2. Coordination 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
3. What is Nervous 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
4. Structure of Neurones
●neurones make up nervous system in mammal
●each neurone has a cell body and nerve fibres
●cell body is a mass of cytoplasm with nucleus 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
6. Types of Neurons
●3 types of neurons:
■sensory neuron
■transmits nerve impulses from receptor to the central
nervous system
■motor neuron
■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 neuron
■connects the sensory neurone to the motor neurone
and also the neurones in the central nervous system
7. Nerve
●bundles of nerve fibres
●usually myelinated and surrounded by a sheath of white
connective tissue
●impulses do not jump from one fibre to another because of
the presence of fatty substance in 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
8. Nerve Impulses Transmitted 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
9. Nerve Impulses Transmitted
across the Synapse
●neurones 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
10. ●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
●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
synapse
11. ○includes brain and spinal cord in higher animal
Central Nervous System (CNS)
Protection of CNS
●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
12. ●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 Cerebrospinal Fluid
13. Brain is divided into three main parts:
●cerebrum
●Cerebellum
●medulla oblongata
Parts of Brain
cerebellum
cerebrum
medulla
oblongata
14. 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
1.sensory areas: receive impulses from receptors
2.motor areas: send out impulses to effectors
3.association area: correlates impulses from different
receptors and assists in producing appropriate responses
15. 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
16. 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
17. Internal Structure of Cerebrum 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 Medulla Oblongata
●outer layer is made up of white matter while inner layer is made up of grey
matter
Internal Structure of Spinal Cord
●arises from medulla oblongata and runs through backbone of mammal
●internal distribution of nerve cell bodies is similar to medulla oblongata
which the outer cortex contains white matter while the inner cortex is in H-
shaped and contains grey matter
●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
19. Grey & White Matter
grey matter
(cell body)
white matter
(nerve fibre)
cerebrum &
cerebellum
outer region
inner region
spinal cord &
medulla oblongata
inner region
outer region
20. Peripheral Nervous System
●consist of cranial nerves and spinal nerves
●these nerves leave CNS and run out to every part of the body
Cranial Nerves and Spinal Nerves
●all are mixed nerves 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
●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
22. ●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
23. Reflex 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
24. Reflex Arc
●neural pathway between receptor and effector
involved in a reflex action
●example is knee jerk reflex
25. Knee Jerk Reflex
1.At the Receptor
○receptor receives stimulus. In this case, tapping stimulates
tendon of knee cap
2.At the Sensory Neurone
○from ending of dendrons of sensory neurones, nerve impulses
fired off
3.Across the Synapse to the Motor Neurone
○through dorsal root of spinal nerve, impulses are carried to
spinal cord
○impulses jump across synapses to motor neurones in grey
matter but in other reflex action, association neurones may
involve
4. To the effector impulses are further transmitted through ventral
root to effector to produce responses
26. ●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
Knee Jerk Reflex
28. ●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
29. Voluntary Actions
●conscious 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
30. Neural Pathway of Voluntary
Action
receptor receives stimulus
sensory neurone carries
nerve impulses to CNS
association neurone carries
impulses to cerebrum
motor neurone carries
impulses to effector
effector gives responses
31. Comparison between Reflex &
Voluntary Actions
Reflex action Voluntary action
Pathway taken by
nerve impulses
Does not involve
cerebrum
Involves cerebrum
Control Automatic, not under
control of will
Voluntary, under
control of will
Speed of response Quicker Slower
Response to the
same stimulus
Always the same Different, depends on
learning from
previous experiences
32. Endocrine Glands
●ductless glands in body
●secrete chemical messengers called hormones
which diffuse directly into the blood
●hormones are carried to target organs by
bloodstream
33. Specificity and Effect of Endocrine
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
34. Comparison between Nervous &
Hormonal Coordination
Nervous coordination Hormonal coordination
Nature of message
transmitted
Nerve impulse Hormone
Method of transmission Nerve impulses
transmitted along nerve
fibres
Hormones carried by
blood vessels
Rate of producing
response
Fast Slow
Duration of effects Short-term Long-term
Area affected Localised to muscles
and glands
Widespread throughout
the whole body
35. Locations of Endocrine Glands
1.pituitary gland: locate below cerebrum and it controls
many other endocrine glands activities in body
2.thyroid glands: in neck
3.islets of Langerhans: in pancreas
4.adrenal glands: above kidney
5.ovaries: in female’s abdominal cavity
6.testes: in male’s scrotal sacs
pituitary
36. Negative Feedback Mechanism
●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
37. Effect 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
38. Secondary Sexual
Characteristics
Boys Girls
1 Growth of pubic hair and
hair on face and in armpits
Growth of pubic hair
2 Breaking of voice and
enlargement of larynx
Growth and development of
breasts
3 Muscle development Widening of hips (pelvic
girdle)
4 Widening of shoulders More fat deposits under skin
