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| Biological Psychology | A branch of psychology concerned with the links between biology and behavior. |
| Neuron | A nerve cell; the basic building block of the nervous system. |
| Dendrite | The bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body. |
| Axon | The extension of a neuron, ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands. |
| 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. |
| 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. |
| Threshold | The level of stimulation required to trigger a neural impulse. |
| Synapse | The junction between the axon tip of the sending neuron and the dendriteor cell body of the receiving neuron. The tiny gap at this juction is called the synaptic gap or cleft. |
| Neurotransmitters | Chemical messengers that traverse the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to recepter sites on the receiving neuron, thereby influencing whether it will generate a neural impulse. |
| Acetylcholine (ACh) | A neurotransmitter that, among its functions, triggers muscle contraction. |
| Endorphins | "Morphine within"- Natural, opiatelike neuortransmitters linked to pain control and to pleasure. |
| Nervous System | The body's speedy, electrochemical communication system, consisting of all the nerve cells of the peripheral and central nervous systems. |
| Central Nervous System (CNS) | The brain and spinal cord. |
| Peripheral Nervous System (PNS) | The sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body. |
| 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. |
| 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. |
| Motor Neurons | The neurons that carry outgoing information from the central nervous system to the muscles and glands. |
| Somatic Nervous System | The division of the peripheral nervous system that controls the body's skeletal muscles. Also called the skeletal nervous system. |
| Autonomic Nervous System | The part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms. |
| Sympathetic Nervous System | The division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations. |
| Parasympathetic Nervous System | The division of the autonomic nervous system that calms the body, conserving its energy. |
| Reflex | A simple, automatic, inborn response to a sensory stimulus, such as the knee jerk response. |
| Neural Networks | Interconnected neural cells. With experience, networks can learn, as feedback strengthens or inhibits connections that produce certain results. Computer simulations of neural networks show analogous learning. |
| Lesion | Tissue destruction. A brain lesion is a naturally or experimentally caused destruction of brain tissue. |
| Electroencephalogram (EEG) | An amplified recording of the waves of electrical activity that sweep across the brain's surface. These waves are measured by electrodes placed on the scalp. |
| CT (Computed Tomography) Scan | A series of X-ray photographs taken from different angles and combined by computer into a composite representation of a slice through the body. Also called CAT scan. |
| PET (Positron Emission Tomgraphy) Scan | A visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task. |
| MRI (Magnetic Resonance Imaging) | A technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain. |
| Brainstem | The oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions. |
| Medulla | The base of the brainstem; controls heartbeat and breathing. |
| Reticular Formation | A nerve network in the brainstem that plays an important role in controlling arousal. |
| Thalamus | The brain's sensory switchboard, located on the top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla. |
| Cerebellum | The "little brain" attached to the rear of the brainstem; it helps coordinate voluntary movement and balance. |
| Limbic System | A doughnut-shaped system of neural structures at the border of the brainstem and cerebral hemispheres; associated with emotions such as fear and aggression and drives such as those for food and sex. Includes the hippocampus, anygdala, and hypothalamus. |
| Amygdala | Two almond-shaped neural clusters that are components of the limbic system and are linked to emotion. |
| Hypothalamus | A neural structure lying below (hypo) the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion. |
| Cerebral Cortex | The intricate fabric of interconnected neural cells that covers the cerebral hemispheres; the body's ultimate control and information-processing center. |
| Glial Cells | Cells in the nervous system that are not neurons but that support, nourish, and protect neurons. |
| Frontal Lobes | The portion of the cerebral cortex lying just behind the forehead; Involved in speaking and muscle movements and in making plans and judgements. |
| Parietal Lobes | The portion of the cerebral cortex lying at the top of the head and toward the rear; includes the sensory cortex. |
| Occipital Lobes | The portion of the cerebral cortex lying at the back of the head; includes visual information from the opposite visual field. |
| Temporal Lobes | The portion of the cerebral cortex lying roughly above the ears; includes auditory areas , each of which receives auditory information primarily from the opposite ear. |
| Motor Cortex | An area at the rear of the frontal lobes that controls voluntary movements. |
| Sensory Cortex | The area at the front of the parietal lobes that registers and processes body sensations. |
| Association Areas | Areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking and speaking. |
| Aphasia | Impairment of language, usually caused by left hemisphere damage either Broca's area (impairing speaking) or to Wernicke's area (impairing understanding). |
| Broca's Area | An area od the frontal lobe, usually in the left hemisphere, that directs the muscle movements involved in speech. |
| Wernicke's Area | A brain area involved in language comprehension and expression; usually in the left temporal lobe. |
| Plasticity | The brain's capacity for modification, as evident in brain reorganization followin damage (especially in children) and in experiments on the effects of experience on brain development. |
| Corpus Callosum | The large band of neural fibers connecting the two brain hemispheres and carrying messages between them. |
| Spilt Brain | A condition in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them. |
| Endrocrine System | The body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream. |
| Hormones | Chemical messengers, mostly those manufactured by the endocrine glands, that are produced in one tissue and affect another. |
| Adrenal Glands | A pair of endocrine glands just above the kidneys. The adrenals secrete the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline), which help to arouse the body in times of stress. |
| Pituitary Gland | The endocrine system's most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands. |
