The brain is the body's control center located in the skull. It controls both voluntary and involuntary activities and enables functions like learning, reasoning, and emotion. The brain has three main parts - the brain stem, cerebellum, and cerebrum. The brain stem controls involuntary activities like breathing. The cerebellum helps coordinate movement. The largest part, the cerebrum, is where most thinking and conscious activity takes place. It is made up of four lobes associated with different functions like reasoning, memory, and vision. Neurons are nerve cells that transmit electrical signals throughout the body to allow responses. The spinal cord extends from the brain down the back and acts as a pathway connecting the brain and peripheral nervous system.

2. I. Brain
– It is the body’s control center. It receives
messages from and sends messages to all organs
and tissues of the body. It controls both voluntary
and involuntary activities. The brain gives you the
ability to learn, to reason, and to feel.
Parts of the Nervous System and Their Functions

3. The brain is protected by three layers of tissues called meninges (sing.
meninx)
Inner layer of the brain – acts as a wall that prevents bacteria from reaching
the brain
Middle layer – supplies the brain with nutrients and oxygen, and cushions it
from shock
Outer layer – lines the inner surface of the skull

4. Main Parts of the Brain
The brain has three parts – the brain
stem, the cerebellum, and the
cerebrum.
A. Brain Stem
- The lowest section of the brain which acts as a pathway for the
messages travelling between some parts of the brain and the spinal cord.
1. medulla – controls involuntary activities like heart rate and breathing
2. pons – connect the major motor and sensory nerves
3. midbrain – controls eye movements and the size of pupils,
coordinates head movements with sound and sight.

5. B. Cerebellum – Lower rear of the brain. It
helps to organize nerve signals going out to
the muscles. It helps to make your
movements smooth and skillful instead of
jerky and clumsy.
C . Cerebrum or Cortex – The largest part
of the human brain, associated with higher
brain function such as thought and action.
This is where most of your thoughts,
feelings, and ideas take place. The
cerebrum makes up about 90% of the
brain.

6. Four (4) regions of cerebrum:
Lobe Associated Area
Frontal Associated with reasoning,
planning, parts of speech,
movement, emotions, and
problem solving.
Temporal Associated with movement,
orientation, recognition,
perception of stimuli.
Parietal Associated with visual
processing.
Occipital Associated with perception and
recognition of auditory stimuli,
memory, and speech.

7. Cortex (also called gray matter) – It is the major site for thinking and for
general consciousness or awareness. This is what you call “mind”. It is also
involved in learning and memory too.
Thalamus – It lies between cerebral cortex and the midbrain. It is
connecting several important processes, including consciousness, sleep
and sensory interpretation.
Hypothalamus - It is only about size of a pearl. Located in the middle part
of the brain, which involved function in emotion, thirst, hunger, and circadian
rhythms. It also control body temperature, heartbeat, kidney functions, and
sleeping pattern.

8. II. Neurons (Nerve Cells)
- Tiny cells in the body that stretches from your back to your toes. It carry
electrical messages from one part of the body to another. These messages
contain information about what is happening and help you respond in the
right way.

9. Types of Neurons:

10. III. Spinal Cord
- The spinal cord begins at the base of the skull. It extends throughout
most of the backbone or the vertebral column.
Function of the Spinal Cord:
The spinal cord is the link between the peripheral nervous system and
the brain. The nerve tracts that make up the white matter in the spinal cord
are the pathways of information to and from the brain.