Unit 3: Sensation and Perception

• neuron: a nerve cell; the basic building block of the nervous system.
• dendrites: the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body.
• 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. (Depolarized) (resting potential = polarized)
• refractory period: a period of inactivity after a neuron has fired.
• Excitatory v. Inhibitory: You have an action potential when the excitatory outnumbers the inhibitory
• threshold: the level of stimulation required to trigger a neural impulse.
• all-or-nothing response: a neuron's reaction of either firing or not firing.
• synapse: the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft.
• neurotransmitters: chemical messengers that cross the synaptic gaps between neurons
• reuptake: a neurotransmitter's reabsorption by the sending neuron
• Acetylcholine (ACH): enables muscle action, learning, and memory
• Acetylcholine associated problems: With Alzheimer's disease, ACH-producing neurons deteriorate
• Dopamine: influences movement, learning, attention, and emotio
• Norepinephrine: helps control alertness and arousal (fight or flight response)
• Serotonin: Affects mood, hunger, sleep, and arousal
• Serotonin associated problems: Under supply linked to depression. Some anti-depressant drugs raise serotonin levels
• Glutamate: A major excitatory neurotransmitter; involved in memory
• GABA associated problems: Under supply leads to seizures, tremors, and insomnia.
• endorphins: "morphine within"—natural, opiate-like neurotransmitters linked to pain control and to pleasure.
• Antagonists: Chemical substances that block or reduce a cell's response to the action of other chemicals or neurotransmitters.
• nervous system: the body's speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems.
• sensory (afferent) neurons: neurons that carry incoming information from the sensory receptors to the brain and spinal cord. (Peripheral)
• motor (efferant) neurons: neurons that carry outgoing information from the brain and spinal cord to the muscles and glands. (Peripheral)
• interneurons: neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and motor outputs. (Central)
• Somatic nervous system: the division of the peripheral nervous system that controls the body's skeletal muscles (skeletal nervous system) (voluntary)
• Autonomic nervous system: the part of the peripheral nervous system that controls the glands and the muscles of the internal organs. It's sympathetic system arouses and parasympathetic calms. (Involuntary)
• Sympathetic nervous system: the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations. (If you get scared). Fight or flight response. (Arousing)
• Parasympathetic nervous system: the division of the autonomic nervous system that calms the body, conserving its energy (Your PARents come home and calm you down) (calming)
• Neural networks: Cluster of neurons that form connections
• Reflexes: simple, automatic responses to sensory stimuli, such as the knee-jerk response
• Endocrine system: the body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream
• Adrenal glands: a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress
• Pituitary gland: "THE MASTER GLAND" the endocrine system's most influential gland

  under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands
• Lesion: tissue destruction. It can occur naturally or experimentally by the caused distruction/remove of brain tissues
• 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 representaion of a slice through the body. Aslo called a CAT scan
• (PET) Positron emission tomography 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 tissues.
• fMRI (functional MRI): A technique for revealing bloodflow and, therefore, brain activity by comparing successive MRI scans. fMRI scans show brain function.