Chapter 35 “The Nervous System ”

1. Chapter 35 “The Nervous System” • 35.1 “The Human Nervous System” • Objective: • List the 3 main structures of a neuron • Describe a Nerve Impulse

2. Neurons • Basic unit of the N.S. • Carry messages in the form of electrical impulses • Made up of: • cell body - largest part • dendrites - carry impulses toward the cell body • axon - carries impulse away from cell body • axon terminal – sends impulse to next neuron

4. Three Types of Neurons • Sensory : body to brain • Motor : brain to body • Interneurons : connect sensory & motor neurons in brain and spinal cord

5. Nerve Impulse • Begins when a neuron is stimulated by env. or another neuron • Resting Potential: a neuron without an impulse • Inside of neuron is more negative than outside • Action Potential: change in charge • Inside of neuron becomes more positive

6. Domino effect passes action potential down axon Inside is negative Resting Potential Inside becomes positive Inside returns to negative

7. Myelin • Myelin sheath: fatty layer which insulates axon • Speeds up impulse

8. Synapse • Synapse: The space between the axon terminal of one neuron and the dendrites of the next neuron. • Axon terminal releases neurotransmitters.

9. 35.2 “Organization of the N.S” • Objective: • Distinguish between the Central Nervous System & the Peripheral Nervous System.

10. The Central Nervous System • Brain • Spinal Cord

11. The Brain • Four lobes, two halves • Major regions: • Cerebrum – conscious activity/thought • Cerebellum – coordinates movement • Brain stem – connect brain and spinal cord, controls many involuntary fxns • Thalamus – receives sensory messages • Hypothalamus – controls primitive needs and emotions

12. The Brain

13. The Spinal Cord • 31 pairs of nerves branch off • Controls reflex arc

14. Peripheral Nervous System • All nerves outside of brain and spinal cord • Sensory – receives internal and external stumuli • Motor – controls muscles and glands

15. Peripheral Nervous System • Motor Division • Somatic NS – controls all voluntary activity • Autonomic NS – involuntary activity • Sympathetic – controls body during times of stress • Ex - speeds up heart rate • Parasympathetic – controls body normally, returns body to normal state after stress • Ex – slows heart rate

16. N.S. Concept Map

17. Chapter 35.3 “The Senses” • Objective: • List and discuss the 5 senses.

18. The Five Senses • Sight, Sound, Taste, Touch, Smell • There are 5 general categories of sense receptors. • Pain receptors • Thermoreceptors - temperature • Mechanoreceptors – touch, sound • Chemoreceptors - chemicals • Photoreceptors - light

19. Vision • Photoreceptors in retina • Rods – detect light • Cones – detect color

21. Hearing • Acoustic Receptors: a special type of mechanoreceptor. • Respond to sound (disturbance of air) • Found in inner ear. • Semicircular canals: fluid filled tubes that help you maintain your balance

22. The Ear Semicircularcanals

23. Smell & Taste • Chemoreceptors • Respond to taste & smell (chemical stimuli) • Found in tongue, roof of mouth, nasal cavity.