7-1 How the Nervous System Works

Transcription

1 7-1 How the Nervous System Works Jobs of the Nervous System 1. Receives 2. Responds to a) : A change or signal in the environment that can make an organism react. b) : What the body does in reaction to a stimulus. 3. Maintains. The Neuron A Message Carrying Cell : A cell that carries information through the nervous system; a nerve cell. : The message that a neuron carries. A neuron has one and many. : Carries impulses toward the cell body. : Carries impulses away from the cell body. Axons and dendrites are sometimes called. : A bundle of nerve fibers. : Picks up stimuli from the internal or external environment and converts each stimulus into a nerve impulse. : A neuron that carries nerve impulses form one neuron to another; usually found in the brain or spinal cord. : A neuron that sends an impulse to a muscle, and the muscle contracts in response. How a Nerve Impulse Travels A nerve impulse begins in the of a neuron, moves toward the, then down the axon to the. : The tiny space between each axon tip and the next structure, such as a dendrite, muscle or cell of another organ. Axon tips release that enable the impulse to cross the synapse.

2 7-2 Divisions of the Nervous System Central Nervous System consists of the, &. Nervous System consists of all the nerves located outside of the Central Nervous System. The Central Nervous System (CNS) The CNS is the center of the body. The part of the CNS that controls most functions is the. :Thick column of nerve tissue, links the brain to most of the nerves in the Peripheral Nervous System. The Brain : Largest part of the brain; interprets input from the senses. Cerebrum controls the movement of Cerebrum carries out complex processes such as learning, remembering, and making judgments. Right half of cerebrum controls the side of body. And vice versa. side of brain associated with creativity, & artistic ability. side of brain associated with math skills, speech, writing, & logical thinking. : Second largest part of the brain; coordinates the actions of your muscles & helps keep your balance. : Lies between the cerebellum and spinal cord; controls the body s involuntary actions (breathing, heartbeat).

3 The Spinal Cord Surrounded & protected by a vertical column. Links &. The Peripheral Nervous System (PNS) Somatic Nervous system controls actions. Autonomic Nervous System controls actions. Reflexes : Automatic response that occurs very rapidly without conscious control. Safety and the Nervous System : Bruise-like injury of the brain. Occurs when soft tissue of the cerebrum bumps against the skull. Spinal cord injuries occur when the spinal cord is cut or crushed resulting in loss of.

4 7-3 The Senses Vision : The clear tissue that covers the front of the eye. : The opening through which light enters the eye. : A circular structure that surrounds the pupil and regulates the amount of light entering the eye; also gives the eye its color. : A flexible structure that focuses light. : Enable you to see black, white & shades of gray. : Enable color vision. Nerve impulses travel from the retina to the cerebrum through the. : Nearby objects can be seen clearly by distant objects look blurry. : Distant objects can be seen clearly but nearby objects look blurry. Hearing Sound is produced by. : Shaped like a funnel, gathers sound waves & directs them down the ear canal. : Membrane that vibrates when sound waves strike it; separates the outer ear from the middle ear. Vibrations from the eardrum pass to the,, and, tiny bones in the middle ear. : A snail-shaped tube that is lined with receptors that respond to sound. Vibrations pass to fluid in the cochlea. As fluid in the cochlea vibrates, it stimulates. Sensory neurons send the impulse to the cerebrum, through the, where the sound is interpreted.

5 Your Sense of Balance : Structures in the inner ear that are responsible for your balance. Moving fluid in the semicircular canals tells the cerebellum about the body s. Smell and Taste The senses of smell and taste work closely together, and both depend on. Chemicals trigger responses in in the nose and mouth. then travel to the brain for interpretation. Touch The sense of touch is found in all areas of the. The dermis has different kinds of receptors:,,, and. 8-1 The Endocrine System The Role of the Endocrine System Controls many of the body s daily as well as long-term changes such as. : An organ of the endocrine system which produces and releases its chemical products directly into the bloodstream.

6 Hormones : The chemical product of an endocrine gland; regulates the activities of different organs & tissues. In some situations, hormones are released by impulses to the brain and then to a specific endocrine. A hormone interacts only with certain, that recognize the hormone s chemical structure. The Hypothalamus : Tiny part of the brain that links the Nervous System and the Endocrine System. Sends nerve messages to control, & other conditions. Produces that control other endocrine glands & organs. Plays a major role in maintaining. The Pituitary Gland : An endocrine gland just below the hypothalamus to control many body activities. Responds to signals from the hypothalamus by releasing its own, some of which act as on switches for other endocrine glands. Other pituitary hormones control body activities directly. Negative Feedback : A process in which a system is turned off by the condition it produces. Ex: The regulation of temperature by a thermostat & the regulation of levels of many hormones in blood. Negative Feedback is an important way that the body maintains.