Click here to load reader

Examville.com – Neuroscience – Important Neurotransmitters

  • View
    213

  • Download
    0

Embed Size (px)

Text of Examville.com – Neuroscience – Important Neurotransmitters

  • 8/14/2019 Examville.com Neuroscience Important Neurotransmitters

    1/5

    Examvilleisaglobaleducationcommunitywhereuserslikeyoucanconnectandinteractwithotherstudentsandteachersfromaroundtheworld.Share,seek,downloadanddiscusseverythinginsideandoutsidetheclassroom.Allyouneedisanemailaddressandapasswordtogetstarted.JOIN US FOR FREE:http://www.examville.com

    Examville.com, LLC June 2009

  • 8/14/2019 Examville.com Neuroscience Important Neurotransmitters

    2/5

    IMPORTANT NEUROTRANSMITTERS

    1.ACETYLCHOLINE This is the cholinergic neurotransmitter.

    It possesses excitatory function.

    Acetylcholine is the transmitter substance at the

    neuromuscular junction

    Nerves in amacrine cell in retina and many regions of brain

    Acetylcholine is synthesized in axon terminals and stored

    inside the vesicles.

    Quick in action and is also destroyed immediately by enzyme

    acetylcholinesterase.

    Produces excitatory function of synapse by opening ligand

    gated sodium channels.

    It is also released by following nerve endings-

    1. Preganglionic parasympathetic nerves

    2. Postganglionic parasympathetic nerves

    3. Preganglionic sympathetic nerves

    4. Postganglionic sympathetic cholinergic nerves

    - Nerves supplying eccrine sweat glands

    - Sympathetic vasodilator nerves in skeletal muscles

    2. NORADRENALINE

    This is the neurotransmitter in adrenergic nerve fibers.

    This is released in the following:

    1. postganglionic sympathetic nerve endings

    2. Cerebral cortex

    3. Hypothalamus

    4. Brainstem

    5. Locus ceruleus in pons

    6. Spinal cord.

    Noradrenaline is the excitatory chemical mediator in many places and in

    very few places it causes inhibition.

    It is believed to be involved in dreams, arousal and elevation of moods.

  • 8/14/2019 Examville.com Neuroscience Important Neurotransmitters

    3/5

    3. DOPAMINE

    This is secreted by nerve endings in the following areas:

    1. Corpus striatum

    2. Hypothalamus

    3. Limbic system

    4. Neocortex

    5. Retina

    6. Small, intensely fluorescent cells in sympathetic ganglia.

    Dopamine possesses inhibitory action.

    The prolactin inhibitory hormone secreted by hypothalamus is dopamine.

    4. SEROTONIN

    Serotonin is known as 5-hydroxy tryptamine.

    It is secreted in the following areas:

    1. Hypothalamus

    2. Limbic system

    3. Cerebellum

    4. Dorsal Raphe nucleus of midbrain

    5. Spinal cord

    6. G.I.Tract

    7. Retina

    It is an inhibitory substance.

    It inhibits impulses of pain sensation in posterior gray horn of spinal cord.

    It is supposed to cause depression of mood and sleep.

    5. HISTAMINE

    It is secreted in nerve endings of hypothalamus, limbic cortex and other parts

    of cerebral cortex.

    It is an excitatory, neurotransmitter.

    It is believed to play an important role in arousal mechanism.

  • 8/14/2019 Examville.com Neuroscience Important Neurotransmitters

    4/5

    6. GAMMA AMINO BUTYRIC ACID (GABA)

    This is secreted in nerve endings at cerebellum, cerebral cortex, retina and in

    nerve endings which are involved in presynaptic inhibition in spinal cord.

    GABA is an inhibitory neurotransmitter.

    It causes inhibition by opening of potassium channels and chloride channels.

    Potassium comes out of synapse and chloride enters in.

    This leads to hyperpolarization which is known as inhibitory postsynaptic

    potential (IPSP).

    7. GLYCINE

    This is secreted by some nerve endings in spinal cord and retina. It isconcerned with direct synaptic inhibition.

    8. GLUTAMATE

    This neurotransmitter is secreted in the cerebral cortex and brain stem.

    This is an excitatory neurotransmitter.

    9. ASPARTATE

    This is an excitatory neurotransmitter substance secreted in spinal cord.

    10. Suibstance P

    Substance P is secreted by endings of nerve fibers (first order neurons) of

    pain pathway in spinal cord and retina.

    It is also the neurotransmitter substance in gastrointestinal tract.

  • 8/14/2019 Examville.com Neuroscience Important Neurotransmitters

    5/5

    11. NITRIC OXIDE

    Nitric oxide (NO) is a neurotransmitter in the central nervous system.

    It is also the important neurotransmitter in the neuromuscular junctions

    between the inhibitory motor fibers of intrinsic nerve plexus and the smooth

    muscle fibers of gastrointestinal tract.

    Nitric oxide acts as a mediator for the dilator effect of acetylcholine on small

    arteries.

    In the smooth muscle fibers of arterioles, nitric oxide activates the enzyme

    guanylyl cyclase, which in turn causes formation of cyclic guanosine

    monophosphate (cGMP) from GMP.

    The cGMP is a smooth muscle relaxant and it causes dilatation of arterioles.

    Thus, nitric oxide indirectly causes dilatation of arterioles.