This document summarizes the key components and functions of the nervous system. It describes the central nervous system consisting of the brain and spinal cord, and the peripheral nervous system containing sensory and motor neurons. It explains the roles of neurons and glial cells, and how neurons communicate with each other through electrical and chemical signals across synapses using neurotransmitters. Specifically, it outlines the anatomy of neurons including dendrites, cell bodies, axons, and myelin sheaths. It also discusses how action potentials are generated and propagated in neurons and the functions of common neurotransmitters like acetylcholine and endorphins.

1. Neurons and
Neurotransmitters
RVS Chatianya Koppala
Assistant Professor
Lovely Professional University

2. Nervous System
– Central nervous system (CNS):
• Brain
• Spinal cord
– Peripheral nervous system (PNS):
• Sensory neurons
• Motor neurons (somatic and
autonomic)

3. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Central Nervous System (CNS)Central Nervous System (CNS)
BrainBrain Spinal CordSpinal Cord
Peripheral Nervous System (PNS)Peripheral Nervous System (PNS)
Sensory NeuronsSensory NeuronsMotor NeuronsMotor Neurons
Somatic Nervous System
• voluntary movements via
skeletal muscles
Somatic Nervous System
• voluntary movements via
skeletal muscles
Autonomic Nervous System
• organs, smooth muscles
Autonomic Nervous System
• organs, smooth muscles
Sympathetic
- “Fight-or-Flight” responses
Sympathetic
- “Fight-or-Flight” responses
Parasympathetic
- maintenance
Parasympathetic
- maintenance
The Nervous System
The Nervous SystemThe Nervous System

4. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Divisions of the autonomic nervous system

5. The Nervous System
• A physical organ system like any other
• 2 main kinds of cells
– Neurons
– Glia

6.  Basic units of the nervous system
 Receive, integrate, and transmit
information
 Operate through electrical impulses
 Communicate with other neurons
through chemical signals
 More about neurons and neuronal
anatomy later
Neurons

7. Glial cells
• 100 billion neurons
• 10x more glial cells
• Glial cells
– Support neurons (literally, provide physical
support, as well as nutrients)
– Cover neurons with myelin
– Clean up debris
– “Housewives”

8. • Regulate
external
environment
(ions, etc.)
• Most abundant
glial cell
• May contribute
to blood-brain
barrier
and to synapses
Astrocytes

9. Three main types of neurons
• Sensory Neurons
• Interneurons
• Motor Neurons

10. Sensory (Afferent) vs. Motor (Efferent)Sensory (Afferent) vs. Motor (Efferent)
e.g., skin
e.g., muscle
Gray’s Anatomy 38 1999
sensory (afferent) nerve
motor (efferent) nerve
Neurons that send signals from the senses,
skin, muscles, and internal organs to the CNS
Neurons that transmit commands from the
CNS to the muscles, glands, and organs

11. The Withdrawal Reflex

12. Neuron Anatomy and Neural
Communication

13. Neurons
Axon of another
neuron
Axon of another
neuron
Cell BodyCell BodyDendritesDendrites
AxonAxon
Myelin
Sheath
Myelin
Sheath
Dendrites of
another neuron
Dendrites of
another neuron

14. Neural Anatomy
 Dendrite
 the bushy, branching extensions of a
neuron that receive messages and
conduct impulses toward the cell body
 Axon
 the extension of a neuron, ending in
branching terminal fibers, through which
messages are sent to other neurons or to
muscles or glands

15. Neural Anatomy and
communication
 Synapse
 junction between the axon tip of the sending
neuron and the dendrite or cell body of the
receiving neuron
 tiny gap at this junction is called the synaptic
gap or cleft
 Synapse movie

16. Specific Parts: The Neuron
Structure

17. Specific Parts: The Neuron
Function
Neurons = 3 functions: Reception, Conduction, Transmission
1.3.
2.

18. Action Potential
When dendrites stimulated, the delicate
balance is altered
Membrane breaks down
Positively charged ions rush in
(depolarization)
Charge = less negative
Causes release of chemicals from
terminal buttons

19. W. W. Norton

20. Relay Race
• Action Potential starts at dendrite
– Through cell body
– Down Axon
– Axon Terminals
• How does it get to the next cell’s dendrites?
• Neurons don’t touch
– Synapse = millionth inch gap
– In synapse = vesicles w/ neurotransmitters
» Chemical messengers that transmit info

21. Communication
• Impulse releases
neurotransmitter from
vesicles
• Neurotransmitter
enters synaptic gap
• Neurotransmitter
binds to receptors on
the receiving neuron

22. Myelin Sheath
–Fatty material made by glial cells
–Insulates the axon
–Allows for rapid movement of
electrical impulses along axon
–Nodes of Ranvier: gaps in myelin sheath
where action potentials are transmitted
–Multiple sclerosis is a breakdown of
myelin sheath
–Speed of neural impulse Ranges from 2 –
200+ mph

23. Myelinization clip
Myelin conduction clip

24. Neurotransmitters
 chemical messengers that traverse the
synaptic gaps between neurons
 when released by the sending neuron,
neurotransmitters travel across the
synapse and bind to receptor sites on
the receiving neuron, thereby
influencing whether it will generate a
neural impulse

25. Neurotransmitters (>60)
• Acetylcholine (ACh)
– 1st
substance identified as NT
– Links motor neurons and muscles (contract or relax)
• e.g. curare vs black widow spider
– Also involved in memory, learning, sleep, dreaming
(acetylcholine movie)
• Endorphins (the brain’s own morphine)
– 1973 injected rats with morphine
– Bound like NTs
– Brain had receptors for exogenous substance?
• Brain must produce its own morphine
• Released during pain and discomfort

26. More neurotransmitters
Receptor binding movie

27. THANKYOU