Post on 18-Dec-2015
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
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
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
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
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
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
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
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