Lymphatic System (Your Immune system and first defense!)

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Lymphatic System (Your Immune system and first
defense!)
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The Lymphatic System

• 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

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The Lymphatic System

• contains immune cells called lymphocytes which
  protect the body against antigens (viruses,
  bacteria, etc.) that invade the body.

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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.

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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.

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Lymph organs

• Besides providing a home for lymphocytes (B-cells
  and T-cells), the  vessels of the lymphatic
  system provide transportation for proteins, fats,
  and other substances in a medium called lymph.

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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)

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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.

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THYMUS

• The site of T-cell maturation

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Spleen

• 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.

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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?

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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.

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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.

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Lymphatic Capillaries
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So how does your body use all of these for
defense?

• First what is an infection?

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Infection is

• The presence and multiplication of a disease
  causing agent a pathogen
• Pathogens include
• Viruses
• Bacteria
• Fungi
• Protozoan

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Nonspecific defense vs Specific defense

• What is the difference?

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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

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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.

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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.

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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.

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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.

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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.

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Specific Defenses

• 3rd line of defense
• Immunity
• Antigens
• Lymphocytes

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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.

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How do we become immune to a bacteria or
pathogen? What do you think?
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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

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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.