2 Nervous System Central nervous system (CNS): Brain Spinal cord Peripheral nervous system (PNS):Sensory neuronsMotor neurons (somatic and autonomic)
3 The Nervous System The Nervous System Central Nervous System (CNS) Peripheral Nervous System (PNS)BrainSpinal CordMotor NeuronsSensory NeuronsSomatic Nervous Systemvoluntary movements via skeletal musclesAutonomic Nervous Systemorgans, smooth musclesSympathetic- “Fight-or-Flight” responsesParasympathetic- maintenance
4 Divisions of the autonomic nervous system RestActionFigure 3.20 on page 89The sympathetic division of the nervous system prepares the body for action, whereas the parasympathetic returns it to a resting state.
5 The Nervous System A physical organ system like any other The main cell of the nervous system are:Neurons
6 The Neuron The basic functional unit of the nervous system. Function: Send impulses to and from the CNS and PNS
8 Dendrite Fine hair-like extensions on the end of a neuron. Function: receive incoming stimuli.Cell Body or Soma The control center of the neuron.Function: Directs impulses from the dendrites to the axon.Nucleus Control center of the Soma.Function: Tells the soma what to do.
9 Axon Pathway for the nerve impulse (electrical message) from the soma to the opposite end of the neuron.Myelin Sheath An insulating layer around an axon. Made up of Schwann cells.Nodes of Ranvier Gaps between schwann cells.Conduction of the impulse. (Situation where speed of an impulse is greatly increased by the message ‘jumping’ the gaps in an axon).
11 Types of Neurons There are 3 types of neurons. Sensory Neurons Neurons located near receptor organs (skin, eyes, ears).Function: receive incoming stimuli from the environment.Motor Neurons Neurons located near effectors (muscles and glands)Function: Carry impules to effectors to initiate a response.Interneurons Neurons that relay messages between other neurons such as sensory and motor neurons. (found most often in Brain and Spinal chord).
13 NervesNerves Collections of neurons that are joined together by connective tissue.Responsible for transferring impulses from receptors to CNS and back to effectors.
14 Three main types of neurons Sensory NeuronsInterneuronsMotor Neurons
15 CNS CNS Sensory vs. Motor sensory nerve e.g., skinNeurons that send signals from the senses, skin, muscles, and internal organs to the CNSmotor nerveCNSe.g., muscleNeurons that transmit commands from the CNS to the muscles, glands, and organsGray’s Anatomy
16 The Withdrawal Reflex Figure 2.5B from: Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.
18 Dendrites of another neuron NeuronsCell BodyDendritesAxonMyelin SheathDendrites of another neuronAxon of another neuron
19 Neural Anatomy Dendrite Axon the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell bodyAxonthe extension of a neuron, ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands
20 Neural Anatomy and communication Synapsejunction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neurontiny gap at this junction is called the synaptic gap or cleftSynapse movie
21 Specific Parts: The Neuron Structure Figure 2.6 from:Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.Source:
22 Specific Parts: The Neuron Function 1.3.2.Figure 2.6 from:Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.Source:Neurons = 3 functions: Reception, Conduction, Transmission
23 Communication Impulse releases neurotransmitter from vesicles Neurotransmitter enters synaptic gapNeurotransmitter binds to receptors on the receiving neuronFigure 2.7 from:Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.Source:
24 Myelin Sheath Fatty material made by glial cells Insulates the axon Allows for rapid movement of electrical impulses along axonNodes of Ranvier: gaps in myelin sheath where action potentials are transmittedMultiple sclerosis is a breakdown of myelin sheathSpeed of neural impulse Ranges from 2 – 200+ mph
26 Neurotransmitterschemical messengers that travel across the synaptic gaps between neuronswhen released by the sending neuron,neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether it will generate a neural impulse