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NEURON AND TRANSMISSION
OF NERVE IMPULSES
THE NEURON
A neuron also known as a neurone
or nerve cell is a cell that carries
electrical impulses. They are the
basic units of nervous system.
Every neuron is made up of
a cell body, dendrites and an axon.
DETAILED STRUCTURE OF NEURON
SOME IMPORTANT TERMS
• SYNAPSE: the junction between the axon of
one neuron and dendrite, cell body or axon of
another neuron is know as synapse.
• SYNAPTIC KNOB: the swelling terminal of
axon or dendrites is known as synaptic knob.
• PRE SYNAPTIC NEURON: the neuron
carrying impulse towards synapse.
• POST SYNAPTIC NEURON: the neuron
carrying impulse away from the synapse.
TRANSMISSION OF NERVER IMPULSES
Nerve impulses have a domino effect.
Each neuron receives an impulse
and must pass it on to the next
neuron. To make sure that the
correct impulse continues on the
path, a series of chemical and
electrical events are carried out by
the neurons.
TWO THEORIES HAVE BEEN PUT
FORWARD TO EXPLAIN THE
TRANSMISSION OF NERVE IMPULSES
ACROSS THE SYNAPSE. THEY ARE;
1. ELECTRICAL TRANSMISSION THEORY
2. CHEMICAL TRANSMISSION THEORY
ELECTRICAL TRANSMISSION THEORY
Impulse transmission
through synapse is
accomplished by
electric current. When
the impulse reach the
pre synaptic knob, the
impulse itself act as
stimulus for the post
synaptic neuron
causing
depolarization. Now
POLARIZATION OF NEURON’S MEMBRANE
1. When the neuron is not
stimulated, its
membrane is said to be
polarized.
2. It means electric charge
on the outside of the
membrane is positive
while on the inside is
negative.
3. The outside of the cell
contains excess sodium
ions while the inside of
RESTING POTENITAL
When the neuron is
inactive and polarized,
it is said to be at its
resting potential. It
remains this way until a
stimulus comes along.
ACTION POTENTIAL
1. A stimulus from a
sensory cell or
another neuron
causes the target to
depolarize toward the
threshold potential.
2. If the threshold of
excitation is reached,
all Na channels open
and the membrane
depolarizes.
3. At the peak action
REPOLARIZATION
1. With potassium ions moving to the
outside, the membrane’s
repolarization restores electrical
balance.
2. Potassium ions move outside and
the sodium ions stay inside the
membrane.
HYPER POLARIZATION
1. More potassium ions are on the
outside than there are on the inside.
2. This cause membrane potential to
drop slightly lower than the resting
potential
3. The membrane have greater potential
is thus said to be hyper polarized.
REFRACTORY PERIOD
1. Refractory period puts everything back
to normal
2. Potassium returns inside while sodium
returns outside.
3. After the na/k pump return the ions to
the rightful sides, the neuron is back to
its normal polarized state until another
impulse comes along.
DIAGRAMMATIC REPRESENTATION
CHEMICAL TRANSMISSION THEORY
Nerve impulses are
conducted across the
synapse with the help of
chemical substances
called neurotransmitter.
The process of chemical
transmission was
discovered by Henry
(1936).
MECHANISM
1. Calcium gate opens.
2. Releasing a neurotransmitter.
3. The neurotransmitter binds with
receptors on the neuron.
4. Excitation or inhibition of the
membrane occurs.
DIAGRAMMATIC REPRESENTATION
Thank you

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Neurons and transmission of nerve impulses

  • 1. NEURON AND TRANSMISSION OF NERVE IMPULSES
  • 2. THE NEURON A neuron also known as a neurone or nerve cell is a cell that carries electrical impulses. They are the basic units of nervous system. Every neuron is made up of a cell body, dendrites and an axon.
  • 4. SOME IMPORTANT TERMS • SYNAPSE: the junction between the axon of one neuron and dendrite, cell body or axon of another neuron is know as synapse. • SYNAPTIC KNOB: the swelling terminal of axon or dendrites is known as synaptic knob. • PRE SYNAPTIC NEURON: the neuron carrying impulse towards synapse. • POST SYNAPTIC NEURON: the neuron carrying impulse away from the synapse.
  • 5. TRANSMISSION OF NERVER IMPULSES Nerve impulses have a domino effect. Each neuron receives an impulse and must pass it on to the next neuron. To make sure that the correct impulse continues on the path, a series of chemical and electrical events are carried out by the neurons.
  • 6. TWO THEORIES HAVE BEEN PUT FORWARD TO EXPLAIN THE TRANSMISSION OF NERVE IMPULSES ACROSS THE SYNAPSE. THEY ARE; 1. ELECTRICAL TRANSMISSION THEORY 2. CHEMICAL TRANSMISSION THEORY
  • 7. ELECTRICAL TRANSMISSION THEORY Impulse transmission through synapse is accomplished by electric current. When the impulse reach the pre synaptic knob, the impulse itself act as stimulus for the post synaptic neuron causing depolarization. Now
  • 8. POLARIZATION OF NEURON’S MEMBRANE 1. When the neuron is not stimulated, its membrane is said to be polarized. 2. It means electric charge on the outside of the membrane is positive while on the inside is negative. 3. The outside of the cell contains excess sodium ions while the inside of
  • 9. RESTING POTENITAL When the neuron is inactive and polarized, it is said to be at its resting potential. It remains this way until a stimulus comes along.
  • 10. ACTION POTENTIAL 1. A stimulus from a sensory cell or another neuron causes the target to depolarize toward the threshold potential. 2. If the threshold of excitation is reached, all Na channels open and the membrane depolarizes. 3. At the peak action
  • 11. REPOLARIZATION 1. With potassium ions moving to the outside, the membrane’s repolarization restores electrical balance. 2. Potassium ions move outside and the sodium ions stay inside the membrane.
  • 12. HYPER POLARIZATION 1. More potassium ions are on the outside than there are on the inside. 2. This cause membrane potential to drop slightly lower than the resting potential 3. The membrane have greater potential is thus said to be hyper polarized.
  • 13. REFRACTORY PERIOD 1. Refractory period puts everything back to normal 2. Potassium returns inside while sodium returns outside. 3. After the na/k pump return the ions to the rightful sides, the neuron is back to its normal polarized state until another impulse comes along.
  • 15. CHEMICAL TRANSMISSION THEORY Nerve impulses are conducted across the synapse with the help of chemical substances called neurotransmitter. The process of chemical transmission was discovered by Henry (1936).
  • 16. MECHANISM 1. Calcium gate opens. 2. Releasing a neurotransmitter. 3. The neurotransmitter binds with receptors on the neuron. 4. Excitation or inhibition of the membrane occurs.