A&P exam 2

Lymphatic system functions

Defends against pathogens & internal threats

Aids in fat absorption

Lymph

Fluid that transports lymphocytes

Lymphocytes

sensitive to specific antigens (cell identifiers)

Types: T cells, B cells, NK cells

Foreign antigens initiate…

An immune response

T cells

Responsible for cel mediated immunity

Types of T cells

CD8 cells, CD4 cells, suppressor T cells

CD8 cells

Attacks foreign/infected body cells

CD4 cells

Stimulates T and B cells, helps control immune response sensitivity

Suppressor T cells

Inhibits T and B cells, helps control immune response sensitivity

B cells

responsible for antibody-mediated immunity

can differentiate into plasma cells when stimulated

plasma cells

produces/secretes antibodies\

Antibody activity peaks 2 weeks after exposure

NK cells

responsible for immunological surveillance

Attacks foreign cells, infected body cells, and cancer cells

lymphatic capillaries marks…

the beginning of the lymphatic system

lymphatic capillaries

endothelial cells overlap, creating one way valves

allows entry of water/solutes/small proteins/cell debris/pathogens

lymphatic vessels

Network of tubes that transport lymph from peripheral tissues to venous system

travels w/ arteries and veins

Lymphatic vessels resemble veins by having:

Tunica externa/media/interna

valves to prevent backflow

Primary lymphatic structures function

Involved in formation/maturation of lymphocytes

Primary lymphatic structures

Red bone marrow, thymus gland

Red bone marrow

location of lymphoid stem cells

site of B cell maturation

Thymus gland

Site of T cell maturation

Diminishes w/age

Secondary lymphatic structures functions

Houses lymphocytes/other immune cells

Where immune responses are initiated

Secondary lymphatic structures

Lymph nodules (Tonsils, MALT)

Lymph organs (lymph nodes, spleen)

Lymph nodules

egg shaped clusters of lymphatic cells w/ some extracellular matrix

lacks capsule

3 tonsil areas:

Pharyngeal, Lingual, Palatine

Pharyngeal tonsil is located at…

Roof and posterior wall of nasopharynx

Palatine tonsil is located at…

Both sides of the back of the throat—lateral walls of the oropharynx

Lingual tonsil is located at…

The very back of the tongue, right before the throat begins

MALT

In the walls of GI, respiratory, urinary, and reproductive tracks (mucosal membranes)

How lymph organs differentiate from lymph nodules

lymph organs are separated from surrounding tissues by a fibrous capsule

lymph nodes

small, detects pathogens before they reach vital organs

locations of lymph nodes

cervical/axillary/inguinal regions + cavities

Spleen

largest lymphatic organ

filters blood

Stores RBCs/platelets

destroys old/defective RBCs/platelets and destroys pathogens

Right lymphatic duct

receives lymph from RIGHT head/neck/thorax/arm

Thoracid duct

Receives lymph from rest of body (whatever right lymphatic duct doesn’t cover)

Lymphatic trunk

Vessels that receive lymph from many efferent lymph vessels

Afferent lymph vessels lead into a…

lymph node

How is fluid forced into a lymph capillary?

Tissue hydrostatic pressure

Where is lymph formed?

In the capillaries from excess fluid in the tissues

Where does lymph enter the blood?

Subclavian veins

Nonspecific defense is also known as..

Innate immunity

Nonspecific defense

Immediate response

Does not distinguish threats from each other

Responds the same to all threats

1st line of defense

Epithelium, hair, exocrine secretions, normal flora

Exocrine secretions contain…

acids, enzymes, and antibodies to destroy pathogens

Phagocytes

White blood cells

Engulfs pathogens/debris

Types of phagocytes

Neutrophils, Monocytes/macrophages, dendritic cells

Neutrophils

attacks once

Monocytes/macrophages

Can attack multiple times

Dendritic cells

Type of monocyte found in mucus/epidermis

Can attack multiple times

Functional characteristics of phagocytes

Diapedesis

chemotaxis

Has receptors to attach to target’s surface

Phagocytes destroy pathogens by..

Engulfing it

breaking it down w/ digestive enzymes

Presenting antigen to lymphocytes (turns it into specific defense)

Chemotaxis

Movement in response to chemical message

Positive=towards message

Negative=away from message

Diapedesis

ability to squeeze between endothelial cells

Nonspecific immunity does not involve..

Antibodies, No cellular memory

Immunological Surveillance (nonspecific)

Destruction of abnormal/infected cells by NK cells

Common defense against cancer cells

NK cells release cytotoxic chemicals called..

Perforins, granzymes

Perforins

Attaches to target’s membrane and creates large pores

Granzymes

Enters cell and initiates apoptosis

How NK cells recognize cancer cells

They usually contain unusual proteins= tumor-specific antigens, that NK cells can recognize

Interferons (nonspecific)

Chemical messengers that coordinate defenses against viral infections

Functions of Interferons (nonspecific)

Attracts/stimulates NK cells

Stimulates macrophage activity

Enhances viral infection resistance

Interferons are released from…

Activated lymphocytes

Activated macrophages

Virus infected cells

Complement (nonspecific)

group of plasma proteins that assist antibodies in destroying pathogens

Activated complement proteins cause…

Opsonization

Inflammation

Cytolysis

Elimination of immune complexes

Opsonization

Binds pathogen to enhance phagocytosis

Inflammation

Activates basophils/mast cells to promote inflammation, and attract phagocytes (releases histamine)

Cytolysis

inserts membrane attack complex, fluid rushes in, causes lysis

How elimination of immune complexes works

Attaches antigen-antibody complex to RBCs to hitch ride to liver/spleen for removal

Inflammatory response (nonspecific)

Localized response bringing more fluid/proteins/immune cells to damaged area

Promotes formation of extra lymph at damaged area by increasing tissue hydrostatic pressure

Releases Mast cells/Basophils

Mast cells, Basophils release… (inflammatory response)

Histamine, Chemotactic factor

Histamine

Causes vasodilation

Increased capillary permeability

Activation of Kinins

Chemotactic factor

Attracts other Leukocytes

Kinins

Causes Vasodilation

Increased capillary permeability

Increases production of cell-adhesion molecules

Stimulates pain receptors

Fever functions

Inhibits bacteria/viruses

Promotes interferon activity

Increases lymphocyte activity

Accelerates tissue repair

How fevers happen

Immune cells release pyrogens

Pyrogens

Proteins that stimulate temperature control center in hypothalamus to raise set point

Specific defense is also known as

Adaptive immunity

Specific defense is…

3rd Line of defense

Delayed response to specific antigens (coordinated by B and T cells)

Acquired immunity (develops in a way that’s not hereditary)

Passive immunity

Antibodies transferred from external source

Effective immediately

can last days to weeks

Types of passive and active immunity

Naturally acquired, artificially acquired

Naturally acquired passive immunity

Passing antibodies from mother to child (placenta/breast milk)

Artificially acquired passive immunity

Antibodies administered to combat infection (antivenom)

Active immunity

Antibodies developed in response to antigen exposure

Lasts months to a lifetime

Takes 5-14 days after exposure to become effective

Naturally acquired active immunity

Develops after exposure to antigens in environment ( immunity after sickness)

Artificially acquired active immunity

Development after administration of an antigen (Vaccines)

Antibodies (immunoglobins)

Small proteins that bind foreign antigens and trigger an immune response

Antigenic determinant (epitope)

Region of antigen that an antibody binds with

Constant region

Forms base of an antibody

Fc (stem) region

Determines function/classification of an antibody

Neutralization (specific)

Antibodies bind w/ sites on pathogen-prevents them from binding w/ body cells

Agglutination (specific)

Clumps foreign cells together

Precipitation (specific)

clumps foreign antigens together

Complement fixation (specific)

Fc region of antibody attaches to complement proteins to activate the complement system

Opsonization (specific)

Fc region of antibody attracts/aids phagocytes

Activation of NK cells (specific)

Fc region of antibody binds NK cells to stimulate release of cytotoxic chemicals

How Specific immunity kills cells

Neutralization

Agglutination

Precipitation

Complement fixation

Opsonization

Activation of NK cells

IgG antibodies

80% of all antibodies

IgG antibodies functions

Neutralization, Agglutination, Precipitation, Opsonization, Activates NK cells, Complement fixation

IgG antibodies Locations

Plasma, Lymph, Cerebrospinal fluid, serous fluid, breast milk

IgM antibodies

First class of antibody secreted after antigen is encountered

IgM concentration declines as IgG production increases

IgM antibodies Functions

Neutralization, Agglutination, Complement fixation