Central NS, Peripheral NS., Autonomic NS, Reflex action and reflex arc

1. Nervous system

2. Brain
• It is one of the largest organs in the body, and
coordinates most body activities.
• It is the center for all thought, memory,
judgment, and emotion.
• Each part of the brain is responsible for
controlling different body functions, such as
temperature, regulation and breathing.

3. Human Brain

5. Cerebrum
• It is the largest section of the brain.
• It is located in the upper portion of the brain and
is the area that processes thoughts, judgment,
memory, problem solving, and language.
• The outer layer of the cerebrum is the cerebral
cortex, which is composed of folds of gray matter.
• The cerebrum is subdivided into the left and right
halves called cerebral hemispheres. Each
hemisphere has 4 lobes.

6. Lobes of Cerebrum
• Frontal lobe: Most anterior portion of the
cerebrum, controls motor function, personality,
and Speech
• Parietal lobe: The most superior portion of the
cerebrum, receives and interprets nerve impulses
from sensory receptors and interprets language.
• Occipital lobe: The most posterior portion of the
cerebrum, controls vision.
• Temporal lobe: The left and right lateral portion
of the cerebrum, controls hearing and smell

7. Parts of Cerebrum

8. Cerebellum
• Second largest portion of the brain
• Located beneath the posterior part of the
cerebrum
• Aids in coordinating voluntary body
movements and maintaining balance and
equilibrium/posture
• Refines the muscular movement that is
initiated in the cerebrum

9. Brain Stem
• Midbrain—acts as a pathway for impulses to
be conducted between the brain and the
spinal cord.
• Pons — means bridge—connects the
cerebellum to the rest of the brain.
• Medulla oblongata—most inferior positioned
portion of the brain; it connects the brain to
the spinal cord.

10. Medulla Oblongata

11. Spinal Cord
• Runs through the vertebral canal
• Center for reflex action
• Passes impulses to the brain
• Extends from foramen magnum to 2nd lumbar vertebra
• Regions
a. Cervical
b. Thoracic
c. Lumbar
d. Sacral
e. Coccygeal
• Gives rise to 31 pairs of spinal nerves - all are mixed nerves

12. Parts of Spinal Cord

13. Peripheral Nervous System
• The second nervous system, known as the peripheral nervous
system, contains all the nerves in the body that lie outside of the
spinal cord and brain.
• These two systems communicate with each other to make sure our
body parts, such as our fingers, can send signals to the central
nervous system for processing in our brains
• The peripheral nervous system consists of 12 pairs of cranial nerves
and 31 pairs of spinal nerves.
• Some of those nerve pairs are exclusively sensory cells, such as cells
that detect information like smell and vision.
• Others are exclusively motor cells, like the eyeballs.
• Also, there are nerve pairs that have both sensory and motor cells,
such as those involved in taste and some aspects of swallowing.
• Sensory cells carry messages to the central nervous system.
• Motor cells carry the signal from the central nervous system to the
internal organs, muscles, and glands in the periphery or the outer
edges of the body.

14. Cranial nerves
• Cranial nerve, in vertebrates, any of the paired nerves of
the peripheral nervous system that connect the muscles and
sense organs of the head and thoracic region directly to
the brain i.e. to and from the brain.
• In higher vertebrates, there are 12 pairs of cranial nerves:
• Olfactory , Optic, Oculomotor , Trochlear, Trigeminal,
Abducent (or abducens), Facial, Vestibulocochlear,
Glossopharyngeal , Vagus, Accessory, and Hypoglossal.
• Cranial nerves are made up of motor neurons, sensory
neurons, or both.
• They have their origin in the brain.

15. Spinal nerves
• Spinal nerve, in vertebrates, any one of many
paired peripheral nerves that arise from the spinal cord.
• In humans there are 31 pairs: 8 cervical, 12 thoracic, 5 lumbar,
5 sacral, and 1 coccygeal.
• Each pair connects the spinal cord with a specific region of the
body.
• Near the spinal cord each spinal nerve branches into two
roots.
• One, composed of sensory fibers, enters the spinal cord via
the dorsal root; its cell bodies lie in a spinal ganglion that is
outside the spinal cord.
• The other, composed of motor fibers, leaves the spinal cord
via the ventral root; its cell bodies lie in specific areas of the
spinal cord itself.

16. Autonomic Nervous System
• The peripheral nervous system is divided into the somatic nervous system
and the autonomic nervous system.
• The somatic nervous system is under voluntary control, and transmits
signals from the brain to end organs such as muscle.
• The Autonomic nervous system is a 'self-regulating' system which
influences the function of organs outside voluntary control, such as
the heart rate, or the functions of the digestive system.
• Autonomic nerve cells are divided into three separate divisions:
• The parasympathetic division is involved with slowing body functions i.e.
re-establishes normal condition after violent act is over.
• Sympathetic division increases body functions i.e. prepare body for
violent action against abnormal conditions.
• They normally oppose each other i.e. antagonistic.
• The enteric division is involved with all the functions in the
gastrointestinal areas, such as the pancreas and the gallbladder.

18. Neuron/Neurone/Nerve cell
• The structural and functional unit of nervous system
• Sensory neurons get information about what's going on inside
and outside of the body and bring that information into the
CNS so it can be processed.
• Motor neurons get information from other neurons and
convey commands to your muscles, organs and glands.
• Interneuron or connector, which are found only in the CNS,
connect one neuron to another. They receive information
from other neurons (either sensory neurons or interneuron)
and transmit information to other neurons (either motor
neurons or interneuron).

19. Neuron

20. Parts of Nerve cell

21. Relay or

22. Differences

23. Reflex action
• For instance, if you picked up a hot coal, the signal from the
sensory neurons in your fingertips would travel to
interneuron in your spinal cord. Some of these interneuron
would signal to the motor neurons controlling your finger
muscles (causing you to let go), while others would
transmit the signal up the spinal cord to neurons in the
brain, where it would be perceived as pain.
• This process commonly called reflex action.
• A reflex, or reflex action, is an involuntary and nearly
instantaneous movement in response to a stimulus.
• The pathway along which nerve impulse travel during the
reflex action is called reflex arc.

25. Reflex arc
Relay neuron or

26. (small gap remains)

27. Glandular System