This document discusses neurotransmitters and how they transmit signals between neurons in the brain and body. It begins by defining neurotransmitters as brain chemicals that communicate information throughout the brain and body. It then describes the basic structure of a neuron with dendrites, a cell body, and an axon. Neurotransmitters are produced in the cell body and travel down the axon to be released at presynaptic terminals into the synaptic cleft between neurons. They can then activate receptors on the receiving neuron. There are inhibitory neurotransmitters like GABA and serotonin that decrease neural activity, and excitatory neurotransmitters like acetylcholine, norepinephrine, and histamine that increase neural activity. The document provides examples of important neurotransmitters and their

1. NARAINO MAJIE Nabiilah
3rd April 2013

2.  Introduction
• Definition
• Structure of Neuron
• Transmission of chemical information
• Release
• Receptors
• Inactivation
 Types of neurotransmitters
• Inhibitory
• Excitatory
 Conclusion
 References

3.  NEUROTRANSMITTERS are the brain chemicals
that communicate information throughout our
brain and body.
 They relay signals between nerve cells, called
“neurons.”
 The brain uses neurotransmitters to tell
• your heart to beat,
• your lungs to breathe, and
• your stomach to digest.
• They can also affect mood, sleep, concentration, weight,
and
• can cause adverse symptoms when they are out of
balance.

4. This is a NEURON
Dendrites are branching
fibers that receive
information from other
neurons
Soma is the cell body
of a neuron. It
contains a
nucleus, ribosomes, m
itochondria, and other
structures. This is
where much of the
metabolic work takes
place
Axon is a thin
fiber where
information is
sent from the
neuron to other
neurons
Soma
Presynaptic
terminals
Presynaptic
terminals are the
point where the
axon releases
chemicals
Dendrites
Axon

5. Neurotransmitter comes from soma
It travels through the axon
From the pre-synaptic terminal it is
taken through the synapse to the
next neuron
Re-uptake sometimes occurs
Transmission of Neurotransmitters

6. Pre-synaptic
Neuron
Post-synaptic Neuron
Neurotransmitters
are sent through
the axon to pre-
synaptic
terminals, and then
to another neuron
Transmission of Neurotransmitters

7. Chemical transducers
released
By electrical impulse
Into the synaptic cleft
From pre-synaptic
membrane
By synaptic vesicles.
Diffuse to the post-
synaptic membrane
React and activate the
receptors present
Leading to initiation of
new electrical signals.

8.  Across a small gap called the synapse.
 An electrical impulse will trigger the migration of
vesicles containing neurotransmitters toward the
presynaptic membrane.
 The vesicle membrane fuse with the presynaptic
membrane releasing the neurotransmitters into the
synaptic cleft.
 Chemicals, called neurotransmitters, are released
from one neuron at the presynaptic nerve terminal.

9.  Neurotransmitters then cross the synapse where
they may be accepted by the next neuron at a
specialized site called a receptor.
 Either depolarization (an excitatory postsynaptic
potential) or hyper polarization (an inhibitory
postsynaptic potential).
 A depolarization makes it MORE likely that an
action potential will fire; a hyper polarization
makes it LESS likely that an action potential will
fire.

10.  It occurs in 4 steps:
◦ Synthesis of transmitter
◦ Storage & release of transmitter
◦ Interaction of transmitter with receptor in postsynaptic
membrane
◦ Removal of transmitter from synaptic cleft

11. Ca2+ Ca2+
Release

12.  There are 2 types of receptors:
◦ Ion-Channel linked receptor
◦ G- Protein linked receptor

13. Inactivation of the transmitter happens in one
of three ways:
 Re-absorption of the neurotransmitter into the
neuron. This is known as reuptake and is the
normal process.
 Destruction of the neurotransmitter with special
chemicals called enzymes. This is known as
enzymatic degradation.
 By the neurotransmitter becoming detached from
the receptor and drifting out of the synaptic cleft.
This is known as diffusion.

14.  Two types:
◦ Inhibitory-inhibit nerve impulses and calm the brain
and help create balance.
◦ Excitatory-propagate nerve impulses and stimulate
the brain.
 Inhibitory neurotransmitters balance mood
and are easily depleted when the excitatory
neurotransmitters are overactive.

15. Action of Inhibitory Neurotransmitters
 Action potential goes down synaptic knobs of
another neuron
 Release of Inhibitory neurotransmitters
 Activation of receptor site on cell membrane
 Opening of potassium channels
 Flow of k⁺ out of cell
 Cell inside becomes –ve
 Leads to local hyper polarization
 Known as Inhibitory Post Synaptic Potential (IPSP)

16. Examples of Inhibitory
Neurotransmitters

17.  SEROTONIN is an inhibitory neurotransmitter –
which means that it does not stimulate the brain.
 Serotonin are necessary for a stable mood and to
balance any excessive excitatory (stimulating)
neurotransmitter firing in the brain.
 Stimulant medications or caffeine can cause a
depletion of serotonin over time.
 Serotonin also regulates many other processes
such as carbohydrate cravings, sleep cycle, pain
control and appropriate digestion.
 Low serotonin levels are also associated with
decreased immune system function.

18. GABA (Gamma-Amino Butyric Acid)
 When brain experiences an abundance of nervous
tension and stress, it can be caused by a surplus of
norepinephrine or epinephrine (adrenaline).
 To neutralize this extra adrenaline, the brain
produces neurotransmitters, one of which is GABA.
 When GABA is out of range (high or low excretion
values), it is likely that an excitatory
neurotransmitter is firing too often in the brain.
 GABA will be sent out to attempt to balance this
stimulating over-firing.

19.  DOPAMINE is a special neurotransmitter because it is
considered to be both excitatory and inhibitory.
 Plays a critical role in the control of movement.
 It has a stimulating effect on the heart, the circulation, the
rate of metabolism, and is able to mobilize many of the
body’s energy reserves.
 It helps to modulate brain activity, control coordination and
movement, and regulate the flow of information to different
areas of the brain.
 Dopamine is believed to release chemicals that allow us to
feel pleasure (e.g. endorphins).
 A massive disturbance of dopamine regulation in the brain
can result in a person no longer being able to respond
emotionally or express his or her feelings in an appropriate
way (e.g. schizophrenia).

20. Action of Excitatory Neurotransmitters
 Action potential goes down synaptic knobs of
another neuron
 Release of Excitatory neurotransmitters
 Activation of receptor site on cell membrane
 Opening of ligand-gated sodium ion channels.
 Flow of Na⁺ in the cell
 Cell becomes less –ve
 Leads to to a local depolarization
 Known as Excitatory Postsynaptic Potential (EPSP).

21. Examples of Excitatory
Neurotransmitters

22.  Norepinephrine also known as noradrenaline
is a excitatory neurotransmitter that is
produced by the adrenal medulla or made
from dopamine.
 High levels of norepinephrine are linked to
anxiety, stress, high blood pressure, and
hyperactivity.
 Low levels are linked to lack of
energy, focus, and motivation.

23.  Histamine is most commonly known for it's
role in allergic reactions but it is also involved
in neurotransmission and can affect your
emotions and behavior as well.
 Histamine helps control the sleep-wake cycle
and promotes the release of epinephrine and
norepinephrine.
 High histamine levels have been linked to
obsessive compulsive
tendencies, depression, and headaches.
 Low histamine levels can contribute to fatigue
and medication sensitivities.

24.  Acetylcholine same as Dopamine can be both Inhibitory
and Excitatory.
 Acetylcholine (often abbreviated ACh) is the most
common neurotransmitter. It is located in both the
central nervous system (CNS) and the peripheral
nervous system (PNS).
 In the central nervous system, acetylcholine acts as part
of a neurotransmitter system and plays a role in
attention and arousal.
 In the peripheral nervous system, this neurotransmitter
is a major part of the autonomic nervous system and
works to activate muscles.
 Acetylcholine is also involved in memory and learning
and is in particularly short supply in people with
Alzheimer's disease.

25.  All chemical messengers in the brain have immense
interconnectivity.
 Their function relies on a system of checks and
balances during each moment of life. If one part of
the system fails, others can’t do their job properly.
 Panic disorder is just one of many physical and
psychological illnesses that are believed to be
influenced by the complex interacting of
neurotransmitters.
 Neurotransmitter levels can now be determined by
a simple and convenient urine test collected at
home. Knowing your neurotransmitter levels can
help you correct a problem today or prevent
problems from occuring in the future.

26.  http://www.neurogistics.com/thescience/wha
tareneurotransmi09ce.asp
 http://antranik.org/actions-of-excitatory-
and-inhibitory-neurotransmitters/
 http://neurogenesis.com/neuro-
transmitters/dopamine/
 http://faculty.washington.edu/chudler/chnt1.
html
 http://www.integrativepsychiatry.net/neurotr
ansmitter.html

28. THANK YOU