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Flashcards in Lymphatic System Deck (58)

lymphatic capillaries

microscopic, closed-ended tubes, parallel the networks of the blood capillaries.

squamous epithelial tissues (endothelium) - thin walls allow tissue fluid from interstitial space to enter lymphatic capillaries.

leads to lymphatic vessels


lymphatic vessels

similar to veins, but thinner.

3 layers: endothelial lining, middle layer of smooth muscle and elastic fiber, and outer layer of connective tissue.

have semilunar valves which prevent backflow of lymph.

leads to lymph nodes.


lymphatic trunk

after leaving lymph nodes, vessels merge into larger lymphatic trunks.

drain lymph from the lymphatic vessels, named for the region they serve (lumbar = lower limbs, lower abdominal


collecting ducts - thoracic & lymphatic

trunks join one of the two collecting ducts: thoracic & right lymphatic.

thoracic is longer and larger of the two
right lymphatic



a lymphatic capillary that absorbs dietary fats in the villi of the small intestine.


bronchomediastinal & intercostal trunk

drains lymph from portions of the thorax


intestinal trunk

drains lymph from abdominal viscera


jugular trunk

drains lymph from neck & head


lumbar trunk

drains lymph from from lower limbs


subclavian trunk

drains lymph from upper limb


R & L subclavian veins + R & L internal jugular veins

once lymph has been cleaned through lymph system, they are returned to the blood through these veins


Relationship between tissue fluid and lymph

lymph is tissue fluid which has entered a lymphatic capillary


4 forces which account for the flow of lymph through the lymphatic system

o Fluid that contains water and dissolved substances leaves bloodstream in the capillary bed via diffusion & filtration

o Proteins cause osmotic pressure in interstitial space to increase, resulting in the flow from the blood capillaries to the interstitial space.

o This results in an increase of hydrostatic pressure in the interstitial space since water always moves to an area of greater osmotic pressure.

o Increasing interstitial (hydrostatic) pressure forces fluid into the lymphatic capillaries.


Explain how lymph flow can be obstructed and state the consequences of lymphatic obstruction

edema caused by surgical removal of portions of the lymphatic system, or blockage by parasites.


lymph node structure and function: afferent lymphatic vessel

lymphatic vessels LEADING to a node


lymph node structure and function: efferent lymphatic vessel

lymphatic vessels LEAVING the node



encloses the lymph node (kind of like a cell wall) and sends extensions called trabeculae into the node to separate it into compartments



superficial region located deep to the capsule and consists of compartments containing germinal centers and sinuses


germinal center / nodules


also called nodules, are dense masses of lymphocytes and macrophages in the compartments of a lymph node that constitute the functional units of the node



indented region in a bean-shaped node




central portion of the lymph node



complex network of chambers and channels in the compartments of a lymph node though which lymph circulates as it passes through the node


identify the major lymph node groups or chains on diagrams

o Cervical region: (chin area) – associated with lymphatic vessels that drain the skin of the scalp and face, as well as tissues of the nasal cavity and pharynx

o Axillary region: UNDERARM receive lymph from vessels that drain the upper limbs, the wall of the thorax, the mammary glands (breasts) and upper wall of the abdomen

o Supratrochlear region: ELBOW AREA - superficially on medial side of elbow. Large in children in response to infections acquired through cuts & scrapes on hands.

o Inguinal: GROIN AREA - receive lymph from lower limbs, external genitalia, lower abdominal wall

o Pelvic cavity: PELVIC AREA (above inguinal)- follow iliac blood vessels – receive lymph from vessels of pelvic viscera

o Abdominal cavity: ABDOMINAL AREA - form chains along mesenteric arteries and abdominal aorta. Receive lymph from abdominal viscera

o Thoracic cavity: UPPER CHEST AREA - in mediastinum and along trachea and bronchi. Receive lymph from thoracic viscera and from internal wall of the thorax


name the major organs of the lymphatic system, state their location and function

lymph nodes - in groups or chains along the paths of larger lymphatic vessels, filter foreign particles and debris from lymph; produce and house lymphocytes that destroy foreign particles and in lymph; house macrophages that engulf and destroy foreign particles and cellular debris carried in lymph

thymus - in mediastinum superior to heart, houses lymphocytes; differentiates thymocytes into T lymphocytes

spleen - upper left portion of abdominal cavity, to the side (lateral) and posterior to stomach; blood reservoir houses macrophages that remove foreign particles, damaged red blood cells, and cellular debris from the blood. contains lymphocytes


distinguish between specific and nonspecific defense mechanisms

nonspecific - protect against many types of pathogens, attacks all the same

specific - protects against particular pathogens and are responsible for the type of resistance called immunity


6 nonspecific defense mechanisms: species resistance

species resistance - species is resistant to certain diseases that other species are susceptible (ex, humans can get measles, gonorrhea, syphilis, but not animals)


6 nonspecific defense mechanisms: mechanical barrier

mechanical barrier - unbroken skin and mucous membranes prevent the entrance of some infectious agents. fluids wash away before they can firmly attach to tissues


6 nonspecific defense mechanisms: chemical barrier

chemical barrier - enzymes in various body fluids kill pathogens. gastric juice (low pH from HCl), tears (lysozyme, destroys bacteria), interferons (blocks replication of viruses), defensins (damage bacterial cell walls and membranes), collectins (grab onto microbes), and complement (stimulates inflammation, attracts phagocytes, enhances phagocytosis).


6 nonspecific defense mechanisms: natural killer cells

natural killer cells - distinct type of lymphocyte that secrets perforins that lyse virus-infected cells and cancer cells


6 nonspecific defense mechanisms: inflammation

inflammation - tissue response to injury that prevents the spread of infectious agents into nearby tissues


6 nonspecific defense mechanisms: phagocytosis

phagocytosis - neutrophils, monocytes, macrophages engulf & destroy foreign particles and cells


6 nonspecific defense mechanisms: fever

fever - elevated body temp inhibits microbial growth and increases phagocytic activity


origin, site of differentiation, location and function of T-lymphocytes

Origin: Stem cells in red bone marrow give rise to lymphocyte precursors.

Site of differentiation: Precursors go to the thymus, where they are processed to become T cells.

Primary location: lymphatic tissues; 70-80% of circulating lymphocytes in blood

Primary function: provide CELLULAR immune response in which T cells interact *directly* with the antigen-bearing agents to destroy them


origin, site of differentiation, location and function of B-lymphocytes

Origin: Red bone marrow

Site of differentiation: some lymphocyte precursors are processed within the bone marrow to become B cells.

Primary location: lymphatic tissue; 20-30% of circulating lymphocytes in blood

Primary functions: provide HUMORAL immune response in which B cells interact *indirectly*, producing antibodies that destroy antigens or antigen bearing agents


IgG location, function

plasma & tissue fluid; defends against bacteria, viruses, and toxins; activates complement


IgA location, function

exocrine gland secretions, defends against bacteria and viruses



plasma; reacts with antigens on some red blood cell membranes following mismatched blood transfusions; activates complement



surface of most B-cells, functions in B cell activation



exocrine gland secretions; promotes inflammation and allergic reactions


discuss the ways that antibodies act: direct attack


agglutination: antigens clump
precipitation: antigens become insoluble
neutralization: antigens lose toxic properties


discuss the ways that antibodies act: activation of complement (antibodies combined with antigens)


opsonization: alters antigen cell membranes so cells are more susceptible to phagocytosis

chemotaxis: attracts macrophages and neutrophils into the region

agglutination: clumping of antigen-bearing cells

lysis: rapid movement of water and ions into foreign cell causing osmotic rupture of foreign cells

neutralization: altering molecular structure of viruses, making them harmless


discuss the ways that antibodies act: localized changes

inflammation - helps prevent the spread of antigens


b cell function

divides repeatedly, expanding its clones, uses cytokines from T cells to proliferate

B cells differentiate further into plasma cells which secrete antibodies (or immunoglobins) which combine w/ antigens on the pathogen and react against it


helper T cell function

specialized T cell which becomes activated when its antigen receptor combines with displayed foreign antigen. once activated, stimulates B cells to produce antibodies specific for the displayed antigen


macrophage function

phagocytizes a bacterium, digesting it in its lysosomes. baterial antigens exit the lysosomes and move to the macrophages surface.


T cells function

recognizes whether antigens are foreign or self; attack directly (cellular), activates B cells (which activate macrophages)


cytotoxic cell function

recognizes and combines with nonself antigens that cancerous cells display on their surfaces near certain MHC proteins. cytokines (secretions) from helper T cells activate cytotoxic T cell, which makes it proliferate, enlarging its clone of cells. bind to the surfaces of antigen bearing cells, where they release perforin which cuts porelike openings, destroying the cells


memory cell function (dormant cell)

provide future immune protection. once activated (from exposure to antigen), it immediately divides and differentiates into a cytotoxic T cell.


mast cell function

produce biochemicals (histamines) that cause the changes associated with inflammation (vasodilation and edema)


primary vs secondary immune response

primary: when B cells or T cells **first** encounter an antigen for which they are specialized to react. during this response, antibodies are produced for several weeks - Later, some remain dormant (memory cells)

Secondary immune response: occurs rapidly if antigen is encountered later because memory cells are present. if identical antigen is encountered in the future, clones of memory cells enlarge


4 major types of immunity: naturally acquired active immunity

mechanism: exposure to live pathogens
result: stimulation of an immune response with symptoms of a disease

you get the disease, and you develop immunity


4 major types of immunity: artificially acquired active immunity

mechanism: exposure to vacine containing weakened or dead pathogens or their components

result: stimulation of an immune response without the symptoms of a disease


4 major types of immunity: artificially acquired passive immunity

mechanism: injection of gamma globulin containing antibodies or antitoxin

result: short-term immunity without stimulating immune response


4 major types of immunity: naturally acquired passive immunity

mechanisms: antibodies passed to fetus from pregnant woman with active immunity or to newborn through breast milk from women with active immunity

result: short-term immunity for newborn without stimulating immune response


immunological changes that take place during an allergic reaction

immune response to a nonharmful substance (hypersensitive)

type 1 - anaphylactic - immediate reaction: overproduced IgE antibodies in response to certain allergens. causes severe inflammation and hives, hay fever, asthma, exzema, or gastric disturbances.
- 1st exposure sensitizes B cells, subsequent exposure causes allergic reactions

Takes 1 -3 hrs to develop
Type 2 - antibody dependent cytotoxic reactions - antigen binds to cell, stimulating phagocytosis and complement-mediated lysis of antigen. transfusion reaction to mismatched blood.

Type 3 - immune complex reactions - phagocytosis and lysis cannot clear widespread antigen antibody complexes from circulation, which blocks small vessels and damages tissues they reach

Type 4 - Delayed reaction allergy: common household or industrial chemicals or cosmetics - foreign substances activate T cells in skin, T cells and macrophages release chemical factors that cause eruptions and inflammation of the skin (dermatitis) (takes 48 hrs)


immunological changes that take place during a tissue rejection reaction

when you have a transplant and your body rejects the tissue and tries to destroy it. transplanted tissue may also produce molecules that harm the recipients tissue - graft-vs-host-disease


immunological changes that take place during autoimmune disease

failure to distinguish self from nonself, producing antibodies called autoantibodies. cytotoxic T cells attack and damage body's tissues and organs


4 different transplant types and example of each

types of grafts:
isograpft: from identical twin - bone marrow
autograft: taken from elsewhere in person's body - skin
allograft: tissue from someone who is not a twin - kidney
xenograft: from different species - pig heart valve