7 The Nervous System PPT-A This ppt: 7 slides Total = 34 slides for 2 hour

PPT-A OUTLINE PPT-B OUTLINE I. Overall Functions II. NS Organization III. Nervous Tissue A. Sensory A. Structural A. Cells B. Integration B. Functional B. Terminology C. Motor C. Functional Classification IV. Physiology A. Electrical Properties B. Action Potentials V. Central Nervous System VI Peripheral Nervous Sys A. Brain A. Nerves B. Spinal Cord B. Autonomic NS PPT-B OUTLINE

I. Overall Functions of the Nervous System A. Sensory input = B. Integration = C. Motor output =

II. Organization of the Nervous System A. Structural Classification 1. *Central nervous system (CNS) = a. *Parts b. *Function 2. *Peripheral nervous system (PNS) = b. *Functions: B. Functional Classification of the Peripheral N.S. 1. Sensory (afferent): 2. Motor (efferent):

III. Nervous Tissue Structure & Function: A. Nervous Tissue Cells 1. *Neuroglia (glial): Support Functions *Support *Insulate *Protect 2. Neurons a. *Function: b. Parts– i) *Cell body ii) *Processes (1) *Dendrites: Describe and give function

*Axon Terminal with*Contain Synaptic Vesicles *Neurotransmitters b. Parts– … (2) *Axons: Axon Hillock: *Axon Terminal with*Contain Synaptic Vesicles *Neurotransmitters c. Synaptic cleft = Synapse—gap between adjacent neurons d. Myelin sheath = Cell that forms it: ii) How forms it: iii) Function: Synapse

Dendrite Cell body Mitochondrion Nissl substance Axon hillock Axon Neurofibrils Collateral branch Nucleus One Schwann cell Node of Ranvier Axon terminal Schwann cells, forming the myelin sheath on axon (a) Figure 7.4a

Neuron cell body Dendrite (b) Figure 7.4b

C. Functional Classification of Neurons *Sensory Neurons: *Receptors 2. *Interneurons (association neurons): Connect sensory and motor neurons 3. *Motor Neurons What are the 3 functional types of neurons? Explain the function of these neuron types. What are Receptors and give 3 examples?

Central process (axon) Sensory neuron Spinal cord (central nervous system) Cell body Ganglion Dendrites Peripheral process (axon) Afferent transmission Interneuron (association neuron) Peripheral nervous system Receptors Efferent transmission Motor neuron To effectors (muscles and glands) Figure 7.6

IV PHYSIOLOGY: Action Potentials A. Functional Properties of Neurons 1. Irritability 2. Conductivity B. The Action Potential The Resting Neuron-- Prior to the Action Potential Inside Neuron next to membrane: more negatives: INSIDE IS NEGATIVE More K+ (less K+ outside) Outside cell membrane: more positives: THE OUTSIDE IS POSITIVE More Na+ (less Na+ inside)

+ POSITIVE CHARGE + + + _ 2. RESULT: STORED ENERGY Action Potential … 2. RESULT: STORED ENERGY Membrane Charges are Polarized ii) Two Ion Concentration Gradients + POSITIVE CHARGE + + __ __ __ NEGATIVE CHARGE K+ Na+ Na+ Na+ + Na+ Na+ Na+ _ K+ K+ K+ K+ K+ K+ Na+

Nerve Impulses … _ + 3. Starting the Action Potential a. Stimulus: maybe sensory or neurotransmitter from an adjacent neuron b. Depolarization = Sodium moves from high to low to inside neuron The inside becomes Positive instead of Negative = Depolarized STIMULUS Na+ Na+ Na+ Na+ Na+ _ Na+ + K+ K+ K+ K+ K+

c. Repolarization Nerve Impulses … + _ Potassium diffuses from High to Low to the outside of the membrane Repolarization: with the loss of positive ions, the inside of the cell membrane is restored to a negative charge K+ + _ Na+ Na+ Na+ K+ K+ K+ K+ K+ Na+ Na+ Na+

d) Redistribution of ions Figure 11.12 Propagation of an action potential (AP) showing change of charges across the axon membrane. d) Redistribution of ions Initial ionic conditions, with potassium inside and sodium outside, are restored using the sodium-potassium pump. PUMP Cell Outside Na+ K+ Cell Inside © 2013 Pearson Education, Inc.

C. Transmission of a Signal at Synapses 1. When action potential reaches the axon terminal Neuron #1 Action Potential Arrives at Axon Terminal. Axon terminal Ca+ Ca+ Ca+ Ca+ Neuron #2 Dendrite

Transmission of a Signal at Synapses … (1) Vesicles move to membrane Axon terminal Synaptic cleft Vesicles 1 Ca+ Ca+ Dendrite Ca+ Ca+ Figure 7.10, step 1

Ca+ Ca+ Ca+ Vesicle fuses with Axon terminal of plasma Neuron #1 membrane. 2 Axon terminal of Neuron #1 Ca+ Ca+ Ca+ Synaptic cleft Neurotransmitter molecules Dendrite or Neuron #2 Figure 7.10, step 2

Ca+ Transmitting neuron Vesicle fuses with plasma membrane. 2 Neurotrans- mitter is released into synaptic cleft. 3 Ca+ Synaptic cleft Neurotransmitter molecules Dendrite Receiving neuron Figure 7.10, step 3

Transmission of a Signal at Synapses ,,, (4) Neurotransmitters diffuse across to dendrite of neuron or to muscle cells Axon Terminal Dendrite

Ca+ AXON TERMINAL Neurotrans- mitter binds to 2nd Cell . Synaptic 5 Neurotrans- mitter binds to 2nd Cell . Ca+ Synaptic cleft Dendrite Figure 7.10, step 4

Transmission of a Signal at Synapses … (6) The 2nd neuron has received the message and, then, it may send its own Action potential Neurotransmitter Ion Receptor 5 Ion channel opens.