Nervous system

1. The Nervous System
Dr. Ghizal Fatima
Assistant Professor
Department of Biochemistry
ERA UNIVERSITY, LUCKNOW,
INDIA

2. Central Nervous System
• Made up of brain and
spinal cord
• Acts as body’s control
center, coordinates
body’s activities
– Impulses travel through
the neurons in your
body to reach the brain
• Central Nervous System
is yellow in this
diagram.

3. Peripheral Nervous System
• Made up of all the nerves that
carry messages to and from the
central nervous system.
• Central Nervous System and
Peripheral Nervous System work
together to make rapid changes
in your body in response to
stimuli.
• Peripheral Nervous System is
green in this diagram.

4. • The central nervous system includes
the brain and spinal cord.
• The brain and spinal cord are protected by bony
structures, membranes, and fluid.
• The brain is held in the cranial cavity of the skull and
it consists of the cerebrum, cerebellum, and
the brain stem.
• The nerves involved are cranial nerves and spinal
nerves.

6. Overview of the entire nervous system
• The nervous system has three main functions:
1 sensory input,
2 integration of data
3 motor output.
Sensory input is when the body gathers
information, by neurons, glia and synapses.
• The nervous system is composed of excitable nerve
cells, neurons and synapses that form between the
neurons and connect them to centers throughout
the body or to other neurons.
• These neurons operate on excitation or inhibition,
and although nerve cells can vary in size and
location, their communication with one another
determines their function.

7. • These nerves conduct impulses from sensory
receptors to the brain and spinal cord.
• The data is then processed by way of
integration of data, which occurs only in the
brain.
• After the brain has processed the information,
impulses are then conducted from the brain
and spinal cord to muscles and glands, which is
called motor output.

8. • The nervous system is comprised of two major parts,
or subdivisions, the central nervous system (CNS) and
the peripheral nervous system (PNS).
• The CNS includes the brain and spinal cord. The brain
is the body's "control center".
• The PNS is a vast network of spinal and cranial nerves
that are linked to the brain and the spinal cord.
• The PNS is then subdivided into the autonomic
nervous system and the somatic nervous system.
• The autonomic has involuntary control of internal
organs, blood vessels, smooth and cardiac muscles.
The somatic has voluntary control of skin, bones,
joints, and skeletal muscle.

9. General functions of the CNS
When the CNS becomes damaged or peripheral
nerves become trapped, it can increase or
decrease your internal organs functionality, it can
affect your facial expressions, i.e. make you frown
a lot

10. • lung capacity is increased or decreased,
bladder can fill , but you are unable to
urinate,
• the muscles in your arms, legs, and torso can
become weaker and more fatty, not from lack
of use, but from the nerves that run from
your spine into them being restricted from
working properly,
• you can suffer headaches, earaches, sore
throats, blocked sinuses.
• Even your ability to orgasm can be affected.

11. Structure of neuron Neurons are highly
specialized for the
processing and
transmission of
cellular signals
The soma (cell body) is the
central part of the neuron. It
contains the nucleus of the cell
The dendrites of a neuron are cellular
extensions with many branches. This is
where the majority of input to the neuron
occurs
The axon carries nerve signals away from
the soma
Axon terminal used to release
neurotransmitter chemicals and
communicate with target neurons

12. • Types of Neurons
• Neurons are usually classified based on the role
they play in the body. Two main types of
neurons are sensory neurons and motor
neurons.
• Sensory neurons carry nerve impulses from
sense organs and internal organs to the CNS.
• Motor neurons carry nerve impulses from the
CNS to organs, glands, and muscles—the
opposite direction.

13. Function
• neurons convey information from tissues and
organs into the CNS.
• Afferent neurons are sensory neurons that carry
nerve impulses from sensory stimuli towards the
central nervous system and brain, while
• efferent neurons are motor neurons that carry
neural impulses away from the central nervous
system and towards muscles to cause
movement.

14. The Synapse
• The place where the axon of one neuron
meets the dendrite of another is called
a synapse.
• Synapses are also found between neurons and
other types of cells, such as muscle cells.
• The axon of the sending neuron does not
actually touch the dendrite of the receiving
neuron. There is a tiny gap between them, the
synaptic cleft

16. The following steps describe what happens when a
nerve impulse reaches the end of an axon.
• When a nerve impulse reaches the end of an axon, the
axon releases chemicals called neurotransmitters.
• Neurotransmitters travel across the synapse between
the axon and the dendrite of the next neuron.
• Neurotransmitters bind to the membrane of the
dendrite.
• The binding allows the nerve impulse to travel through
the receiving neuron.

17. The cortex: Thinking and
voluntary movements
The brain stem: breathing
and sleep are controlled
here.
The basal ganglia:
coordinate messages
between multiple other
brain areas.
The cerebellum:
coordination and balance.

18. BRAIN
• The brain is one of the largest and most complex organs in the
human body.
made up of more than 100 billion nerves that communicate in
trillions of connections called synapses.
The brain is also divided into several lobes:
• The frontal lobes are responsible for problem
solving and judgment and motor function.
• The parietal lobes manage sensation, handwriting,
and body position.
• The temporal lobes are involved with memory and
hearing.
• The occipital lobes contain the brain's visual
processing system.

19. • The brain is found in the cranial cavity. Within it
are found the higher nerve centers responsible for
coordinating the sensory and motor systems of
the body (forebrain). The brain stem houses the
lower nerve centers (consisting of midbrain, pons,
and medulla),
• Medulla:control center for respiratory,
cardiovascular and digestive functions.
• Pons: control centers for respiration and
inhibitory functions. Here it will interact with the
cerebellum

20. • Cerebrum: the frontal in control of
specialized motor control, learning, planning
and speech;
• parietal in control of somatic sensory
functions; occipital in control of vision; and
temporal lobes which consists of hearing
centers and some speech.

21. • Cerebellum: part of the brain located posterior
to the medulla oblongata and pons.
• produce smooth, graceful motions. The main
function of the cerebellum is coordination.
• The cerebellum is also responsible for balance
and posture.
• It also assists us when we are learning a new
motor skill, such as playing a sport or musical
instrument.
• Recent research shows that apart from motor
functions cerebellum also has some emotional
role.

24. The Limbic System and Higher Mental
Functions
• The Limbic System is a complex set of
structures found just beneath the cerebrum
and on both sides of the thalamus. It combines
higher mental functions.
• It is often referred to as the emotional nervous
system. It is not only responsible for our
emotional lives, but also our higher mental
functions, such as learning and formation of
memories.

25. • The Limbic system explains why some things seem
so pleasurable to us, such as eating and why some
medical conditions are caused by mental stress,
such as high blood pressure. There are two
significant structures within the limbic system and
several smaller structures that are important as
well. They are:
• The Hippocampus: primary contributor to memory.
• The Amygdala: control of such activities and
feelings as love, friendship, affection, and
expression of mood. The amygdala is the center for
identification of danger and is fundamental for self
preservation. The amygdala is the nucleus
responsible for fear.

26. • The Thalamus: emotions
• The Hypothalamus: sexuality, combativeness,
and hunger, also plays a role in emotion.
lateral parts seem to be involved with
pleasure and rage, while the medial part is
linked to aversion, displeasure, and a
tendency to uncontrollable and loud laughing

27. Diseases of the Limbic System
• Schizophrenia
• Depression
• Bipolar Disorder

28. The Peripheral Nervous System
• The peripheral nervous system includes 12
cranial nerves 31 pairs of spinal nerves.
• It can be subdivided into
the somatic and autonomic systems.
• It is a way of communication from the central
nervous system to the rest of the body by
nerve impulses that regulate the functions of
the human body.

29. The Peripheral Nervous System
• The twelve cranial nerves are
• I Olfactory Nerve for smell
• II Optic Nerve for vision
• III Oculomotor for looking around
• IV Trochlear for moving eye
• V Trigeminal for feeling touch on face
• VI Abducens to move eye muscles
• VII Facial to smile, wink, and help us
• Vestibulocochlear to help with balance, equilibrium, and hearing
• IX Glossopharyngeal for swallowing and gagging
• X Vagus for swallowing, talking, and parasympathetic actions of
digestion
• XI Spinal accessory for shrugging shoulders
• XII Hypoglossal for tongue more divided into different regions as
muscles

30. • Spinal nerves take their origins from the spinal
cord.
• They control the functions of the rest of the
body.
• In humans, there are 31 pairs of spinal nerves:
8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1
coccygeal.

32. The Autonomic System
• The Autonomic system deals with the visceral
organs, like the heart, stomach, gland, and the
intestines. It regulates systems that are
unconsciously carried out to keep our body
alive and well, such as breathing, digestion
(peristalsis), and regulation of the heartbeat.

33. • The ANS has two main divisions:
• Sympathetic
• Parasympathetic
• Both divisions work without conscious effort,
and they have similar nerve pathways, but the
sympathetic and parasympathetic systems
generally have opposite effects on target tissues
(they are antagonistic).
• By controlling the relative input from each
division, the autonomic system regulates many
aspects of homeostasis.

34. • Function of the autonomic nervous system
• The autonomic nervous system controls internal body
processes such as the following:
• Blood pressure
• Heart and breathing rates
• Body temperature
• Digestion
• Metabolism (thus affecting body weight)
• The balance of water and electrolytes (such as sodium and
calcium)
• The production of body fluids (saliva, sweat, and tears)
• Urination
• Defecation
• Sexual response

35. sympathetic division does the following:
• Prepares the body for stressful or emergency
situations—fight or flight
• Thus, the sympathetic division increases heart
rate and the force of heart contractions and
widens (dilates) the airways to make breathing
easier.
• It causes the body to release stored energy.
• Muscular strength is increased.
• This division also causes palms to sweat, pupils to
dilate, and hair to stand on end.
• It slows body processes that are less important in
emergencies, such as digestion and urination.

36. parasympathetic division does the following:
• Controls body process during ordinary
situations.
• Generally, the parasympathetic division
conserves and restores. It slows the heart rate
and decreases blood pressure. It stimulates the
digestive tract to process food and eliminate
wastes. Energy from the processed food is used
to restore and build tissues.

37. Division Effects
Sympathetic Increases the following:
•Heart rate and force of heart contractions
•Release of energy stored in the liver
•The speed at which energy is used to perform body functions while a
person is at rest (basal metabolic rate)
•Muscle strength
Widens the airways to make breathing easier
Causes sweaty palms
Decreases functions that are less important in an emergency (such as
digestion and urination)
Controls the release of semen (ejaculation)
Parasympathetic Stimulates the digestive tract to process food and eliminate
wastes (in bowel movements)
Slows the heart rate
Reduces blood pressure
Controls erections