| A | B |
|---|
| Neuron | Consists of a cell body, containing the nucleus and cell organelles, and long, thin extensions called neuron fibers that convey signals |
| Central Nervous System (CNS) | One of two main anatomical divisions of most nervous systems. Consists of the brain and, in vertebrates, the spinal cord. |
| Peripheral Nervous System (PNS) | One of two main anatomical divisions of most nervous systems. Made up mostly of nerves that carry signals into and out of the CNS. |
| Nerve | A cable-like bundle of neuron extensions tightly wrapped in connective tissue |
| Ganglia | Clusters of neuron cell bodies |
| Integration | The interpretation of the sensory signals and the formulation of appropriate responses |
| Motor output | The conduction of signals from integration centers to effector cells |
| Effector cells | Cells that perform the bodily responses to stimuli (e.g., muscle cells or gland cells) |
| Sensory neurons | Bring message (stimuli/information) from sensory receptors into the CNS |
| Interneurons | Integrate data and relay appropriate signals to other interneurons or motor neurons; located entirely within CNS |
| Motor neurons | Send signals from within CNS out to the effector cells |
| Cell body | Where the neurons organelles are located; also the site from which dendrites and the axon branch off |
| Dendrites | Numerous; branch off from cell body; they RECEIVE signals from other cells and bring message TOWARDS the cell body |
| Axon | Singular; branch off from cell body; they SEND signals to other cells, carrying message AWAY from the cell body |
| Glia | Supporting cells that help neurons function normally. They may nourish neurons, insulate their axons, or help maintain properties of surrounding fluid |
| Myelin sheath | Resembles chain of oblong beads (called Schwann cells in PNS); speeds up conduction of signal along axons |
| Nodes of Ranvier | The spaces between Schwann cells; the only points along the axon that are “leaky” |
| Synaptic terminal | The very end of an axon; generally each axon ends in hundreds of these |
| Synapse | The site of communication between a synaptic terminal and another cell |
| Membrane potential | The potential energy that exists as a result of an electrical charge difference across a neuron’s plasma membrane |
| Resting potential | -70mV; this potential energy exists because of differences in ionic composition of fluids inside and outside the cell (more Na+ outside in resting state) |
| Sodium-potassium pumps | These pumps actively transport Na+ OUT of the cell and K+ IN, thereby helping to keep the concentration of Na+ low in the cell and K+ high. |
| Action potential | An “all-or-nothing” event that is always of the same magnitude. Only will occur if the signal is strong enough to reach the threshold voltage. |
| Threshold | The minimum change in the membrane’s voltage that must occur to generate the action potential |
| Synaptic cleft | Found only in chemical synapses, not in electrical synapses. A narrow gap across which neurotransmitters are released from pre-synaptic cells to post-synaptic cells. |
| Synaptic vesicles | Small, membranous sacks that hold and release neurotransmitters into the synaptic cleft; fuse with the plasma membrane of the pre-synaptic cell only. |
| Cephalization | An evolutionary trend toward concentration of the nervous system at the head end |
| Centralization | The presence of a CNS distinct from a PNS |
| Blood-brain barrier | A selective mechanism in brain capillaries that keeps out many chemicals such as metabolic wastes; maintains stable chemical environment for the brain |
| Brain and the spinal cord | The two components of the central nervous system (CNS) |
| Cerebrospinal fluid | A fluid that cushions the CNS and assists in the supply of nutrients, hormones, and the removal of wastes. Travels through central canal of spine and the vesicles of the brain. |
| Meninges | A layer of connective tissue that protect the brain and spinal cord. |
| White matter (spinal cord) | Composed mainly of axons (with their whitish myelin sheaths) |
| Grey matter (spinal cord) | Composed mainly of nerve cell bodies and dendrites |
| Forebrain | Composed of cerebrum (cerebral hemispheres/cortex) and the diencephalon (thalamus, hypothalamus, posterior pituitary, pineal gland) |
| Hindbrain | Composed of the pons and the medulla oblongata (both part of the brainstem), as well as the cerebellum |
| Brainstem | Medulla oblongata, pons, midbrain. Conducts data to and from other brain centers; helps maintain homeostasis; coordinates body movements |
| Cerebellum | Coordinates body movement; plays role in learning and in remembering motor responses |
| Thalamus in, it sorts data, serving as a sensory input AND output center for data going to and from the cerebrum. | Located in the forebra |
| Hypothalamus | Located in the forebrain, it serves as a homeostatic control center, controlling the pituitary gland and the various hormones released therein |
| Cerebrum | Performs sophisticated integration, playing a major role in memory, learning, speech, emotions, and the formulation of complex behavioral responses |
| Corpus callosum | A thick band of nerve fibers that facilitates communication between the cerebral hemispheres, enabling them to process information together |
| Basal nuclei | Groups of neurons located directly under the corpus callosum that are important in motor coordination. Degenerate in Parkinson’s disease. |
| Reticular formation | Located in the brainstem, this structure filters out unimportant stimuli, thus preventing the cerebral cortex from being overwhelmed. |
| Limbic system | Controls much of human emotion, memory and learning. Includes parts of thalamus and hypothalamus, as well as two cerebral structures: the amygdale and the hippocampus. |
| Hippocampus | Part of the limbic system. Involved in both the formation of memories and their recall. |
| Amygdala | Part of the limbic system. Central in recognizing emotional component of memories (e.g., a smell eliciting an emotional response). |
