Classification of nervous system

1. What is nervous system?
Nervous system is our body’s
command center. Originating from
our brain, it controls our movements,
thoughts and automatic responses to
the world around us. It also controls
other body systems and processes,
such as digestion, breathing and
sexual development (puberty).

2. Functionsof Nervous system:
The 4 main functionsof the nervous system are:
1.Reception of general sensoryinformation
(touch, pressure,temperature, pain,
vibration)
2.Receiving and perceiving special
sensations (taste, smell, vision, sounds)
3.Integration of sensoryinformation from
different parts of the body and
processing them
4.Responsegeneration

3. These major functions can again be dividedintotwo major categories.
1.Somatic functions,whichpeoplecan control voluntarily,such as blinking
of the eyelids
2.Autonomicfunctions,whichpeoplecannotcontrol,such as the beating of
the heart

4. Classification of Nervous System:

5. The brain is like a committee of
experts. All the parts of the
brain work together, but each
part has its own special
properties. The brain can be
divided into three basic units:
the forebrain, the midbrain,
and the hindbrain.

6. Forebrain(Telencephalon): also called prosencephalon, it
includes the telencephalon, which contains
the cerebral hemispheres, and, under these, the diencephalon,
which contains the thalamus, hypothalamus, epithalamus,
and subthalamus. The forebrain is the
largest and most highly developed
part of the human brain: it consists
primarily of the cerebrum.
The cerebrum is split into two halves
(hemispheres) by a deep fissure.
Despite the split, the two cerebral
hemispheres communicate with each
other through a thick tract of nerve
fibers that lies at the base of this fissure.

7. Although the two hemispheres seem to be mirror images of each other, they are
different. For instance, the ability to form words seems to lie primarily in the left
hemisphere, while the right hemisphere seems to control many abstract
reasoning skills. the right cerebral hemisphere primarily controls the left side of
the body and the left hemisphere primarily controls the right side. When one side
of the
brain is damaged, the
opposite side of the body is
affected. For example, a stroke
in the right hemisphere of the
brain can leave
the left arm and leg paralyzed.

8. Cerebral cortex
Cerebral cortex is the outer
Most layer of brain. Its surface
has many folds, giving it a
wrinkled appearance. The
folds consist of many deep
grooves called sulci and
raised areas called gyri.

9. Cortex is divided into four lobes: frontal, parietal, temporal and occipital. Each of
these lobes is responsible for processing different types of information.
Collectively, your cerebral cortex is responsible for the higher-level processes of
the human brain, including language, memory, reasoning, thought, learning,
decision-making, emotion, intelligence and personality.

10. Cerebral cortex and the cerebrum
Cerebral cortex is the outer
layer that lies on top of cerebrum.
Cerebrum is the largest area of
brain. Cerebrum divides
brain into two halves called
hemispheres. The hemispheres are
attached by a bundle of nerve fibers
called the corpus callosum.
The corpus callosum allows
two hemispheres to communicate
with each other.

11. Diencephalon: Thalamus
The thalamus is a small structure, located right
above the brainstem responsible for relaying
sensory information from the sense organs.
It is responsible for transmitting motor information
for movement and coordination. It is found in the
limbic system within the cerebrum. This limbic
system is mainly responsible for the formation of
new memories and storing past experiences.
Hypothalamus: The hypothalamus is a small and essential part of the brain,
located precisely below the thalamus. controls appetite, peristalsis, the rate of
heartbeat, and blood pressure and forms an axis with the pituitary gland which is
the main link between the nervous and the endocrine systems.

12. Midbrain, also called mesencephalon, region of the developing
vertebrate brain that is composed of the tectum and
tegmentum. The midbrain serves important functions in motor
movement, particularly
movements of the eye, and
in auditory and visual
processing.
a.The tectum (from Latin
for “roof”) makes up the
rear portion of the midbrain.
Tectum controls eye
movements, approach, and
avoidance movements and is
formed by two paired rounded swellings, the superior and Inferior colliculi.

13. The superior colliculus (SC) is a multisensory midbrain structure
that integrates visual, auditory, and
somatosensory spatial information
to initiate orienting movements of
the eyes and head toward salient
objects in space. The superior
colliculus receives input from the
retina and the visual cortex and
participates in a variety of visual
reflexes, particularly
the tracking of objects in the
visual field.

14. The inferior colliculus is a part of the midbrain that serves as a main
auditory(sound) center for the body. Its primary roles are signal
integration, frequency recognition, and pitch discrimination. Bilateral
damage to the inferior colliculi results in deafness, whereas unilateral
damage may result in the inability to localize sound.
The tegmentum is located in front of
the tectum. It consists of fibre tracts
and three regions distinguished by
their colour—the red nucleus, the
gray, and the substantia nigra. These
regions are involved in the
coordination of
sensorimotor information.

15. Difference between tectum and tegmentum:
The tectum is the dorsal part of the midbrain while the
tegmentum is the ventral part of the midbrain.
Tegmentum is located between
the ventricular system and
distinctive basal or ventral
structures at each level. It
forms the floor of the
midbrain (mesencephalon)
whereas the tectum forms
the ceiling.

16. The hindbrain
It is located at the lower back part of the brain
and includes most of the brainstem
(containing the medulla and pons), and
the cerebellum. The metencephalon is the
embryonic part of the hindbrain that
differentiates into the pons and the
cerebellum. The metencephalon grows into
the cerebellum and pons of the adult brain,
and the myelencephalon will become the
medulla of the adult brain. The hindbrain is a
conduit for information passing between
the forebrain and the spinal cord.

17. Brainstem
The brainstem is the structure that connects
the cerebrum of the brain to the spinal cord
and cerebellum. It is composed of four
sections in descending order: the
diencephalon, midbrain, pons, and
medulla oblongata.

18. Pons is a part of brainstem, a structure that links brain
to spinal cord. It handles
unconscious processes and jobs,
such as your
sleep-wake cycle and
breathing. It also contains several
junction points for nerves that control
muscles and carry information from
senses in your head and face.
Medulla oblongata: The bottom part of
the brainstem helps regulate your
breathing, heart rhythms, blood
pressure and swallowing..

19. Whereas the pons is located in the upper part of the
brainstem, the medulla oblongata is a structure located in the
lower half of the brainstem. Just because the medulla oblongata
is beneath the pons doesn't mean it's any less significant. In fact,
they often work in tandem on issues such as breathing.
The spinal cord
The spinal cord extends downward from the base of your
brain. It's made up of nerve cells and groups of nerves that carry
messages between your brain and the rest of your body. Spinal
cord injuries can result from damage to the vertebrae, ligaments or
disks of the spinal column or to the spinal cord itself.

20. Functions of Spinal Cord
.Control body movements
It receives Signals from brain to other
body parts and
controls movements. It also directs
autonomic (involuntary) functions
like breathing rate as well as bowel
and bladder function.
•Reports senses to brain. It transits signals
from other parts of body to the brain and
helps brain to record and process
sensations like pressure or pain.

21. •Manages reflexes. Spinal cord controls
ome reflexes (involuntary movements)
wihout involving your brain. For example,
spinal cord manages patellar reflex
(involuntarily moving your leg when
someone taps your shin in a certain spot)
relex action, is an involuntary, unplanned
sequence or action and nearly
instantaneous movement in response
to a stimulus. A reflex is made possible
by neural pathways called reflex arcs
which can act on an impulse before that
impulse reaches the brain.

22. The Ventral Root of the spinal nerve contains outgoing, efferent (meaning
to "bear away from") fibers that carry information destined to control
motor or glandular function. The cell bodies of these motor neurons are
located in the ventral horns of the spinal cord's central grey region.
Dorsal roots contain sensory axons which carry signals into the
CNS. Ventral roots contains motor axons which carry signals from
CNS-originating neurons to muscles and glands

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