AIM: How does the Nervous System work and how does it help the body maintain homeostasis? DO NOW: What is the function of the nervous system? What are the three types of neurons? What are their functions? Nervous System Vocabulary: neuron, cell body (soma), axon, dendrites, myelin sheath, synapse, neurotransmitter, receptor, central nervous system, peripheral nervous system, stimulus, impulse, regulation, effector, action potential, membrane (resting) potential, depolarization Have out HW for me to check Results and Discussion section due via turnitin.com on 12/23 (extended) HW due Tuesday pg 900 questions 1-5 and pg 905 ques 5 Exam on Wednesday circulation, respiration and the nervous system
Function of the Nervous System Process Information Stores Information Controls Voluntary movements Controls Involuntary process and actions Stimulus Vs Response
Parts of the Nervous System Central Nervous System Brain Spinal Cord Peripheral Nervous System Autonomic Nervous System Somatic Nervous System
What is Regulation? Control and coordination of all life functions 2 systems involved Stimulus: change or activity in the environment that causes a change in the organism; physical, chemical Receptors Response: action or movement resulting from a stimulus Effectors Impulses: electrical messages sent over a nerve cell (neuron)
Aim: How is an action potential propagated in the nervous system? Do Now: What is the central nervous system? Distinguish between sensory, motor and interneurons Results and Discussion section due via turnitin.com on 12/23 (extended) HW due Tomorrow pg 900 questions 1-5 and pg 905 ques 5 Exam on Wednesday circulation, respiration and the nervous system
Review of Do Now Central Nervous System Sensory Neurons Motor Neurons Brain and spinal cord Sensory Neurons Carry signals betewen the central nervous system and a sense organ. Motor Neurons Carry signals between the central nervous system and a muscle Interneurons Carry signals between sensory and motor neurons Demyelination
Neuron Sketch the diagram of a neuron below, and label each part AND its function. (See page 897) What would you expect to happen if a person had a disease in which the myelin sheath is destroyed? Sensory, motor, interneurons Axon terminals Myelin sheath Nodes Cell body Axon Nucleus Dendrites
Membrane Potential Describe the difference in charge between the inside and outside of the nerve cell (a). How is this difference maintained? Explain based on the picture above (b). Be specific!
Follow-up Questions Why is it impossible for ions to travel across the membrane by simple diffusion? How do ions travel across the cell membrane (two ways)? What do you think would happen if the sodium channels in a nerve cell were suddenly opened? The potassium channels? What effect would each of these events have on the membrane potential?
Aim: How is an action potential propagated in a neuron Do Now: How does an influx of Na+ change the membrane potential? What about an influx of K+? Have out HW Test on Thursday
The Action Potential Aim: How is an action potential propagated in the nervous system?
Cool Neuroscience Animation! http://outreach.mcb.harvard.edu/animations/actionpotential.swf
Review Questions How does an action potential stop, i.e., how does a nerve cell return to its resting (membrane) potential? Why is an action potential an all or none event? If action potentials are all or none events, how does the nervous system distinguish between strong and weak stimuli?
The Action Potential Resting potential established by Sodium Potassium pump Sodium-potassium pump (3 Na+ out, 2 K+ in) Stimulation: Channels open Na+ in and K+ out Threshold Reversal of charges All or none event Like the Domino effect
Dendrite of adjacent neuron The Synapse Direction of Impulse Dendrite of adjacent neuron -Junction between axon of one neuron and dendrites of another -Neuron can transfer an impulse to another cell How would abnormal levels of neurotransmitters affect the function of the nervous system? Axon Receptor Vesicle Electrical vs. Chemical Signaling Axon terminal Synaptic cleft Neurotransmitter
Questions For Review How does the nervous system couple electrical and chemical signaling? What events take place at the junction between two neurons? What is an action potential? Define depolarization. How does a neuron distinguish between a strong stimulus and a really strong stimulus? What is a synapse? What type of signaling takes place at the synapse?