Advertisement Upgrade to remove ads

CNS

Brain and spinal cord enclosed in bony coverings

PNS

nerve = bundle of axons in connective tissue

Sensory (afferent) divisions

Going to CNS

Motor (efferent) divisions

CNS to effectors that divides into the ANS and Somatic motor division

Sensory (afferent) neurons

Detect changes in body and external environment
Info transmitted into brain or spinal cord

Interneurons

Most abundant, bring info between afferent and motor, connect afferent and efferent

Motor (efferent) neuron

Sends signals out to muscles and gland cells

Excitability (irritability)

Ability to respond to changes in the body and external environment called stimuli
Respond electrically

Cell body

Perikaryon = soma
Single, central nucleus with large nucleolus, cytoskeleton of microtubules and neurofibrils

Dendrites

Projections for receiving signals

Axon

Arising from axon hillock for rapid conduction

Oligodendrocyte

Form myelin sheaths ONLY in CNS

Ependymal cells

produce CSF (cerebral spinal fluid)

Microglia

(macrophages) formed from monocytes

Neuroglial Cells

support cells for neurons

Neuroglial tumor

Brain cancer

Astrocytes

Most abundant glial cells
- contribute to Blood Brain Barrier (BBB) and regulate composition of brain tissue fluid

Schwann

Cells make myelin in the PNS

Node of Ranvier

Gaps between myelin segments

Trigger Zone

Initial segment (area before 1st schwann cell) and axon hillock

Speed of Nerve Signals

Large, myelinated fibers > small, myelinated fibers > small, unmyelinated fibers

Regeneration of Peripheral Nerves

Occurs if soma and neurilemmal tube is intact

Types of Nerve Injury

1. Laceration
2. Evulsion - worst prognosis
3. Compression - Best prognosis

Resting Membrane Potentials

~-70mV inside the cell comparing to outside the cell
- electrolytes such as Na+ and K+ pump in/out to maintain the equilibrium

Local Potentials

1. Occurs on a part of the neuron when that part has been stimulated
2. They are graded and decremental (it gets weaker as spread out more)
3. Reversible, work like a dimer

Action Potentials

Electrical information found on axon, only be found within an axon and it will only occur if that trigger zone said it should occur

Characteristics of AP

1. All-or-nothing
2. Always be the same, if it occurs, it occurs all the way
like a light switch
3. Irreversible

Absolute Refractory period

Axon cannot have another action potential

Relative Refractory period

Action potential/axon can make another action potential, but the stimulus for that to occur has to be greater than normal

Purpose of Refractory Period

Preventing back-fire of the conduction, so the electrical msg only go down one direction

Saltatory Conduction

Myelinated fibers insulate the fibers, make the skips down, only the nodes of Ranvier conduct down

Neuron use other chemicals as neurotransmitters

Acetylcholine
Amino acid neurotransmitters
Monoamines
Neuropeptides

Excitatory postsynaptic potentials neurotransmitters

Glutamate and Asparate
Increase the mV

Inhibitory postsynaptic potentials

GABA and Glycine
Decrease the mV

Temporal Summation

Single synapse receives many ESPS's in short time

Spatial Summation

Single synapse receives many EPSP's from many cells

Converging circuit

Taking msg from a whole lot different nerve cells and stimulate the axon hillock

Diverging circuit

Same nerve cells spreads out to many different nerves

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set