1. The Nervous System

2. Nervous System Nervous System: Collects information, processes, and responds to internal and external environment –Quick, short term changes

3. Overview of Nervous System Stimulus: Something in environment causes a response Neuron: Cell that sends messages (neurotransmitters) Response: Reaction to environmental conditions RESPONSE! synapse

4. The Neuron Neurons build into nerves!

5. Parts of the Neuron Dendrites –Receive messages from previous neurons –Send message to cell body Cell Body –Contains nucleus and cytoplasm

6. Parts of the Neuron: Cont’d Axon –Long fiber that carries messages away from the cell body Myelin Sheath –Insulating membrane helps send the signal down the axon Nodes of Ranvier –Gaps between Schwann Cells –Impulse jumps from one node to next Schwann Cells –Cells that make myelin

7. Parts of the Neuron: Cont’d Axon Terminals –Branches at the end of an axon –Contain synapses where neurotransmitters are released

8. Synapses Synapse –Space between neurons –Carry messages or impulses from one nerve to the next Neurotransmitters –Chemical messages sent between neurons

9. How does a neuron work? Summary 1.Neurotransmitter received from another neuron goes through cell body 2.Impulse travels down the axon 3.Neurotransmitter released into synapse 4.Neurotransmitter received by protein receptors in dendrites of next neuron

10. A closer look how an impulse travels down the axon Polarization- differences in charge ( + or -) Resting All channels are closed High K+ concentration inside, high Na+ outside of axon Negative inside (-70 mV)

11. How an impulse is carried down the axon Action Potential Impulse in progress –Na+ channel opens –High Na+ and K+ concentration inside –Positive inside (+30 mV)

12. How does a neuron work? http://outreach.mcb.harvard.edu/animation s/actionpotential.swf

13. Types of Neurons Receptor & Sensory (Afferent) Neurons (Sensory Organs  Spinal Cord and Brain) Motor & Effector (Efferent) Neurons (Spinal Cord and Brain  Muscles and Glands) Interneurons Sends Messages between Nerves (Sensory, Receptor, Motor, and other Interneurons)

14. Reflex Arc Receptor Sensory Neuron Interneuron Motor Neuron Effector (Muscle) Afferent Neurons Efferent Neurons No brain involved! Spinal Cord

15. Central Nervous System (CNS) Consists of the brain and spinal column

16. The Spinal Cord Gray Matter –Consists of cell bodies White Matter –Consists of axons

17. Parts of the Brain Corpus Collasum Meninges- protective covering of the brain/spinal cord Occipital

18. Brain AreaFunction MeningesProtection of spinal cord and brain CerebrumMemory center CerebellumCoordination and balance MedullaInvoluntary processes Spinal CordNerves from brain ThalamusRelay center between brain and spinal cord HypothalamusHomeostasis- hunger, thirst, hormones Connects nervous and endocrine systems OccipitalVision & Hearing Corpus CollasumConnects left and right brain

19. Peripheral Nervous System Peripheral Nervous System- connects the central nervous system to the rest of the body Somatic- voluntary Autonomic- involuntary –Parasympathetic- at rest –Sympathetic- fight or flight

20. Malfunctions Meningitis- swelling of meninges Cerebral Palsy- birth defect, affects muscle coordination Stroke- blood clot to the brain Polio- viral illness Multiple sclerosis (MS)- break down of myelin sheath- impairs movement

21. Malfunctions Drug Addictions Stimulants –Increase the number of neurotransmitters Depressants –Decrease the number of neurotransmitters

22. HONORS EXTENSTION: Other Animals’ Nervous Systems Hydra –No brain –Nerve Net –Respond to stimuli

23. HONORS EXTENSION: Other Animals’ Nervous Systems Earthworm –Central Nervous System (CNS) Primitive brain –Ganglia- cluster of nerves Nerve cord

24. HONORS EXTENSION: Other Animals’ Nervous Systems Grasshopper Central Nervous System (CNS) Sensory Organs (Antannae, Tympana- ears, cilia, mouth, eyes