2. Introduction
to the Nervous
System
• In biology, the nervous system is a highly complex
part of an animal that coordinates its actions and
sensory information by transmitting signals to and
from different parts of its body.
• The nervous system is the body's primary
controlling, regulatory and communication system.
It's the hub of all mental function, including thought,
learning, and memory. Along with the endocrine
system, the nervous system is responsible for the
management and maintenance of homeostasis. The
nervous system, through its receptors, keeps us in
contact with our surroundings, both external and
internal.
3. • Like other systems in the body, the nervous system is composed of
organs, principally the brain, spinal cord, nerves, and ganglia. They also
consist of various tissues, including nerve, blood, and connective tissue.
Together these carry out the complex activities of the nervous system.
• The various activities of the nervous system can be grouped together as
three generals, overlapping functions:-
Sensory
Integrative
Motor
4.
5. • Sensory feedback is translated to
electrical signals called nerve
impulses that are sent to the brain.
Signals are pulled together to
generate stimuli, to develop
impressions, or to add to memory;
choices are taken at each moment
based on the sensory feedback. It's
integration.
• Sensory receptors detect changes, called
stimuli, which occur inside and outside the
body. They monitor such things as
temperature, light, and sound from the
external environment. Inside the body, the
internal environment, receptors detect
variations in pressure, pH, carbon dioxide
concentration, and the levels of various
electrolytes. All this gathered information is
called sensory input.
The sensory input and integration, the nervous system
responds by sending signals to muscles, causing them to
contract, or to glands, causing them to produce secretions.
Muscles and glands are called effectors because they
cause an effect in response to directions from the nervous
system. This is the motor output or motor function.
8. Organization of the Nervous
System
• The nervous system is divided into two subdivisions: the
central nervous system (CNS) and the peripheral nervous
system (PNS).
• The two halves of the nervous system work together in
order for your body to properly communicate its
sensations and needs.
9. The Central Nervous System
• The forebrain, midbrain, hindbrain, and spinal cord form
the central nervous system (CNS), which is one of two
great divisions of the nervous system. The brain is
protected by the skull, while the spinal cord, which is
about 17 inches (43 cm) long, is protected by the
vertebral column.
• It is referred to as “central” because it combines
information from the entire body and coordinates activity
across the whole organism.
10. • The CNS consists of the brain and
spinal cord.
• The brain is the most complex organ
in the body and uses 20 percent of
the total oxygen we breathe in.
• The brain consists of an estimated
100 billion neurons, with each
connected to thousands more.
• The brain can be divided into four
main lobes: temporal, parietal,
occipital and frontal.
Fast facts on the central
nervous system
11. • The PNS consists of the nerves and ganglia
outside the brain and spinal cord.
• The primary role of the PNS is to connect the
CNS to the organs, limbs, and skin.
• These nerves extend from the central nervous
system to the outermost areas of the body.
• The peripheral system allows the brain and
spinal cord to receive and send information to
other areas of the body, which allows us to
react to stimuli in our environment
Peripheral
Nervous System
12.
13. • Parasympathetic system: This helps maintain
normal body functions and conserve physical
resources. Once a threat has passed, this
system will slow the heart rate, slow breathing,
reduce blood flow to muscles, and constrict the
pupils. This allows us to return our bodies to a
normal resting state.
• Sympathetic system: By regulating the flight-or-
fight response,1
the sympathetic system
prepares the body to expend energy to respond
to environmental threats. When action is needed,
the sympathetic system triggers a response by
accelerating heart rate, increasing breathing rate,
boosting blood flow to muscles, activating sweat
secretion, and dilating the pupils.
Autonomic
nervous system
The autonomic system is the part of the
peripheral nervous system that's
responsible for regulating involuntary body
functions, such as blood flow, heartbeat,
digestion, and breathing.
14.
15.
16. Neurons
Neurons, or nerve cells, carry
out the functions of the nervous
system by conducting nerve
impulses. They are highly
specialized. This means that if a
neuron is destroyed, it cannot be
replaced.
17. Review: Introduction to the Nervous System
Here is what we have learned from this Introduction to the Nervous System:
• The nervous system is the major controlling, regulatory, and communicating system in the
body. It is the center of all mental activity including thought, learning, and memory.
• The various activities of the nervous system can be grouped together as three generals,
overlapping functions: sensory, integrative, and motor.
• The central nervous system consists of the brain and spinal cord. Cranial nerves, spinal
nerves, and ganglia make up the peripheral nervous system.
• The Peripheral nervous system is divided in Autonomic nervous system and sensory
nervous system.
• Basic ideas for neuron and how they look .
