ROLE OF HUMAN NERVOUS SYSTEM

1. 3.2 THE ROLE OF THE
HUMAN NERVOUS SYSTEM
(PART 2)
BY MIGHTY CHONDRION: AYSHWARYA RAJ, KAVINA DEVI, ISHANTINI, IRINA
KESUMA, THASHAAYANY, KAUSALYAH

2. TRANSMISSION PATHWAY OF INFORMATION

4. VOLUNTARY ACTION
WHAT IS VOLUNTARY ACTION?
• VOLUNTARY ACTION IS AN ANTICIPATED GOAL ORIENTATED MOVEMENT. THIS PSYCHOLOGICAL
CONCEPT IS PART OF COGNITIVE PSYCHOLOGY, PHILOSOPHY, NEUROLOGY, CRIMINOLOGY, AND MANY
OTHER FIELDS. IT IS ASSOCIATED WITH CONSCIOUSNESS AND WILL.
TYPES OF NERVOUS ACT
INVOLVES SKELETAL
MUSCLES
(Eg: Raising your
hands to answer a
question)

5. PERIPHERAL NERVOUS SYSTEM (PNS)
• TWO MAIN FUNCTIONS OF PERIPHERAL NERVOUS SYSTEM IS:
 TRANSMITS SIGNALS TO THE CENTRAL NERVOUS SYSTEM (CNS) FOR PROCESSING.
 SYNAPTIC TERMINAL CONTAINS ABUNDANT MITOCHONDRIA (GENERATE ENERGY FOR THE TRANSMISSION OF
NERVE IMPULSES ACROSS THE SYNAPSE).
 THE CEREBRUM IS RESPONSIBLE FOR ALL VOLUNTARY ACTIONS WHILE THE MEDULLA OBLONGATA CONTROLS
INVOLUNTARY ACTIONS.
VOLUNTARY ACTIONS INVOLVING SKELETAL MUSCLES
• VOLUNTARY ACTIONS SUCH AS WALKING AND TALKING ARE UNDER CONSCIOUS CONTROL.
• VOLUNTARY CONTROL OF THE SKELETAL MUSCLES IS GOVERNED BY THE CEREBRAL CORTEX OF THE CEREBRUM
• IN FORMATION THAT REACHES THE CEREBRAL CORTEX OR THE CONSCIOUS LEVEL RESULTS IN A PERCEPTION OF
THE EXTERNAL ENVIRONMENT.

6. THE PATHWAY OF TRANSMISSION OF INFORMATION IN
VOLUNTARY ACTION

7. THE IMPORTANCE OF REFLEX ACTION
• PROVIDE AN IMMEDIATE WITHDRAWAL FROM HARMFUL AND DANGEROUS STIMULI
• COORDINATE RAPID AUTOMATIC RESPONS TO STIMULI WITHOUT CONCIOUS CONTROL FROM
THE BRAIN.FOR EXAMPLE,WHEN A PERSON ACCIDENTALLY TOUCHES A VERY HOT OBJECT
• SINCE THIS TYPE OF REFLEX INVOLVES ONLY THE SPINAL CORD,THE BRAIN IS RESERVED FOR
MORE COMPLEX TASKS AND ANALYTICAL FUNCTIONS
• ALTHOUGH MOST REFLEX ACTIONS INVOLVE THE SPINAL CORD,SOME REFLEX ACTIONS
HOWEVER INVOLVE THE BRAIN,FOR EXAMPLE THE OPENING AND THE CLOSING OF THE PUPIL
OF THE EYE
• ALTHOUGH THIS REFLEX INVOLVES THE BRAIN,IT IS AN AUTOMATIC RESPONSE OF WHICH WE
HAVE NO CONTROL OVER

8. THE KNEE-JERK
• THE RUBBER HAMMER HITS A TENDON THAT CONNECTS THE QUADRICEPS MUSCLE IN THE
THIGH TO A BONE IN THE LOWER LEG
• AS THE HAMMER STRIKES THE KNEE,THE FORCE STRETCHES THE QUADRICEPS MUSCLES
AND STIMULATES THE STRETCH RECEPTORS IN THE MUSCLES,TRIGERRING NERVE IMPULSES
• AFFERENT NEURONES TRANSMIT THE INFORMATION TO THE EFFERENT NEURONES IN THE
SPINAL CORD
• THE EFFERENT NEURONES TRANSMIT THIS INFORMATION TO THE QUADRICEPS MUSCLE AND
THE MUSCLE CONTRACTS,JERKING THE LOWER LEG FORWARD

9. INVOLUNTARY ACTIONS WHICH INVOLVE SMOOTH MUSCLES,CARDIAC MUSCLES OR GLANDS
• CONNECTS THE
MEDULLA
OBLONGATA
AND
HYPOTHALAM
US WITH THE
INTERNAL
ORGANS AND
REGULATES
THE INTERNAL
BODY
PROCESSES
THAT REQUIRE
NO
CONSCIOUS
EFFORT
THE AUTONOMIC
NERVOUS SYSTEM
CONTROLS
INVOLUNTARY
ACTIONS INVOLVING
INVOLVING THE
GLANDS,THE
CARDIAC MUSCLES
OF THE HEART AND THE
SMOOTH MUSCLES OF
THE INTERNAL ORGAN
SUCH AS THE
INTESTINES

10. • SINCE THE INFORMATION FOR VOLUNTARY ACTIONS DOES NOT INVOLVE THE CEREBRAL CORTEX OF THE CEREBRUM,THE
RESPONSES ARE AUTOMATIC.
• THIS MEANS THE AUTOMATIC NERVOUS SYSTEM PERMITS VITAL FUNCTIONS SUCH AS HEARTBEATS AND BLOOD CIRCULATION
TO CONTINUE EVEN DURING STATES OF UNCONSCIOUSNESS SUCH AS SLEEPING OR FAINTING WHEN VOLUNTARY ACTIONS
HAVE STOPPED.
• THE AUTOMATIC NERVOUS SYSTEM CAN BE DIVIDED INTO
- THE SYMPATHETIC DIVISION
- THE PARASYMPATHETIC DIVISION
• THESE DIVISIONS WORK TOGETHER,USUALLY WITH INHIBITING THE ACTIONS OF THE INTERNAL ORGANS
• BOTH SYSTEMS ARE CONNECTED TO THE SAME ORGANS IN THE BODY AND ACT IN OPPOSITION TO MAINTAIN HOMEOSTASIS
• SYMPATHETIC DIVISION
-PREPARES THE BODY FOR STRESSFUL SITUATIONS OR AN EMERGENCY,IN WHICH THE
RESPONSES ARE ASSOCIATED WITH’FIGHT OR FLIGHT’.
-INCREASES THE PULSE RATE,HEARTBEAT RATE,BLOOD PRESSURE AND BREATHING RATE
-SLOWS DOWN THE DIGESTIVE SYSTEM SO THAT MORE BLOOD IS AVAILABLE TO CARRY OXYGEN
TO THE VITAL ORGANS SUCH AS THE BRAIN,HEART AND MUSCLES
• PARASYMPATHETIC DIVISION
-PREPARES THE BODY DURING ORDINARY SITUATIONS OR BRINGS ON THE RESPONSES
ASSOCIATED WITH A RELAXED STATE
-DECREASES THE PULSE RATE,BLOOD PRESSURE AND BREATHING RATE
-STIMULATES THE DIGESTIVE SYSTEM TO CONTINUE BREAKING DOWN FOOD

11. DISEASES OF THE NERVOUS SYSTEM
• PARKINSON’S DISEASE
 A PROGRESSIVE DIORDER OF THE CENTRAL NERVOUS SYSTEM THAT TYPICALLY AFFECTS
VICTIMS AROUND THE AGE OF 60 YEARS ONWARDS. IT IS DUE TO REDUCED LEVELS OF
DOPAMINE IN THE BRAIN.
 IT AFFECTS MUSCULAR MOVEMENTS, CAUSING TREMOURS OR TREMBLING OF THE ARMS,
JAWS, LEGS AND FACE.
 THE PATIENTS ALSO HAVE DIFFICULTY IN MAINTAINING NORMAL POSTURES AND EXPERIENCE
IMPAIRD BALANCE AND COORDINATION.

12. • ALZHIMER’S DISEASE
 A NEUROLOGICAL DISORDER WHICH AFFECTS VICTIMS AROUND THE AGE OF 60 YEARS
ONWARDS, CAUSES THE LOSS OF REASONING AND THEE ABILITY TO CARE ONESELF.
 CAUSE OF DISEASE IS STILL UNKNOWN BUT FACTORS SUCH AS GENETIC, ENVIROMENTAL OR
THE AGING PROCESS ITSELF CAN LEAD TO ALZHEIMER’S DISEASE.
 INDIVIDUALS WITH THIS DISEASE PFTEN BECOME CONFUSED, FORGETFUL, AND LOSE THEIR
WAY ALTHOUGH THEY ARE IN PLACES WHICH ARE FAMILIAR TO THEM.
 AS THEIR MINDS CONTINUE TO DETORIATE, PATIENTS MAY LOSE THE ABILITY TO READ, WRITE,
EAT , WALK AND TALK.

13. • CEREBROVASCULAR ACCIDENT (CVA)/ STROKE
 CAUSED WHEN A BLOOD VESSEL IN THE BRAIN MAY BURST CAUSING INTERNAL BLEEDING.
 CAN ALSO BE CAUSED WHEN A CLOT ARISES IN A BRAIN BLOOD VESSEL ( A THROMBUS) , OR
ARISES ELSEWHERE ( EMBOLUS) AND TARVEL TO GET STUCK IN A BRAIN VESSELWHICH THEN
DEPRIVES THE BRAIN TISSUE OF OXYGEN.
 DEPENDING UPON THE AREA OF THE BRAIN WHICH IS INVOLVED, THE PATIENT MAY SUFFER
PARALYSIS, LOSS OF SPEECH OR LOSS OF VISION.

14. QUIZ OH QUIZ!!!
1. List two other disease related to the nervous system other than the ones mentioned earlier.
2. Differentiate Voluntary and Involuntary action.
3. What does the peripheral nervous system consist of?
4. What is the function of synapses?
5. Give three examples of neurotransmitters.