o,level biology notes.

1. Coordination
and Response
Khadija Parekh

2. 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

3. What is Nervous Coordination ?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 NeuronesStructure 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

5. cytoplasm dendron
cell membrane
nucleus
nucleus of cell which
makes the myelin sheath
axon
direction of nerve
impulses

6. Types of NeuronsTypes of Neurons
• 3 types of neurons:
• sensory neuron
• motor neuron
• association neuron
• 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 neurone
• connects the sensory neurone to the motor neurone and
also the neurones in the central nervous system

7. NerveNerve
• 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 FibreNerve 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 acrossNerve Impulses Transmitted across
the Synapsethe 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
synapse

11.  includes brain and spinal cord in higher animal
Central Nervous System (CNS)Central Nervous System (CNS)
Protection of CNSProtection 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 FluidFunctions of Cerebrospinal Fluid

13. brain is divided into three main parts:
•cerebrum
•Cerebellum
•medulla oblongata
Parts of BrainParts of Brain
cerebellum
cerebrum
medulla
oblongata

14. CerebrumCerebrum
• 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. CerebellumCerebellum
• 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 OblongataMedulla 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 CerebellumInternal 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 OblongataInternal 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 CordInternal 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

18. white matter
grey matter
central canal
spinal cord
spinal nerve

19. Grey & White MatterGrey & 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 SystemPeripheral 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 NervesCranial 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

21. dorsal root ganglion
dorsal root (sensory nerve)
association
neurone
spinal cord
ventral root (motor nerve)motor neurone
sensory neurone
effector
(muscle)
receptor
(pain)
Spinal Nerve

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 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

24. Reflex ArcReflex 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

27. dorsal root ganglion
dorsal root (sensory nerve)
association
neurone
spinal cord
ventral root (motor nerve)motor neurone
sensory neurone
effector
(muscle)
receptor
(pain)
Reflex arc : sensory, association, motor neurones

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 ActionsVoluntary 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 ofNeural Pathway of
Voluntary ActionVoluntary 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 &Comparison between Reflex &
Voluntary ActionsVoluntary 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 GlandsEndocrine 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 GlandsSpecificity 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 NervousComparison between Nervous
& Hormonal Coordination& 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 GlandsLocations 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 MechanismNegative 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 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

38. Secondary Sexual CharacteristicsSecondary 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