The Lymph-Vascular System
The lymph-vascular system (also referred to as the lymphatic system)
is the second subsystem of circulation. Lymph is a colorless liquid pro-
duced as a byproduct in the process through which plasma passes nour-
ishment to capillaries and cells. Lymph also nourishes the parts of the body
not reached by blood, such as the far extremities.
Lymph travels through lymph nodes or glands that filter out toxic sub-
stances, like bacteria, and adds antibodies to the fluid. Swollen or tender
lymph nodes indicate infection in the body.
There are over 100 lymph nodes in the body that act as barriers to infec-
tion from one part of the body to another. As the lymph nodes take on this
protective task, they may swell and cause pain. The lymph nodes most
often affected in this way are in the neck and under the arms. Many other
circumstances may be causing the swelling, but a doctor should be con-
sulted at the first sign of any swelling in these areas.
The Nervous System
The study of the nervous system is called Neurology.
The nervous system coordinates and
controls the overall operation of the human body.
The nervous system is divided into three subsystems:
1. The central or cerebrospinal nervous system
2. The peripheral nervous system
3. The autonomic or sympathetic nervous system
Primary components of the nervous system include the brain, spinal cord and nerves.
components of the nervous system, operating in harmony, receive and interpret stimuli and send
messages away from the nerve cell to the appropriate tissues, muscles and organs.
The Central Nervous System
The central or cerebrospinal nervous system is composed of the brain, spinal cord and spinal
and cranial nerves.
The central nervous system is responsible for all voluntary body action.
The brain controls all three subsystems of the nervous system.
For that reason, it is referred
to as the command center. The brain is the largest of the nerve tissues and is located in the crani-
The average human brain weighs between 44 and 48 ounces
Anatomically, the brain can
be conveniently divided into four parts.
ANATOMY AND PHYSIOLOGY
system picks up
leaked fluid and
plasma proteins and
returns them to the