I. General organization of nervous system
A. CNS
1. brain
2. spinal cord
B. PNS
1. sensory
2. motor a. Somatic b. ANS
-sympathetic
-parasympathetic

II. Nervous Supporting Cells - neuroglia
A. Astrocytes
1.
Connect to capillaries
2.
Mopping up chemical environment of brain as far as potassium ions and neurotransmitters
3.
Help to create blood brain barrier

B. Microglia
• 1. spider-like phagocytes
• 2. debris, dead brain cells, bacteria

C. Ependymal cells
• 1. lines cavities in CNS
• 2. beating of cilia moves cerebrospinal fluid
• 3. fluid nourishes and cushions
CNS
• 4. creates CSF in the choroid plexi of the brain’s ventricles

D. Oligodendrocytes
• 1. wrap axons of several nerve cells with fatty layer
• 2. produces myelin sheath
• 3. speeds conduction
• 4. located with the CNS

E. Schwann cells
• 1. located outside of CNS
• 2. produce myelin sheath as do the oligodendrocytes
• 3. takes several Schwann cells to produce the myelin sheath for one axon of one nerve cell

F. Glia cells in general
• 1. resemble neurons
• 2. not excitable
• 3. supportive cells
• 4. capable of repeated mitosis
• 5. gliomas-glial tumors

III. Neurons
A. Structure
• 1. cell body
• 2. nissl bodies-rer
• 3. dendrites
• 4. axon
• 5. axon hillock
• 6. axon collateral
• 7. axon terminals
• 8. neurotransmitters
• 9. synaptic cleft

B. Myelin sheath
• 1. functions
• 2. PNS-Schwann cell
• 3. Node of Ranvier
• 4. Can form a pathway for regrowth of damaged axon
• 5. multiple sclerosis

C. Neurons classified by function
• 1. afferent
• 2. interneuron
• 3. efferent
• 4. ganglia
• 5. nuclei
• 6. gray matter
• 7. white matter

D. Neurons classified by structure
• 1. multipolarmost common
• 2. bipolarlocated in some sensory organs such as the eye
• 3. unipolarsensory neuron

IV. Neuron physiology
• A. Membrane traits
• 1. semipermeable
• 2. Na/K ion pump
• 3. Leak gates
•
•
• 4. gated channels a. Ligand-gated b. Voltage-gated

B. Resting membrane characteristics
• 1. semipermeable
• 2. negative charged proteins
• 3. relatively impermeable to Na and
Cl ions
• 4. bit more permeable to K ions
• 5. due to action of Na/K ion pump notice separation of ions
• 6. potassium ions leak out due to K ion leak channels

C. Resting membrane potential
• 1. at rest, interior of cell possesses slightly negative charge
• 2. -70 mV
• 3. due to K ion movement mainly
• 4. diffusion out
• 5. electrical attraction in
• 6. slightly more positive charge outside
• 7.
http://www.youtube.
com/watch?v=YP_P6b
YvEjE

D. Changing the resting membrane potential in a resting neuron
• 1. depolarization
• 2. hyperpolarization
• 3. changes in extracellular K ions (hypokalemia)
• 4. changes in extracellular Na ions
• 5. changes in extracellular Ca ions
• a. Ca ions are attracted to negative proteins of Na gated channels
• b. If Ca ion concentration falls-fewer Ca ions attached to Na gated channels-causes channels to openproduces???hypocalcemia
• c. If Ca ion levels rise-???

E. Graded potentials
• 1. strictly local event
• 2. caused by change in local ion gates
• 3. change brought about by several possible stimulus sources
• 4. chemical, voltage changes, temperature, mechanical stimulation
• 5. may be excitatory or inhibitory
• 6. conducted but in a decremental manner

F. Action potential
• 1. produced by graded potentials
• 2. threshold potential
• 3. intiates series of membrane gate changes
• 4. wave of depolarization
• 5. repolarization
• 6. hyperpolarization
• 7. return to normal
• 8. all-or-none
• 9. https://highered.mcgrawhill.com/sites/007249585
5/student_view0/chapter
14/animation__the_nerve
_impulse.html

G. Refractory period
• 1. definition
• 2. absolute
• 3. relative

H. Frequency carries information
• 1. action potentials don’t vary in magnitude
• 2. threshold stimulus produces one action potential
• 3. submaximal stimuli produce increasing frequency of action potentials until
• 4. maximal stimulus-lowest stimulus strength that produces maximum frequency of action potentials
• 5. supramaximal stimulus

I. Propagation of action potentials
• 1. concentration difference of ions on either side of membrane represents potential energy-kind of like of cocked gun
• 2. stacked dominoes waiting to fall over
• 3. one domino falling over initiates a wave of action potentials spreading out like the ripples in a pond
• 4. each action potential is just as strong as the previous action potential
• 5. strength does not diminish as nerve impulse moves down the axon
• 6. http://highered.mcgrawhill.com/sites/9834092339/student_view0/chapter44/action_poten tial_propagation_in_an_unmyelinated_axon.html
• 7. http://www.youtube.com/watch?v=DJe3_3XsBOg

V. Synapses
A. Anatomy
• 1. presynaptic membrane
• 2. synaptic cleft
• 3. postsynaptic membrane
• 4. synaptic vesicles
• 5. receptor sites for transmitter substance

B. Physiology of synapse
• 1. action potential arrives
• 2. Calcium ion channels open
• 3. synaptic vesicles fuse with membrane
• 4. transmitter substance released
• 5. diffusion of transmitter substance
• 6. binding to receptors
• 7. creates a graded potential
• 8. may bring postsynaptic membrane to threshold
• 9. nerve gas-blocks cholinesterase
• 10. IPSP or EPSP

C. You tube of synaptic events
• http://www.youtube.com/watch?v=LT3VKAr4r oo

D. Types of Synapses
• 1. axo-dendritic
• 2. axo-somatic
• 3. axo-axonic
• a. Presynaptic inhibition of enkephalins and endorphins in brain sensory neurons blocking
Ca channels
• b. Presynaptic facilitation due to serotonin releasecauses Ca channels to open

E. Post synaptic fiber as a neural integrator
• 1. temporal summation
• 2. spatial summation
• 3. neural integrator