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CH 10 – Nervous System. Basic Structure and Function. System Function. Sensory (internal & external) Integration Motor. Major Organs. Central Nervous System (CNS) Brain Spinal Cord. Peripheral Nervous System (PNS) Connect brain to the rest of the body. Pieces and Parts. Neural Tissue

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CH 10 – Nervous System

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ch 10 nervous system

CH 10 – Nervous System

Basic Structure and Function

system function
System Function
  • Sensory (internal & external)
  • Integration
  • Motor
major organs
Major Organs
  • Central Nervous System (CNS)
    • Brain
    • Spinal Cord
  • Peripheral Nervous System (PNS)
    • Connect brain to the rest of the body
pieces and parts
Pieces and Parts
  • Neural Tissue
    • Neurons
    • neuroglial cells
  • Blood Vessels
  • Connective Tissue
neural tissue
Neural Tissue
  • Neurons
  • Neuroglial Cells

Generalized Model of a myelinated neuron.

Tissue made of these kinds of cells appear white: “white matter” of brain and spinal cord.

(Nissl Bodies)

some differences
Some differences
  • Nissl bodies (RER)
  • Axon hillock
  • Soma = body
  • Space between neurons
  • Chemicals (neurotransmitters) cause an electric charge (action potential) to travel through a nerve
  • Calcium and sodium ions are essential to the process
  • Lead (Pb) will replace calcium ions in the body and interfere with neurotransmitter release
peripheral nervous system
Peripheral Nervous System
  • Sensory = afferent
  • Motor = efferent
    • Somatic (voluntary)
    • Autonomic (involuntary)
autonomic functions
Autonomic Functions
  • Parasympathetic
    • Rest and Digest
      • Stimulates peristalsis
      • Lowers blood pressure
      • Slows breathing
      • Stimulates anal sphincter
  • Sympathetic
    • Fight or Flight
      • Blood vessels constrict
      • Heart beats faster
      • Breathing quickens
      • Peristalsis stops
unmyelinated axons
Unmyelinated axons
  • Gray matter in brain and spinal cord
types of neuroglial cells
Types of Neuroglial Cells
  • Astrocyte Star-shaped cells that provide physical and nutritional support for neurons
  • Microglia:digest parts of dead neurons.
  • Oligodendroglia: Provide the insulation (myelin) to neurons in the central nervous system.
  • Ependymal: line the central canal
  • Schwann Cells: Provide the insulation (myelin) to neurons in the peripheral nervous system.
neuroglial fun facts
Neuroglial Fun Facts
  • Neuroglial cells account for half the brain’s volume
  • Most brain tumors are from neuroglial cells that divide too often
  • Researchers are trying to develop implants of neuroglial cells that secrete chemicals to treat Alzheimers, MS and Parkinson disease
neuron not so fun fact
Neuron Not-so-Fun Fact
  • Mature neurons in CNS do not divide
  • What you got, is what you got
    • Unless neural stem cells are stimulated to proliferate
  • Axons may regenerate
  • Tangled mass of sensory axons
  • Damaged neurons that don’t repair can do this.
stimuli disrupt homeostasis
Stimuli disrupt homeostasis
  • Light, temperature or pressure cause ion channels to open and the voltage changes
  • If stimuli reaches a certain threshold, it generates an action potential
  • Several sub-threshold potential stimuli can can generate an action potential via summation

Neuron stimulation causes sodium channels to open

Sodium flows in and makes the local area positive

Positive charge triggers same action further down the axon

Behind the action potential Potassium channels open to let K+ ions flow out and reestablish polarization

low on ca
Low on Ca+ ?
  • It takes calcium ions to close voltage gated channels
  • If there aren’t enough Ca+, the gates may be stuck in the open position. (Tetany)
  • 30 different kinds!!
  • Synthesized in cytoplasm of synaptic knobs
  • Release is triggered by calcium ions diffusing IN through voltage gated ion channels
drugs can alter neurotransmitter levels
Drugs can alter neurotransmitter levels
  • Tryptophan affects serotonin (makes you sleepy)
  • Nicotine tricks neurons into releasing dopamine
  • Curare blocks acetylcholine
spent neurotransmitters
Spent Neurotransmitters
  • Some are decomposed by enzymes
  • Some are returned to the presynaptic neuron by neuroglial cells