A). Sensory input
B). Integration:
C). Response
 |
Neurons
I). Function
A). Sensory input
B). Integration:
C). Response
II). Division of the Nervous System
A). Central Nervous System: (CNS)
 | Brain and Spinal Cord only |
B). Peripheral Nervous System
| Outside CNS |
1). Sensory or afferent division:
| Carries impulses to CNS |
2). Motor or efferent division
| Carries impulses from the CNS. |
i). Somatic Nervous System
| voluntary |
ii). Autonomic Nervous System
| involuntary |
a. Parasympathetic
b. Sympathetic
III). Types of cells
|
A). Non nervous or glial cells.
1). Astrocytes
2). Microglia
3). Ependymal
4). Oliodendrocytes
5). Satellite cells
6). Schwann cells form myelin sheaths
|
B). Neurons
|
1). Structure
i). cell body or soma
| endoplasmic reticulum called the nissl body. |
ii). Processes or tracts (nerves)
a). Dendrites: input region
b). Axon: Carries information away
c). Synaptic knobs or Axonal terminals Releases neurotransmitters.
2). Axons
a). myelin sheath
| protects and electrically insulates fibers |
| conduct nerve impulses faster than nonmylenated fibers. |
b). nodes of Ranvier:
| spaces between the sheaths |
The action potential skips to the nodes
|
IV). Nerve Impulse
A). Terms
1). Resting membrane Potential:
| Polarized |
2). Depolarization:
| Change in ion concentration |
3). Hyperpolarization
| Change in ion concentration inside becomes more negative |
4). Graded Potential
| Localized change in ion; subthreshold |
5). Action Potential
| Change in ion concentration that does not decrease over distance. |
B). Action Potential
Stages of an Action Potential
|
polarized resting potential |
 |
depolarizes | |
|
repolarizes |
|
undershoot phase | |
Undershoot : the K+ channels stay open once resting potential is reached;
hyperpolarizing the cell.
|
C). Propagation
| Cannot be depolarized again until the membrane has reached resting potential. |
| The action potential moves at a constant velocity |
D). All or none phenomenon
| Not all depolarizations result in action potentials |
| The depolarization must reach the threshold point |
E). Refractory period
| absolute refractory period cannot respond to another stimuli. |
| relative refractory period The threshold is higher |
F). Impulse Velocity
| Strong stimuli result in more nerve impulses |
| Not stronger impulses or faster |
V). Synapse
| junction that carries information between neurons. |
A). Types
1). Electrical synapse: ions to cross junction
2). Chemical synapse
| neurotransmitters |
|
Impulse |
|
releases Ca++ (in neuron) | |
|
± neurotransmitter released ± binds to receptors± |
|
ion channels open on postsynaptic membrane | |
B). Termination of neurotransmitter
1). Degradation enzymes
2). Neurotransmitter reabsorbed
3). Diffusion of the neurotransmitter
VI). Types of Neurotransmitters
A). Excitatory Synapses
| neurotransmitters results in the depolarization of postsynaptic membrane. |
| Creating localized graded response. |
(dendrites do not have action potentials)
IF THE GRADED RESPONSE IS STRONG ENOUGH TO BE CARRIED TO THE AXON A FULL ACTION POTENTIAL WILL RESULT
 |
B). Inhibitory Synapses
| Binding neurotransmitters reduces the postsynaptic membranes ability to create an action potential. |
| Induces hyperpolarization. |
C). Integration or Summation of Synaptic Events
 |
It takes more than one synaptic event to create an action potential.
Presynaptic inhibition =
excitatory neurotransmitter by one neuron +
inhibitory neurotransmitter of another neuron
VII) Neurotransmitters
A). Acetylcholine (ACh)
B). Biogenic Amines
1). Dopamine
2). Norepinephrine
3). Epinephrine
4). Serotonin
C). Amino Acids
D). Peptides
1). endorphins
E). Novel or Miscellaneous