NEURONS

1
NEURONS

• Receive Information

• Transmit Information

2
NEURONS

• Receive Information

• Transmit Information

3

• CELL BODY maintains the entire neuron in
  working order
• NUCLEUS DNA instructions for the regulation of
  the neuron

4
DENDRITES branchlike extensions that arise from
the cell body

• receive signals from other neurons, muscles or
  sense organs

• number dramatically increases after birth

5
NEURILEMMA thin membrane

• Allows neuron to repair
• Neurons in brain spinal cord do not have

• insulates the axon

AXON carries signals away from the cell body
6
6

• RESTING POTENTIAL
• When a nerve cell is not active
• Concentration of negatively charged particles
  inside
• Membrane impermeable to positively charged sodium
  ions outside

• ABSOLUTE REFRACTORY PERIOD
• Recovery period lasting a few thousandths of a
  second
• Neuron cannot carry another impulse

• RELATIVE REFRACTORY PERIOD
• Neuron has not completely returned to resting
  state
• Can be caused to fire by a very strong stimulus

7
NOVOCAINE

• Blocks the membranes sodium gates

• Prevents sodium ions from entering the membrane

• Prevents pain signals from reaching the brain

8
RATE OF TRAVEL

• Small, unmyelinated fiber .6 to 2 meters/sec.

• Large, myelinated fiber 120 meter/sec.

9
ACTION POTENTIAL
Threshold

• Action potential occurs when stimulus reaches
  critical magnitude

• Neurons have different thresholds thresholds
  for given neurons change

All-Or-None Law

• Size of the nerve impulse does not depend on the
  strength of the stimulus initiating

• Strength speed of nerve impulse depends upon
  the characteristics of the neuron

Nondecremental

• Action potential travels to the farthest ends of
  the axon

• Does not fade or die out regardless of the length
  of the axon

10
(No Transcript)