1. Unit 2 Notes: Basics, Cells & Organization

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

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

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

5. (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)

8. (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)

10. (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)

13. (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

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

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

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

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

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

25. (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

28. (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)

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

30. (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

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

32. (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.)