Download Electricity within the body

 Introduction.
 The nervous system and the neurons.
 Electrical potential of nerve.
 Electrical signals from muscles-(Electromyogram).
 Electrical signals from heart-(Electrocardiogram).
 Electrical signals from the brain-(Electroencephalogram).
 Electrical signals from eye-(Elecrtrooculogram).
 There are two aspects of electricity and magnetism in
medicine:
1. Electrical and magnetic affect generated inside body.
2. Applications of electricity and magnetism to the
surface of body (cardiovascular instrumentations).
 Electrical and magnetic affect generated inside body
serves for:
 Essentially all functions and activities of the body which
involves electricity. For the control the operation of
nerve, muscles and different organs.
 Controls various internal organs such as the heart,
intestines, and glands.
Autonomic nervous system (just to look)
 The basic structural unit of the nervous system is a neuron.
A nerve cell specialized for the
a-reception.
b-interpretation.
c-transmission of the electrical messages.
 Neuron consists of a cell body that receives electrical
messages from other neurons through contacts called
synapses located on the dendrites.
 The neuron transmits an electrical signal out word along axon
Axons are ≈ 1 (m) long.
 The axon carries the electrical signal to muscle, gland, or
other neurons.
 Axon terminals: Transmit electrical messages (information)
from the neuron to muscles, glands or other neurons.
Basic structural unit of the nervous
system (neuron).
 Across the surface or membrane of every neuron
is an electrical potential difference.
 This due to the presence of more negative ions on
the inside of the membrane than the outside , the
neuron said to be polarized .
 The inside of the cell is typically 60 -90 mv more
negative than outside.
Intracellular fluid
Intracellular fluid
 When the neuron is stimulated a large
momentary of change in the resting potential
occurs at the point stimulation.
 This potential change called action potential
propagates along axon.
 The action potential is the major method of
transmission of signals within the body.
 The stimulation may be caused by various
physical and chemical stimuli such as heat, light,
sound, and others.
 The record of the potentials from muscles during rest
and contraction is called EMG
 Resting potential across the membrane of a muscle
fiber is similar to resting potential across a nerve fiber.
 A muscle is made up of many motor units. A motor unit
consists of a single branching neuron from brain or
spinal cord.

• The action potential travels along an axon and is
transmitted across the motor end plates into the muscle
fibers causing them to contract.
Latency or latent period is defined as follows: The period
(interval, delay) elapsed between the presentation of a stimulus
and the obvious response such as the contraction of a muscle.
 Surface electrode : Attached to the skin, measures
the electrical signals from many motor units.
 Needle electrode : This is inserted under the skin,
measure single motor unit activity.