Flashcards in Lymphatic System Deck (58)
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
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.
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
a lymphatic capillary that absorbs dietary fats in the villi of the small intestine.
bronchomediastinal & intercostal trunk
drains lymph from portions of the thorax
drains lymph from abdominal viscera
drains lymph from neck & head
drains lymph from from lower limbs
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
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