 |
Shopping Cart 
Checkout
|
 |
 |
|
|
Home : Other Subjects : Psychology Study Guides : 101 : Neurons, Hormones, and the Brain : The Nervous System
|
|
The Nervous System
The nervous system is a complex, highly coordinated network of
tissues that communicate via electro chemical signals. It is responsible for
receiving and processing information in the body and is divided into two main
branches: the central nervous system and the peripheral nervous system.
The Central Nervous System
The central nervous system receives and processes information
from the senses. The brain and the spinal cord make up the central nervous
system. Both organs lie in a fluid called the cerebrospinal fluid,
which cushions and nourishes the brain. The blood-brain barrier protects the cerebrospinal fluid by blocking many drugs and toxins. This barrier
is a membrane that lets some substances from the blood into the brain but keeps
out others.
The spinal cord connects the brain to the rest of the body.
It runs from the brain down to the small of the back and is responsible for spinal reflexes, which are automatic behaviors that require no
input from the brain. The spinal cord also sends messages from the brain to the
other parts of the body and from those parts back to the brain.
The brain is the main organ in the nervous system. It
integrates information from the senses and coordinates the body’s
activities. It allows people to remember their childhoods, plan the future,
create term papers and works of art, talk to friends, and have bizarre
dreams. Different parts of the brain do different things.
The Peripheral Nervous System
All the parts of the nervous system except the brain and the spinal cord
belong to the peripheral nervous system. The peripheral nervous
system has two parts: the somatic nervous system and the autonomic nervous
system.
The Somatic Nervous System
The somatic nervous system consists of nerves
that connect the central nervous system to voluntary skeletal
muscles and sense organs. Voluntary skeletal muscles are muscles
that help us to move around. There are two types of nerves
in the somatic nervous system:
- Afferent nerves carry information from the muscles and sense organs to the central nervous system.
- Efferent nerves carry information from the central nervous system to the muscles and sense organs.
The
Autonomic Nervous System
The autonomic nervous system consists of nerves
that connect the central nervous system to the heart, blood vessels,
glands, and smooth muscles. Smooth muscles are involuntary
muscles that help organs such as the stomach and bladder carry out their
functions. The autonomic nervous system controls all the automatic
functions in the body, including breathing, digestion, sweating,
and heartbeat. The autonomic nervous system is divided into the
sympathetic and parasympathetic nervous systems.
- The sympathetic nervous system gets the body ready for emergency action. It is involved in the fight-or-flight response, which is the sudden reaction to stressful or threatening situations. The sympathetic nervous system prepares the body to meet a challenge. It slows down digestive processes, draws blood away from the skin to the skeletal muscles, and activates the release of hormones so the body can act quickly.
- The parasympathetic nervous system becomes active during states of relaxation. It helps the body to conserve and store energy. It slows heartbeat, decreases blood pressure, and promotes the digestive process.
|
|
||||||||||||||||
|
||||||||||||||||
|
||||||||||||||||
©2006 SparkNotes LLC, All Rights Reserved.