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