action potential A large transient depolarization event, including polarity reversal, that is conducted along the membrane of a muscle cell or a nerve fiber. afferent neuron Nerve cell that carries impulses toward the central nervous system; initiates nerve impulses following receptor stimulation. arachnoid Weblike; specifically, the weblike middle layer of the three meninges. astrocytes CNS cells responsible for physical support and maintaining blood brain barrier autonomic nervous system Efferent division of the peripheral nervous system that innervates cardiac and smooth muscles and glands; also called the involuntary or visceral motor system.
axon bipolar neurons blood brain barrier brain stem Neuron process that carries impulses away from the nerve cell body; efferent process; the conducting portion of a nerve cell. neuron with 2 processes extending for it's cell body-- one axon, one dendrite; common in sensory systems Mechanism that inhibits passage of materials from the blood into brain tissues; reflects relative impermeability of brain capillaries. The part of the brain composed of the midbrain, pons, and medulla oblongata and connecting the spinal cord with the forebrain and cerebrum. cerebral spinal fluid a fluid produced by the choroid plexus within the ventricular system of the brain
depolarization Loss of a state of polarity; loss or reduction of negative membrane potential. diencephalon Composed of the epithalamus, thalamus, and hypothalamus; begins where midbrain ends dura mater Outermost and toughest of the three membranes (meninges) covering the brain and spinal cord. efferent neurons neurons that conduct impulses away from the central nervous system. ependymal cells Line cavities of brain and spinal cord; secrete and circulate cerebrospinal fluid (CSF).
gray matter Gray area of the central nervous system; contains cell bodies and unmyelinated fibers of neurons. 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 interneuron neuron neuron, serving as part of the conduction pathway between sensory and motor neuron; also called association neurons Meissner's corpuscle A sensory receptor located in the dermis of the skin, which is sensitive fine touch. microglia are phagocytes, destroys and breaks down damaged cells
myelin Fatty insulating sheath that surrounds all but the smallest nerve fibers. neuroglia Nonexcitable cells of neural tissue that support, protect, and insulate the neurons. neuron Cell of the nervous system specialized to generate and transmit nerve impulses. nuclei collections of nerve cell bodies inside the central nervous system oligodendrocytes a cell that holds nerve fibers together and produces the myelin sheath around axons in the central nervous system
Pacinian corpuscle a type of nerve ending located in the subcutaneous layer that is sensitive to pressure parasympathetic nervous system the division of the autonomic nervous system that calms the body, conserving its energy; rest and digest response peripheral nervous system cranial and spinal nerves that extend beyond the CNS proprioceptors Receptor located in a joint, muscle, or tendon; concerned with locomotion, posture and muscle tone. reflex Automatic reaction to stimuli.
repolarization Movement of the membrane potential to the initial resting (polarized) state. 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 myelinsheathed regions of membrane. Schwann cells somatic nervous system subarachnoid space Supporting cells of the peripheral nervous system responsible for the formation of myelin. Division of the peripheral nervous system that provides the motor innervation of skeletal muscles; also called the voluntary nervous system. a space in the meninges beneath the arachnoid membrane and above the pia mater that contains the cerebrospinal fluid
sympathetic nervous system A subdivision of the autonomic nervous system that activates nerves, glands and visceral muscles in times of stress or threat; fight or flight response synaptic cleft The gap between two communicating neurons thalamus the structure of the brain that relays messages from the sense organs to the cerebral cortex tract A collection of nerve fibers in the central nervous system having the same origin, termination, and function. white matter located in the CNS; myelinated axons in bundles (tracts) with few cell bodies