A+P 2 Unit 3 Exam Prep

what is lymph propelled by?

skeletal muscle, breathing, nearby artery pulsations, smooth muscle wall contractions

primary lymphoid structures

red bone marrow, thymus

secondary lymphoid structures

spleen, tonsils, lymph nodes, MALT

lymphatic trunks

formed by union of largest collecting vessels; drain to large areas of body

jugular trunks drain

head and neck

subclavian trunks drain

arms, breast tissue, superficial thoracic wall

bronchomediastinal trunks drain

deep thoracic structures

intestinal trunk drains

most abdominal structures

lumbar trunks drain

lower limbs and pelvis

cisterna chyli

enlarged sac where the thoracic duct starts

lymphangitis

lymphatic vessels appear as painful red lines under the skin due to infection or inflammation of larger lymphatic vessels

primary lymphoid organs

areas where immune cells are produced and mature

red bone marrow purpose and location

produces red and white blood cells; found in flat bones and long bones

thymus purpose and location

has endocrine and immune function, trains and develops T cells; located in the mediastinum above the heart

regions of the thymus

fibrous capsule with trabeculae (protective outer layer of CT), cortex (made up of thymocytes that mature into T cells; eliminates weak T cells), medulla (network of reticular cells; responsible for eliminating T cells that have autoimmune tendencies)

secondary lymphoid structures

areas where mature immune cells circulate and patrol for foreign invaders

spleen purpose

processes dying RBCs, stores platelets and monocytes, acts as blood filter

red pulp

phagocytosis of bacteria in blood, phagocytosis of dying/defective RBCs, iron and hemoglobin recycling, blood reservoir and storage site for RBCs and platelets

white pulp

phagocytosis of bacteria in blood, immune response to infection

how does blood flow into spleen?

splenic artery

central artery

a division of the splenic artery surrounded by B cells, T cells, and RBCs

if spleen is removed, what organs take over its functions?

liver and bone marrow

what do lymph nodes do?

filter lymph and house WBCs

how does lymph flow into a lymph node?

via multiple afferent lymphatic vessels

how does lymph flow out of a lymph node?

through one efferent lymphatic vessel

capsule

thick layer of dense irregular CT that covers the node

trabeculae

extensions of the capsule that divide the node into compartments

cortex contains

lymphoid nodules with germinal centers with B cells and macrophages, mantle zone with T cells, macrophages, and dendritic cells, and cortical sinus lined with macrophages

medulla contains

strands of CT fibers called medullary cords that support B and T cells and macrophages

buboes

inflamed, tender lymph nodes caused by infections or cancer cell entrapment

appendix purpose

as a child, activates mature B cells; as an adult, harbors healthy gut bacteria

MALT

secondary lymphoid structures made up of a diffuse system of small concentrations of lymphoid tissue associated with mucosae

lymphoid nodules

small clusters of immune cells surrounded by small ECM but no capsule; found in all human tissues

tonsils purpose

gather and remove pathogens in food or air

peyer’s patches

clusters of lymphoid follicles in wall of distal portion of small intestine

peyer’s patches purpose

destroy bacteria and prevent them from breaching intestinal wall; help generate lymphocytes that remember pathogens

prions

type of protein that can trigger normal proteins to fold abnormally

haptens

small molecules that when combined with a larger carrier molecule, can elicit an immune response

cytokines

chemicals that interact with receptors on cell surface

cytokines types

interleukins, interferons, tumor necrosis factors, and colony stimulating factors

first line of defense

external body membranes (skin and mucous membranes)

how does skin protect?

commensal microbiota, epidermis, dermis, sebaceous gland secretions, sweat gland secretions

how do mucous membranes protect?

commensal microbiota, mucous, cilia, epithelium, connective tissue

second line of defense

antimicrobial proteins, phagocytes, other immune cells

second line of defense symptoms

fever, inflammation, cellular defenses, antimicrobial proteins and chemicals

antimicrobial proteins purpose

attack microorganisms directly or by hindering their ability to reproduce

interferons

proteins released by cells infected by viruses

interferons purpose

enter neighboring cells, stimulating them to produce proteins that block viral reproduction and protect them from infection; activate NK cells to destroy virus-infected cells via apoptosis

complement system

includes 20 proteins that circulate in blood and recognize pathogens by directly binding or binding to antibodies on the pathogen

MAC complex

initiates cytolysis by forming a protein pore in the microbe’s plasma membrane and fluid rushing into the cell causing it to burst

pattern recognition receptors recognize

non-self antigens and infectious agents

toll-like receptors recognize

a particular class of microbe

MHC proteins allow

an antigen to be presented on a cell’s surface

MHC class 1 proteins

found on almost all nucleated body cells with a fragment of a protein/antigen

MHC class 2 proteins

found on antigen-presenting cells and hold foreign antigens; allow innate immune cells to talk to adaptive immune system

third line of defense

adaptive immune system - specific, systemic, memory

humoral immunity

antibody-mediated

antigenic determinants (epitopes)

specific part of the antigen that is recognized by an antibody

antibody composition

several proteins assembled together by disulfide bonds into an arm region, hinge region, and stem region, with two heavy chains and two light chains

variable region

where antigen binds; specific to each epitope on antigen surface

constant region

region that stay constant no matter what antigen it’s binding

IgM

in blood plasma, B-cell surface receptor; first antibody produced in immune response

IgA

external secretions; neutralization in mucous membranes

IgD

in B-cell surface receptor; identifies epitope and gets B cells ready for activation to make more antibodies

IgG

in body fluids; immune response in tissues, used for passive immunity, activates NK cells, longest-lasting immunity

IgE

in blood; produced during allergic reaction, produced due to parasitic infection, activates mast cells and basophils, attracts eosinophils

neutralization

block sites on pathogens or toxins to prevent them from binding to our cells

agglutination

grab on to more than one foreign antigen at a time, creating clumps; antibody cross-links whole cells

precipitation

like agglutination, but with molecules instead of whole cells; antibody cross-links circulating particles

complement activation

activation of complement proteins for assembly into membrane attack complex for cell lysis; amplifies immune response

activation of NK cells

Fc region of antibody binds to an NK cell, triggering release of cytotoxic chemicals

opsonization

Fc region of antibody binds to receptors of phagocytic cells, triggering phagocytosis

cell-mediated immunity

mediated by cells and targets cells

lymphocyte formation

T cells that pass thymus test will lose either CD4 or CD8 receptors

lymphocyte selection

lymphocytes that do their jobs well survive, others are killed

lymphocyte positive selection

in cortex of thymus, tests to see if pre-T cell binds to an MHC molecule on a thymic cell; cells that pass survive to undergo negative selection

lymphocyte negative selection

in medulla of thymus, tests whether pre-T cell binds to a self antigen on a dendritic cell

selective loss of CD4 or CD8 protein

the cells that survive differentiate into either a CD4 T cell or CD8 T cell by selectively losing one of the surface proteins

lymphocyte migration

selected cells move to secondary lymphoid structures where encounter real-world antigens

lymphocyte activation

physical contact between lymphocyte and antigen, lines that are successful are cloned

CD8 T-cell activation

foreign antigen interacts with MHC class 1 molecule

CD4 T-cell activation

foreign antigen interacts with MHC class 2 molecules; produces Il-2 (activates CD8 T-cells) and IL-4 (activates B-cells)

B-cell activation

free antigen binds to a B-cell receptor and other receptors; some memory B-cells and others become plasma cells

lymphocyte effector response

how lymphocytes kill foreign invaders

CD4 T-cell effector response 

migrate to infection site and release IL-2 to regulate innate and adaptive immune cells at infection site

CD8 T-cell effector response

migrate to infection site and destroy infected cells by inducing apoptosis

B-cell effector response

differentiate into plasma cells that stay in lymph nodes and produce antibodies against antigens

naturally acquired active immunity

formed in response to actual bacterial or viral infection

artificially acquired active immunity

formed in response to a vaccine or dead or weakened pathogens

naturally acquired passive immunity

antibodies delivered to fetus via placenta or to infant through milk

artificially acquired passive immunity

injection of serum