1. The Nervous System
Control and coordinate the body parts and processes.
It receives sensory stimuli from internal and external environments.
It responds in a coordinated manner.

2. Two Division Of The Nervous System
The central nervous system (CNS)
Made up of the brain and spinal cord.
The control center of the body.
Receives and transmits messages
to all body parts.
The peripheral Nervous System
Made up of cranial and spinal
nerves.
Take messages to and from
CNS.

3. Autonomic Nervous System (ANS)
regulates the functions of our internal organs such as the heart, stomach and intestines.
The ANS is part of the peripheral nervous system.
also controls some of the muscles within the body.
We are often unaware of the ANS because it functions involuntary and reflexively.
 For example, we do not notice when blood vessels change size or when our heart beats faster.

4. Main Parts of The Brain
Cerebrum
The bulk of the brain
Responsible for voluntary actions.
Control speech, thinking, emotions and personality.
Coordinates messages to and
from the brain.

5. Cerebellum
Controls muscular coordination, balance, posture and muscle tone.
Medulla Oblongata
Control involuntary activities of internal organs such as heart beat, breathing, peristalsis, temperature regulation.

6. Hypothalamus
Found at the base of the brain
Helps to regulate human body temperature
Control our appetite
Controls our sexual behaviour
Controlling how we response emotionally

7. Pituitary Glands
It is found at the back of
the nose.
Has an oval shape.
Release hormone that
control the functioning
of other glands.
The pituitary gland is refer to as the master gland.

8. Neurone and Nerve
Nerves in a dissection appear as white threads. These threads consists of bundles of fiber bound together in one sheath.
Inside the fibres are the long
processes from the cell
bodies of nerve cells. A
whole nerve cell is called a
neurone.

9. Parts of a Neurone
Axon
Carries electrical impulses
Away from the cell body.
Dendrites
Carries impulses towards
Cell body.
Myelin Sheath
Surrounds axon and
dendrons.

10. It has an insulating
effects on the activities
that take place in a
Neurone.
Cell Body
It has a spherical shape.
It contains the nucleus.

11. Types of Neurones
Sensory neurones
Take electrical impulses from the sense organs to the central nervous system.
Relay neurones
Found in central nervous system.
They transfer information between sensory and motor neurones.
Processing information.

12. Motor Neurones
The collect information from the central nervous system and take it to the different body organs when responding to stimulus.

13. Synapses
This is a small gap at the ends of neurones.
This tiny gap prevent the joining of neurones.
Impulses go across this gap from the end of one neurone to the next one inline.
Synapses are located between
the dendrites of two neurones
, or the dendrites and cell bodies
to which they are applied.

14. Neurotransmitter
This is a chemical substance that is release when nerve impulses arrive at the synapse.

15. Types of Actions
Voluntary Actions
These are actions that we consciously choose to do.
For example we see a ripe orange on the tree and pick it. However before you pick it, you will examine it carefully before making the decision to pick it.

16. Involuntary Action
An action that is not under the person’s control.
It happens automatically, without
the person thinking about it.
The simplest type of involuntary
action is a reflex action.
This is an automatic response, over which you have no conscious control.

17. Spinal Reflex Action This gives us a quick response to stimulus.
Impulses pass from sense organ to
the spinal cord and straight back to
the effectors muscles.
This quickly moves the body parts away.
This serves to protect the part of the body near the dangerous external stimulus.

18. When You touches Something Hot
When the hand touches hot plate temperature and pain receptors in skin are stimulated.
Sensory neurons then conduct impulse along the arm, to spinal cord.

19. The sensory neurons enter the dorsal dorsal root of spinal cord.
Impulses passes across spinal cord to relay neurons.
After making a quick decision, relay then send impulse to motor neurons.

20. Motor neurons leave spinal cord at the ventral root.
Motor neurons take impulse to the effector muscle of arm, telling them to contract .
Arm is then removed from hot plate.

21. Knee- Jerk Reflex
There is no relay neurone.
The stimulus passes directly from sensory to motor neurone.
A doctor perform this to check that your nervous system actions are working properly.

22. Conditioned Reflex
Some reactions have to be learned
first.
After that they can be done without
conscious thought.
The child learning to walk and riding a
bicycle are examples.
At first they are voluntary movements.
Later they are performed without conscious thought.

23. They are called condition reflexes because they have to be acquired through learning.
Once learned they are controlled by part of the brain which is not concerned with conscious thoughts.

25. Protection of the Eye
The eye ball is in a cavity
(socket) of the skull that
protects it from knocks.
Eyebrows prevent sweat from entering the eye.
The eyelids prevent the entry of substances such as windblown grit.
Tears lubricate the surface of the eye, when we blink.
Eyelashes help prevent the entry of dust and grit.

26. The Human Eye
The Pupil Reflex
Pupil is smaller in bright light and larger in dim light.
A reflex action which controls the amount of light entering eyes.

27. In Bright Light
In bright light, circular muscle in iris contracts.
This enlarges the iris
Hence reducing pupil’s size.

28. In Dim Light
Radial muscles contract.
Iris gets smaller which make pupil larger in size.

29. Pigment Accustoms The Eye To Dim Light
When in bright light the pigment is bleached out.
These pigments take time to regenerate in order for you to see in the dark.
It may take up to 30 minutes for all the rods pigments to regenerate when you enter dim light.
This accounts for the difficulty in seeing at first on entering a dark room.

30. Accommodation
The way the lens brings about fine focusing on the retina.
The lens is elastic and its focal
length can be change.
Focal length of the lens is longer
for viewing distant objects as
the lens get thinner.
Focal length of the lens is shorter
for viewing near objects as the
lens get fatter.

31. Eye Defects Long Sight/ Hyperopia When near objects cannot be
focused on the retina.
The diverging rays of light are not sufficiently refracted.
The image form behind the retina.
Light rays from distant objects can be seen clearly, as they need less refraction.

32. Cause of Long Sight
By a short eyeball
A weak lens
Correction
Can be corrected by
wearing glasses with a
a convex lens.

33. Short Sight / Myopia
Can see near objects
clearly as the light rays
need more refraction.
Distant objects appear
blurred.
Parallel light rays are refracted too much and focus in front of the retina.

34. Cause of Short sight
A long eyeball
Lens refracting the light
too much (Strong lens).
Short Sight Correction
Can be corrected by
wearing glasses with
Concave lens.

35. Astigmatism
This is cause when the cornea become uneven.
Vision becomes distorted.
Parallel vertical or longitudinal
bars appear to bend.
Light rays focus at different points
on the retina.

36. Glaucoma
often associated with a buildup of pressure inside the eye.
The increased pressure can damage the optic nerve, which transmits images to the brain.
If damage to the optic nerve from high eye pressure continues, glaucoma will cause permanent loss of vision.

37. Why Does Pressure Rise in the Eye to Cause Glaucoma?
When eye fluid isn't circulating normally in the front part of the eye.
Normally, this fluid, called aqueous humor, flows out of the eye through a mesh-like channel.
If this channel becomes blocked, fluid builds up, causing glaucoma. 

38. Cataracts
 Occur when there is a buildup of protein in the lens that makes it cloudy.
This prevents light from passing clearly through the lens, causing some loss of vision.