A&P Ch. 21: Immune System

SPC BSC 2086 Ch 21: Immune System

Immune system

provides resistance to disease

innate, adaptive

Immune system is made up of what two intrinsic systems

Innate (nonspecific)

This defense system constitutes first and second lines of defense

First line of defense

external body membranes (skin and mucosae)

Second line of defense

antimicrobial proteins, phagocytes, and other cells (inhibit spread of invaders; inflammation most important mechanism)

third line of defense

attacks particular foreign substances (takes longer to react than innate); adaptive defense system

functional

Immune system is a _ system rather than organ system

Innate responses

_ release proteins that alert cells of adaptive system to foreign molecules

Innate defenses

_ do have specific pathways for certain substances

is not

innate defense system (is/ is not) antigen specific

B cells

which cells pertain to humoral (liquid) immunity

T cells

which cells pertain to cellular immunity

Keratin

_ is resistant to weak acids and bases, bacterial enzymes, and toxins

chemicals

Skin and mucous membranes produce protective __ that inhibit or destroy microorganisms

Acid mantle

acidity of skin and some mucous secretions inhibits (microbe) growth; called _

lysozyme, enzymes

_ of saliva, respiratory mucus, and lacrimal fluid kills many microorganisms; _ in stomach kill many microorganisms

Mucin

sticky mucus that lines digestive and respiratory tract traps microorganisms

Defensins

antimicrobial peptides that inhibit microbial growth

pattern recognition receptors

Many second-line cells have _that recognize and bind tightly to structures on microbes, disarming them before they do harm

Toll-like receptors (TLRs)

play central role in triggering immune responses

Phagocytes

white blood cells that ingest and digest (eat) foreign invaders

Neutrophils

most abundant phagocytes, but die fighting; become phagocytic on exposure to infectious material

Macrophages

develop from monocytes and are chief phagocytic cells; most robust phagocytic cel

Free macrophages

wander through tissue spaces; example: alveolar macrophages

Fixed macrophages

permanent residents of some organs; examples: stellate macrophages (liver) and microglia (brain)

Phagocytosis

Process starts when phagocyte recognizes and adheres to pathogen’s carbohydrate “signature”

Opsonization

immune system uses antibodies or complement proteins as opsonins that coat pathogens

opsonins

Act as “handles” for phagocytes to grab on to, enhancing phagocytosis

natural killer (NK) cell

Nonphagocytic, large granular lymphocytes that police blood and lymph

apoptosis

natural killer cells kill by inducing _ in cancer cells and virus-infected cells

inflammatory response

Natural killer cells secrete potent chemicals that enhance _

Perforins

_ permeate cell membrane to release contents of the cell

Inflammation

_ is triggered whenever body tissues are injured. can be due to trauma, heat, irritating chemicals, or infections by microorganisms

increase repair

Benefits of inflammation: localizes infection and _ of injured tissues

dilation of blood vessels

Redness & heat due to inflammation happens because of _

nerves

Swelling due to inflammation compresses _ and causes pain

Inflammatory chemical release

first stage of inflammation; Chemicals are released into ECF by injured tissues or immune cells

histamine

_ released by mast cells is key inflammatory chemical attracts macrophages; example of Inflammatory chemical release

Kinins, prostaglandins (PGs), cytokines

inflammaotry mediators that cause vasodilation of local arteries, Make capillaries leaky, and attract phagocytes to the area

Vasodilation and increased vascular permeability

second stage of inflammation; results in local swelling which pushes on nerve endings causing pain

edema

another word for swelling

hyperemia

Vasodilation causes _, congestion with blood, which leads to redness and heat

exudate

increased capillary permeability causes _, fluid containing clotting factors and antibodies, to leak into tissue

prostaglandins and kinins

Pain caused by inflammation can also result from release of toxins from bacteria or released _

edema

Benefits of _; Surge of fluid in tissue sweeps foreign material into lymphatic vessels, Delivers clotting proteins and complement to area

fibrin mesh

Clotting factors form _ that acts as scaffold for repair. Mesh also isolates injured area so invaders cannot spread

Phagocyte mobilization

last stage of inflammation; Neutrophils flood area first; macrophages follow

complement

If inflammation is due to pathogens, _ is activated; adaptive immunity elements arrive

Leukocytosis

step 1 of phagocytosis; release of neutrophils from bone

Margination

step 2 of phagocytosis

cell adhesion molecules (CAMs) , neutrophils

in margination, endothelial cells of capillaries in inflamed area project _ into vessel lumen that grab onto passing _, causing them to slow and roll along, clinging to vessel wall

Diapedesis

step 3 of phagocytosis; neutrophils flatten and squeeze between endothelial cells, moving into interstitial spaces

Chemotaxis

step 4 of phagocytosis; WBCs are drawn to an area of inflammation

monocytes

“late-arrivers” replace dying neutrophils and remain for cleanup prior to repair

macrophages

12 hours after leaving bloodstream, monocytes are transformed into _

Attacking microorganisms or hindering reproduction

Antimicrobial proteins enhance innate defense by _

Interferons

antimicrobial proteins that prevents replication of the virus

Complement proteins

antimicrobial proteins activated by antigen-antibody complexes and some microoranisms directly, enhanced cell lysis, phagocytosis and inflammation

Fever

Abnormally high body temperature that is systemic response to invading microorganisms

pyrogens

during fever, Leukocytes and macrophages exposed to foreign substances secrete _

Pyrogens

_ act on body’s thermostat in hypothalamus, raising body temperature

iron and zinc

fever causes liver and spleen to sequester _

increases, increases

fever _ metabolic rate, which _ rate of repair

Adaptive immune system

specific defensive system that eliminates almost any pathogen or abnormal cell in body

amplifies

Adaptive immune system _ inflammatory response and activates complement

adaptive immune system

recognizes and targets specific antigens responsible for determining which lymphocyte cell or cells will eventually become activated

systemic

adaptive immune system is _: not restricted to initial site

memory

adaptive immune system has _: mounts an even stronger attack to “known” antigens

extracellular

Humoral immunity has _ targets

Humoral immunity

Antibodies, produced by lymphocytes, circulate freely in body fluids

B cells

Does humoral immunity deal with T cells or B cells

T cells

Does cellular immunity deal with T cells or B cells

Antigens

substances that can mobilize adaptive defenses and provoke an immune response

hapten (incomplete)

antigens can be complete or _

external surface

Antigens are present of the _ of the cells

red bone marrow

where do both T and B lymphocytes originate

origin

first step in lymphocyte development, maturation, and activation

Maturation

second step in lymphocyte development, maturation, and activation

primary lymphoid organs

Lymphocytes are “educated” in a 2-3 day process and mature in _

Immunocompetence

lymphocytes must be able to recognize only 1 specific antigen; a reason that lymphocytes are “educated”

Self-tolerance

lymphocytes must be unresponsive to own antigens; one reason why lymphocytes must be educated

Seeding secondary lymphoid organs and circulation

Exported from primary lymphoid organs to “seed” secondary lymphoid organs.

second step in lymphocyte development, maturation, and activation

third step in lymphocyte development, maturation, and activation

antigen encounter and activation

fourth step in lymphocyte development, maturation, and activation

antigen encounter and activation

when a lymphocytes antigen receptors bind its antigens, that lymphocytes can be activated

proliferation and differentiation

fifth step in lymphocyte development, maturation, and activation

proliferation and differentiation

activated lymphocytes multiply and then differentiate into effector and memory cells

antigen presenting cells (APCs)

Engulf antigens and present fragments of antigens to T cells for recognition

dendrites, macrophages, B cells

types of antigen presenting cells (APCs)

Dendritic cells

Phagocytize pathogens that enter tissues, then enter lymphatics to present antigens to T cells in lymph node

connective tissues and epidermis

Where are dendritic cells found

connective tissue and lymphoid organs

where are macrophages found?

macrophages

Present antigens to T cells, which not only activates T cell, but also further

activates this type of cell

macrophage

this type of cell can trigger powerful inflammatory responses and recruit additional defenses

B cells

Present antigens to helper T cell to assist their own activation; Do not activate naive T cells

B cells

_ are activated when antigens bind to surface receptors, cross-linking them

plasma cells

Secrete specific antibodies at rate of 2000 molecules per second for 4 to 5 days, then die

memory cells

Clone cells that do not become plasma cells become _

memory cells

Mount an immediate response to future exposures to same antigen; Provide immunological memory

Primary immune response

cell proliferation and differentiation upon exposure to antigen for the first time