1. Structure of the nervous system
@ Macroscopic level
Brain & nerves
@ Microscopic level
Neurons & Glial Cells

2. Macroscopic: Divisions of the Nervous System
Central (inside skull & spine)
Brain
Spinal Cord
Peripheral (outside skull & spine)
Nerves

3. Central Nervous System
Brain

4. Divisions of the human brain

5. Specialization of function
Different regions of the brain are associated with different function

6. Spinal Cord Reflex Group activity Spinal cord lesion
Ouch! That hurts, dude!
Spinal cord
lesion
Here is where spinal cord lives.
Nerves leave spinal cord from between vertebrae (thus if discus moves, or pinch) there is pain (similar to facia paralysis following inflamation of facial nerve, or oppression of optic nerve by pituitary tumor).
Would sensation be abolished by:
a spinal cord lesion?
polio?
- Would the reflex be abolished by:
- a spinal cord lesion?
- polio?

7. Peripheral Nervous System
Somatic System:
- controls voluntary muscle
Autonomic System:
- controls glands & internal organs
- has two subcomponents
- Sympathetic (adrenaline): arousal
- Parasympathetic: calm

8. Figure 3.28 The Autonomic Nervous System

9. Levels of Investigation
Brain Areas
(visual system)
Cells
(neurons)
Molecules
(neurotransmitters)

10. Microscopic level: Neurons

11. Neurons: Its many shapes & sizes

12. Neuron: basic parts Cell Body football field Dendrite Campus
Axon wide a street
Axon long as Philly - Ohio
Cell membrane thick as pinky finger
Synaptic cleft thick as thumb
# synapses (same number as Villanova students)
axon terminals
Some axons are wrapped burrito-style by fatty cells (glial cells)
- increases speed at which neurons communicate)
- white in color (white matter vs gray matter
- is destroyed by multiple sclerosis

13. Neuron: its physiology
What makes neurons different from other cells?
Neurons process and transmit electrical impulses
Neuron’s cell membrane is electrically charged (interior is more negative)
Neurons influence each other’s charge (‘communicate’)
Soma or “cell body”: The cell body of a neuron, which contains the nucleus.
Dendrite: A branched treelike structure attached to the soma of a neuron; receives information from the terminal button of other neurons
Synapse: A junction between the terminal button of an axon and the membrane of another neuron.
Axon: The long, thin cylindrical structure that conveys information from the soma of a neuron to its terminal button.
Terminal button: The bud at the end of a branch of an axon; forms synapses with another neuron; sends information to that neuron.
Neurotransmitter: A chemical that is released by a terminal button; has an excitatory or inhibitory effect on another neuron

14. How do neurons process and transmit electrical impulses?
A. dendrites receive input from other neurons
B. axon sends neural impulse to axon terminal
C. a neurotransmitter (NT) is release and makes contact with another neuron (synapse)
Soma or “cell body”: The cell body of a neuron, which contains the nucleus.
Dendrite: A branched treelike structure attached to the soma of a neuron; receives information from the terminal button of other neurons
Synapse: A junction between the terminal button of an axon and the membrane of another neuron.
Axon: The long, thin cylindrical structure that conveys information from the soma of a neuron to its terminal button.
Terminal button: The bud at the end of a branch of an axon; forms synapses with another neuron; sends information to that neuron.
Neurotransmitter: A chemical that is released by a terminal button; has an excitatory or inhibitory effect on another neuron

15. Synapse Communication Steps NT is released from pre-synaptic neuron
NT binds to receptors in post-synaptic neuron
Opens Na+ channels
Sodium rushes in (activation)
If enough Na+ rushes in => depolarization (action potential)
NT released by post-synaptic neuron
Pre-synaptic neuron
Presynaptic membrane: The membrane of a terminal button that lies adjacent to the postsynaptic membrane and through which the neurotransmitter is released.
Synaptic cleft: The space between the presynaptic membrane and the postsynaptic membrane.
Synaptic vesicle: A small, hollow, beadlike structure found in the terminal buttons; contains molecules of a neurotransmitter.
Postsynaptic receptor: A receptor molecule in the postsynaptic membrane of a synapse that contains a binding site for a neurotransmitter.
Neurotransmitter-dependent ion channel: An ion channel that opens when a molecule of a neurotransmitter binds with a postsynaptic receptor
Excitatory postsynaptic potential (EPSP): An excitatory depolarization of the postsynaptic membrane of a synapse caused by the liberation of a neurotransmitter by the terminal button.
Inhibitory postsynaptic potential (IPSP): An inhibitory hyperpolarization of the postsynaptic membrane of a synapse caused by the liberation of a neurotransmitter by the terminal button.
Neuromodulator: A naturally secreted substance that acts like a neurotransmitter except that it is not restricted to the synaptic cleft but diffuses through the extracellular fluid.
Post-synaptic neuron

16. Other important facts Various Neurotransmitters (NT):
Dopamine
Adrenaline
Serotonin
Acetylcholine
For each NT,various receptors
- nicotine & muscarine
Drugs can act by
- modifying amount of NT, or
- binding to receptor (nicotine)
The net effect on neuron could be:
- activation (action potential)
- inhibition

17. Cells of the Nervous System
Glia (Greek=glue)
Many types (oligodendrocites, schwann cells, astrocytes, and microglia)
More prevalent than neurons (10:1)

18. Complexity of CNS 1011 (100 billion) neurons
each neuron interacts with 1, others
=> trillion connections (that’s a big #)
Many other factors:
Neurotransmitters
Receptors
Genes, Glial cells etc.

19. Glial Cells
Functions: support, immunology (defense), nutrition for neurons, guide migration of neurons during development, maintain ion balance, etc.
Form myelin which helps the speed of the action potential. In Multiple Sclerosis, the myelin is broken down and axons become less efficient.
Myelin sheath: A sheath that surrounds axons and insulates them, preventing messages from spreading between adjacent axons.
Node of Ranvier: A naked portion of a myelinated axon, between adjacent oligodendroglia or Schwann cells.

20. Copyright © Allyn & Bacon 2004

21. Copyright © Allyn & Bacon 2004

22. Blood-brain barrier
Basal ganglia lesion (hiperdensities) due to increased bilirubin in newborn (kernicterus)
Movement disorder
Blood-brain barrier: A semipermeable barrier between the blood and the brain produced by cells in the walls of the brain’s capillaries.
Area postrema: A region of the medulla where the blood-brain barrier is weak; poisons can be detected there and can initiate vomiting

23. Spared images

24. Figure 3.3 The Nervous System

25. Figure 3.24 Spinal Column, Ventral View

26. Vertebra of Spinal column
Here is where spinal cord lives.
Nerves leave spinal cord from between vertebrae (thus if discus moves, or pinch) there is pain (similar to facia paralysis following inflamation of facial nerve, or oppression of optic nerve by pituitary tumor).

27. Figure 3.26: Spinal Cord Cross Section

28. Figure 3.25 The Spinal Cord