Lymphatic Immune Systems Lymphatic System Lymph vessels Lymph

Lymphatic & Immune Systems

Lymphatic System • Lymph vessels • Lymph Nodes and Lymph Organs

Lymph Vessels • Lymph capillaries flow into larger vessels • Enter circulatory vessels through the right lymphatic duct and left thoracic duct

Lymph • Excess tissue fluid leaked from the blood capllaries • transport is aided by contractions of smooth muscle in the vessel walls • one way only-- back towards the heart • assisted by valves

Lymph Nodes • Clustered along vessels • lymph moves through them • lymphocytes and phagocytic cells within them remove bacteria, viruses and debris before it returns to the blood

Other Lymph Organs • Spleen • Tonsils • Thymus • Peyer’s Patches

Spleen • Located in the left abdominal cavity below the diaphragm • Site for lymphocyte proliferation and immune surveillance • Destroys worn out red blood cells and recycles the parts

Spleen Location

Tonsils • Ring the pharynx (throat) • traps and removes bacteria or other foreign pathogens entering the throat; generate “memory” lymphocytes • tonsils in the posterior wall of the nasopharynx (pharyngeal) are called adenoids • can become congested with bacteria- red, swollen and sore-- tonsillitis

Thymus • Located in the inferior neck, under the sternum over the heart • Prominent in newborns-active in the 1 st year-- atrophies after puberty • T lymphocytes mature and become able to defend against pathogens in the immune response

Peyer’s Patches • On the walls of the intestines • macrophages capture and destroy bacteria preventing them from penetrating the intestine wall • generate “memory” lymphocytes for long term immunity

Body Defense Non specific vs. Specific

Non specific Respond immediately to any threat • Surface membranes • Phagocytes • Natural killer cells • Inflammatory Response • Complement and Interferon • Fever

Surface Membranes • Physical Barriers – Skin – Mucous membranes – Lysozymes in fluids – Keratin – Cilia

Phagocytes • Macrophages that engulf and destroy pathogens

Natural Killer Cells • Act non specifically to lyse any virus containing or malignant cells

Anti microbial chemicals • Complement and Interferon

Complement • refers to a group of circulating proteins that can become attached to foreign cells such as bacteria, fungi, or mismatched RBC and cause the cells destruction.

Interferon • secreted by virus infected cells that are ready to die. The interferon attaches to neighboring cells and protects those cells from a viral infection

Fever • helps the body by increasing metabolism, speeding up repair, and sequestering (hiding) iron and zinc that is necessary for bacteria to reproduce

Specific = Immune system • It targets against specific antigens

Antigens • Any substance capable of exciting our immune system and provoking a response –Foreign invaders = non-self Major Histocompatibility Complex (MHC) = Self

Antibodies • Antibodies = immunoglobulins = Igs proteins secreted by activated B cells in response to an antigen • They are capable of binding specifically with that antigen • They don’t specifically kill-they tag them for destruction

The Immune Response • 1. ) It is antigen specific • 2. ) It is systemic • 3. ) It has memory

Cells of the Immune System • Lymphocytes • Macrophages

Lymphocytes • From hematoblasts of bone marrow – T cells – develop immunocompetence in thymus – B cells develop immunocompetance in the bone marrow

Immunocompetance • signaled by the appearance of antigen specific receptors on the surface of lymphocytes

2 Arms of the Immune System • Humoral- deals with antibody- antigen reactions to fight foreign invaders • Cellular- deals with cell to cell interactions, where different T cells bind with problem cells to destroy them

Humoral Immune System • Free antigens or antigen presenting macrophages can activate Helper T Cells that activate B cells • Those B cells give rise to plasma cells and memory B cells • The plasma cells become antibody secreting machines • The memory B cells may exist in the body for years enabling it to respond immediately if there is subsequent infection

What is an antigen presenting macrophage? 1. A macrophage engulfs an invader 2. Some of the foreign antigens appear on the surface of the macrophage 3. A lymphocyte (helper T cell) is activated by the foreign antigens on the surface of the macrophage

4. The B Cell finds an antigen that matches it’s receptor 5. It waits until it is activated by a helper T cell 6. It divides to produce plasma B cells and memory B cells 7. Plasma cells produce antibodies to react with the pathogen’s antigens

8. Phagocytes will “eat” pathogen cells that are tagged with an antibody 9. If the same intruder invades the body, the memory cells will mount an immediate attack

• Primary response- peaks in about 10 days, then declines over 4 -5 weeks • Secondary response-faster, more prolonged, and more effective (involves memory B cells)

Active & Passive Humoral Immunity Active Humoral Immunity Passive Humoral Immunity • Naturally acquired: Infection- contact with pathogen • Naturally acquired: Antibodies pass from mother to fetus via placenta or breast milk • Artificially acquired: Vaccine- dead or Injections of immune attenuated serum-gamma globulins (antibodies) (weakened) pathogen

Cellular Immune Response • Cellular immunity involves four different types of T Cells: • Helper T cells, suppressor T cells, cytotoxic T cells, and memory T cells • T Cells must recognize self and non self

T cells • They cannot recognize free antigens, the antigens must be presented to the T cell

• Activated helper T cells will help activate cytotoxic T cells • Cytotoxic T cells will kill viral infected cells and cancerous cells

Cytotoxic (killer) T Cell Antigen Macrophage Cell Mediated Immunity Helper T Cell MHC Antigen B Cell Humoral Immunity

Suppressor T cells • Suppressor T cells slow or stop the activity of B and T cells once the infection or attack by foreign cells has been conquered

Organ Transplant and Rejection Types of transplants: Autografts- from self Isograft- genetically identical (twin) Allograft- unrelated person Xenograft- animal

• Before a graft is attempted, ABO antigens must match and at least 75% of MHC antigens must match • After surgery, immunosuppressive drug therapy must be started to avoid rejection • Leaves the patient open to infection

Allergies • The body mounts a vigorous immune response in which the immune system causes tissue damage fighting a perceived threat • Triggered by release of histamine and Ig. E antibodies bound to mast cells • Symptoms: sneezing, runny nose, itchiness, watery eyes, hives, smooth muscle constriction, anaphylactic shock

Immunodeficiencies • SCID- a congenital deficiency of both B and T cells • AIDS- cripples the immune system by interfering with the activity of helper T cells

Autoimmune Diseases • The immune system loses its ability to distinguish friend from foe • The body produces antibodies and sensitized T cells that attack and damage its own tissues

Autoimmune Diseases: • MS- multiple sclerosis-nervous system issues are a result • Type 1 Diabetes- destroys pancreatic Beta cells • SLE- Systemic Lupus Erythematosus-attacks tissues • RA(Rheumatoid arthritis)-attacks joints • Crohn’s disease-attacks large intestine (sometimes the small intestine)-causes malnourishment • Celiac disease-gluten causes body to attack small intestine-causes malnourishment • ALS (amyotrophic lateral sclerosis)-attacks motor neurons in brain, spinal cord and muscles-leads to death