A&P Lecture Exam II

lymphatic system

this system functions to transport and house lymphocytes and other immune cells, and return excess tissue fluid to blood to maintain blood volume

lymph

the components of ___ are water, dissolved solutes, a small amt. of protein, sometimes cell debris, pathogens, cancer cells, B & T lymphocytes, + lymphoid macrophages

lymphatic capillaries

small, closed-ended vessels interspersed around most blood capillaries; absent in avascular tissues, red marrow, spleen, and CNS; walls have overlapping endothelial cells (1-way mini valves) and anchoring filaments to hold endothelial cells to nearby structures

lymphatic capillaries, lymphatic collecting vessels, lymphatic trunks, lymphatic ducts

path of lymph back to the heart

(use commas and spaces between, also “lymphatic” before each)

valves

these prevent pooling and backflow of lymph

pumps

skeletal muscle and respiratory are both types of ___ to help move lymph

lymphatic trunks

fed by lymphatic (collecting) vessels, include jugular, subclavian, broncho-mediastinal, intestinal, and lumbar

lymphatic ducts

fed by lymphatic trunks: have two: right and thoracic

primary lymphatic structures

involved in formation and maturation of lymphocytes, red bone marrow and thymus

secondary lymphatic structures

do not form lymphocytes, but house them and other immune cells

sites of immune response initiation and include lymph nodes, spleen, tonsils, and lymphatic nodules, also include MALT

red bone marrow

located between the trabeculae of spongy bone (in flat bones of the skull, ribs, sternum, vertebrae, ossa coxae, heads of humerus, and femur

also the site of hemopoiesis

hemopoiesis

production of blood’s formed elements, t-lymphocytes migrate to thymus to complete maturation

thymus

causes t-cell maturation

larger in children than adults

• grows until puberty, then regresses; gradually replaced by adipose tissue

lymphatic organs

have a complete capsule of dense irregular CT (spleen, lymph nodes)

lymphatic structures

have incomplete capsule or lack one (tonsils, MALT, diffuse lymphatic nodules)

lymph nodes

filter lymph, remove unwanted substances

components:

• afferent lymphatic vessels

• efferent lymphatic vessel

  • cortex that contains lymphatic nodules

lymphatic nodules

within lymph nodes, contain germinal centers

• site of dividing B lymphocytes and some macrophages

• mantle zone contains t-lymphocytes, macrophages, dendritic cells

also contain cortical sinuses

• connective tissue fibers that support B-lymphocytes, T-lymphocytes, and macrophages

• medullary sinuses: tiny open channels lined with macrophages

spleen

the largest lymphatic organ surrounded by connective tissue capsule

• surrounded by connective tissue capsule

• trabeculae divide spleen into red and white pulp

  • eat foreign particles, clear defective erythrocytes and platelets, store erythrocytes and platelets

white pulp

the tissue of the spleen: T & B lymphocytes & macrophages (monitor blood)

red pulp

the tissue of the spleen: storage site for erythrocytes and platelets, macrophages phagocytize bacteria and debris

tonsils

immune surveillance of inhaled/ingested substances, have tonsillar crypts and lymphatic nodules with germinal

tonsillar crypt

invaginations that trap material

tonsils

types of ___ include pharyngeal, palatine, and lingual

lymphatic nodules

clusters of lymphatic cells with some extracellular matrix, scattered nodules called “diffuse lymphatic tissue,” (found in every body organ), in some areas, group to form larger structures (MALT)

MALT

located in GI, resp, genital, and urinary tracts

prominent in small intestines, especially ileum

peyer patches

peyer patches

large collections of lymphatic nodules that form bulges in ileum wall

immune system

• protects us from infectious agents & harmful substances

• composed of numerous cellular and molecular structures

  • function together to provide immunity

pathogenic agents

can damage or kill a host, major categories:

• bacteria

• viruses

• fungi

• protozoans

• multicellular parasites

  • prions

leukocytes

formed in red bone marrow prior to circulating in the blood

innate immunity

• non-specific

• present at birth

• doesn’t require prior exposure

• protects against a variety of different substances (nonspecific)

  • includes barriers of skin and mucosal membranes, nonspecific cellular and molecular internal defenses

adaptive immunity

• specific

• acquired

• heightened + hastened

• involves specific T and B lymphocytes

• a particular cell responds to one foreign substance but not another

• memory cells (faster more effective response)

innate immunity

responds nonspecifically to a range of harmful substances

1st line of defense

innate immunity, skin and mucosal membrane - EXTERNAL

2nd line of defense

innate immunity, cellular defenses (neutrophils, macrophages, dendritic cells, etc.), chemicals such as interferon and complement, physiological processes such as inflammation and fever -INTERNAL

neutrophils and macrophages

undergo phagocytosis - initiate respiratory burst

antigen presenting cells

macrophages and dendritic cells

• antigens are presented on APC surface to T-lymphocytes

basophils and mast cells

release histamine and heparin

• cause vasodilation and increase cap permeability

  • chemicals attract immune cells (chemotactic)

NK cells

destroy a variety of unwanted cells

• virus and bacteria-infected cells, tumor cells, cells of transplanted tissue

  • release cytotoxic chemicals perforin and granzymes

eosinophils

attack multicellular parasites

• participate in immune responses of allergy and asthma

  • engage in phagocytosis of antigen-antibody complexes

interferons

impede viral spread

• INF-y produced by t-lymphocytes and NK cells

  • stimulates macrophages to destroy virus-infected cells

• INF-a & INF-B produced by leukocytes and virus-infected cells

  • bind to neighboring cells and prevent their infection

    • trigger synthesis of enzymes that destroy viral nucleic acids, inhibit synthesis of viral proteins

  • stimulate NK cells to destroy virus-infected cells

complement system

group of over 30 plasma proteins

• 2 types of complement activation

  • classical pathway - requires antibody to attach to foreign substance

  • alternative pathway - complement binds to wall of bacterial or fungus

opsonization, inflammation, cytolysis, elimination of immune complexes

inflammation

an immediate response to ward off unwanted substances

• local, nonspecific response of vascularized tissue to injury

cell-adhesion molecules

these cause leukocyte adhesion

margination

1st step: adherence of leukocytes to endothelial CAMs

diapedesis

2nd step: cells escape blood vessel walls

chemotaxis

3rd step: leukocytes migrate toward

• macrophages may release pyrogens (fever-induces molecules)

kinins

stimulate pain receptors, increase cap perm., increase CAMs

cell-mediated

branch of adaptive immunity involving cytotoxic T-lymphocytes

humoral

branch of immunity involving B-lymphocytes, plasma cells, & antibodies

antigen

substance that binds a T-lymphocyte or antibody

• usually a protein or large polysaccharide

• examples

  • protein capsid of viruses

  • cell wall of bacteria/fungi

  • bacterial toxins

• distinguish self vs non-self

  • in autoimmune, attacks self

antigenic determinants

aka epitope

• specific site on antigen recognized by immune system

haptens

small foreign molecules that induce immune response when attached to a carrier molecule (e.g., toxin in poison ivy)

CD4 cells

helper T-lymphocytes are these types of cells

• assist in cell-mediated, humoral, and innate immunity

• interact with MHC class II molecules (found on APCs)

CD8 cells

cytotoxic T-cells are these types of cells

• directly kill cells

• interact with MHC class I molecules (all nucleated cells)

MHC I

• glycoproteins

• continuously synthesized and modified by rough ER, then inserted into cell membrane

  • display fragments of proteins that were bound in RER

    • in healthy cells, immune system recognizes endogenous antigens as self and ignores them

    • if fragments are from an infectious agent, immune systems considers as non-self

      • cytotoxic T-cells recognize and attempt to destroy cell

MHC II

• glycoproteins

• displayed on professional APCs

• synthesized and modified by RER, sent to membrane

• exogenous antigens brought into cell through phagocytosis

• fragments loaded onto MCH class II and embedded in plasma membrane

  • provides means of communicating with helper Ts

antigen challenge

first encounter between antigen and lymphocyte

• usually occurs in secondary lymphatic structures

  • antigen in blood taken to spleen

  • antigen penetrating skin transported to lymph node

  • antigen from respiratory, GI, urogenital tracts, in tonsils, or MALT

clonal selection

once activated, “specific” clones are produced

• all cells have same TCR or BCR that matches specific antigen

IL-2

this released from helper-T cells activates cytotoxic t-cells

apoptosis

programmed cell death

helper T-lymphocytes

regulate cells of adaptive and innate immunity

cytotoxic t-lymphocytes

destroy unhealthy cells by apoptosis

plasma cells

produce antibodies

cytokines

help activate B-lymphocytes, activate cytotoxic t-lymphocytes with cytokines, and stimulate activity of innate system cells

cytotoxic t-lymphocytes

activated and memory cytotoxic t-cells migrate to infection site to destroy infected cells that display the antigen

• after recognizing antigen, cytotoxic t-cell releases granules containing perforin and granzymes (cytotoxic chemicals)

• perforin forms channel in target cell membrane

• granzyme enter channel and induce death by apoptosis

plasma cells

these cells synthesize and release antibodies

• cells remain in lymph nodes

• produce millions of antibodies during 5-day life span

  • antibodies circulate through lymph and blood until encountering antigen

  • antibody titer: circulating blood concentration of antibody against specific antigen

antibody titer

circulating blood concentration of antibody against a specific antigen

antibodies

immunoglobulins produced B-cells

• tag pathogens for destruction

• good defense against viruses, bacteria, toxins, yeast spores

  • Y shaped

  • binding site at ends of arms

  • 5 classes are madge

neutralization

antibody physically covers antigenic determinant of pathogen

agglutination

clumping of cells, antibody cross-links antigens of foreign cells causing clumping

precipitation

antibody cross-links circulating antigens (e.g., viral particles)

forms antigen-antibody complex that becomes insoluble and precipitates

complement fixation

fc region of IgG and IgM can bind complement for activation

opsonization

• more likely target cell will be seen by phagocytic cells

• some phagocytes have receptors for Fc regions

  • snicker doodles or grease pig

active immunity

• results from direct encounter with pathogen

• occurs naturally by direct exposure to antigen

• can occur artificially through exposure through vaccine

• memory cells against specific antigen are formed

passive immunity

• obtained from another individual

  • natural and artificial

natural passive immunity

arises from transfer of antibodies from mother to fetus (through placenta or milk)

artificial passive immunity

occurs when serum containing antibodies transferred from one person to another

acute hypersensitivities

allergy

• occurs within seconds

• overreaction of immune system to a noninfectious substance, allergen

  • pollen, latex, peanuts

• may cause symptoms such as runny nose, watery eyes, vomiting, diarrhea, etc.

subacute hypersensitivities

occurs within 1-3 hours, involve humoral immunity

delayed hypersensitivities

occur 1-3 days (cell-mediated immunity)

bacteria

single-celled prokaryotes

• small, 1-2 um, cell with both a membrane and cell wall

• varied types - spherical (cocci), rodlike (bacilli), coiled (spirilla)

• most are harmless, but some virulent

virus

pieces of DNA or RNA in a protein shell

• not cells, much smaller

• only about 1/100 of a micrometer

• obligate intracellular parasites

  • must enter cell to reproduce

  • direct infected cell to make copies of nucleic acid and capsid (shell)

  • may kill host cell

fungi

eukaryotic cells with membrane and cell wall

• include molds, yeasts, multicellular fungi that produce spores

• release proteolytic enzymes including inflammation

• cause superficial diseases in the integument

  • can infect mucosal linings or cause internal infections

protozoans

eukaryotic cells without a cell wall

• intracellular and extracellular parasites

  • malaria, trichomoniasis

prions

fragments of infectious proteins

perfusion

delivery of blood per time per gram of tissue

arteries

carry blood away from the heart

veins

carry blood back to the heart

capillaries

sites of gas and nutrient exchange

great vessels

pulmonary trunk, aorta, superior and inferior vena cava, pulmonary veins

semilunar valves

open to allow blood to flow through the heart; close to prevent backflow

pulmonary circulation

carries deoxygenated blood from right side of heart to lungs

• blood vessels return blood to left side of heart

systemic circulation

moves oxygenated blood from left side of heart to systemic cells

at systemic cells (skin, muscles), blood exchanges gases, nutrients, and wastes

thoracic cavity

between lungs in mediastinum, base, apex

pericardium

sac around the heart

fibrous pericardium

outermost covering of heart

• dense irregular CT

• anchors heart and prevents it overfilling

serous pericardium

2 layers (pericardium)

• parietal layer - attaches to fibrous pericardium

• visceral layer - attaches directly to heart

coronary sulcus

separates atria from ventricles

• groove extending around circumference of heart

interventricular sulcus

separate left from right ventricles

ventricles

have thicker walls than atria

• pumping chambers