NERVOUS SYSYTEM

2. LO-To understand the function of
nervous system
Components of nervous system

4. Purpose of the Nervous System
• The nervous system is a complex
network of cells that transmit
impulses (also called ‘messages’) to
and from the brain and spinal cord
to different parts of the body.
• This network governs how our bodies
respond to different situations and
sensations.

5. Components of the Nervous System
brain
spinal chord
nerves

11. The brain can use around 20% of all the body’s oxygen.
Every brain neuron makes connections with around
10,000 other brain cells.
The average brain weighs about three pounds and is over
five inches long.
Brain Facts
The brain contains cells, called neurons, that send messages. There are 100 billion
neurons in the human brain, which is about the same number of stars estimated
to be in the Milky Way galaxy.
Scientists are constantly working to understand the brain better, and we still
don’t fully understand everything!

12. However, more recent
research has shown
that many skills, for
example, responding to
music, are split between
areas of both
hemispheres of
the brain.
The right side of the
brain controls the left
side of the body.
The left side of the brain
controls the right side of
the body.
The Hemispheres
It was once believed that
each side of the brain
was used for different
abilities and skills, with
the right side of the brain
being the “creative” side
and the left hand being
the “logical” side.

13. Three Main Areas
The brainstem is the part of the brain linked by the spinal cord
to the rest of the body. A little like a superhighway, it is responsible for all
unconscious activities, such as breathing.
The smaller and rear part
of the brain is called the
cerebellum and is mainly
responsible for motor
control (your movements)
and balance.
The front and larger part
of the brain is called the
cerebrum. It is
responsible for the senses,
thinking, and memory.

14. The Cerebrum Lobes
The different lobes each perform
different functions and are linked to different senses.
frontal lobe
temporal lobes occipital lobe
parietal lobe
The cerebrum is split into different areas called lobes.

15. Part of the frontal lobe is connected to speech ability.
This area of the brain is involved in decision-making,
judgment, and impulse control.
The frontal lobe is the control panel
for your personality and the way you
communicate.
The Frontal Lobe
The frontal lobe is where you do your problem-solving and conscious motor
control (movements).

16. These lobes are also responsible for object and
facial recognition.
The temporal lobes are involved with
short-term memory.
The temporal lobes are located on the sides
of the brain and are linked closely to your hearing.
The Temporal Lobe
The temporal lobes are connected with musical rhythm.

17. This lobe is also responsible for your spatial awareness
and navigational skills (proprioception).
Spoken language is processed and understood in
this lobe.
The parietal lobe is all about the
senses and interpreting things, including pain and touch.
The Parietal Lobe
The sense of touch is processed here, including being able to recognize a word
someone is “writing” on your skin through the sense of touch.

18. Occipital comes from the Latin word occiput, meaning
“back of the head.”
Different areas of the occipital lobe focus on spatial
perception, color, and movement.
The occipital lobe controls visual
processing, and it gets its information from the eyes.
The Occipital Lobe

19. Language and Reading
This is because there are so many different skills involved in these tasks.
Think how long it took you to learn to read and write!
There are a few different lobes that are involved in language and reading..

20. The Cerebellum
This part of the brain helps your motor skills (movements) by controlling
coordination, balance, and timing.
Cerebellum is a Latin word meaning “little brain.”

21. The Brainstem
The brainstem is the central part of the brain (like the apple core) and joins into
the spinal cord.
It is made up of three different parts: the medulla oblongata, the pons, and the
midbrain.
The brainstem does three jobs:
1. It controls various functions related to
hearing, movement, and responses to
the environment.
2. It enables activities such as chewing,
blinking, and tear production.
3. It is in charge of things you
automatically do (like breathing), the
sleep cycle, and circulating blood.
Click here to look inside

22. The brain and the spinal cord together form the central
nervous system (CNS).
It runs from the brain to the bottom of your spine
and is protected by the spinal column (vertebrae).
The spinal cord is the information
superhighway of the nerves, connecting the brain to
the rest of the body.
The Spinal Cord
In adults, the spinal cord is about 18 inches long and has a diameter of close to
one-half of an inch.

23. How can you protect your spinal cord?
Why do you think it’s important to protect your spinal cord?
Turn and Talk

24. What is the nervous system?
The Nervous System is split into the Central
Nervous System (CNS) and the Peripheral Nervous
System (PNS).
The CNS is the brain and spinal cord.
The PNS transmits electrical impulses to and from
the CNS.

25. What is the nervous system?
1. What does the Central Nervous System consist of?
2. What role does the Peripheral Nervous System have?
The central nervous system consists of the brain and spinal cord.
The peripheral nervous system transmits electrical impulses to and from
the central nervous system.

26. Voluntary and Involuntary Responses
Voluntary responses are things that you can control, for example picking
up a pen, kicking a ball.
Your brain sends an impulse down the spinal cord which then passes an
impulse to your motor neurones to complete the action.

27. Voluntary and Involuntary Responses
Involuntary responses are things you can’t control.
These are how you react to pain, your eyes dilating and contracting, your
heart beating etc.

29. NEURONS
•Neurons are the building blocks of
the nervous system. They receive
and transmit signals to different
parts of the body. This is carried
out in both physical and electrical
forms. There are several different
types of neurons that facilitate the
transmission of information.

35. sensory
receptors
sensory
neuron
interneuron
motor
neuron
effector

37. The Reflex Arc
PNS
CNS

38. • A Simple Nerve Circuit – the Reflex Arc.
– A reflex is an autonomic response.

39. REFLEX ARC
•An involuntary or automatic, action
that your body does in response to
something without you even having
to think about it.

40. The Reflex Arc
PNS
CNS

41. 1. Nerves
• Nerves are the long fibres that transmit messages from the brain and
spinal cord (the central nervous system) to the rest of the body (the
peripheral nervous system) and back again.
• Your brain contains billions of nerve cells called neurons that act as the
‘messengers’ between your brain and spinal cord and the rest of the body.
• The ‘messages’ carried back and forth dictate how
we move, think, learn and behave.
• There are two ways that the nervous
system receives stimuli:
• Sensory neurons are activated
through touch, sight, smell, sound and
taste.
• Motor neurons carry the messages away
from the brain and spinal cord to the
rest of the body.

42. 2. Brain
• The brain forms part of the central nervous system and consists of many
folds and grooves; it is protected by the bones in your skull.
• Despite its importance, the brain only weighs around 1,4kg!
• When the brain receives a message from anywhere in
the body, it tells the body how to react.
• The brain is divided into three areas:
• The forebrain
• The midbrain
• The hindbrain
• Each of these areas has different functions
and they all communicate with each other.
• The brain is attached to the spinal cord
through the brain stem.

43. 3. Spinal Cord
• The spinal cord is a long (45,7cm)
bundle of nerves that forms part of
the central nervous system.
• It runs from the brain stem down
your spine and extends to the other
parts of your body
• The spinal cord is also protected:
ring-shaped bones called vertebrae
and a special fluid called
cerebrospinal fluid cushion the
nerves.
• Peripheral nerves stem from the
spinal cord to the rest of the body
like threads.

44. 4. Sensory Organs
• The peripheral nervous system is the second part of the nervous system
within our bodies and stems from the central nervous system through the
spinal cord.
• The peripheral nervous system carries neurons to various muscles and organs
in the body.
• Sensory organs are muscles and organs based
on the five senses:
• ears (hearing)
• nose (smelling)
• eyes (seeing)
• skin (feeling)
• tongue (tasting)
• These organs are responsible for
gathering information all throughout
the body and sending it via sensory
nerves to the central nervous system.

45. Main Processes in the
Nervous System
• The nervous system is responsible for key processes in the body
and the body cannot optimally function if parts of it are
damaged.
• The nervous system sends and receives electrical impulses from
multiple sources at any given moment and determines how we
sense the world around us.

46. Main Processes in the Nervous System
These processes are:
Sound waves are transformed into electrical signals that
travel along the auditory nerve to the brain. This makes us
understand what we are hearing.
Hearing
Seeing and understanding what you are seeing are complex
processes. Light enters your eye upside-down and stimulates
specialised cells in your eye. These cells broadcast signals to
the brain along the optic nerve, where they are turned
around and interpreted as sight.
Seeing
The skin allows us to feel and experience everything around
us through touch. There are millions of nerve endings called
receptors in the skin, muscles, bones and joints, internal
organs and the circulatory system. These receptors respond
to pressure, pain, movement and temperature.
Feeling

47. Main Processes in the Nervous System
Taste buds on your tongue and parts of your mouth can
distinguish between different flavours: sweet, sour, bitter and
salty. These receptors and the receptors in the nose work very
closely together. The taste and scent of food are sent to the
brain where it is processed and interpreted.
Tasting
Nerve cells in the lining of your nose
react to molecules in the air. They send
messages to the brain which interprets
the smell accordingly and recognises
any of +- 10 000 different smells!
Smelling

48. Main Processes in the Nervous System
It is important to maintain a balance within the human
body. It includes regulating our body temperature. Our
bodies need to be kept at about 37ᵒC to work best. If the
body is too hot, the brain might try and cool the body
down through increased sweating. When you are very
cold, your body will shiver to generate heat energy. Your
nervous system controls these responses to changes in
body temperature.
Regulating

49. Health Issues Involving the Nervous System
• The loss of nervous function, where nerves ‘die’ and cease to function
as they should, is also known as neuropathy.
• Neuropathy can be caused by the following factors:
Traumatic brain and spinal cord injuries
Any damage to the brain or spinal cord can have harmful effects on
the human body. For example, people who break their necks in an
accident frequently damage their spinal cord. This prevents the
brain from sending and receiving messages to the body and the
person can become either partly or fully paralysed.
Strokes
Brain cells begin to die when blood flow to the
brain is cut off, even after just a few minutes
without blood or oxygen. This can cause a stroke
where a part of the brain function is lost.

50. Degenerative disorders
There are several problems related to the nervous system that causes a
gradual loss of function over time. This includes Alzheimer's Disease,
Parkinson's Disease and Multiple Sclerosis.
Health Issues Involving the Nervous System
Diabetic complications
Uncontrolled diabetes can lead to a lack of proper functioning of the
nerves, making patients lose sensation in their extremities (hands and
feet) first but eventually affecting more organs and senses.
Mental health problems
Examples are depression, anxiety disorder and personality disorders.

51. Health Issues Involving the Nervous System
Other sensory organ problems
These include deafness, blindness and short-sightedness