This document summarizes the anatomy and organization of the nervous system. It describes the basic structural components of neurons, including dendrites, cell bodies, axons, and myelin sheaths. It distinguishes between unipolar neurons, which transmit sensory input, and multipolar neurons, which organize motor output. Neuroglia are described as supporting, insulating and protecting neurons. The organization of the central and peripheral nervous systems is outlined, along with the somatic, autonomic, sympathetic and parasympathetic divisions.

1. ANATOMY
Unit 2 Notes:
Cells &
Organization

2. (1) Neurons
• 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. (2) Unipolar Neurons
• Use: Afferent Input (Sensory Input)
• Main Job:
– Get message to CNS
– Let CNS process and decide
(NO need to have cell body right by dendrites)
• Process:
– Dendrites connected to sensory organ
– Message sent to cell body  Out Axon
– Message sent out of axon terminal

7. (3) Multipolar Neurons
• Use: Efferent Output (Motor Output)
• Main Job:
– Organize messages by importance
– Make organs do things
(Important to have cell body right next to dendrites)
• Process:
– Cell body directly connected to dendrites
– Dendrites coming from CNS / Efferent path  effected organ

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

10. (5) Astrocytes
• Connect neurons to capillaries
• Transfer blood-nutrients to neurons
(and neuron waste
to blood)

13. (6) Microglia
• Phagocytize neuron debris and infectious agents.

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

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

19. (9) Schwann & Satellite Cells
• Schwann Cell:
–Form Myelin Sheath around axons
–Cover Oligodendrocytes
• Satellite Cell:
–Protective Cushioning
–Surround Cell body of neurons

20. (10) 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

22. (11) 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)
PARASYMPATHETIC
(REST & DIGEST)
SYMPATHETIC
(FIGHT / FLIGHT)

23. (12) Defining the Levels
• Sensory = Afferent = Going to the CNS
• Motor = Efferent = Going away from the CNS
• Somatic = Voluntary
• Autonomic = Involuntary
• Sympathetic = Emotional
• Parasympathetic = Non-Emotional

24. (13) Voluntary Responses
• Voluntary = You consciously choose to move a
body part / respond.
• Pathway:
Stimulus
Sensory / Afferent
Division
Central Nervous System
Motor / Efferent
Division
Effector Organ
Somatic Division

25. (14) Involuntary Emotional Responses
• Involuntary = Without control.
• Emotional = Scared, Anxious, Angry, Happy,
Excited
• Pathway:
Stimulus
Sensory / Afferent
Division
Central Nervous System
Motor / Efferent
Division
Effector Organ
Autonomic
Division
Sympathetic
Division

26. (15) Involuntary Non-Emotional Responses
• Involuntary = Without control.
• Non-Emotional = Every day homeostatic
mechanisms.
• Pathway:
Stimulus
Sensory / Afferent
Division
Central Nervous System
Motor / Efferent
Division
Effector Organ
Autonomic
Division
Parasympathetic
Division