Coordination

Anita Meiska Putri, S.Pd

 TABLE OF CONTENTS

01. 02.
Central Nervous System Peripheral Nervous System
Text Book 330-343 Text Book 330-343

Anita Meiska Putri, S.Pd

 Nervous system
The nervous system enables humans to react to their surroundings and to coordinate
their behaviour.
• A stimulus is any change in the soundings. These
are detected by receptors (cells that detect a
change) and information passes along cells
(neurones) as electrical impulses to the central
nervous system (CNS).

• The CNS is the brain and spinal cord.

• The CNS coordinates the response of effectors

which may be muscles contracting or glands
secreting hormones.

stimulus  receptor  coordinator  effector  response

Anita Meiska Putri, S.Pd
Nervous System

Structurally, nervous system is classified into

two types central nervous system (CNS) and
peripheral nervous system (PNS). The central
nervous system comprises of the brain and
spinal cord.

Anita Meiska Putri, S.Pd

 Central Nervous
System (CNS)

Anita Meiska Putri, S.Pd

 Brain
• Our brain can be divided into three main parts the cerebrum,
the cerebellum, and brain stem. Cerebrum is the largest part
of brain which can be further divided into right and left halves
called hemisphere.

• Cerebellum is responsible for movement and coordination. It

gives you sense of balance and thus prevents you from
falling down.

• Brainstem includes midbrain, pons, and medulla

oblongata. It controls your body's involuntary actions like
breathing, heart rate, and blood pressure. Brain comes under
a system called nervous system.

• Medulla – is located in the lower part of the brain stem it is

responsible for involuntary coordination such as
breathing, swallowing and heart rate
Anita Meiska Putri, S.Pd
Spinal Cord

• The spinal cord is the bridge that connects

the brain to peripheral nervous system. It
starts from medulla oblongata and stretches
to lumbar region of the spine of vertebral
column.

Anita Meiska Putri, S.Pd

 Peripheral
Nervous System
(PNS)

Anita Meiska Putri, S.Pd

Peripheral Nervous System (PNS)

Anita Meiska Putri, S.Pd

Peripheral Nervous System (PNS)
• The peripheral nervous system is a
network of nerves spread across our
body.

• Think of peripheral nervous system as

a network of highway that connects
the body with central nervous system.
This highway has two-way traffic.

• PNS consists of total 43 pairs of nerve.

Among which, 12 originating brain
named as cranial nerves and 31
originated from spinal cord hence
called as spinal nerves.

Anita Meiska Putri, S.Pd

 Neuron

Anita Meiska Putri, S.Pd

Neuron
• Neuron is the basic unit of nervous system. It is the nerve cell
which transmit electrical signals to brain.

• A neuron has three parts, dendrites, soma or cell body, and

axon. Dendrites, servers input device for neuron, because it
receives input from other nerve cells. Soma or cell body of
neuron, contains nucleus. Axon, server's output device, from
where it transmits electrical response to other neurons.

Anita Meiska Putri, S.Pd

Neuron

There are three types of neuron, each with different functions :

1. Sensory neurons : transmit impulses from receptors to the CNS

2. Intermediate neurons (also known as relay or connector neurones) :
transmit impulses from sensory neurones to motor neurons
3. Motor neurons : transmit impulses from the CNS to effectors.
Anita Meiska Putri, S.Pd
Structure of Neuron
• Myelin is an insulating layer that
surrounds the axons of neurons.
Composed primarily of lipids, myelin
helps to prevent action potentials, which
are the electrical signals that travel along
axons, from decaying due to electrical
current leaking out through the axonal
membrane.

• Myelinated axons thus conduct action

potentials more quickly and efficiently
than unmyelinated axons, and because
of this many neurons in the nervous
systems are myelinated..
Anita Meiska Putri, S.Pd
Structure of Neuron
• Myelin does not cover an axon fully. Instead, there
are intermittent gaps in the myelin where the axon is
exposed to extracellular space. These gaps are
called nodes of ranvier and the sections of myelin
that are adjacent to the nodes of ranvier are called
internodes. The nodes of ranvier are rich in sodium
channels, which open in response to an action
potential traveling down an axon, allowing positive
sodium ions to rush in.

• This influx of sodium ions rejuvenates the action

potential and helps to prevent it from dying out as it
proceeds along the axon. Because the nodes of
Ranvier are not myelinated, however, the action
potential slows down at each node and speeds up as
it travels along the myelinated internode.

Anita Meiska Putri, S.Pd

 Structure of Neuron
• Myelin is formed by glial cells, but the particular
type of glial cell responsible for myelinating axons is
different in the peripheral and central nervous
systems.

• In the peripheral nervous system, glial cells called

schwann cells form myelin. Each schwann cell
wraps around one segment of an axon many times to
form one internode.

• In the central nervous system, oligodendrocytes

form myelin. One oligodendrocyte can produce
dozens of internodes on multiple axons. Because
myelin is white, myelinated axons appear white and
make up what is known as the white matter of the
brain.
Anita Meiska Putri, S.Pd
A Reflex Arc

• Figure 15.8 shows how a sensory neuron, an intermediate neuron and a motor neuron work
together to bring about a response to a stimulus.

• A reflex arc is the pathway along which impulses are transmitted from a receptor to an
effector without involving ‘conscious’ regions of the brain.

Anita Meiska Putri, S.Pd

A Reflex Arc
• Figure 15.8 shows the structure of a spinal
reflex arc in which the impulse is passed from
neuron to neuron inside the spinal cord.

• Reflex action, is an involuntary and nearly

instantaneous movement in response to a
stimulus. A reflex action is made possible by
neural pathways called reflex arcs which can
act on an impulse before that impulse reaches
the brain.

• Reflex actions are a very useful way of

responding to danger signals such as the touch
of a very hot object on your skin or the sight of
an object flying towards you.

Anita Meiska Putri, S.Pd

Plantae

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 Synapses
• Most communication between neurons occurs at a specialized
structure called a synapse. A synapse is an area where two
neurons come close enough to one another that they are
able to pass chemical signals from one cell to another.

• The neurons are not actually connected, but are separated by

a microscopically small space called the synaptic cleft. The
cleft is less than 40 nm wide; by comparison a human hair is
about 75,000 nanometers.

• The role of synapse are :

1. Synapses ensure one-way transmission.
2. Synapses allow integration of impulses
3. Synapses allow the interconnection of nerve pathways
4. Synapses are involved in memory and learning.

Anita Meiska Putri, S.Pd

 Synapses
• The neuron where the signal is initiated is
called the presynaptic neuron, while the neuron
that receives the signal is called the
postsynaptic neuron.

• In the presynaptic neuron, there are chemical

signals called neurotransmitters that are packaged
into small sacs called vesicles. Each vesicle can
contain thousands of neurotransmitter molecules.

• When the presynaptic neuron is excited by an

electrical signal called an action potential, this
causes the vesicles to fuse with the presynaptic
membrane and release their contents into the
synaptic cleft.

Anita Meiska Putri, S.Pd

 Synapses
• Once they are in the synaptic cleft,
neurotransmitters interact with receptors on the
postsynaptic membrane. They bind to these
receptors and can cause an action to occur in
the postsynaptic cell as a result.

• This action may involve increasing the likelihood

that the postsynaptic cell will become activated
and fire an action potential, or decreasing it.
Eventually, the neurotransmitter molecules must
be cleared from the synaptic cleft. Some of
them will simply drift away in a process called
diffusion.

Anita Meiska Putri, S.Pd

 Muscle

Anita Meiska Putri, S.Pd

Muscle Tissue
• Muscle tissue is made up of special muscle cells that have the ability to
contract when stimulated so they can generate a force producing
movement.

• There are three types of muscle tissue in the body, skeletal muscle
tissue or also known as striated muscle tissue, cardiac muscle tissue,
and smooth muscle.

• Let’s take a look at the difference between those three muscle

tissues at the table here. You can find the table on your textbook
page 344.

Anita Meiska Putri, S.Pd

Anita Meiska Putri, S.Pd
Thank You 