Download Chapter 14 - Lymphatic System

Chapter 14 Lecture Notes
page 1
A. functions
1. production of lymphocytes (cloning) in response to foreign antigens
a. types of antigens
pathogens (bacteria, viruses, fungi, protozoans
cancer cells
foreign proteins such as bacterial toxins
b. cloning is the production of exact genetic copies by mitosis
only the lymphocytes that can “fight” the antigens are activated,
saving time and energy while still providing protection
against a wide variety of potential pathogens
c. the clone members produce an immune response
cell-mediated - T lymphocytes attack and destroy cancer cells
or cells that are infected with viruses
antibody-mediated – B lymphocytes make antibodies (protein
molecules that can recognize the antigen)
the antibodies prevent the pathogens from infecting new
cells and help other immune system components to
eliminate the pathogens
BIOL 2404
Strong/Fall 2006
Chapter 14 Lecture Notes
page 2
2. returning excess tissue fluid (about 3 liters per day) and other materials
(proteins, lipids) to the blood
in addition, this forces a sample of extracellular fluid to pass through a
series of lymph nodes on its way back to the blood; cells in the lymph
nodes check the fluid going through them for the presence of pathogens
and cancer cells and initiate an immune response if they are detected (this
is called immune surveillance)
B. lymph vessels
lymph consists of excess tissue fluid and proteins that have leaked
out of capillaries
1. lymphatic capillaries are very small, blind-ended tubes located
everywhere except the CNS
 they are made of endothelial cells that overlap but are not completely
attached to each other
 fluid and large molecules can easily enter the lymphatic capillaries
through openings between the cells
BIOL 2404
Strong/Fall 2006
Chapter 14 Lecture Notes
page 3
2. lymphatic capillaries empty into larger lymphatic vessels that are similar
to veins
3. all lymphatic vessels eventually empty into either the:
a. thoracic duct - legs, abdomen, left head, left arm, left thorax
 the thoracic duct enters the left subclavian vein just before the
internal jugular vein
b. right lymphatic duct - right head, right arm and right thorax
 the right lymphatic duct enters the right subclavian vein just
before the internal jugular vein
C. lymphoid organs
1. lymph nodes are small (1 to 25 mm) organs situated along the lymphatic
vessels
 afferent lymphatic vessels enter lymph nodes, allowing lymph to
flow among the lymphatic cells
 on the other side of the lymph node, an efferent lymphatic
vessel takes the lymph away
 lymph nodes contain lymphocytes and macrophages that detect
anything that should not be present in the lymph and
initiate an immune response against it
BIOL 2404
Strong/Fall 2006
Chapter 14 Lecture Notes
page 4
 lymph nodes are located wherever there are lymph vessels, but
there are large clusters of them in certain regions of the
body:
o cervical
o axillary
o inguinal
2. thymus
 located in mediastinum superior to heart
 function is T lymphocyte maturation
 decreases in size after puberty
3. spleen
 located lateral to stomach in upper left abdomen just below
diaphragm
BIOL 2404
Strong/Fall 2006
Chapter 14 Lecture Notes
page 5
 macrophages remove abnormal blood cells
 lymphocytes initiate immune response against antigens (similar to
what lymph nodes do with lymph)
 injury to the spleen can cause extensive internal bleeding because of
it’s large blood supply
o often requires removal
o functions are redundant
4. mucosa-associated lymphoid tissue (MALT)
 consists of masses of lymphoid tissue (containing lymphocytes)
located in the lining of the respiratory, digestive, urinary and
reproductive tracts (areas where microbes may enter the body)
 the lymphocytes detect microbes and initiate an immune response
against them
a. the tonsils are very large masses of lymphoid nodules located in
the pharynx
 pharyngeal
 palatine
 lingual
 tubular - surrounds opening of pharyngotympanic
b. Peyer’s patches are lymphoid nodules located in the ileum (last
section of the small intestine)
BIOL 2404
Strong/Fall 2006