3.2- The Human Nervous System

8/4/2019 3.2- The Human Nervous System

1/43

1

SEKOLAH BERASRAMA PENUH INTEGRASI GOPENG

CHAPTER 3 :COORDINATION

&RESPONSE

Prepared by :-EN. MUHD FAZLI BIN DOLLAH

Biology Teacher


2/43

2


3/43

3

LEARNING OUTCOMES

To state the role of nervous system,

To draw & label a diagram to show the organisation of the

nervous system,

To name the main parts of the brain & state their functions


4/43

4

Body activities are controlled & coordinated bythe nervous system & the endocrine system.

Nervous system sending out nerve impulses.

Endocrine system secreting hormones

Nervous system only found in animals.

Hormones can be found in both animals &plants.


5/43

5

The Role of the Nervous Systema) Important in detecting changes in the

external as well as internal environment.

b) Sends nerve impulses to effectors so as torespond appropriately to the changes.

c) Coordinates various functions & activitieswhich occur inside the body.


6/43

6

Organisation of the nervous systemmade up of the Central Nervous System (CNS) & the

Peripheral Nervous System (PNS)

NERVOUS

SYSTEM

CENTRAL

NERVOUS

SYSTEM (CNS)

PERIPHERAL

NERVOUS

SYSTEM (PNS)

Brain Spinal Cord Cranial Nerves Spinal Nerves


7/43


8/43

8

CENTRAL NERVOUSSYSTEM


9/43

9

Human Brain

The expanded anterior end of the spinal cord.Weight = 1.5 kg & controls all parts of the body(directly @ indirectly).

Surrounded by protective membranes called themeninges. Cerebrospinal fluid (CSF) is foundbetween these layer. supply the neurones inthe brain with O2 & nutrients & removes wasteproduct.

Grey matter forms the outer part of the humanbrain, interior of the brain is made up ofwhitematter.


10/43

10

BRAIN Grey matter contains

the cell bodies ofneurones

White matter containsthe myelinated axons of

the neurones.


11/43

11


12/43

12

Cerebrum

The biggest part of the brain. Made up of 2 cerebralhemispheres.

The centre for thinking, reasoning, speech & memory.It integrates impulses from various sensory organs &receptors.

Initiates & controls all voluntary actions (walking, writing,singing)


13/43

13

CEREBELLUM

-Made up of grey matter(outside) & white matter(inside).

-Has 2 hemispheres.

-Coordinates movement &maintains body balance.


14/43

14

Medulla

Oblongata

Controls & coordinates all involuntary actions.

Digestion, respiration, & heart beat.


15/43

15

PARTS NOTES

Pituitarygland

At the base of the cerebrum.

Secreting various hormones to control body functions suchas growth, osmoregulation & reproduction


16/43

16

HYPOTHALAMUS

Above the pituitary

gland.

Contains severalimportant centres thatcontrol bodytemperature,osmoregulation,

sexual function, thirst,hunger, emotionalactivity & sleep


17/43

17

THALAMUS Made up of 2 masses of

grey matter.

Lies deep in the cerebralhemispheres.

Contain stations forimpulses that enter thebrain

Gives us the awarenessof impulses as sensationssuch as pain, touch &temperature.


18/43

18

LEARNING OUTCOMES

To draw & label a diagram of a cross section of

the spinal cord,

To state the main functions of the spinal cord,

To label the structure of an efferent neurone,

To identify the type of the neurone fromdiagrams given,


19/43

19

SPINAL CORD A dorsal cylinder of neurones

extending from the raindownwards to the level of the2nd lumbar vertebra.

Protected & enclosed bymembranes called meninges &by the vertebral column.

To relay messages to & from thebrain & in some instances,processes, that is, integrates,

sensory information directly

reflex action (knee jerkresponse)


20/43

20

The central area (grey matter)

made up of motor neurone cell

bodies, synapes & unmyelinated interneurones.

Lighter area (white matter) largely composed of myelinated

neurones


21/43

21

Each side of thespinal cord are 31pairs of projections =roots.

Each pair consists ofa dorsal root & aventral root.

The roots unite toform a spinal nerve.

The dorsal root has aganglion (a cluster ofcell bodies ofneurones)


22/43

22

Two main functions of spinal cord :

Connects the peripheral nervous systemto the brain. (sensory organ SC brain SC effectors)

Acts as a minor integrating centre inproducing simple reflex responses such asthe withdrawal of the hand from the hotobject.


23/43

23


24/43

24

NEURONE

A nerve cell

Dendrites & dendrons function inreceiving nerve impulses &transmitting them to the cellbody.

The axon transmits impulsesfrom the cell body to the terminal

dendrites.

The end of each terminal dendriteis a knob known as the synaptic

knob transmitting impulses to


25/43

25

The myelin sheath is a fatty

material which surrounds the

axon except at the nodes of

Ranvier speeding up the

transmission of impulses.

(impulses hop from one node of

Ranvier to the next).

3 types of neurones sensory

neurone (afferent neurone),

interneurone (relay neurone) &

motor neurone (efferent

neurone).


26/43

26

TYPES FUNCTION

SENSORY

NEURONE

(AFFERENT

NEURONE)

Receives impulses from the

sensory organs / receptors &

transmits them to the centralnervous system to be

interrupted.

INTERNEUR

ONE(RELAY

NEURONE)

Transmits impulses from the

central nervous system to the

effector organs to elicit

responses.

MOTORNEURONE

(EFFERENT

NEURONE)

Join the sensory organs with the

motor neurones.

Th d f t i i f


27/43

27

The mode of transmission ofinformation along the neurone

Information is transmitted along aneurone (electric charges)

A neurone is at rest pump out Na+,pump in K+ by active transport (sodium-potassium pump)

When the neurone is stimulated thesodium-potassium pump breaks down &the ions move in the opposite direction.


28/43

28

The pathway of transmission ofinformation from receptor to effectors

Stimuli are received byreceptorssend out

information in the form of

nerve impulses

Transmitted along the sensoryneurone to the CNS

integrates & interprets the

information send out

impulses to the effectors viamotor neuroneeffector

response is elicited.


29/43

29

Transmission of informationacross a synapse

Synapse = a location where a neurone transfersits impulse to another neurone.

2 neighbouring neurones are not directly

connected together but are separated by a verynarrow gap = synaptic cleft

Each terminal dendrite of a pre-synaptic neurone

ends in a synaptic knob.

The synaptic knob is separated from a dendriteof the post-synaptic knob by a synapse @synaptic cleft.


30/43

30

Transmission of information/nerve impulse along aneurone occurs in the form ofelectric signals, thetransmission of information/ nerve impulse across

a synapse occurs by chemical means.

Within each synaptic knob can be found numeroussynaptic vesicles contain chemicals known asneurotransmitter (acetylcholine & noradrenaline).

When an impulse arrives at the terminal dendrite,synaptic vesicles in the synaptic knobs will releaseneurotransmitter into the synaptic cleft.

The neurotransmitter diffuses across the synapticcleft & finally arrives at the dendrite of the post-synaptic neurone & excites it to produce an

impulse.


31/43

31

Th l f th


32/43

32

The role of the synapse

Enable a neurone to have connection with

many othe neurones makes us moresensitive to stimuli, enable to producemultiple responses.

Ensure that impulses flow in one directiononly, from a terminal dendrite of one

neurone to the dendrite of the next neuronebecause neurotransmitters are only producedby terminal dendrites.

VOLUNTARY ACTION & INVOLUNTARY ACTION


33/43

33

VOLUNTARY ACTION & INVOLUNTARY ACTION

Voluntary action= an action which under onesconscious control. (writing, walking, eating,

raising)

Initiated by the cerebrum. Cerebrum Impulseseffector organ (hand) response

Involuntary action = an action which cannot becontrolled by our conscious mind. Not involvethe cerebrum but rather the medulla oblongata

or the spinal cord.

May involve skeletal muscles or smooth muscle.(knee-jerkresponse)


34/43

34


35/43

35

Examples of involuntary action : theregulation of blood pressure, the beating of

heart, secretion of a gland (sweating duringhot)


36/43

36

Reflex Action & Reflex Arc Reflex action = rapid response which is obtained

automatically without conscious thought.

Examples : Rapid & automatic withdrawal of hand when it

accidentally touches a hot object Automatic closing of the eyes when an insect flys towards

the eyes

The knee-jerk reflex

Reflex arc = the pathway of a transmission of nerveimpulse which produces a reflex action


37/43

37

A reflex action which involves the brain =cranial reflex

A reflex action which involves the spinalcord = spinal reflex


38/43

38

DISEASES RELATED TO THE NERVOUS SYSTEMPARKINSONS DISEASE (PARKINSONISM) Caused by progressive

degeneration of the basalganglia of the brain.

The brain releases less of a

neurotransmitter calleddopamine. Leads to tremors ofthe hands & legs & rigidity ofparts of the body.

Appears wide-eyed withuncontrolled drooling.

Vision, hearing & intelligence

are not affected.


39/43

39

EPILEPSY The most common disorders of the brain.

Short, recurrent attacks (epilepticseizures) initiated by the discharge ofelectricity from millions of nuerones in the

brain sensory organs & effector organsmay be stimulated.

The person may see, hear or smellsomething which is actually non-existent.

Skeletal muscle may contract involuntary,lose urinary & bowel control.


40/43

40

MULTIPLES SCLEROSIS

Caused by progressive destruction & scarring ofthe myelin sheath of neurones in the centralnervous system.

Affects young & middle-aged adults.

Unsteady gait, shaky limbs, rapid involuntarymovements of eyes & speech difficulties.

Suspected to be due to an abnormal response toa viral infection.


41/43

41

poliomyelitis Caused by an infection of nerves by thepoliovirus paralysis.

Usually occurs during childhood.

The GM of the SC is destroyed.

Infection of the brain may cause death.


42/43

42

Alzheimers disease A disorder of elderly folks.

Caused by degeneration of neurones inthe brain

Intellectual impairment, memory loss,confusion, irritability & loss of orientationin time & space.

No treatment.


43/43

3.2- The Human Nervous System

Documents

Transcript of 3.2- The Human Nervous System