The nervous system is comprised of neurons and glial cells. Neurons transmit electro-chemical signals while glial cells provide support. The brain and spinal cord are surrounded by three layers of meninges and bathed in cerebrospinal fluid. The brain is divided into four lobes which control different functions and is separated into two hemispheres connected by the corpus callosum. The peripheral nervous system connects the brain and spinal cord to the rest of the body and controls both voluntary and involuntary functions.

1. NERVOUSSYSTEM
Prepared by
Mr. Abhay Rajpoot
HOD (Dep. of Medical Surgical)
abhayrajpoot5591@gmail.com

3. Neuron Cell
The brain and spinal cord are made up of many
cells, including neurons and glial cells. Neurons
are cells that send and receive electro-chemical
signals to and from the brain and nervous system.
There are about 100 billion neurons in the brain.
There are many more glial cells; they provide
support functions for the neurons, and are far
more numerous than neurons.

18. Meninges
There are three layers of meninges around the brain and spinal
cord. The outer layer, the dura mater, is tough,
white fibrous connective tissue.
The middle layer of meninges is arachnoid, a thin layer resembling
a cobweb with numerous threadlike strands attaching it to the
innermost layer. The space under the arachnoid, the subarachnoid
space, is filled with cerebrospinal fluid and contains blood vessels.
The pia mater is the innermost layer of meninges. This thin,
delicate membrane is tightly bound to the surface of the brain and
spinal cord and cannot be dissected away without damaging the
surface.

20. Brain lobes
The brain is separated into four parts (lobes) that
are all responsible for different jobs.
The four lobes are:
 The frontal lobe
 The parietal lobe
 The temporal lobe
 The occipital lobe

22. VENTRICVLE OF THE BRAIN

23. Cerebrospinal fluid
Cerebrospinal fluid plays an important role in cushioning and
protecting the brain from major shocks. It also plays an important role
in the homeostasis and metabolism of the central nervous system.
CSF Flow
•CSF is produced from arterial blood by the choroid plexus of the
lateral and fourth ventricles
•CSF flows through the inter ventricular foramina into the third
ventricle.
•CSF flows down the cerebral aqueduct into fourth ventricle.
•CSF flows out two lateral apertures and one median aperture.
•CSF fills subarachnoid space and bathes external surface of brain and
spinal cord.
•At the arachnoid villi (granulations), CSF is reabsorbed into the
venous blood of dural venous sinuses.

25. Two Hemispheres
The surface of the brain, known as the cerebral cortex, is
very uneven, characterized by a distinctive pattern of folds
or bumps, known as gyri (singular: gyrus), and grooves,
known as sulci (singular: sulcus). These gyri and sulci
form important landmarks that allow us to separate the
brain into functional centers. The most prominent sulcus,
known as the longitudinal fissure, is the deep groove that
separates the brain into two halves or hemispheres: the left
hemisphere and the right hemisphere.

26. The two hemispheres are connected by a thick band of
neural fibers known as the corpus callosum, consisting
of about 200 million axons. The corpus callosum
allows the two hemispheres to communicate with each
other and allows for information being processed on
one side of the brain to be shared with the other side

30. Blood-Brain Barrier (BBB)
•The BBB consists of endothelial cells lining the brain capillaries.
•It serves to restrict and control the movement of substances between the
general circulation and brain extracellular fluid.
•It helps regulate the volume and composition of fluid surrounding the brain,
thus contributing to homeostasis of the CNS.
• This can be controlled hormonally, or by surrounding cells like
astrocytes.
•The BBB Is able to act as a barrier due to:
• tight junctions that restrict movement of substances between endothelial
cells
• specific transport proteins that determine which substances can cross
the barrier
•In conditions where drugs need to be administered to treat neurological
conditions, the drugs need to be designed to bypass the restrictive barrier.
•Pathological conditions associated with the central nervous system may alter
BBB function.

33. Peripheral Nervous System
Connects body to brain & spinal cord
 12 pairs of nerves from your brain(cranial
nerves)
 31 pairs from your spinal cord(spinal
nerves)
Bundles of sensory and motor neurons held
together by connective tissue

34. Peripheral nervous system
PNS
 All neural tissue outside CNS constitute PNS
 It is composed of
a)Nerves: Bundles of axons in NS constitute nerves, depending
on location such a bundle may be called as rootlet, root,
trunk,division,cord, ramus, branch.
A network of interjoining of nerves called as plexus.
1)Cranial:motor(3,4,6,11,12),sensory(1,2,8),&mixed(5,7,9,10)
2)Spinal: mixed(31)
b)Nerve endings sensory=receptors
Motor=effectors
c)Nerve ganglia 1)sensory=dorsal or sensory root ganglia
2)motor(autonomic)sympathetic&
parasympathetic

38. Functions of PNS
 It receives sensations from receptorsby
way of sensory nerve fibres.It transmits
these sensations to CNS
 It also carries motor orders from CNS to
muscles & glands (effectors) by means of
motor nerve fibres.

39. Somatic Nervous System
Controls voluntary actions
Made up of the cranial and spinal nerves
that go from the central nervous system to
your skeletal muscles

40. Autonomic Nervous System
Controls involuntary actions-those not
under conscious control-such as your
heart rate, breathing, digestion, and
glandular functions