Nervous+System

Vocabulary List ** Section 1 ** · **Neurons **: Basic unit of structure and function in the nervous system; conducts impulses throughout the nervous system; composed of dendrites, the cell body, and axons. · **Dendrite: **Branch like extension of a neuron; transports impulses towards the cell body. · **Axon: **A single cytoplasmic extension of a neuron; carries impulses away from a nervous cell. · **Synapse: ** Tiny space between one neuron’s axon and another neuron’s dendrite over which a nerve impulse must pass. · **Neurotransmitter: **Chemicals released from an axon that diffuse across a synapse to the next neuron’s dendrites to initiate a new pulse. · **Central Nervous System: **In humans, the central control center of the nervous system made up of the brain and spinal cord. · **Peripheral Nervous System: **Division of the nervous system made up of all the nerves that carry messages to and from the central nervous system. · **Cerebrum: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Largest part of the brain composed of two hemispheres connected by bundles of nerves; controls conscious activities, intelligence, memory, language, skeletal movement, and senses. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Cerebellum: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Rear portion of the brain; controls balance, posture, and coordination. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Medulla Oblongata: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Part of the brain stem that controls involuntary activities, such as breathing and heart rate. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Somatic Nervous System: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Portion of the nervous system composed of cranial nerves, spinal nerves, and all of their branches; voluntary pathway that relays information mainly between the skin, CNS, and the skeletal muscles. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Reflex: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Automatic response to a stimulus; reflex stimulus travels to the spinal column and sent directly back to the muscle. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Autonomic Nervous System: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">In humans, portion of the peripheral nervous system that carries impulses from the CNS to the internal organs; produces involuntary responses. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Sympathetic Nervous System: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Division of the autonomic nervous system that controls many of the body’s internal functions during times of stress. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Parasympathetic Nervous System: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Division of the autonomic nervous system that controls many of the body’s internal functions when the body is at rest. ** Section 2 ** · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Taste bud: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Sensory receptors located on the tongue that result in taste perception. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Retina: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Thin layer of tissue found at the back of the eye made up of light sensors and sensory neutrons. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Rod: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Receptor cells in the retina that are adapted for vision in dim light, also helps detect shapes and movement. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Semicircular canals: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Structures in the inner ear, containing fluid and hairs that help the body maintain balance. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Cochlea: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Snail shaped structure in the inner ear containing fluid and hairs; produces electrical impulses that the brain interprets and sound. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Cone: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Receptor cells in the retina adapted for sharp vision in bright light and color detection. ** Section 3 ** · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Addiction: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Psychological and/or physiological dependence. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Stimulant: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Drug that increases the activity of the central and sympathetic nervous system. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Tolerance: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">As the body becomes less responsive to a drug and an individual needs larger of more frequent doses of the drug to achieve the same effect. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Withdrawal: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Psychological response or physiological illness that occurs when a person stops taking a drug. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Depressant: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Type of drug that lowers or depresses the activity of the nervous system. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Drug: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Chemical substance that affects body functions. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Hallucinogen: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Drug that simulates the CNS so that the user becomes disoriented and sees, hears, feels, tastes, or smells things that are not there. · **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Narcotic: **<span style="font-family: "Cambria","serif"; font-size: 12pt; line-height: 115%;">Type of pain relief drug that affects the CNS.
 * The Nervous System **

Summary ** The Nervous System ** The nervous system is composed of little nuerons that are the basic units. These nuerons conduct impulses that send messages to the brain. There are three regions of a neuron. The first one is a dendrite. The dendrites carry impulses to the cell body. The second is an axon. Axons are extensions and carry impulses away from the cell body. The third is the cell body. The cell body contains the nucleus. There are three types of neurons. Sensory nuerons carry impulses from the body to the spinal cord and brain. Interneurons are in the brain; they process incoming impulses and pass responses to motor neurons. Motor neurons carry these impulses to a muscle or a gland. There are two types of nervous systems. The central nervous system contains the spinal cord and the brain. The peripheral nervous system contains the somatic nervous system, which is voluntary reactions and relays information to skeletal muscles, and the autonomic nervous system that controls involuntary reactions and relays information to internal organs. ** The Senses ** Chemical molecules of objects contact the receptors in your nose and mouth that allow you to smell and taste. In your nose there is hair like nerve endings that initiate impulses in the olfactory nerve connected to the brain. Taste and smell are closely related. The retina, located at the back of the eye, uses receptors and sensory neurons and rods and cones to interpret images. Behind the retina there is the optic nerve which leads to the brain where the brain forms the visual image. The senses of hearing balance and touch are responses to mechanical stimulation. We are able to hear the vibrations from sounds through the malleus, the incus, and the stapes. The stapes vibrates and causes the membrane of the oval window to move. These vibrations cause the fluid in cochlea to also move. Eventually electrical impulses travel along auditory nerve to the cerebrum. Balance is maintained by the semicircular canals. Nerve impulses in the inner ear convert information about the position of your head to your brain about the body’s equilibrium. Touch uses receptors, in the dermis of the skin, that convert the stimulus to a nerve impulse. Changes in pressure, temperature, pain, and other things from the external environment are sensed by the touch receptors. ** The Effects of Drugs ** Drugs interact with the receptor sites in cells used by neurotransmitters of the nervous system hormones of the endocrine system. Medicinal uses of drugs include relieving pain and to prevent of cure a disease. However, many times drugs are misused and abused. This can cause serious health problems or even death. Drug abuse involves uses of illegal drugs or prescriptions and can have serious effects on the nervous system. People may have an addiction to drugs and may later need to deal with tolerance and withdrawals. Common types of misused drugs are stimulants, which include cocaine, amphetamines, caffeine and nicotine; Depressants, such as alcohol and barbiturates; narcotics, anabolic steroids, and natural and synthetic hallucinogens. To break these drug addictions people need medical and psychological therapy. Already nicotine patches have been made to break addictions to tobacco.