dpt

1. TOPIC:
NERVOUS SYSTEM (FLOW OF ELECTRICITY IN
HUMAN BODY)
NEURONS (ELECTRICAL ACTIVITY IN NEURON)

2. The nervous system is the human organ system that
coordinates all of the actions, by transmitting electrical
signals to and from different parts of the body.

3. integration and coordination
metabolism
homeostasis

4. SSSS
Parasympathetic
nervous system

5. ELECTRICAL ACTIVITY OF BRAIN
 Electricity is everywhere, even in the human body. Our cells are
specialized to conduct electrical currents. Electricity is required for
the nervous system to send signals throughout the body and to
the brain, making it possible for us to move, think and feel.
 The brain consists of billions of cells, half of which are neurons
and half are those which facilitate the activity of neurons.

6. NEURONS
Basic structural and functional unit of nervous
system is neuron.
Structure of Neurons :

7. x
MYELIN SHEATH AND NODES OF RANVIER
Axons are covered by Schwann cells. Schwann cells
are further covered by myelin sheath, which an electrical
insulator. That’s why axons are also called myelinated
fibers.
A non-myelinated region between two Schwann cells is
called NODES OF RANVIER.
Impulse jump from one node of ranvier to another
node.

8. Sensory neurons
Sensory neurons get information about what's going on
inside and outside of the body and bring that information
to the CNS so it can be processed
Interneuron
Interneurons, which are found only in the CNS. They
receive information from sensory neurons and transmit
information to motor neurons.
Motor neurons
Motor neurons get information from other neurons and
convey commands to your muscles, organs and glands.

9. Example of neuron function:

10. NERVE IMPULSE
A wave of electrochemical changes that travel across
the length of neurons.
Electrochemical refers to “electric potential” i.e.,
capacity to do electrical work.
Two types of electrical potentials are there:
• RESTING MEMBRANE POTENTIAL
• ACTION MEMBRANE POTENTIAL
RESTING MEMBRANE POTENTIAL:
Its value is minus 70mV, with the inside of the
membrane negative with respect to the outside.

11. ACTION MEMBRANE POTENTIAL
Movement of these ions across the cell membrane
generates an electrical pulse known as an action
potential.
Our nervous system uses these action potentials to
send signals around our body. Without electrical
impulses in our bodies, we couldn't read this page, stand
up straight, react to pain or even have a heartbeat.
 Its value is 50mV.

12. Stimulus not
enough to
trigger action
potential
Threshold
stimulus
Depolarization
Opening of sodium
gates
Repolarization
Opening of potassium
gates and they diffuses
out of cell
Potassium gates
closed
50

13. STEPS OF ACTION POTENTIAL
Threshold stimulus causes the inside of the cell to
depolarize.
Depolarization: voltage gated Na+ channels open and
these ions enter cell. Electrical potential changes from -
70mV to zero and then reaches 50mV.
Repolarization: depolarization of axon membrane
causes potassium gates to open. Potassium ions
diffuses out of cell.
RESTORATION OF RESTING MEMBRANE
POTENTIAL
•Sodium gates start to close.
•Sodium potassium pump continue to work during this

14. Synapse
THE JUNCTION BETWEEN AXON TERMINAL OF ONE NEURON AND THE
DENDRITE OF ANOTHER NEURON WHERE INFORMATION FROM ONE
NEURON IS TRAMSMITTED TO ANOTHER, IS CALLED SYNAPSE. THE
SYNAPTIC TRANSMISSION TAKE PLACE IN FORM OF MESSAGE WHICH
IS TRANSMITTED ACROSS SYNAPSE IN FORM OF CHEMICAL
MESSENGER CALLED NEUROTRANSMITTER.