Chapter 31 The Nervous System

1. Chapter 31The Nervous System By: Aubrey Fischer Jenny Czech

2. 31.1 The Function of the Nervous System: • Send and receive messages within the body • Respond to stimuli Neuron- basic unit of structure and function of the nervous system

3. 31.1 • peripheral nervous system: network of nerves and supporting cells that carries signals into and out of the central nervous system • central nervous system: includes the brain and spinal cord; processes information and creates a response that is delivered to the body • cell body: largest part of a typical neuron, contains the nucleus and much of the cytoplasm • Dendrite: extension of the cell body of a neuron that carries impulses from the environment or from other neurons toward the cell body • Axon: long fiber that carries impulses away from the cell body of a neuron • myelin sheath: insulating membrane surrounding the axon in some neurons • resting potential: electrical charge across the cell membrane of a resting neuron

4. 31.1 • action potential: reversal of charges across the cell membrane of a neuron; also called a nerve impulse • Threshold: minimum level of a stimulus that is required to cause an impulse • Synapse: point at which a neuron can transfer an impulse to another cell • Neurotransmitter: chemical used by a neuron to transmit an impulse across a synapse to another cell

5. 31.1 Types of Neurons: • Sensory Neurons: Impulse from sense organ to spinal cord/brain • Motor Neurons: Impulse from brain/spinal cord to muscles and glands • Interneurons: Connect sensory and motor neurons

6. 31.1 Nerve Transmission: • Messages are electrical and chemical signals • An electric charge is conducted down a neuron (Dendrite to axon) • Axon is covered in an insulating layer called a myelin sheath to speed up impulses • As it reaches the end of the axon, chemicals (neurotransmitters) are released across the synapse (gap between neurons) to the next neuron • The message continues neuron to neuron

7. 31.2 Vocab • Reflex: quick, automatic response to a stimulus • Cerebrum: part of the brain responsible for voluntary activities of the body; the “thinking” region of the brain • cerebral cortex: outer layer of the cerebrum of a mammal’s brain; center of thinking and other complex behaviors

8. 31.2 Vocab • Thalamus: brain structure that receives messages from the sense organs and relays the information to the proper region of the cerebrum for further processing • Hypothalamus: structure of the brain that acts as a control center for recognition and analysis of hunger, thirst, fatigue, anger, and body temperature • Cerebellum: part of the brain that coordinates movement and controls balance • brain stem: structure that connects the brain and spinal cord; includes the medulla oblongata and the pons • Dopamine: neurotransmitter that is associated with the brain’s pleasure and reward centers

9. 31.2 Central Nervous System • Brain- control center; transmits and receives messages • Cerebrum • Cerebellum • Brain Stem (midbrain, pons, medulla oblongata.) • Spinal Cord- connects brain with rest of the nervous system

10. 31.2 Addiction and the Brain: • Dopamine – neurotransmitter released with pleasurable activities • Addictive drugs cause large release of dopamine (resulting in “high”) • Brain reacts by reducing number of receptors for dopamine  normal activities no longer produce the pleasure they once did

11. 31.3 Vocab • somatic nervous system: part of the peripheral nervous system that carries signals to and from skeletal muscles • reflex arc: the sensory receptor, sensory neuron, motor neuron, and affecter that are involved in a quick response to a stimulus • autonomic nervous system: part of the peripheral nervous system that regulates activities that are involuntary, or not under conscious control; made up of the sympathetic and parasympathetic subdivisions

12. 31.3 Peripheral Nervous System: • Link between the central nervous system and the rest of the body • Network of nerves throughout the body *Made of many neurons

13. 31.3 Sensory Division: • Transmits impulses from sense organs to central nervous system • Uses sensory receptors • Chemoreceptors • Photoreceptors • Mechanoreceptors • Thermoreceptors • Pain receptors

14. 31.3 Motor Division: • Transmits impulses from central nervous system to muscles or glands Somatic nervous system: regulates activities under conscious controlAutonomic nervous system: regulates activities that are automatic or involuntary Autonomic nervous system: regulates activities that are automatic or involuntary

15. 31.4 Vocab • taste bud: sense organs that detect taste • Cochlea: fluid-filled part of inner ear; contains nerve cells that detect sound • semicircular canal: one of three structures in the inner ear that monitor the position of the body in relation to gravity • Cornea: tough transparent layer of the eye through which light enters • Iris: colored part of the eye

16. 31.4 Vocab • Pupil: small opening in the iris that admits light into the eye • Lens: structure in the eye that focuses light rays on the retina • Retina: innermost layer of the eye; contains photoreceptors • Rod: photoreceptor in the eyes that is sensitive to light but can’t distinguish color • Cone: in the eye, a photoreceptor that responds to light of different colors producing color vision

17. 31.4 Senses: • Vision- eyes • Hearing and Balance- ears • Smell and taste- nose and mouth • Touch- skin

18. 31.4 • Hearing/balance Mechanoreceptor • Smell Chemoreceptor • Taste • Touch Mechanoreceptor Pain receptor Thermoreceptor • Vision Photoreceptor