Spinal cord Transmits messages from the brain to the other areas of the body Efferent away from the brain out to the body Produces muscle action Afferent from the periphery to the brain ID: 598022
Download Presentation The PPT/PDF document "Neurons and Neurotransmitters" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Neurons and NeurotransmittersSlide2
Spinal cord
Transmits messages from the brain to the other areas of the body.
Efferent – away from the brain out to the body
Produces muscle action
Afferent – from the periphery to the brain
Relays information from the sensory organsSlide3
Facts About Neurons
There are about 1000 billion
Each can be connected to over 10s of 1000s of other neuronsSlide4
What they do
Sensory Neurons – take info from the world
Inter neurons make the connection between motor and sensory neurons – they do the thinking
makes the connection between sensation and action
Motor neurons - dictate to the musclesSlide5
All or Nothing
Neurons either fire or not. Sensation and action are graded by number of neurons triggered and/or frequencySlide6
The GAP
Between each neural dendrite and axon there is a tiny space (about 1/10,000th
of a mm).
This gap is called a synapse.Slide7
Its a Chemical Thing
When a neuron fires the axon shoots chemicals through the synapse and they affect the dendrites.
These chemicals are called neurotransmitters.Slide8
Neurotransmitters are contained within a structure called the
presynaptic
membrane.
Once released neurotransmitter molecules are picked up by receptors - structures that appear on cellular surfaces that pick up molecules that fit into them like a "lock and key"Slide9
Receptors are located in postsynaptic membrane of another nearby neuron.
Once the neurotransmitter is picked up by receptors in the postsynaptic membrane, the molecule is internalized in the neuron and the impulse continues. Slide10
Each neurotransmitter binds only to specific receptors on the postsynaptic membrane.
There are a number of types of receptors for different neurotransmitters.
This binding eventually brings about a change in the electrical state of the postsynaptic cell either exciting or inhibiting it. Slide11
Action of neurotransmitter can be decreased or neutralized by:
Glial cells which remove neurotransmitters from the synaptic cleft
reuptake, where the chemical is taken back to the axon that released it
blocking, whereby the flow by substances that attach to specific receptors is blockedSlide12
For Example:
The release of various neurotransmitters can excite or inhibit neurons.
This means the understanding of neurotransmitters is very important to pharmaceuticals.Slide13
Pharmaceuticals
Drugs developed to treat illnesses related to neurotransmitters are either Agonists or Antagonists.
There are currently at least 50 identified neurotransmitters
.
Agonists – increase the effects of a neurotransmitter, makes more of it, or stops the minimizing of it
Antagonist – slows down neurotransmitters either because they destroy or inhibit production, or they “paste over” dendrites so that neurotransmitters cannot connectSlide14
Specific Neurotransmitters
Acetylcholine
Acetylcholine is linked with learning and memory formation
A lack of acetylcholine in the brain is thought to be partly responsible for the symptoms of
Alzheimer's disease
.
* See study by Martinez and Kesner, 1991, on lab miceSlide15
Dopamine
Dopamine is concentrated in very specific groups of neurons collectively called the basal ganglia.
A decreased brain dopamine concentration is a contributing factor in Parkinson’s disease.
Increased amounts have other effects.Slide16
Serotonin
In
addition to mood control, serotonin has been linked with a wide variety of functions, including the regulation of sleep, pain perception, body temperature, blood pressure and hormonal activity.
* See study by
Kasamatsu
and Hirai, 1999, on
zen
meditationSlide17
SSRIs?????
Selective Serotonin Reuptake Inhibitors Used to regulate depression (Prozac, Zoloft, Paxil)High levels = bliss, happiness, hallucinations
Low levels =sleep disruption, depression, fatigue, anxiety Slide18
Other Drugs?
Heroin = mimics endorphins by binding to endorphin receptorsMorphine = stimulates endorphin production
Cocaine = Increases dopamine production (blocks reuptake)
Marijuana = THC blocks reuptake and normal functioning of
anandamide
, dopamine
and serotonin
(neurotransmitters)
Slide19
How neurotransmitters
impact behaviour?