Upload
abhishek-panchal
View
218
Download
0
Embed Size (px)
Citation preview
8/2/2019 Neuro Transmit Tter
1/19
8/2/2019 Neuro Transmit Tter
2/19
Central Nervous System (CNS)
Brain Spinal Cord
Peripheral Nervous System (PNS)
Sensory NeuronsMotor Neurons
Somatic Nervous System
voluntary movements viaskeletal muscles
Autonomic Nervous System organs, smooth muscles
Sympathetic
- Fight-or-Flight responsesParasympathetic
- maintenance
THE NERVOUS SYSTEM
The Nervous System
8/2/2019 Neuro Transmit Tter
3/19
DIVISIONSOFTHEAUTONOMICNERVOUSSYSTEM
8/2/2019 Neuro Transmit Tter
4/19
8/2/2019 Neuro Transmit Tter
5/19
2 main kinds of cells Neurons
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
8/2/2019 Neuro Transmit Tter
6/19
Basic units of the nervous system Receive, integrate and transmit
information
Operate through electrical impulses
Communicate with other neurons
through chemical signals.
8/2/2019 Neuro Transmit Tter
7/19
Sensory Neurons
Interneurons: Connects sensory and motor neurons
Motor Neurons
8/2/2019 Neuro Transmit Tter
8/19
Sensory (Afferent) vs. Motor (Efferent)
e.g., skin
e.g., muscle
Grays Anatomy 381999
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
8/2/2019 Neuro Transmit Tter
9/19
8/2/2019 Neuro Transmit Tter
10/19
Axon of another
neuron
Cell BodyDendrites
Axon
MyelinSheath
Dendrites ofanother neuron
8/2/2019 Neuro Transmit Tter
11/19
Dendrite
the bushy, branching extensions of a neuronthat receive messages and conduct impulses
toward the cell body Axon
the extension of a neuron, ending in
branching terminal fibers, through whichmessages are sent to other neurons or tomuscles or glands
8/2/2019 Neuro Transmit Tter
12/19
Synapse junction between the axon tip of the
sending neuron and the dendrite or cell
body of the receiving neurontiny gap at this junction is called the
synaptic gap or cleft
8/2/2019 Neuro Transmit Tter
13/19
Impulse releasesneurotransmitter
from vesicles
Neurotransmitterenters synaptic gap
Neurotransmitter
binds to receptorson the receiving
neuron
8/2/2019 Neuro Transmit Tter
14/19
8/2/2019 Neuro Transmit Tter
15/19
Neurotransmitters are endogenous
chemicals that transmit signals from a
neuron to a target cell across a synapse
8/2/2019 Neuro Transmit Tter
16/19
8/2/2019 Neuro Transmit Tter
17/19
17
Neurotransmitter Postsynaptic
effectDerived from
Site of
synthesisPostsynaptic
receptorFate Functions
1.Acetyl choline
(Ach)Excitatory Acetyl co-A +
CholineCholinergic
nerve endings
Cholinergic
pathways of
brainstem
1.Nicotinic
2.Muscarinic
Broken by acetyl
cholinesteraseCognitive functions
e.g. memory
Peripheral action e.g.
cardiovascular
system
2. Catecholamines
i. Epinephrine
(adrenaline)
Excitatory in
some but
inhibitory in
other
Tyrosine
produced in
liver from
phenylalanine
Adrenal
medulla and
some CNS
cells
Excites both
alpha &
beta
receptors
1.Catabolized to
inactive product
through COMT &
MAO in liver
2.Reuptake into
adrenergic nerve
endings
3.Diffusion awayfrom nerve
endings to body
fluid
For details refer
ANS. e.g. fight or
flight, on heart,
BP, gastrointestinal
activity etc.
Norepinehrine
controls attention &
arousal.
ii.Norepinephrine Excitatory Tyrosine, foundin pons.
Reticular
formation, locuscoerules,
thalamus, mid-
brain
Begins inside
axoplasm of
adrenergic
nerve ending iscompleted
inside the
secretary
vesicles
12
12
iii. Dopamine Excitatory Tyrosine CNS,concentrated in
basal ganglia
and dopaminepathways e.g.
nigrostriatal,
mesocorticolim
bic and tubero-
hypophyseal
pathway
D1 to D5
receptorSame as above Decreased dopamine
inparkinsons
disease.
Increased dopamineconcentration causes
schizophrenia
8/2/2019 Neuro Transmit Tter
18/19
18
NeurotransmitterPostsynaptic
effectDerived from
Site of
synthesisPostsynaptic
receptorFate Functions
3. serotonin(5HT)
Excitatory Tryptophan CNS, Gut(chromaffin
cells) Platelets
& retina
5-HT1 to 5-HT
7
5-HT 2 A
receptor mediate
platelet
aggregation &
smooth muscle
contraction
Inactivated by MAOto form 5-
hydroxyindoleacetic
acid(5-HIAA) in
pineal body it is
converted to
melatonin
Mood control, sleep,pain feeling,
temperature, BP, &
hormonal activity
4. Histamine Excitatory Histidine Hypothalamus Three types H1,H2 ,H3 receptors
found in
peripheral tissues
& the brain
Enzyme diamineoxidase
(histaminase) cause
breakdown
Arousal, painthreshold, blood
pressure, blood flow
control, gut
secretion, allergic
reaction (involved in
sensation of itch)
5. Glutamate Excitatory
75% ofexcitatory
transmission
in the brain
By reductive
amination ofKrebs cycle
intermediate
ketoglutarate.
Brain & spinal
cord e.g.hippocampus
Ionotropic and
metabotropicreceptors.
Three types of
ionotropic
receptors e.g.
NMDA, AMPA
and kainate
receptors.
It is cleared from the
brain ECF by Na+
dependent uptake
system in neurons
and neuroglia.
Long term
potentiationinvolved in memory
and learning by
causing Ca++ influx.
8/2/2019 Neuro Transmit Tter
19/19
19
NeurotransmitterPostsynaptic
effectDerived from
Site of
synthesisPostsynaptic
receptorFate Functions
6. Aspartate Excitatory Acidic amines Spinal cord Spinal cordAspartate & Glycine form an excitatory /
inhibitory pair in the ventral spinal cord
7. Gama amino
butyric
acid(GABA)
Major
inhibitory
mediator
Decarboxylation
of glutamate by
glutamate
decarboxylase
(GAD) byGABAergic
neuron.
CNS
GABAA
increases the Cl- conductance,
GABAB is
metabotropic
works with G
protein GABA
transaminasecatalyzes.
GABAC
found
exclusively in
the retina.
Metabolized by
transamination to
succinate in the citricacid cycle.
GABAA causes
hyperpolarization
(inhibition)
Anxiolytic drugs like
benzodiazepine cause
increase in Cl- entry
into the cell & causesoothing effects.
GABAB cause
increase conductance
of K+ into the cell.
8. Glycine Inhibitory
Is simple aminoacid having
amino group and
a carboxyl group
attached to a
carbon atom
Spinal cord
Glycine receptormakes
postsynaptic
membrane more
permeable to Cl-
ion.
Deactivated in thesynapse by simple
process of
reabsorbtion by active
transport back into
the presynaptic
membrane
Glycine is inhibitory
transmitted found in
the ventral spinal
cord. It is inhibitory
transmitter to