular canals
A coiled tube in the inner ear of birds and mammals that contains the hearing organ, the organ of corti.
organ of corti
The hearing organ in birds and mammals, located within the cochlea
the floor of the middle canal of the inner ear.
Fluid-filled channels in the inner ear that detect changes in the head's rate of rotation or angular movement.
one of two fluid-filled inner-ear chamber containing hair cells that detect the position of the head relative to gravity. The other being the saccule
One of two fluid-filled inner-ear chamber containing hair cells that detect the position of the head relative to gravity. The other being the utricle
active movement from place to place
a skeletal system composed of fluid held under pressure in a closed body compartment; the main skeleton of most cnidarians, flatworms, nematodes, and annelids
A hard, external skeleton that protects an animal and provides points of attachment for muscles.
A hard skeleton located within the soft tissues of an animal; includesspicules of sponges, the hard plates of echinoderms, and the cartilage and bony skeletons of many vertebrates.
components of the skeletal system that support the central trunk of the body; the skull, backbone, and rib cage in a vertebrate.
Components of the skeletal system that support the fins of a fish or the arms and legs of a land vertebrate; cartilage and bones of the shoulder girdle, pelvic girdle, and forelimbs and hind limbs.
a type of fibrous connective tissue that joins bones together at the joints.
A joint that allows rotation and movement in several planes. Examples in humans are the hip and shoulder joints.
A joint that allows movement in only one plane. In humans, examples include the elbow and knee.
a joint that allows precise rotations in multiple planes. An example in humans is the wrist.
yellow bone marrow
A tissue found within the central cavities of long bones, consisting mostly of stored fat.
red bone marrow
A specialized tissue found in cavities in the ends of bones that produces blood cells.
A skeletal disorder characterized by thinning, porous, and easily broken bones; most common among women after menopause and often related to low estrogen levels
Fibrous connective tissue connecting a muscle to a bone.
Striated muscle attached to the skeleton. The contraction of striated muscles produces voluntary movements of the body.
contractile thread in muscle cell (fiber) made up of many sarcomeres. Longitudinal bundles of this make up a muscle fiber.
The fundamental unit of muscle contraction, composed of thin filaments of actin and thick filaments of myosin; the region between two narrow, dark lines, called z lines, in the myofibril.
The smaller of the two myofilaments consisting of two strands of actin and two strands of regulatory protein coiled around one another
A filament composed of staggered arrays of myosin molecules; a component of myofibrils in muscle fibers
The theory explaining how muscle contracts, based on change within a sarcomere, the basic unit of muscle organization, stating that thin (actin) filaments slide across thick (myosin) filaments, shortening the sarcomere; the shortening of all sarcomeres in a myofibril shortens the entire myofibril
A MOTOR NEURON AND ALL THE MUSCLE FIBER IT CONTROLS
A synapse between an axon of a motor neuron and a muscle fiber.
exercising muscles at a level at which sufficient oxygen remains available for aerobic respiration.
Exercising muscles until they no longer receive adequate oxygen and must switch to anaerobic respiration.