Lymphatics and Immune System
network of vessels and various lymphoid tissues and organs scattered throughout body
Major Components of the Lymphatic System
2. Lymphatic Vessels
3. Lymphatic/Lymphoid Tissues
4. Lymphoid Organs
Protein-containing interstitial fluid/extra cellular fluid that has entered the lymphatic vessels
System of drainage vessels that collects excess protein-containing interstitial fluid & returns to blood stream
Aggregates of lymphocytes (white blood cells) and macrophages interspersed throughout the body
Densely-packed reticular elements & cells
Produce and/or house immune system cells (lymph nodes, spleen, thymus, tonsils, others)
Functions of Lymphatic Systems
1. Fluid Recovery
2. Immune System Function
3. Lipid Absorption
Returns fluid filtered from blood capillaries to blood stream
Immune System Function
Houses immune system cells that monitor body fluids for foreign or abnormal substances
Special lymph vessels absorb lipids from digest system
Receive lymph from covering lymphatic trunks
Right Lymphatic Duct
Drains lymph from upper arm, right side of head, right thorax and empties into right subclavian vein
Drains lymph from rest of body and empties into left subclavian vein
Provides residence and sit of proliferation for lymphocytes and allows immune surveillance of infusing lymph by lymphocytes and macrophages
In pharyngeal region; have crypts to trap and survey incoming material
In thorax, most active during youth; strinks to fibrous mass in adults and maturation of lymphocytes
Curves around left side of stomach; red blood cell graveyard and fetal red blood cell production
Peyer's Patches & Appendix
Limit/control bacterial growth
What are the two intrinsic defense systems to provide immunity?
Innate (Nonspecific) Defense System & Adaptive (Specific) Defense System
Innate Defense System
Defense against all foreign substances.
Adaptive Defense System
Mounts defensive responses specific against specific foreign substances. Takes Longer to enact but has memory.
Innate & Adaptive Defense System
Both worth independently and together to protect body from infectious microorganisms, cancer cells, transplanted organs, mismatched blood.
Skin & Mucosea. Physical barriers to keep pathogens out of body. Secretions of these barriers also resist pathogens:
1. acidity of secretions of skin, vagina
2. HCl and digestive enzymes of stomach mucosa
3. Lysozyme of saliva and tears
4. Mucous and defensin proteins of mucosae
Cells, Inflammation, Antimicrobial Proteins, Fever.
Cells that engulf and digest foreign particles. Macrophages and Neutrophils
"Big Eaters" derived from monocytes
Mechanism of engulfment of large foreign particle. Key is initial adherence/recognition/binding. Enhanced by opsinization.
Coating with marker (i.e. antibody)
Steps of Phagocytosis
1. Phagocyte adheres to microbe.
2. Phagocyte forms pseudopods that eventually engulf the particle.
3. Phagocytic vesicle is fused with a lysosome.
4. Microbe in fused vesicle is killed and digested by lysosomal enzymes within the phagolysosome, leaving residual body.
5. Indigestible and residual material is removed by exocytosis.
Natural Killer Cells
Subset of lymphocytes. Contact cells and check their identity, lyse and kill cancer cells or virus-infected cells, and induce apoptosis in target cells.
Release killing substance from cytoplasmic granules onto invading parasites (worms).
Tissue response to injury or infection. Caused by blow, heat, chemicals, bacteria, virus, fungi, allergic reaction.
4 Signs of Inflammation
Redness, heat, swelling, & pain
Inflammatory Chemical Release
Inflammatory process begins with the release of inflammatory chemicals: cytokines, histamine, kinins, prostaglandins, complement.
Fluid, antibodies, clotting factors leak from nearby capillaries and forms a gel-like mesh to limit spread of infection.
White blood cells attracted to place of infection
Phagocyte Mobilization Process
Injured cells release factors that cause neutrophils to be released from bone marrow into blood.
In inflamed area, endothelial cells of blood vessels display cell adhesion molecule (CAMs) on surface. Bind to complementary CAMs on neutrophils. Neutrophils cling to vessel walls here.
Neutrophils squeeze through capillary or venule wall out into inflamed tissue
Neutrophils continue to follow source of chemical signal to sites of infection to phagocytose foreign sustances and cellular debris.
Increase body temperature in response to pyrogens secreted by white blood cells and macrophages exposed to foreign substances
Fevers increases metabolism which ________.
Fevers causes liver & spleen to sequester iron & zinc which _____.
Prevents bacteria from growing
General Characteristics of Adaptive Immune Defenses
Specificity, Systemic, & Memory
Recognizes and responds against particular pathogens or foreign substances
Immunity not restricted to infection site only
After initial exposure, adpative defense system mounts quicker, stronger attacks on previously-encountered pathogens.
What are the major arms of adaptive immune defenses?
Humoral and cellular immunity
antibody-based that binds to foreign substances
White blood cells themselves attack foreign invaders
Substances that provoke an immune response; provoke antibody production.
What can act as an antigen?
Almost any foreign molecule, especially proteins.
Clonal Selection and Differentiation of B cells
Proliferation/ Clone formation -> plasma cells & memory cells
Immunological Memory; Primary & Secondary Responses
Clonal Selection and differentiation upon first exposure to particular antigen
-usually lag of 3-6 days (few B cells multiply & differentiate to plasma cells)
-Antibody level peak at about day 10 then decline
-sets up immunological memory
Re-exposure to same antigen that stimulates more memory cells.
-faster, stronger, prolonged, more effective
-Antibody levels remain high weeks-months
Neutralization, precipitation, opsinization, complement fixation
Antibodies binds/masks dangerous parts of a molecule. Antigens lose toxic properties.
Antigen become insoluable
Alters antigen cell membranes so cells are more susceptible to phagocytosis
Help activate complement (20 proteins) that establish membrane attack complex (MAC)
Cell-mediated Immune Response
Essential for when pathogens (virus) invades host cells (not accessible to antibodies)
Carry out cellular-mediated immunity
What are the two major types of T cells.
Helper T Cells & Cytotoxic T Cells
Helper T Cells
Have CD4 glycoprotein receptors
Cytotoxic T Cells
Killer T Cells & Have CD8 glycoprotein receptors
Contact killing involves _________.
Perforin & Granzyme
Protein that establishes water pores in target cell. Swelling & bursting.
Protease that enters target cell via pores. Degrades protein inside.
Programmed cell death
Abnormal behavior of immune cells, phagocytes, or complement protein complex. Can be congenital or acquired.
Genetic defects producing deficit of B cells and T cells. Little or no protection against disease-causing organism.
Cancer of B cells; symptoms of swollen lymph glands
caused by HIV, which kills Helper T cells; impairs immune system. Virus has high mutation rate, very difficult to treat/combat, and uses a reverse transcriptase to produce DNA from its own RNA code, which then gets incorporated into host cell genome to produce more virus.
Immune system fails to distinguish self from nonself and attacks own body cells
Destroys white matter in brain and spinal cord- attacking myelin sheath
Immune system causes tissue damage as it fights perceived threat, usually harmless to body