Nervous System

1. Nervous System

2. Nervous System Brain Central Nervous System Spinal Cord Nervous system Sensory Nerves Peripheral Nervous System Somatic Motor Nerves Automatic

3. Function of the nervous system: Controls and coordinates functions throughout the body

4. The Neuron – nerve cell nucleus Axon terminals Dendrite – reception of nerve impulses from other cells Cell body – contains the cell nucleus Axon – carries the nerve impulse away from the cell body Myelin sheath – insulating membrane Cell body Myelin sheath nodes axon dendrites

5. Nerve Impulse Moves like the flow of electrons through a wire

6. Nerve Impulse 2 Phases: resting potential – the neuron membrane is positive outside and negative inside; the sodium-potassium pump moves sodium out while bringing in potassium action potential – negative outside and positive inside; as the nerve impulse moves along the neuron from the dendrites through the cell body to the axon, polarity changes across neuron membrane;

8. Practice Label the indicated parts. A B C

9. Synapse location where nerve impulse moves from one neuron to the next Tiny gap where the nerve impulse is transferred by chemical neurotransmitters

10. Divisions of the nervous system Central nervous system (CNS) – brain & spinal cord Peripheral nervous system (PNS) – nerves to other parts of the body Sensory – provides brain with information from the senses Motor – carries information from the CNS to the muscles & glands, divided into somatic nervous system (voluntary movement) and automatic nervous system (involuntary movement)

11. The Brain Controls and coordinate body activities Meninges – tough covering over the brain & spinal cord Cerebrum (gray matter) – controls voluntary activities, intelligence Cerebellum – back of skull; coordinates & balances actions of muscles & body

12. The Brain Brainstem – pons and medulla oblongata regulates the flow of information between the brain & body controls blood pressure, heart rate, breathing, & swallowing

13. The Brain Thalamus – receives messages from the senses & sends them to cerebrum Hypothalamus – control center that detects and analyzes hunger, thirst, fatigue, anger, & body temperature controls and coordinates nervous & endocrine systems

14. thalamus cerebrum hypothalamus midbrain cerebellum pons Medulla oblongata

15. Practice Which part of my brain…?

16. Reflex Arc Quick automatic response to stimulation like blinking or sneezing Nerve impulse goes to the spinal cord & back to muscles without passing through the brain

17. The Senses • Eye – light passes though the cornea, pupil (opening at the front of the eye) & lens to the retina. • Retina – consists of rods (sensitive to light) & cones (distinguishes color) • Optic nerve – sends messages from the retina to the brain

18. Vitreous humor Muscle Lens Fovea Aqueous humor Cornea Pupil Optic nerve Iris Blood vessels Ligaments Retina Choroid Sclera

19. Ear • Has 3 tiny bones - hammer, anvil, stirrup • Conduct sound vibrations: tympanum, hammer, anvil, stirrup, oval window, cochlea • Semicircular canals – three fluid-filled tiny canals, assist in balance

20. Stirrup Hammer Oval window Anvil Semicircular canals Cochlear nerve Cochlea Bone Auditory canal Tympanum Eustachian tube Round window

21. Taste buds – on the tongue, detect taste

22. Smell – detected by olfactory bulbs in nasal passages • Touch – skin has sensory receptors to temperature, touch, and pain

23. Drugs that affect the nervous system: • Stimulants – increase actions (heart rate, increase neurotransmitters in brain) • Include: caffeine, nicotine, cocaine • Depressants – decrease activity (heart rate) • Include: marijuana, alcohol