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Leidy Esquivel Per 2 Lymphatic/Immune System - Coggle Diagram
Leidy Esquivel Per 2 Lymphatic/Immune System
Cells involved in the immune system and their fucntions
Natural Killer (NK) Cells
- Can kill cancer and virus-infected cells before adaptive immune system is activated
Macrophages
- develop from monocytes and are chief phagocytic cells; most robust
phagocytic cell
T cells
- Provide defense against intracellular antigens
CD4 cells
become helper T cells that can activate B cells, other T
cells, and macrophages; direct adaptive immune response
CD8 cells
become cytotoxic T cells that are capable of destroying cells
harboring foreign antigens
Neutrophils
- most abundant phagocytes, but die fighting; become phagocytic on
exposure to infectious material
Helper T cells
-
Help activate B cells and other T cells
Induce T and B cell proliferation
Secrete cytokines that recruit other immune cells
Cytotoxic T cells
Directly attack and kill other cells
Activated TC cells circulate in blood and lymph and lymphoid organs in search of body cells displaying antigen they recognize
Regulatory T cells
- Important in preventing autoimmune reactions
Purpose and examples of First, Second and Third line of defense
Second Line of defense
Have pattern recognition receptors that recognize and bind
tightly to structures on microbes
Antimicrobial proteins, phagocytes, and other cells
Inflammation
- Triggered whenever body tissues are injured
Third Line of defense
Attacks particular foreign substances
Takes longer to
react than innate)
First Line of Defense
External body membranes
Skin and mucous
Physical barrier to most microorganisms
Keratin is resistant to weak acids and bases, bacterial enzymes, and toxins
Mucosae provide similar mechanical barriers
Antigens and antibodies
Antigens
Targets of all adaptive immune responses
Characteristics
Can be a complete antigen or hapten
Contain antigentic determinants
Can be a self-antigen
Substances that can mobilize adaptive defenses and provoke an immune
response
Self-Antigens
Coded by genes of major histocompatibility complex (MHC) and unique to each
individual
Contain groove that can hold piece of self-antigen or foreign antigen
All cells are covered with variety of proteins located on surface that are
not antigenic to self, but may be antigenic to others in transfusions or grafts
Antigen-Presenting Cells
Macrophages
Widely distributed in connective tissues and lymphoid organs
Also trigger powerful inflammatory responses and recruit additional defenses
B lymphocytes
Do not activate naive T cells
Present antigens to helper T cell to assist their own activation
Dendritic cells
Found in connective tissues and epidermis
Act as mobile sentinels of boundary tissues
Antibodies
Capable of binding specifically with antigen detected by B cells
Neutralization
Antibodies block specific sites on viruses or bacterial exotoxins
Prevent antigens from binding to receptors on tissue cells
Simplest, but one of most important defensive mechanism
Antigen-antibody complexes undergo phagocytosis
Proteins secreted by plasma
cells
Agglutination
Allows for antigen-antibody complexes to become cross-linked into large
lattice-like clumps
Process referred to as agglutination
Complement fixation and activation
Main antibody defense against cellular antigens
When several antibodies are bound close together on same antigen,
complement-binding sites on their stem regions are aligned
Precipitation
Soluble molecules are cross-linked into complexes
Complexes precipitate out of solution
Precipated complexes are easier for phagocytes to engulf
Disorders associated with the Immune System
Rheumatoid arthritis
: destroys joints
Myasthenia gravi
s: impairs nerve-muscle connections
Human immunodeficiency virus (HIV)
Characterized by severe weight loss, night sweats, and swollen lymph nodes
HIV is transmitted via body fluids: blood, semen, and vaginal secretions
Cripples immune system by interfering
with activity of helper T cells
Multiple sclerosis
: destroys white matter myelin
Hodgkin’s disease
- An acquired immunodeficiency that causes cancer of B cells,
which depresses lymph node cells and thus leads to immunodeficiency
Graves’ disease
: causes hyperthyroidism
Severe combined immunodeficiency (SCID) syndrome
Defective adenosine deaminase enzyme allows accumulation of metabolites
lethal to T cells; fatal if untreated
Treatment
- bone marrow transplants
Genetic defect with marked
deficit in B and T cells
Type 1 diabetes mellitus
: destroys pancreatic cells
Systemic lupus erythematosus
: affects multiple organs
Glomerulonephritis
: damages kidney
Location of Lymphatic organs and their functions
Primary lymphoid organs
Thymus
Extends into mediastinum and partially overlies heart
Functions -
Most active and largest in size during childhood
Stops growing during adolescence, then gradually atrophies
Still produces immunocompetent cells, though more
Bilobed lymphoid organ found in inferior neck
Red Bone Marrow -
blood and immune cells are produced
Secondary lymphoid organs
Spleen
Blood-rich organ about size of fist, located in left side of abdominal cavity
Function
Site of lymphocyte proliferation and immune surveillance and response
Cleanses blood of aged blood cells and platelets
Peyer’s patches
Structurally similar to tonsils
Functions
Destroy bacteria, preventing them from breaching intestinal wall
Generate “memory” lymphocytes
Clusters of lymphoid follicles in wall of distal portion of small intestine
Tonsils
Lingual tonsil
- lumpy collection of follicles at base of tongue
Pharyngeal tonsil -
located in posterior wall of nasopharynx
Palatine tonsils
- at posterior end of oral cavity
Tubal tonsils -
surround openings of auditory tubes into pharynx
Form ring of lymphatic tissue around pharynx; appear as swellings of mucosa
Function
- Gather and remove pathogens in food or air
Appendix
Contains large numbers of lymphoid follicles
Functions
Destroy bacteria, preventing them from breaching intestinal
Generate “memory” lymphocytes
Offshoot of first part of large intestine
Lymph nodes
Principal secondary lymphoid organs of body
Functions
Cleansing the lymph: act as lymph “filters”
Prevent unwanted substances from being delivered to blood
Innate(natural) immune defenses and Adaptive(acquired) immune defenses
Innate immune defense
Nonspecific
Innate defenses do have specific pathways for certain substances
Uses the first and second lines of defense to stop attacks by
pathogens
Adaptive immune defense
Specific defensive system that eliminates almost any
pathogen or abnormal cell in body
Characteristics
Systemic -
Not restricted to initial site
Memory -
Mounts an even stronger attack to “known” antigens
Specific -
Recognizes and targets specific antigens
Humoral response and cellular response
Humoral response
Antibodies, produced by lymphocytes, circulate freely in body fluids
Bind temporarily to target cell
Cellular response
Lymphocytes act against target cell
Directly by killing infected cells
Indirectly by releasing chemicals that enhance inflammatory response; or
activating other lymphocytes or macrophages
T cells provide defense against intracellular antigens
Artificial vs. Naturally acquired immunity and Passive and Active Immunity
Passive immunity
Naturally
Antibodies delivered to fetus via placenta or to infant
through milk
Artificially
Injection of serum, such as gamma globulin
Occurs when ready-made antibodies are introduced into
body
Active immunity
Naturally
Formed in response to
actual bacterial or viral infection
Artificially
Formed in response to
vaccine of dead or attenuated pathogens
Occurs when B cells encounter antigens and produce
specific antibodies against them
Major functions of the Lymphatic & Immune systems
Lymphatic system
Returns fluids leaked from blood vessels back to blood
Circulates ~ 3L interstitial fluid per day
Lymphatic vessels
- elaborate network of drainage vessels
Immune system
Functional system rather than organ system
Defends the body against infection, whilst protecting the body's own cells.
Provides resistance