Autonomic nervous system in mammals

What is Peripheral nervous system (PNS) ?

Includes all neurones that are not part of the central nervous system (CNS)

Subdivided into somatic nervous system and autonomic nervous system.

Somatic Nervous system• Contains nerves that carry impluses from external

sensory receptor to the CNS and motor nerve which carry impulses to the skeletal muscles.

• Control voluntary movement under conscious control

• Important in reflex action

Autonomic Nervous System

• Contains only motor nerve.• Regulates involuntary activity of glands,

cardiac and smooth mucles• Connect medulla oblongata and

hypothalamus with the internal organ and regulates the internal body processes that require no conscious effort.

• Contains the sympathetic and parasympathetic system. They will act antagonistically.

Somatics Nervous System

Single neurone

Autonomic Nervous System

preganglionic postganglionic neurone neurone

Central nervous system

Skeletal mucle

Central nervous system

Glands, cardiac or smooth muscles

ganglion

Difference between sympathetic nervous system and parasympathetic nervous system

Central Nervous System

Sympathetic system Parasympathetic system

Origin of nerve and distribution

Nerve emerge from thoracic and lumbar regions of CNS. Distributed over wider regions of the body

Nerve emerge from cranial and sacral region of CNS. Limited distribution to the body.

Difference between sympathetic nervous system and parasympathetic nervous system

Central Nervous System

Sympathetic system Parasympathetic system

Location of ganglion

Close to spinal cord Close to effector

Difference between sympathetic nervous system and parasympathetic nervous system

Central Nervous System

Sympathetic system Parasympathetic system

Neurotransmitter secreted at the junction with effector tissues

Norepinephrine secreted by adrenegic neurone

Acetycholine secreted by cholinergic neurone

Difference between sympathetic nervous system and parasympathetic nervous system

Central Nervous System

Sympathetic system Parasympathetic system

Inactivation of neurotransmitter at synapses

Reuptake process to reabsorb norepinephrine

Enzyme acetylcholinesterase degrades acetycholine into choline and acetate

Difference between sympathetic nervous system and parasympathetic nervous system

Central Nervous System

Sympathetic system Parasympathetic system

Preganglionic nerve fibre

Short preganglionic fibre

Long preganglionic fibre

Postganglionic nerve fibre

Long preganglionic fibre

Short preganglionic fibre

Central nervous system

Acetycholine

produced

Acetycholine

produced Effector organ

Sympathetic nervous system

Parasympathetic nervous system

Difference between sympathetic nervous system and parasympathetic nervous system

Central Nervous System

Sympathetic system Parasympathetic system

General effect Increase metabolic rateIncrease metabolic levelsIncreases rhythmic activities

No increase in metabolic rateDecrease metabolic levelDecrease rhythmic activities

Difference between sympathetic nervous system and parasympathetic nervous system

Central Nervous System

Sympathetic system Parasympathetic system

Condition when active

Dominant during danger, stress, activates the body for emergencies, to produce ‘flight and fight’ responses, alertness

Dominant during rest, prepares body for relaxation, conservation of energy and digestive activity.

Difference between sympathetic nervous system and parasympathetic nervous system

Central Nervous System

Sympathetic system Parasympathetic system

Overall effect Excitatory homeostatic effect

Inhibitory homeostatic effect

Intercostal mucles.

Stimulates to increase ventilation rate

Decrease ventilation rate

Difference between sympathetic nervous system and parasympathetic nervous system

Central Nervous System

Sympathetic system Parasympathetic system

Bronchioles Dilates bronchioles Constricts bronchioles

Heart Increase heart rate Decrease heart rate

Urinary system

Contracts bladder sphincter

Relaxs bladder sphincter

Difference between sympathetic nervous system and parasympathetic nervous system

Central Nervous System

Sympathetic system Parasympathetic system

Digestive system

Constricts blood vessels in gutSlows peristaltic movementsInhibit secretion of digestive juices

Dilate blood vessels in gutStimulates peristalsisStimulates secretion of digestive juice

Difference between sympathetic nervous system and parasympathetic nervous system

Central Nervous System

Sympathetic system Parasympathetic system

Skin -Contracts erector pili mucles, so body hair become erect-Increase sweat production-Stimulates vasocontriction

Stimulates vasodilation

Difference between sympathetic nervous system and parasympathetic nervous system

Central Nervous System

Sympathetic system Parasympathetic system

Iris of the eye Dilation of pupil Constriction of pupil

Adrenal medulla

Secretion of adrenaline and noradrenaline ( increase blood glucose level, heartbeat rate, breathing rate and metabolic rate)

No comparable effect

Drug Abuse• Chemical substance that causes a change in the

natural chemical environment and functioning the body.

• Used in medicine help to prevent, diagnose and treat diseases or injuries.

What is psychoactive drug?• Interfere with the nervous system and causes

changes in the mental state and behaviours.• Overdosing such as, cocaine, heroin, morphine

and alcohol can lead to over addiction of the drug

Normal dopamine function

Nerve cells of limbic system in the brain release dopamine

Synaptic cleft Dopamine bind to

Receptors on the postsynaptic membrane stimulates pleasure pathway

Giving feeling of euphoria

Reuptake of neurotransmitters dopamineInto the synaptic knob for recycle and reuse

How cocaine affect ther nervous system by altering the mechanism of synaptic transmission

Nerve cells of limbic system in the brain release dopamine

cocaine Synaptic cleft cocaine bind to

Transport molecule blocks the reuptake of dopamine

Level of dopamine higher and remain longer in synaptic cleft

Stimulates the pleasure pathway

Give drug users a short period of an intense of feeling euphoria & increase sense of energy and alertness for last

5 - 30 minutes.

Feel irritable, fatigue, restless and depressed (overcome: repeat the usage of cocaine )

By snorting or smoking

• Acts as a neuromodulator – causes abnormally large amount of neurotransmitter to remain in the synapses for long period of time.

• Continued chronic cocaine use, body responds to “excess” supply in synaptic cleft by producing less neurotransmitter dopamine and decreasing the number of dopamine receptor.

• Users normally will experienced severe depression, irritabiliy, aggressive paranoid behaviour, auditory, and tactile hallucinations & dependent to the drug (increase in taking of drug to produce euphoric effect)

• Nasal bleeding, hallucinations, heart attack, respiratory failure, seizures, brain damage, stroke, and death from overdose of cocaine.

• Baby born to drug addict may suffer from neurological and developmental problems.

• Hepatitis B and AIDS are spread when drug addicts share needles with infected users

Curare • Nondepolarising acetycholine antagonist• Have similar shape with acetycholine. • Binds to the acetycholine receptors on the postsynaptic

membrane (prevent acetycholine from binding them at the neuromuscular junction.)

• Receptors x activated, no action potential generated in postsynaptic cell.

• Blockage of impulse transmission between the nerves and voluntary muscles.

• Voluntary muscles cannot contracts in response to nervous stimulation

• Cause flaccid paralysis – cause the animails dead on suffocation• Uses in small doses to relax muscle in certain surgical

operations.