2. Events of an Action Potential (label the graph below):
BIO 1007 Lecture Outlines | BIO 1007 Resources | Mrs. Caley Opsal's Home | IVCC Home | Contact Us
I. Fundamentals of the Nervous System
A. Divisions of the Nervous System
1. CNS
a. Brain
b. Spinal cord
2. PNS
a. Sensory (Afferent)
b. Motor (Efferent)
1. Somatic (voluntary)
2. ANS (involuntary)
a. Sympathetic
b. Parasympathetic
B. Definition of Terms:
1. Neurons -
2. Neuroglia -
3. Nerve fibers -
4. Nerve impulse -
5. Nerves -
6. Sensory receptors -
7. Stimulus - anything that elicits a response from the nervous system8. Effectors - respond to impulses coming from the CNS (i.e. muscles and glands)
9. Myelin -
10. Dendrites -
11. Axons - send information AWAY from the neuron (synaptic terminals or knobs communicate with other cells or effectors)
12. Ganglion -
13. Nucleus -
C. Functions of the Nervous System
1. Sensory Input
2. Integration
3. Motor outputD. Structure of an Axon
1. Schwann cells
3. Myelin Sheath
4. Nodes of Ranvier
E. Neurons
1. General structure
a. Cell body (soma)
b. Axon
c. Dendrite/s
d. Myelin sheath
e. Nissl bodies -represent RER
2. Structural Classification of Neurons
a. Unipolar
b. Bipolar
c. Multipolar
3. Functional Classification of Neurons
a. Sensory (Afferent) neurons
b. Interneurons (Association neurons)
c. Motor (Efferent) neurons
F. Neuroglia
1. Astrocytes
2. Oligodendrocytes
3. Microglia
4. Ependymal cells (ependyma)
5. Schwann cells (only in PNS)
II. Neurophysiology
A. Cell Membrane Potential (refer to figure 8-7 in text)
1. Resting cell distribution of ions
a. High potassium ions _____________ the cell
b. High sodium ions _____________ the cell
c. High negatively charged particles (anions) ___________ the cell
d. Resting membrane potential (-70 mV)
**Changes in Membrane Potential Lead to Action Potentials (AP)**
This electrochemical gradient can do work in the form of an AP
Action potential - series of electrochemical changes that occur along the membrane of an axon; an action potential is an all-or-none phenomenon and is propagated from the beginning of the axon to its end
Hyperpolarization - membrane potential is getting more negative, usually due to an increase in K+ permeability
Depolarization - membrane potential is approaching zero (due to influx of Na+) and will peak at ~+30 mV
Graded potential - a localized change in membrane potential that spreads in both directions along a nerve fiber; the degree of depolarization decreases with distance (amount of potential change depends on stimulus intensity)
Threshold stimulus -
Summation is possible
Subthreshold stimulus -
Refractory period -
2. Events of an Action Potential (label the graph below):
a. Increase in Na+ permeability and reversal of membrane potential.
b. Decrease in Na+ permeability
c. Increase in K+ permeability and repolarization
C. The Synapse
1. Presynaptic neuron
2. Postsynaptic neuron
3. Synaptic cleft
4. Postsynaptic Potentials:
Excitatory postsynaptic potential (EPSP)
-stimulates a neuron to depolarize
Inhibitory postsynaptic potential (IPSP)
-stimulates a neuron to hyperpolarize
D. Neurotransmitters (NTs)
1. Excitatory NTs (not entirely true!)
a. Acetylcholine
b. Norepinephrine ("noradrenaline")
2. Inhibitory NTs (not entirely true, either!)
a. Seratonin
b. Gamma amino butyric acid (GABA)
c. Dopamine
E. Neuropeptides (Neuromodulators) - alters a neuron's response to a NT
1. Enkephalins - relieve pain
2. Beta-endorphin - more potent pain-reliever than enkephanlins
3. Substance P - PAIN!!
III. So What Have We Covered So Far??
A. In a resting neuron (i.e. one that is exhibiting resting membrane potential)....
1. What is the distribution of sodium and potassium ions?
2. What is the charge inside the neuron?
3. What accounts for the net negative charge inside the neuron?B. With regard to graded potentials....
1. How are they different than action potentials?
2. Are they an "all or none" event?C. With regard to action potentials....
1. On what part of the neuron are they generated?
2. Do they begin with depolarization or repolarization?
3. Are they an "all or none" event? What does that mean?
4. Do they vary in terms of their strength?D. With regard to the synapse...
1. How does the presynaptic neuron communicate with the postsynaptic neuron?
2. What is the space between the 2 neurons called?
3. How are calcium ions involved?
4. What would an excitatory postsynaptic potential stimulate in a neuron on the receiving end?
5. What would an inhibitory postsynaptic potential stimulate in a neuron on the receiving end?
6. What is summation?
Last Updated 05/26/06
