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Elena Baechli (period 5) Lymphatic & Immune system - Coggle Diagram
Elena Baechli (period 5)
Lymphatic & Immune system
Major functions of the Lymphatic & Immune systems
Lymphatic system
returns interstitial fluid and leaked plasma proteins back to blood via
Lymphatic vessels (lymphatics): elaborate network of drainage vessels
Once interstitial fluid enters lymphatics, it is called lymph
Immune system
immune system provides resistance to disease
Made up of two intrinsic system
Innate (nonspecific) defense system
Constitutes first and second lines of defense
Adaptive (specific) defense system
Third line of defense attacks particular foreign substances (takes longer to
react than innate)
Innate and adaptive defenses are intertwined
Location of Lymphatic organs and their functions
Location: include spleen, thymus, tonsils, lymph nodes, other lymphoid tissues
Lymphoid organs are grouped into two functional categories
Primary lymphoid organs: areas where T and B cells mature—red bone marrow
and thymus
T and B cells originate in bone marrow, but only B cells matures there; T cells
mature in thymus
Secondary lymphoid organs: areas where mature lymphocytes first encounter
their antigen and become activated
Nodes, spleen, MALT (mucosa-associated lymphoid tissue) and diffuse
lymphoid tissues
Purpose and examples of First, Second and Third line of defense
First line of defense: external body membranes (skin and mucosae)
stop attacks by pathogens (disease-causing microorganisms)
Physical barrier to most microorganisms
Skin and mucous membranes produce protective chemicals that inhibit or destroy microorganisms
acid
enzymes
mucin
Surface barriers breached by nicks or cuts trigger the internal second line of defense that
protects deeper tissues
Second line of defense: antimicrobial proteins, phagocytes, and other cells (inhibit spread of invaders; inflammation most important mechanism)
Innate system necessary if microorganisms invade deeper tissues; includes:
phagocyte
natural killer cells
inflammatory response
antimicrobial proteins
fever
Many second-line cells have pattern recognition receptors that recognize and bind
tightly to structures on microbes, disarming them before they do harm
Third line of defense attacks particular foreign substances (takes longer to
react than innate)
Two main branches of adaptive system
humoral (antibody-mediated) immunity
Antibodies, produced by lymphocytes, circulate freely in body fluids
bind temporarily to target cell
cellular (cell-mediated) immunity
lymphocytes act against target cell
Directly—by killing infected cells
Indirectly—by releasing chemicals that enhance inflammatory response; or
activating other lymphocytes or macrophages
Innate(natural) immune defenses and Adaptive(acquired) immune defenses
innate defenses
Surface barriers
skin
mucous membranes
Internal defenses
phagocytes
natural killer cells
inflammation
antimicrobial proteins
fever
adaptive defenses
Humoral immunity
B cells
Cellular immunity
T cells
Humoral response and cellular response
humoral response
Active
Naturally acquired
infection; contact with pathogen
Artificially acquired
vaccine; dead or attenuated pathogens
Passive
Naturally acquired
antibodies passed from mother to fetus via placenta; or to infant in her milk
Artificially acquired
injection of exogenous antibodies (gamma globulin)
cellular response
T cells provide defense against intracellular antigens
Some T cells directly kill cells; others release chemicals that regulate immune response
T cells are more complex than B cells both in classification and function
Helper, cytotoxic, and regulatory T cells are activated T cells
Two populations of T cells
CD4 cells usually become helper T cells (TH) that can activate B cells, other T
cells, and macrophages; direct adaptive immune response
CD8 cells become cytotoxic T cells (TC) that are capable of destroying cells
harboring foreign antigens
Antigens and antibodies
Antibodies
also called Immunoglobulins (Igs)—are proteins secreted by plasma cells
antibody classes
Five major classes: IgM, IgA, IgD, IgG, and IgE
Antibodies do not destroy antigens; they inactivate and tag them
Defensive mechanisms used by antibodies
neutralization
agglutination
precipitation
complement fixation
Overall T- or Y-shaped antibody monomer consists of four looping polypeptide chains linked by disulfide bonds
Capable of binding specifically with antigen detected by B cells
Antigens
substances that can mobilize adaptive defenses and provoke an immune
response
Targets of all adaptive immune responses
Most are large, complex molecules not normally found in body (non self)
Characteristics of antigens
Can be a complete antigen or hapten (incomplete)
Contain antigentic determinants
Can be a self-antigen
Artificial vs. Naturally acquired immunity
Active humoral immunity
naturally acquired: formed in response to actual bacterial or viral infection
artificially acquired: formed in response to vaccine of dead or attenuated pathogens
Passive humoral immunity
Naturally acquired: antibodies delivered to fetus via placenta or to infant
through milk
Artificially acquired: injection of serum, such as gamma globulin
Passive vs. Active immunity
Active humoral immunity occurs when B cells encounter antigens and produce specific antibodies against them
Passive humoral immunity occurs when ready-made antibodies are introduced into body
Cells involved in the immune system and their functions
Two populations of T cells
CD4 cells usually become helper T cells (TH) that can activate B cells, other T cells, and macrophages; direct adaptive immune response
some become regulatory T cells, which moderate immune response
Can also become memory T cells
CD8 cells become cytotoxic T cells (TC) that are capable of destroying cells
harboring foreign antigens
Helper, cytotoxic, and regulatory T cells are activated T cells
Naive T cells are simply termed CD4 or CD8 cells
Two types of lymphocytes
B lymphocytes (B cells)—humoral immunity
T lymphocytes (T cells)—cellular immunity
Dendritic cells
plasma cells
memory cells
Found in connective tissues and epidermis
Macrophages
Widely distributed in connective tissues and lymphoid organs
B lymphocytes
Present antigens to helper T cell to assist their own activation
Disorders associated with the Immune system
Immunodeficiency: congenital or acquired conditions that impair function or production of immune cells or molecules
Severe combined immunodeficiency (SCID) syndrome: genetic defect with marked deficit in B and T cells
Defective adenosine deaminase (ADA) enzyme allows accumulation of metabolites
lethal to T cells; fatal if untreated
Hodgkin’s disease is an acquired immunodeficiency that causes cancer of B cells,
which depresses lymph node cells and thus leads to immunodeficiency
Human immunodeficiency virus (HIV) cripples immune system by interfering
with activity of helper T cells
Autoimmune disease results when immune system loses ability to distinguish self from
foreign
Autoimmunity: production of autoantibodies and sensitized TC cells that destroys body
tissues
Hypersensitivities: immune responses to perceived (otherwise harmless) threat that cause
tissue damage
acute (type I) hypersensitivities (allergies); begin in seconds after contact
with allergen, antigen that causes allergic reaction
Rheumatoid arthritis: destroys joints
Myasthenia gravis: impairs nerve-muscle connections
Multiple sclerosis: destroys white matter myelin
Graves’ disease: causes hyperthyroidism
Type 1 diabetes mellitus: destroys pancreatic cells
systemic lupus erythematosus (SLE): affects multiple organs
Glomerulonephritis: damages kidney