| A | B |
|---|
| brain | The complex mass of neural cells and related cells encased in the skull. |
| neuron | An individual nerve cell. |
| dendrites | Extensions of the cell body that receive messages from other neurons. |
| axons | Neuron branches that transmit messages to other neurons. |
| nerve | A bundle of long neurons outside the brain and spinal cord. |
| myelin seath | The insulating fatty covering wrapped around part of the neuron. |
| synapse | The space between the axon of one neuron and the dendrite of another. |
| neurotransmitters | Chemical substances, produced by axons, that transmit messages across the synapse. |
| central nervous system | The brain and nerve fibers that make up the spinal cord. |
| peripheral nervous system | The network of nerves that branches from the brain and spinal cord to all parts of the body. |
| afferent neurons | Neurons that transmit messages from sense organs to the central nervous system. |
| efferent neurons | Neurons that transmit messages from the central nervous system to organs and muscles. |
| interneuron | Neurons in the central nervous system that connect other neurons. |
| somatic nervous system | The division of the peripheral nervous system that carries messages from the sense organs, muscles, joints, and skin to the central nervous system and from the central nervous system to the skeletal muscles. |
| autonomic nervous system | The division of the peripheral nervous system that controls the involuntary actions of internal body organs, such as heartbeat and breathing, and is important in the experience of emotion. |
| sympathetic division | The division of the autonomic nervous system that generally activates internal organs during emotional arousal or when physical demands are placed on the body. |
| parasympathetic division | The division of the autonomic nervous system that generally "calms" internal organs. |
| hindbrain | The lowest part of the brain, located at the rear base of the skull. |
| medulla | The swelling at the top of the spinal cord responsible for controlling breathing and a variety of reflexes. |
| pons | The part of the hindbrain that is involved with balance, hearing, and some parasympathetic functions. |
| cerebellum | Two rounded structures behind the pons involved in the coordination of muscle movements, learning, and memory. |
| midbrain | The small part at the top of the hindbrain that serves primarily as a reflex center for orienting the eyes and ears. |
| forebrain | The parts of the brain, including the thalamius, hypothalamus, and cerebral cortex, that cover the hindbrain and midbrain and fill much of the skull. |
| thalamus | The part of the forebrain that primarily routes sensory messages to appropriate parts of the brain. |
| hypothalamus | The small part of the forebrain involved with motives, emotions, and the functions of the autonomic nervous system. |
| limbic system | A complex brain system, composed of the amygdala, hippocampus, septal area, and cingulate cortex, that works with the hypothalamus in emotional arousal. |
| cerebral cortex | The largest structure in the forebrain, controlling the conscious experience and intelligence and being involved with the somatic nervous system. |
| frontal lobes | The part of the cerebral cortex in the front of the skull involved in planning, organization, voluntary motor movements, and speech. |
| parietal lobes | The part of the cerebral cortex located behind the frontal lobes at the top of the skull containing the somatosensory area. |
| occipital lobes | The part of the cerebral cortex, locatated at the base of the back of the head, that plays an essential role in processing of sensory information from the eyes. |
| endocrine system | The system of glands that secretes hormones. |
| hormones | Chemical substances, produced by endocrine glands, that influence internal organs. |
| pituitary gland | The body's master gland, located near the bottom of the brain, whose secretions help regulate the activity of the other glands in the endocrine system. |
| adrenal glands | Two glands on the kidneys, which are involved in phyisical and emotional arousal. |
| islets of Langerhans | Endocrine cells in the pancreas that regulate the level of sugar in the blood. |
| gonads | The glands that produce sex cells and hormones important in sexual arousal and that contribute to the development of secondary sex characteristics. |
| thyroid gland | The gland below the voice box that regulates metabolism. |
| parathyroid glands | Four glands embedded in the thyroid that produce parathormone. |
| pineal gland | The endocrine gland that is largely responsible for the regulation of biological rhythms. |
| genes | The hereditary units made up of deoxyribonucleic acid. |
| chromosomes | The strips in cell nuclei that contain genes. |
