PROPOSED LESSON
PLAN/NOTE FOR THE FOURTH WEEK ENDING 7th OCTOBER, 2022/2023 ACADEMIC
SESSION
SUBJECT: BASIC SCIENCE
TOPIC: THE NERVOUS
SYSTEM AND SENSE ORGANS
CLASS: GRADE 9
NUMBER OF STUDENTS: 16
AVERAGE AGE: 13+ YEARS
GENDER: MIXED
PERIOD: 3RD &
4TH PERIOD ON MONDAY AND WEDNESDAY RESPECTIVELY
DURATION: 40 MINUTES
DATE: 03/10/2022
SPECIFIC OBJECTIVES: By
the end of the lesson the students should be able to;
i.
explain the Nervous System, Central Nervous And Peripheral Nervous System; ii.
discuss sense organs.
ENTRY BEHAVIOUR/
PREVIOUS KNOWLEDGE: Students are familiar with
INSTRUCTIONAL
METHODS/TECHNIC: Questions, simulation, visual.
INSTRUCTIONAL
MATERIALS:
INTRODUCTION: Questions posed
to the students include
Question 1: What
is a skeleton?
STEPI: NERVOUS SYSTEM, CENTRAL NERVOUS AND
PERIPHERAL NERVOUS SYSTEM
The nervous system is
a complex network of nerves and cells that carry messages to and from the brain
and spinal cord to various parts of the body. The proper functioning of these
nerves ensures that each organ system, such as the cardiovascular,
gastrointestinal, and immune systems, can adequately communicate with one
another.
The nervous system
includes the central nervous system (CNS) and peripheral nervous system (PNS).
The CNS is made up of the brain and spinal cord, whereas the PNS is made up of
the somatic and autonomic nervous systems.
The
brain
On average, the brain
weighs between 1.3 to 1.4 kg, with about 60% of the brain consisting of fat.
The remaining 40% of the brain consists of protein, water, carbohydrates, and
salts.
The brain can be divided
into four distinct regions: the brainstem, cerebrum, cerebellum, and
diencephalon. Taken together, these different areas of the brain control
thought, memory, emotion, touch, motor skills, vision, breathing, hunger,
temperature, and all other processes that occur within the body.
The brain consists of
both gray and white matter. Gray matter, which is darker in color and surrounds
white matter, consists of neuron somas, and round central cell bodies.
Conversely, white matter, which is lighter in color and comprises the inner
portion of the brain, is primarily made up of axons, the long stems that
connect neurons.
Gray matter typically
processes and interprets information, whereas white matter transmits
information to other areas of the nervous system.
The
brainstem
The brainstem, located
in the middle of the brain, is the stalk-like part of the brain that connects
the brain to the spinal cord and is only about one inch long. This region
regulates essential functions such as blood
pressure,
breathing, heart rhythms, and swallowing.
The brainstem can be
further subdivided into the midbrain, pons, and medulla.
The midbrain, otherwise
known as the mesencephalon, is crucial for regulating eye movements, emotions,
hearing, and long-term memory. Notably, the substantia nigra, rich in dopamine
neurons, is located within the midbrain and is often affected by Parkinson's
disease.
The pons is the starting
location for four of the 12 cranial nerves. Some of the different functions
regulated by the pons include facial movements, hearing, breathing, and
balance.
The medulla is located
at the bottom of the brainstem where the brain and spinal cord meet. This
region of the brainstem regulates breathing, heart rate, and blood pressure.
Additionally, the medulla maintains reflective activities such as sneezing,
vomiting, coughing, and swallowing.
The
cerebrum
The cerebrum is the most
significant part of the brain and is lined by a deeply folded layer of nerve
tissue called the cerebral cortex. Located at the front of the brain, the
cerebrum is divided into the right and left cerebral hemispheres, both
connected by the corpus callosum.
The right hemisphere is
responsible for creating awareness, emotions, facial expression perception,
posture, and prosody, whereas the left hemisphere is dominant in language and
pre-processing social emotions. The right hemisphere controls the left side of
the body, whereas the left hemisphere controls the right side.
The hemispheres are
divided into four lobes, which include the frontal, temporal, parietal, and
occipital lobes.
The frontal lobe is
anterior to the central sulcus and regulates voluntary movements, speech,
memory, emotions, personality, judgment, motor function, planning, organizing,
and short-term memory.
The parietal lobe is
posterior to the central sulcus and above the occipital lobe. This lobe
controls spatial relationships, allowing individuals to understand where their
body is compared to surrounding objects. Furthermore, the parietal lobe allows
for perceiving sensations like pain and touch.
Broca's and Wernicke's
areas are essential for speech production and understanding. Broca's area,
which controls the ability to produce speech, is located in the frontal lobe.
Conversely, Wernicke's area, which allows individuals to understand spoken
language, is located in the parietal lobe.
The temporal lobes are
located at the sides of the brain and are inferior to the lateral fissure.
These lobes are essential for visual, smell, and taste processing, sound and
language interpretation, memory, and hearing.
The occipital lobe is
located in the posterior portion of the brain behind the parietal and temporal
lobes and is responsible for processing visual data, including colors and
shapes.
The
cerebellum
The cerebellum is
located beneath the temporal and occipital lobes and above the brainstem. The
cerebrum is responsible for regulating voluntary motor function, coordination,
and balance. Recent studies have indicated that the cerebellum may also be
involved in thought, emotions, and social behaviors, as well as the
pathophysiology of addiction, autism, and schizophrenia.
The
diencephalon
The diencephalon
includes the thalamus and hypothalamus. The thalamus is a relay center for
sensory data, whereas the hypothalamus transmits hormonal signals to the body
through the pituitary gland.
The thalamus and
hypothalamus, together with the amygdala and hippocampus, comprise the limbic
system. The amygdala regulates emotion, memory, as well as the brain's reward
system, stress, and the 'fight or flight' response to threats.
The hippocampus, located
underneath each temporal lobe, is vital for long-term memory. This structure
also has a role in learning, navigation, and spatial perception.
The
spinal cord
The spinal cord is a
long tube-like structure that extends from the brain. The spinal cord can be
classified into cervical, thoracic, and lumbar areas located in the neck,
chest, and lower back.
A total of 31 pairs of
nerves and nerve roots comprise the spinal cord. The spinal cord region from
which a pair of spinal nerves originates is called the spinal segment.
The cervical spinal cord
consists of eight nerves that originate from the neck and run mainly to the
face and head.
A total of twelve pairs
of nerves can be found within the thoracic region of the spinal cord. These
nerves allow for movements in the upper body, including extension of the chest,
upper back, and abdomen.
An additional ten pairs
of nerves originate from the lower back, with five nerve pairs in the lumbar
and sacral regions. The lumbar nerve pairs proceed to the legs and feet,
whereas the sacral nerve pairs extend from the low back into the pelvis.
The
meninges
The meninges are three
membranous layers that cover and protect both the brain and spinal cord. The
meninges layers include the dura mater, arachnoid, and pia mater.
The dura mater is the
outermost meninges layer and can be further subdivided into the periosteal and
meningeal layers. The middle meninges layer is the arachnoid, a web-like layer
of connective tissue that does not contain any nerves or blood vessels.
Finally, the pia mater is the thinnest meninges layer.
Neurons
The neuron, the basic
unit of the nervous system, is a specialized conductor cell that receives and
transmits electrochemical nerve impulses between the brain and the rest of the
nervous system.
A neuron consists of a
cell body, dendrite, and axon. The cell body contains the nucleus, which
controls cellular activities and contains genetic material.
Dendrites are branched
projections that extend from the cell body and receive signals from other
neurons.
Electrical signals
travel down a long and thin process known as an axon, which extends from the
cell body. These chemical signals, more commonly referred to as
neurotransmitters, travel between neurons through a space known as the synapse.
Sensory neurons carry
signals from sensory receptors to the brain, whereas motor neurons carry
signals from the brain to other nerves, muscles, and glands. The third class of
neurons includes interneurons.
The myelin sheath
insulates neurons and is continuous along the axons or dendrites, except at the
nodes of Ranvier. Myelin, which consists of fat and proteins, provides
protection to the neuron, propagates electrical impulses between neurons, and
maintains the strength of the signal as it travels down the axon.
The
PNS
The PNS consists of both
the somatic and autonomic nervous systems. Taken together, these systems
transmit information from different areas of the body to the brain and ensure
that signals sent from the brain are transmitted to other areas of the body.
The
somatic nervous system
The somatic nervous
system (SNS) consists of peripheral nerve fibers that carry sensory information
or sensations from peripheral organs to the CNS. The SNS also includes motor
nerve fibers that exit the brain to carry commands for movement to the skeletal
muscles.
For example, upon touching
a hot object, sensory nerves carry information about the heat to the brain.
Subsequently, the brain, through motor nerves, commands the hand muscles to
withdraw it immediately. This process takes less than one second to complete.
The neural cell body that carries this information often lies within the brain
or spinal cord and projects directly to a skeletal muscle.
The
autonomic nervous system
The autonomic nervous
system (ANS) controls the nerves of the body's inner organs that cannot be
controlled consciously. The ANS can be further subdivided into the sympathetic,
parasympathetic, and enteric nervous systems. Some of the different activities controlled
by the ANS include the heartbeat, digestion, subconscious breathing, blood
pressure, and sexual arousal.
STEPII: SENSE
ORGANS
Sense organs are
specialized organs that help to perceive the world around us. They are an
integral part of our lives and it is the only way that enables us to perceive
the environment.
Sense organs provide
the required data for interpretation through various organs and a network of
nerves in response to a particular physical phenomenon. These senses govern our
association and our interaction with the environment.
We have five sense
organs, namely:
·
Eyes
·
Ears
·
Nose
·
Tongue
·
Skin
These five sense
organs contain receptors that relay information through the sensory neurons to
the appropriate places within the nervous system.
EVALUATION:
i.
Explain the Nervous System, Central Nervous And Peripheral Nervous System; ii.
Discuss sense organs.
SUMMARY:
i. The nervous system is a complex network of nerves and cells
that carry messages to and from the brain and spinal cord to various parts of
the body.
ii. Sense organs are specialized organs that
help to perceive the world around us.
ASSIGNMENT:
1.
explain the Nervous System, Central Nervous And Peripheral Nervous System; 2.
discuss sense organs.
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