Coordination in MammalCoordination in Mammal

coordination is the way in which

receptors detect stimuli, and then

nerve impulses are sent to the

effectors

in mammals, coordination is carried

out through the activities of nervous

system and the endocrine system

nervous coordination is brought about by transmission of nerve impulses between receptors and effectors through nerve fibres

endocrine coordination is brought

about by hormones secreted from

endocrine glands

What is Nervous What is Nervous Coordination ? Coordination ? nervous system of mammal consists

of central nervous system(CNS) and

peripheral nervous system

CNS includes brain and spinal cord

and the peripheral nervous system

includes cranial nerves and spinal

nerves

Structure of NeuroneStructure of Neuroness neurones make up nervous system in ma

mmal each neurone has a cell body and nerve fi

bres cell body is a mass of cytoplasm with nucl

eus inside and it is called ganglion nerve fibres are cytoplasmic processes of

neurones and there are two types, one is dendron and the other is axon

dendron transmits nerve impulses towards cell body while axon transmits nerve impulses away from cell body

nerve fibres may be protected by a fatty layer which serves as an insulator to prevent the spread of nerve impulses and help to speed up the rate of transmission

cytoplasm dendron

cell membrane

nucleus

nucleus of cell which makes the myelin sheath

axon

direction of nerve

impulses

Types of NeuronesTypes of Neurones there are three types of neurones: sensory

neurone, motor neurone and association neurone

- sensory neurone: transmits nerve impulses from receptor to the central nervous system sensory neurone

- motor neurone: transmits nerve impulses from central nervous system to effectors. The axon branches at its end to form many motor end plates which are attached to muscle fibres

- association neurone: connects the sensory neurone to the motor neurone and also the neurones in the central nervous system

motor neurone

NerveNerve

bundles of nerve fibres

usually myelinated and surrounded by a sheath of white connective tissue

nerve fibre

neurone

nerve

in sensory nerves, there may be ganglia where the cell bodies are situated

nerve fibres found inside the central nervous system do not have insulating fatty layers

impulses do not jump from one fibre to another because of the presence of fatty substance in nerve

neurone

Nerve Impulses TransmitNerve Impulses Transmitted in Nerve Fibreted in Nerve Fibre

stimulation of the receptors may initiate nerve impulses and this follows “All-Or-None” principle

ALL impulses are alike regardless

of the site from which they are

fired off impulses travel very quickly in one direction from dendron to axon of the same neurone

Nerve Impulses Nerve Impulses Transmitted across the Transmitted across the

SynapseSynapseneurones are not in direct contact with each other. A small gap called synapse exist between two neurones

impulses need to jump across the synapse as to travel from one end of axon to dendron of another neurone

Synapses

ending of axon secretes a chemical which diffuses into synapse and stimulates the next neurone to pass on the impulse

the chemical is unstable and will be destroyed later

synapse

presence of synapse enables nerve impulses to travel only from axon of one neurone to dendron of another neurone

it also allows higher level of nervous coordination as one neurone can be linked with a number of other neurones

•includes brain and

spinal cord in higher

animal

Central Nervous Central Nervous SystemSystem

brain

spinal cord

brain is enclosed in cranium of skull while spinal cord is enclosed in vertebral column

CNS is also enveloped in three layers of meninges and between the inner two layers is a cavity filled with cerebrospinal fluid

Protection of Central Protection of Central Nervous SystemNervous System

skull

vertebral column

act as a cushion for absorbing external shock

nourish neurones inside as it enables diffusion of oxygen and food to the nerve cells

it also filled up cavity called ventricle in brain and in the central canal of spinal cord

it also helps in preventing collapse of CNS

Functions of CerebroFunctions of Cerebrospinal Fluidspinal Fluid

External view of the brain

brain is divided into three main parts:

cerebrum, cerebellum and medulla

oblongata

Parts of BrainParts of Brain

cerebellum

cerebrum

medulla oblongata

Brain--CerebrumBrain--Cerebrum lies in the front part of brain and divided

into two cerebral hemispheres connected by nerve fibres

surface of cerebrum is highly folded to increase area for coordination

centre of thinking, memory, reasoning, imagination, learning and voluntary actions

divided into three functional areas

motor area

sensory area

association area

- sensory areas: receive impulses from

receptors

- motor areas: send out impulses to

effectors

- association area: correlates impulses

from different receptors and assists

in producing appropriate responses

Brain--CerebellumBrain--Cerebellum

lies below the back part of cerebrum

centre for muscular coordination and involved in control of body balance

damage of cerebellum will lead to a loss of ability to maintain balance

Brain--Medulla OblongataBrain--Medulla Oblongata

lies at the floor of cerebellum

reflex centre for controlling involuntary actions such as breathing, heartbeat, swallowing, coughing, sneezing and salivation

damage of medulla oblongata may lead to death

Medulla oblongataMedulla oblongata

medulla oblongata

Internal Structure of Internal Structure of Cerebrum and CerebellumCerebrum and Cerebellum outer layer is made up of gray matter

which consists of nerve cell bodies

inner layers consist of nerve fibres and is white in colour and is called white matter

Internal Structure of Internal Structure of Medulla Oblongata Medulla Oblongata

outer layer is made up of white matter while inner layer is made up of grey matter

Internal Structure of Spinal Internal Structure of Spinal CordCord arises from medulla oblongata and ru

ns through backbone of mammal internal distribution of nerve cell bodi

es is similar to medulla oblongata which the outer cortex contains white matter while the inner cortex is in H-shaped and contains grey matter

white matter grey matt

er central canal

spinal cord

spinal nerve

in the central region of grey matter is central canal and filled with cerebrospinal fluid reflex centre for controlling involuntary actions and it also transmits impulses to and from brain

Grey & White MattersGrey & White Matters

grey matter(cell body)

white matter

(nerve fibre)

cerebrum & cerebellumouter

region

inner region

spinal cord &medulla

oblongatainner region

outer region

Peripheral Nervous SystemPeripheral Nervous System

consist of cranial nerves and spinal nerves

these nerves leave CNS and run out to every part of the body

spinal nerve

cranial nerve

Cranial Nerves and Spinal Cranial Nerves and Spinal NervesNerves

Cranial Nerve

- twelve pairs of cranial nerves in

mammal

- most of cranial nerves arise from

lateral sides of medulla oblongata

Spinal Nerve

- there are 31 pairs of spinal nerves in

human

dorsal root ganglion

dorsal root (sensory nerve)

associationneurone

spinal cord

ventral root (motor nerve)motor neurone

sensory neurone

effector(muscle)

receptor(pain)

Spinal Nerve

- all are mixed nerve carrying both sensory and motor neurones

- each spinal nerve has a dorsal root

and ventral root

- dorsal root contains ganglion which

contains nerve cell bodies

- cells in dorsal root ganglion are sensory neurones and impulses travel through dorsal root to spinal cord from spinal nerve

- ventral root carries motor nerve fibres and their cell bodies are found in H-shaped grey matter of spinal cord

Experiment to Experiment to Initiate Knee Jerk Initiate Knee Jerk

ReflexReflex

What happens to the leg immediately after tapping?Ans: It kicks up at once.

Does the same action occur again if the knee is tapped the second time?Ans: Yes.

Reflex ActionReflex Action simple reflex action is a quick, inborn

and automatic response of an animal to

a stimulus and cerebrum does not

involve in the response

protective in function and need not be

learnt

same stimulus initiates the same

responses at different times

examples like withdrawal from hot

objects, blinking, coughing, sneezing

and pupil size

Reflex ArcReflex Arc neural pathway between receptor and eff

ector involved in a reflex action example is knee jerk reflex

Knee Jerk Reflex

At the Receptor receptor receives stimulus. In this

case, tapping stimulates tendon of

knee cap

At the Sensory Neurone from ending of dendrons of sensory neu

rones, nerve impulses fired off Across the Synapse to the Motor Neurone through dorsal root of spinal nerve,

impulses are carried to spinal cord

To the effector impulses are further transmitted through

ventral root to effector to produce responses

impulses jump across synapses to motor neurones in grey matter but in other reflex action, association neurones may involve

in knee jerk, effector is muscles in upper leg which it will contract when impulses are received so the leg jerks up and it is an example of spinal reflex action as only spinal cord is involved

dorsal root ganglion

dorsal root (sensory nerve)

associationneurone

spinal cord

ventral root (motor nerve)motor neurone

sensory neurone

effector(muscle)

receptor(pain)

Reflex arc : sensory, association, motor neurones

spinal reflexes can occur in deep sleep and do not depend on awareness but impulses can still pass form sensory neurones up the spinal cord to brain

other reflex actions like blinking,

coughing and sneezing are cranial

reflex action and take place in

medulla oblongata

Voluntary ActionsVoluntary Actionsconscious response to a certain

stimulus

involves cerebrum of brain and

mammals are aware of all the steps of

the response

may differ from time to time as

mammals can gain experiences and

store them in cerebrum so they can

choose how to response to the same

stimulus

Neural Pathway of VoNeural Pathway of Voluntary Actionluntary Action

receptor receives

stimulus sensory neurone carries nerve impulses to C

NS association neurone carries impulses to cerebrum

motor neurone carries impulses to effector

effector gives responses

reflex action voluntary action

pathway taken by nerve

impulses

not involving cerebrum

involving cerebrum

automatic, not under

control of the will

voluntary, under control of

the willcontrol

Comparison between Reflex Comparison between Reflex & Voluntary Actions & Voluntary Actions

reflex action voluntary action

speed of response slowerquicker

different, depend on

learning from previous

experiences

response to the same stimulus

always the same

To measure To measure your Reaction your Reaction

TimeTime

Does your reaction time improve with practice ?Ans: Yes.

mark on your thumb

Was your reaction time quicker with or without the ruler touching your hand?Ans: The reaction time was quicker without ruler

touching the hand.

mark on your thumb

Explain.Ans: It is because the sensory pathway from eye to b

rain is much shorter than that from finger-tips to the brain.

mark on your thumb

Endocrine GlandsEndocrine Glands ductless glands in body secrete chemical messengers called h

ormones which diffuse directly into the blood

hormones are carried to target organs by bloodstream

Specificity and Effect of EndSpecificity and Effect of Endocrine Glandsocrine Glands

usually, target organ respond to a particular hormones only so hormones are specific

hormonal coordination is slow and takes a longer time for response to appear but its effect can last for a long period of time

Comparison between Nervous Comparison between Nervous & Hormonal Coordination & Hormonal Coordination

method of transmission

nerve impulses transmitted along n

erve fibres

hormones carried by

blood vessels

hormonal coordination

nervous coordination

nature of message

transmittedhormonenerve impulse

duration of effects

short-term long-term

hormonal coordination

nervous coordination

rate of producing response

slowfast

area affectedlocalised to muscles and glands

widespread throughout the whole

body

Locations of Endocrine Locations of Endocrine GlandsGlands pituitary gland: locate below cerebrum and i

t controls many other endocrine glands activities in body thyroid glands: in neck islets of Langerhans: in pancreas adrenal glands: above kidney ovaries: in female’s abdominal cavity testes: in male’s scrotal sacs

pituitary

Sites of Six Main Endocrine Sites of Six Main Endocrine Glands in Human Body Glands in Human Body

Negative Feedback Negative Feedback MechanismMechanism

secretion of hormones follows negative feedback mechanism which means that any decrease in the level of a factor switches on a series of corrective actions to restore the factor to normal level and vice versa

an example is insulin which is secreted by islets of Langerhans in pancreas to liver through blood vessels to control blood glucose level

high blood glucose level

after a heavy meal

normal blood glucose level

in pancreas more insulin

secreted

liver glucose glycogen + more glucose taken up by cells for resp

iration

low blood glucose level

long time after a meal

normal blood glucose level

in pancreas less insulin secreted

liver glycogen glucose + less glucose taken up by cells for res

piration

Effect of Sex HormonesEffect of Sex Hormones puberty occurs between the ages of 11-

14 years when a child become sexually

mature

ovaries in females and testes in males

become functional and secrete sex

hormones for development of

secondary sexual characteristics which

are physical changes for sexual

awareness

Secondary Sexual Secondary Sexual CharacteristicsCharacteristics

Boys Girls

growth of pubic hair and hair on face (facial hair) and in armpit

s (axillary hair)

growth of pubic hair

breaking of voice and enlargement of

larynx

growth and development of

breasts

Boys Girls

muscle development

widening of hips(pelvic

girdle)widening of shoulders

more fat deposits under

skin

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