Transcript Think, think, think…

Lymphatic System (Your Immune
system and first defense!)
The Lymphatic System
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consists of organs, ducts, and nodes
transports a watery clear fluid called lymph
distributes immune cells throughout the body
interacts with the blood circulatory system to
drain fluid from cells and tissues
The Lymphatic System
• contains immune cells called lymphocytes
which protect the body against antigens
(viruses, bacteria, etc.) that invade the body.
Main functions
• to collect and return interstitial fluid, including
plasma protein to the blood, and thus help
maintain fluid balance
• to defend the body against disease by producing
lymphocytes
• to absorb lipids (fats) from the intestine and
transport them to the blood.
Lymph organs
• include the bone marrow, lymph nodes,
lymphocytes, spleen, and thymus.
• Precursor cells in the bone marrow produce
lymphocytes.
• B-lymphocytes (B-cells) mature in the bone
marrow.
• T-lymphocytes (T-cells) mature in the thymus
gland.
Lymph organs
• Besides providing a home for lymphocytes (Bcells and T-cells), the vessels of the lymphatic
system provide transportation for proteins,
fats, and other substances in a medium called
lymph.
BONE MARROW
• site of maturation of B lymphocytes
• Many pre-B cells die in the bone marrow
• B cells that survive this selection process leave
the bone marrow through efferent blood
vessels. (Makes your white blood cells)
THYMUS
• Flat, bi-lobed organ situated
above the heart and below
the thyroid gland
• Makes T-cells. Most of which
are inactive until your
endocrine system secretes a
hormone called thymosins
to activate and mature
them.
THYMUS
• The site of T-cell maturation
• Creates lymphocytes for the
destruction and recycling of old
red-blood cells. The spleen is
also a blood reservoir.
• It supplies the body with blood
in emergencies such as a bad
cut. The spleen is also the
location where white blood
cells trap organisms.
• Located under the diaphragm
on the left side.
• Mono causes the spleen to
increase.
Spleen
Tonsils
• Tonsils are clusters of lymphatic tissue that
line the nose, mouth, and throat (pharynx).
• Lymphocytes and macrophages in the tonsils
provide protection against harmful substances
and pathogens that may enter the body
through the nose or mouth.
• Why did they used to remove tonsils a few
years ago?
Lymph nodes
• Human lymph nodes are
bean-shaped and range in size
from a few millimeters to
about 1-2 cm
• They may become enlarged
due to a tumor or infection.
• Bacteria and viruses are sent
here to be destroyed by the
large number of lymphocyte
and macrophages present.
Lymph
• means clear water and it is basically tissue
fluid composed of water and dissolved
substances that have come from the blood.
• It can also carry bacteria or pathogens that
the body needs to get rid of.
• The lymph is drained from the tissue in vessels
called lymph capillaries. Forms a network just
like the cardiovascular system.
• Goes from lymphatic capillaries to vessels to
the lymph nodes and then back to the blood.
Lymphatic Capillaries
So how does your body use all of
these for defense?
• First what is an infection?
Infection is…
•The presence and multiplication of a
disease causing agent – a pathogen
•Pathogens include:
•Viruses
•Bacteria
•Fungi
•Protozoan
Nonspecific defense vs Specific
defense
•What is the
difference?
Nonspecific Defense
•General protection against many types of pathogens
•1st layer of defense:
–Species resistant
–Mechanical barriers
•2nd layer of defense
–Chemical barriers
–Fever
–Inflammation
–Phagocytosis
What do you think Species
resistant means?
• Only certain species are supposed to be able
to get that disease.
• What are some examples of
mechanical barriers?
• Skin, hair, outside body fluids (sweat), etc.
Chemical barriers
•Enzymes in the body are a chemical barrier to
pathogens.
•Enzymes and other fluids in the body have a
certain pH which is lethal to many pathogens
entering the stomach.
•Tears are antibacterial.
•Salt from perspiration kills bacteria on skin.
•Lymphocytes and fibroblasts chemically respond
to viruses or tumors.
Fever
•Elevated body temperature reduces the
level of iron in the blood. Iron is needed for
bacteria and fungi to survive in high
temperatures. Growth of bacteria and
fungi is reduced.
•Phagocyctic cells attack more when
temperature rises.
Inflammation
•Tissue response to injury and
infection = localized redness, swelling,
heat, and pain
•Inflammation walls off the site of
infection so that the infection cannot
spread throughout the body.
•The increase in blood and fluids to
the area brings phagocyctic cells and
clotting factors to the area – keeping
the infection contained.
Phagocytosis
•Neutrophils engulf smaller particles
•Monocytes engulf and digest larger particles
•Phagocytosis removes foreign particles from the
lymph; phagocytes in the blood stream and tissues
remove particles from the spleen, liver, or bone
marrow.
Specific Defenses
•3rd line of defense
•Immunity
•Antigens
•Lymphocytes
Antigens/Antibodies
•Remember antigens are found on the cell surface
(Think of the red blood cell)
•During fetal development the lymphatic system
begins to recognize “self” cells and tissue and
responds to the “nonself” (foreign antigens) cells
and tissues
•Receptors on lymphocyte help the cell to recognize
foreign antigens.
•Antibodies are in the plasma and fight off foreign
substances that they can bind to.
How do we become immune to a
bacteria or pathogen?
What do you think?
Lymphocytes
• B cells and T-cells (Your fighter cells)
•T cells: Attach to foreign antigen-bearing cells,
such as bacteria. May secrete a toxin to kill the
foreign antigen. Create memory cells. Multiple
types of them.
•B cells: Produce antibodies. Carried by body
fluids and react in different ways to destroy
specific antigens or antigen-bearing particles
Your assignment
• Create a disease. Make a info pamphlet on the
disease. Make sure you include:
• The organs of the lymphatic system that are
used to help cure the disease.
• The organ that the disease is affecting.
• The symptoms of the disease
• The lines of defense that the body uses for the
disease.
• Needs to have some color on it and pictures.
This will be checked for a grade Due
tomorrow.