Lymphatic and Immune system• Chapter 17
Lymphatic System
• System consists of– Lymph fluid– Lymphatic vessels– Structures and organs consisting of lymphatic tissue
– Red bone marrow– Lymphocytes
TortoraPages 454-455
Functions of Lymphatic System• Draining interstitial fluid
• Transporting lipids and lipid soluble vitamins A,D, E, and K
• Carries out immune responses
TortoraPage 456
Lymphatic and Interstitial fluid
• Same fluid - different areas.– Interstitial fluid bathes cells.– Lymphatic fluid is I.F. in lymphatic vessels.
• Contains same materials as plasma except no proteins
Lymphatic capillaries
– Lie between cells– Open– Collect interstitial fluid.
– Fluid moves due to pressure.
– Flaps open, allow fluid in, then close
Tortora 456
Lymphatic Vessels
• Lymphatic vessels– Carry lymph fluid– Similar structure as veins with
– Thinner walls & more
valves.– Skeletal and muscular pumps move it towards the heart.
Tortora pg 457
Return to veins
• Lymphatic fluid is returned to circulatory system via the jugular & subclavian veins
• 20 L of plasma become IF every day
• 17 L goes back to heart via the veins
• 3 L becomes lymph
Tortora456-457
Lymph Nodes
– Located along lymphatic vessels.
– Arranged in groups.
– Afferent vessel leads to node.
– Efferent leads away.
– Valves do not let lymph fluid move backwards.
Tortora pg 458-459
Lymphatic nodes
– 600 located in the body
– Concentrated at axillae, mammary glands, throat and groin
– Foreign materials are filtered and destroyed in nodes.
– Macrophages destroy by phagocytosis
– Lymphocytes destroy by a variety of immune responses
Tortora pg 458
Macrophages
Two cross sections of a lymph node: macrophages, which appear as red in the top image, are sticky cells that act like flypaper, trapping viruses and bacteria when they enter the lymph node. Green and blue show other structural elements of the node. In the bottom picture, B cells are red and the structural elements of the node are in green and blue
Swollen lymph nodes
Tonsils & spleen
• Tonsils:– Large nodules grouped together.
– Contains T and B lymphocytes.
• Spleen– Largest mass of lymphatic tissue.
– Stores blood.– Stores 1/3rd of the body’s platelets
– Destroys broken RBCs & platelets.
Thymus gland– Contains T cells, dendritic cells, and macrophages.
– Immature T cells arrive here from the red bone marrow.
– 2% “graduate” to be mature T cells.
– Mature T cells leave the thymus via the blood, are carried to the lymph nodes, spleen, and other lymphatic tissues.
Tortora 458
Lymph Circulation
• Fluid from plasma of blood.
• Interstitial fluid.• Lymph Vessels and nodes– Lymphatic capillaries
– Lymphatic vessels.– Lymph nodes.
• Back to plasma.
Thursday 5/8/03Pages 383-388
Lymph Circulation
• Lymph fluid is moved by;– Skeletal muscles
compressing vessels.– Valves insure one way
flow.
• Edema– Fluid gain in the
interstitial spaces.– Can be due to blocked
lymphatic vessels or nodes.
Thursday 5/8/03Pages 383-388
Innate Resistance to Disease
Monday 5/12/03Pages 388-388
• Pathogens are disease causing organisms.
• Pathogens produce toxins or toxic waste products.
• Your ability to ward off pathogens is resistance.
• Lack of resistance is susceptibility.
Skin & Mucous Membranes
• Skin is 1st defense against pathogens.
• Mechanical factors– Many layers of epithelial cells.
– Role of keratin.– Role of Mucus membranes.
– Mucus– Cilia– Role of lacrimal apparatus
– Role of Saliva
Monday 5/12/03Pages 388-388
Skin & Mucous Membranes
• Chemical Factors factors;– Oil glands secrete sebum.
– Perspiration– Lysozymes– Gastric juice– Vaginal Secretions.
Monday 5/12/03Pages 388-388
Defenses Against Microbes
• Second line of defense.– Interferon
• Proteins produced by cells infected by viruses.
• Binds to receptor sites of other cells.
– Complement• Group of about 20 proteins.
• Found in the plasma of blood.
• Inhance immune system.
Monday 5/12/03Pages 388-388
Defenses Against Microbes
• Natural killer cells– Type of lymphocyte.– Ability to kill microbes and some cancer cells.
– Located in spleen, lymph nodes, bone marrow, and blood.
• Phagocytes– Macrophages are monocytes that morph.
• Wandering and fixed.– Neutrophils
• Hi
Monday 5/12/03Pages 388-388
Phagocytosis Monday 5/12/03Pages 388-388
• Chemotaxis– Phagocytes move towards
higher concentration of chemicals.
• Adherence– Phagocytes attach to
microbe.– Role of complement.
• Ingestion– Pseudopod surrounds
microbe.– Phagocytic vesicle is
formed.– Vesicle fuses to
lysosome.– Microbe is digested.– Wastes are released by
exocytosis.
Inflammation Monday 5/12/03Pages 388-392
• Caused by pathogens, abrasions, chemical irritations.
• Symptoms– Redness– Pain– Heat– Swelling
Inflammation Monday 5/12/03Pages 388-392
• Stages of inflamation– Vasodialation &
increased permeability of blood vessels.
– Phagocyte migration.
• Usually within an hour.
• Chemotaxis & emigration
• Repair
Types of Immunity
Monday 5/12/03Pages 388-392
• Immunity refers to “specific” resistance to certain pathogens.
• An antigen is any substance that triggers an immune response.
• Acquired immunity is gained due to contact with an antigen.
Types of Immunity
Monday 5/12/03Pages 388-392
• Four types of acquired immunity:
1. Naturally acquired active immunity.• Response to pathogens in every day life.
2. Naturally acquired passive immunity.
• Natural transfer of resistance. Nursing baby.
3. Artificially acquired active immunity.
• Acquired through vaccinations.4. Artificially acquired passive
immunity.• Injection of antibodies.
Types of Immunity
TortoraPages 428-437
• Two forms of adaptive immunity:
– Cell mediated immunity• Cells directly attack specific antigen
(pathogens)
– Antibody mediated immunity• Antibodies are produced to attack
specific antigen.
– Self tolerance is critical• Lack of self tolerance results in autoimmune
diseases
T Cells and Cell Mediated Immunity
• Role of MHCs– Major
histocompatibility complex proteins
– Role of MHCs in transplants
• T Cells destroy antigen– Macrophages
present antigen to T cells.
– T cells sensitize.– T cells clone.
TortoraPages 428-437
Antigens and Antibodies
• Antigens are chemical substances not recognized as self.– Whole pathogens– Toxins– Parts of pathogens
• Antibodies are plasma proteins called globulins
TortoraPages 428-437
B Cells and Antibody-Mediated immunity• Antibodies
are proteins produced by plasma cells.– Converted B
lymphocytes.– B lymphocytes were
shown the antigen by macrophages.
– B cells now recognize antigen.
– Some B cells become memory cells,
TortoraPages 428-437
B Cells and Antibody-Mediated immunity• Primary
response– Slower to develop
• Secondary response– Much faster and
stronger.
TortoraPages 428-437
Action of Antibodies
• Neutralizing the antigen.
• Immobilize bacteria.
• Agglutination of antigen.
TortoraPages 428-437
Structure of Antibodies
• Made by B lymphocytes
• Shaped like a “Y”
• One arm is always the same.
• Other two arms are specifically shaped to antigen.
• B cells become “memory cells”.
TortoraPages 428-437