Unit 2 Notes: Basics, Cells & Organization

(1) Function Respond to stimuli Process information Communicate Maintain homeostasis Basic Pathway: Sensory Input  Integrate & Process  Motor Output

(2) Structure Made of: Brain Spinal cord Neurons Junctions Has a complex organization (hierarchy) of sensory and motor levels.

(3) Brain & Spine Brain divided into lobes Spinal cord = communication highway All nerves communicate through Spine Example: Paralysis

(4) Neuron Neuron = Nerve Cell Types: Multipolar + Unipolar Basic Structural Components: Dendrites (Incoming) Cell Body (Integrate + Process) Axon (Outgoing) Myelin Sheath (Insulation + Speed) Axon Terminal (Final Destination)

(5) Unipolar Neurons Use: Afferent Input (Sensory Input) Dendrites connected to sensory organ Message sent to cell body  Out Axon Message sent out of axon terminal FOCUS: Get message to CNS Let CNS process and decide (NO need to have cell body right by dendrites)

(6) Multipolar Neurons Use: Efferent Output (Motor Output) Multi = Lots of extensions coming from cell body Cell body directly connected to dendrites Dendrites coming from CNS / Efferent path  effected organ FOCUS: Organize messages by importance Make organs do things (Important to have cell body right next to dendrites)

(7) Neuroglia Function: Support, insulate and protect neurons. Types: Cannot transmit nerve impulses Can continuously divide through mitosis Types: Astrocytes Microglia Ependymal Oligodendrocytes Schwann Cells & Satellite Cells

(8) Astrocytes Star-Shaped glia cells Connect neurons to capilaries Transfer blood-nutrients to neurons (and neuron waste to blood)

(9) Microglia Spider-Shaped glia cell Phagocytize neuron debris and infectious agents. Phagocytize??  Eat or Engulf

(10) Ependymal Cells Pillow-Shaped cells Line brain and spinal cord cavities Beat cilia + Circulate cerebrospinal fluid Provide Shock Absorption

(11) Oligodendrocytes Flat, Straw-Shaped cells Wrap around a neuron’s axon Fatty insulation for axon (myelin sheath)

(12) Schwann & Satellite Cells Schwann Cell: Form Myelin Sheath around axons Cover Oligodendrocytes Satellite Cell: Protective Cushioning Surround Cell body of neurons

(13) Junctions Junction = Meeting of Neuron + Neuron or Neuron + Organ A.K.A.  Synapse, Synaptic Cleft Nerve Impulse  Axon  Axon Terminal  Release Neurotransmitter Neurotransmitter = Chemical Message Causes an effect Binds with cell membrane on other side

(14) Nervous System Organization CENTRAL NERVOUS SYSTEM PERIPHERAL NERVOUS SYSTEM (SENSORY / AFFERENT INPUT) PERIPHERAL NERVOUS SYSTEM (MOTOR / EFFERENT OUTPUT) BODY (INITIAL STIMULUS / IMBALANCE) AUTONOMIC (INVOLUNTARY) SOMATIC (VOLUNTARY) SYMPATHETIC (FIGHT / FLIGHT) PARASYMPATHETIC (REST & DIGEST)

(15) Peripheral Nervous System (PNS) Organizes messages sent TO and AWAY from the CNS. 2 Divisions: Sensory/Afferent Input Motor/Efferent Output

(16) Sensory vs. Motor SENSORY: (INPUT) MOTOR: (OUTPUT) Afferent Input (toward from body) Sends message from body part  Brain Response to initial stimulus or Imbalance MOTOR: (OUTPUT) Efferent Output (away from body) Sends message from CNS  effector organ *Effector Organ = Organ which responds Includes 2 Divisions… Autonomic Somatic

(17) Somatic vs. Autonomic Voluntary Actions (Conscious Decisions) Skeletal Muscle AUTONOMIC: Involuntary Actions (Happens w/o Thought) Includes 2 Divisions… Parasympathetic Sympathetic

(18) Parasympathetic vs. Sympathetic “Rest & Digest” Regular body functions (digestion, blinking, gas exchange, sleep, etc.) SYMPATHETIC: “Fight or Flight” Body functions ONLY during heightened emotion (change in heart rate, perspiration, change in blood flow, etc.)