2. NERVOUS SYSTEM
• IT CONTROLS AND CO-ORDINATE THE HUMAN BODY AND GIVES QUICK RESPONSE TO THE
BODY.
• CLASSIFICATION OF NERVOUS SYSTEM
1.CENTRAL NERVOUS SYSTEM (CNS)
a) BRAIN
b) SPINAL CORD
2. PERIPHERAL NERVOUS SYSTEM (PNS)
a) SOMATIC NERVOUS SYSTEM
b) AUTONOMIC NERVOUS SYSTEM
I) SYMPATHETIC NERVOUS SYSTEM
II) PARASYMPATHETIC NERVOUS SYSTEM
3. NERVOUS SYSTEM
• CNS: IT IS A MAIN SYSTEM OF OUR BODY WHICH CONSIST OF BRAIN AND SPINAL CORD WHICH
COORDINATE WITH THE BODY.
• PNS: IT CONSIST OF ALL NERVES OF OUR BODY WHICH TRANSMIT INFORMATION FROM BODY TO
BRAIN AND BRAIN TO BODY.
• SOMATIC N.S: IN THIS VOLUNTARY MOVEMENT HAPPENED( WHICH WE CAN CONTROL).E.G :
HAND MOVEMENT, WALKING.
• AUTONOMIC N.S: IN THIS,INVOLUNTARY MOVEMENT HAPPENED( WHICH ARE NOT IN
CONTROL).E.G: BREATHING, HEART RATE.
4. ORGANISATION AND FUNCTION OF ANS
• ANS INVOLVES INVOLUNTARY RESPONSES OF THE BODY
• IT IS DIVIDED INTO 2 PARTS:
• 1.SYMPATHETIC N.S
• 2. PARA SYMPATHETIC N.S
5. DIFFERENCE BETWEEN SYMPATHETIC AND PARA
SYMPATHETIC N.S
Sympathetic n.s Para sympathetic n.s
It involved in fight and flight response. Involves in maintaining homeostasis and also permits the
rest and digest response
Active during stressful conditions, preparing the body to
face them.
Active during relaxing times, restoring normal.
It has shorter neuron pathways, hence faster response time Has longer neuron pathways hence slower response time
Increases heart beat, muscles tense up Reduces heart beat, muscles relaxes
Pupil dilates to let in more light Pupil contracts
Saliva secretion is inhibited Saliva secretion increases, digestion increases
On fight or flight situation, adrenaline is released from
adrenal glands, more glycogen is converted to glucose
No such functions exist in fight or flight situation.
Its ganglia are linked up to form a chain Its ganglia remain isolated
6. DIFFERENCE BETWEEN SYMPATHETIC AND PARA
SYMPATHETIC N.S
Sympathetic N.S
It works through neurotransmitter , adrenaline It works through release of acetylcholine.
It enhances all the involuntary functions It retards all the involuntary functions
Contracts urinary bladder muscles Relaxes urinary bladder
Inhibits secretion of pancreatic juice Promotes secretion of pancreatic juice
It is formed by 22 pairs of sympathetic ganglia and 2
sympathetic cords which run parallel to vertebral
column
It has nerve fibre which run along with cranial and
spinal nerves
7. CO TRANSMITTER
• CO TRANSMISSION IS THE RELEASE OF SEVERAL TYPES OF NEUROTRANSMITTER FROM A SINGLE NERVE
TERMINAL.
• CO TRANSMITTER : IT IS A CHEMICAL SUBSTANCE THAT IS RELEASED ALONG WITH PRIMARY
NEUROTRANSMITTER.
• IN ANS. PRIMARY NEUROTRANSMITTER -- ACH
• CO TRANSMITTER : PURINES: ATP
• PEPTIDES : VASO INTESTINAL PEPTIDE
• NITRIC OXIDE
• PROSTAGLANDIN
• E.G: ON RELEASE OF ACH, VIP ALSO GETS RELEASE.
• DIAGRAM( FROM K.D TRIPATHY PG NO: 97)
8. NEUROHUMORAL TRANSMISSION
• IT IS THE PROCESS OF TRANSFER OF ANY MESSAGE OR SIGNAL FROM ONE NEURON TO ANOTHER
NEURON WITH THE HELP OF ANY CHEMICAL MESSENGER ( NEUROTRANSMITTER , HORMONES)
• NEURO + HUMORAL = NERVE OR NEURON + CHEMICAL MESSENGER
• FOR THIS PURPOSE, INITIALLY NEUROTRANSMITTER IS SYNTHESIZED AND STORED IN VESICLE IN
NERVE TERMINALS
• DIAGRAM
• NEUROHUMORAL TRANSMISSION INVOLVES FOLLOWING STEPS:
1. IMPULSE CONDUCTANCE
2. TRANSMITTER RELEASE
3. TRANSMITTER ACTION ON POST JUNCTIONAL MEMBRANE
4.POST JUNCTIONAL ACTIVITY
5. TERMINATION OF TRANSMITTER ACTION
9. NEUROHUMORAL TRANSMISSION INVOLVES FOLLOWING
STEPS:
• 1. IMPULSE CONDUCTANCE :
• AT RESTING STATE(WHEN NERVE IMPULSE IS NOT TRANSMITTED FROM NEURON), RESTING
TRANSMEMBRANE POTENTIAL IS -70MV.
• NA+ ION HAVE HIGH CONC. AT OUT SIDE THE CELL AND MORE +VE CHARGE AT OUT SIDE THE PLASMA
MEMBRANE
• K+ ION HAVE HIGH CONC.AT INSIDE THE CELL AND MORE –VE CHARGE AT INSIDE THE PLASMA
MEMBRANE
• DEPOLARISATION : WHEN ANY KIND OF STIMULUS DETECTED THEN IT CHANGES THE RESTING
MEMBRANE POTENTIAL LESS POTENTIAL ( INCREASE)
• IF STIMULUS CHANGE RESTING POTENTIAL (-70 MV) TO (-55MV) THEN IT IS CALLED THRESHOLD
POTENTIAL..
•
10. NEUROHUMORAL TRANSMISSION INVOLVES FOLLOWING
STEPS:
• THRESHOLD POTENTIAL OPEN NA+ ION CHANNEL. SO NA+ ION ENTERS INSIDE THE CELL AND +VE
CHARGE PRODUCE INSIDE THE CELL AND –VE AT OUTSIDE THE CELL IT IS CALLED DEPOLARISATION.
• STIMULUS CONTINUES INCREASE THE POTENTIAL, NOW WHEN POTENTIAL REACH AT (+20 MV TO +30
MV) IT OPEN K+ ION CHANNEL AND K+ ION MOVE OUTSIDE THE CELLS.
• THE IONIC DISTRIBUTION IS NORMALISED DURING THE REFRACTORY PERIOD BY THE ACTIVATION OF NA+
K+ PUMP.
• THE CYCLE OF DEPOLARISATION AND REPOLARISATION IS CALLED ACTION POTENTIAL.
• 2) TRANSMITTER RELEASE : NERVE IMPULSE PROMOTES FUSION OF VASCULAR MEMBRANE THROUGH
CA++ ENTRY WHICH FLUIDIZED MEMBRANE
• THIS PROMOTES TRANSMITTER TO GET RELEASE FROM VESICLE IN SYNAPTIC CLEFT.
11. NEUROHUMORAL TRANSMISSION INVOLVES FOLLOWING
STEPS:
• 3) TRANSMITTER ACTION ON POST JUNCTION MEMBRANE :
• THE TRANSMITTER RELEASE AND ATTACHED WITH SPECIFIC RECEPTOR ON POST JUNCTIONAL MEMBRANE
AND DEPENDING ON NATURE IT INDUCE 2 TYPES OF ACTION
• 1) EPSP : EXCITATORY POST SYNAPTIC POTENTIAL
• 2) IPSP : INHIBITORY POST SYNAPTIC POTENTIAL
• 4) POST JUNCTIONAL ACTIVITY
• EPSP: INC. IN PERMEABILITY TO ALL CATION = NA+, CA++ INFLUX CAUSE DEPOLARISATION, AND EFFLUX
OF K+ WHICH LEADS TO NERVE IMPULSE, CONTRACTION IN MUSCLES, SECRETION IN GLANDS.
• IPSP : INC. PERMEABILITY TO SMALLER ION OR ANIONS K+ MOVES OUT AND CL- MOVES IN RESULTING
HYPERPOLRISATION
12. NEUROHUMORAL TRANSMISSION INVOLVES FOLLOWING
STEPS:
• 5) TERMINATION OF TRANSMITTER ACTION :
• NEUROTRANSMITTER IS DEGRADED LOCALLY OR ANY OTHER MECHANISM
• IT CAN ALSO BE DEGRADED BY ENZYMATIC ACTION.
13. CLASSIFICATION OF NEUROTRANSMITTER
• THESE ARE THE CHEMICAL MESSENGER WHICH TRANSMIT SIGNAL FROM ONE NEURON TO TARGET
CELLS.
• THEY CAN BE CLASSIFIED IN TWO TYPES :
• 1) STRUCTURAL
• 2) FUNCTIONAL
1) STRUCTURAL CLASSIFICATION
a. AMINES :
EPINEPHRINE , NOREPINEPHRINE , DOPAMINE , SEROTONIN , HISTAMINE
B AMINO ACID AND AMINO ACID DERIVATIVES :
GLUTAMATE , ASPARTATE , GLYCINE, GABA
C. PURINES :
ADENOSINE , ATP ( ADENOSINE TRIPHOSPHATE)
14. CLASSIFICATION OF NEUROTRANSMITTER
D. GAS : NITRIC OXIDE
E. MISCELLANEOUS : ACETYLCHOLINE
2) FUNCTIONAL CLASSIFICATION:
a) EXCITATORY NEUROTRANSMITTER
EG: GLUTAMATE , ASPARTATE, ADRENALINE AND NORADRENALINE, HISTAMINE , NITRIC OXIDE
AND ACETYLCHOLINE
B) INHIBITORY NEUROTRANSMITTER:
EG : GABA, GLYCINE, ADRENALINE AND NORADRENALINE , DOPAMINE AND SEROTONIN
15. NEUROTRANSMITTERS
1) ACETYLCHOLINE: (LEARNING) INVOLVED IN THOUGHT, LEARNING AND MEMORY. IT ACTIVATES MUSCLE
CONTRACTION IN THE BODY AND IS ALSO ASSOCIATED WITH ATTENTION AND AWAKENING
2) ADRENALINE ( FIGHT OR FLIGHT) IT IS PRIMARILY RELEASED BY THE ADRENAL GLAND BUT SOME
NEURONS MAY SECRETE IT AS A NEUROTRANSMITTER. IT S PRODUCED IN STRESSFUL SITUATION ,
INCREASE HEART RATE AND BLOOD FLOW. LEADING TO PHYSICAL BOOST AND HEIGHTENED
AWARENESS.
3) NOR ADRENALINE ( CONCENTRATION ) IT IMPROVE ATTENTION AND RESPONDING ACTIONS IN THE
BRAIN. CONTRACTS BLOOD VESSELS
4) DOPAMINE : (PLEASURE) FEELING OF PLEASURE, ALSO ADDICTION , MOVEMENT AND MOTIVATIONAL
5) SEROTONIN : ( MOOD) CONTRIBUTES TO WELL BEINGS AND HAPPINESS. HELPS SLEEP CYCLE AND
DIGESTIVE SYSTEM REGULATION.
16. NEUROTRANSMITTERS
6) GABA : (CALMING) CALM FIRING NERVES IN THE CNS. HIGH LEVEL WILL IMPROVE FOCUS AND LOW
LEVEL WILL CAUSE ANXIETY. ALSO CONTRIBUTES TO MOTOR CONTROL AND VISION.
7) HISTAMINE : RELEASED BY MAST CELLS, INVOLVED IN LOCAL IMMUNE RESPONSES. CONTRACTION OF
SMOOTH MUSCLE TISSUE OF THE LUNGS, UTERUS AND STOMACH
8) GLUTAMATE (MEMORY) INVOLVED IN LEARNING AND MEMORY. IT REGULATES DEVELOPMENT AND
CREATION OF NERVE CONTACTS.
17. PARASYMPATHOMIMETICS
• SYNONYM: CHOLINOMIMETIC, CHOLINERGIC AGONIST, CHOLINERGIC DRUGS, CHOLINERGIC SYSTEM
• DEFINITION :THESE ARE THE CHEMICAL AGENTS OR DRUGS WHICH COPY THE ACTION OF ACH IN
PARASYMPATHETIC NERVOUS SYSTEM.
• PARASYMPATHOMIMETIC = PARASYMPATHO (PARASYMPATHETIC N.S) + MIMETIC (MIMIC, COPY THE
ACTION)
• THESE DRUGS BIND WITH CHOLINERGIC RECEPTORS AND GIVE THEIR ACTION.
• WHEN THE NEUROTRANSMITTER OF PARASYMPATHETIC NERVOUS SYSTEM (ACH) IN BODY IS LESS AS PER
DEMAND THEN WE USE DRUGS EXTERNALLY WHICH ACT AS A CHOLINERGIC
NEUROTRANSMITTER/PARASYMPATHOMIMETICS EG : ACETYLCHOLINE , CARBACHOL, PHYSOSTIGMINE,
NEOSTIGMINE.
19. BIOSYNTHESIS OF ACH
• DIAGRAM
• ON ARRIVAL OF ACTION POTENTIAL AT THE NERVE ENDINGS, IN PRESENCE OF CALCIUM, FREE ACH ARE
RELEASED IN TO SYNAPTIC CLEFT BY THE PROCESS OF EXOXYTOSIS.
• THE ACTIVE ACH COMBINES WITH THE CHOLINERGIC RECEPTORS ( MUSCARINIC AND NICOTINIC) ON
POSTSYNAPTIC MEMBRANE OF TARGET ORGAN.
• THIS ACH ACTIVATES THE CHOLINERGIC RECEPTOR ON THE POSTSYNAPTIC MEMBRANE LEADING TO THE
DEPOLARIZATION OF THIS MEMBRANE. THUS THE IMPULSE IS TRANSMITTED ACROSS THE SYNAPSE.
• THE ACH RELEASE IN SYNAPTIC CLEFT IS RAPIDLY HYDROLYSED BY THE ENZYME ACETYLCHOLINESTERASE
(ACHE) WITHIN FEW MILLISECONDS.
• A PART OF CHOLINE IS REABSORBED BY NERVE ENDINGS AND LATER REUSED IN ACH SYSTHESIS
• A PSEUDOCHOLINESTERASE ENZYME OCCURS IN THE PLASMA AND LIVER , SERVES TO METABOLIZE
INGESTED ESTERS AND ACH.
