Chapter 20- The Lynphatic System And Immunity Flashcards
What does the immune system do? What is it composed of?
Works to defend the body against internal/external threats
Consists of cells and proteins located in the blood and tissues of other systems like the lymphatic— leukocytes and immune proteins located in the plasma
What is the lymphatic system? What does it consist of?
Group of organs and tissues that work with the immune system and participate in a number of functions
Consists of lymphatic vessels and lymphatic tissues and organs
What are lymphatic vessels?
A system of blind-ended tubes
What are lymphatic tissues and organs?
Clusters of lymphoid follicles like tonsils, lymph nodes, spleen and thymus
Functions of the lymphatic system
Regulation of interstitial fluid volume
Absorption of dietary fats
Immune functions
What is lymph?
Fluid that exits the extra cellular space and enters the lymphatic vessels
What happens to excess fluids in the extra cellular space?
It is picked up by the lymphatic vessels, transported through the body and returned to the cardiovascular system
Lymphatic circulation
Lymph is collected in vessels called lymph-collecting vessels which merge and form larger vessels called lymph trunks
How many lymph trunks drain from specific body regions?
Nine
What is the cisterns chyli?
Large, swollen vessel that the intestinal and lumbar trunks drain into
Two ducts that the cisterns chyli and other lymph trunks drain into
Thoracic duct
Right lymphatic duct
Where does lymph drain into the blood of the low pressure venous circuit?
Subclavian veins
What assist lymph in being transported against gravity?
Valves
Contracting skeletal muscles
Smooth muscle in the walls of lymph-collecting vessels
What are the lymphatic capillaries?
Where lymphatic vessels begin
Surround blood capillary beds
Blind-ended, one way system
Are the cells of lymphatic capillaries tightly joined? Why?
No, they are able to flap open and closed allowing large volumes of fluid to enter the lymphatic capillaries
What happens when the pressure in the IF decreases?
Endothelial cells flap shut
Lymphatic system precisely controls the amount of fluid between our cells
What are lymph nodes?
Cluster of lymphoid organs along lymphatic vessels.
Limit the spread of pathogens throughout the body by acting as filters
What is reticular tissue?
Predominant type of tissue of lymphatic system.
Loose connective tissue contains specialized cells and reticular fibers that form nets to trap pathogens
What is mucosa-associated lymphatic tissue? (MALT)
Loosely organized clusters of lymphoid tissue that protects mucous membranes.
Where is specialized MALT found?
Tonsils
Prayers Patches
appendix
Where are specific clusters of lymph nodes located?
Under the arms- axillary
In the neck- cervical
In the groin- inguinal
In the abdominal cavity- me sent Eric
What are the small lymphatic vesselsncalled that lymph flows through before moving through the reticular network?
Afterward lymphatic vessels
Which vessels does lymph flow through after is has been filtered of pathogens?
Efferent lymphatic vessels
What is the function of the lymph nodes?
To trap 90% of pathogens in lymph and prevent them from being delivered to the blood where they could spread to other tissues
What is the largest lymphoid organ that protects the body from pathogens that have entered the blood?
The spleen
Two-lobed organ that secretes hormones to generate T cells capable of protecting the body from pathogens
Thymus
What is the body’s first line of defense?
Surface barriers
Cutaneous and mucous membranes
What is the body’s second line of defense?
Innate immunity
Responds to all pathogens the same way using antimicrobial proteins
Exist in the blood even in the absence of a stimulus
What is the body’s third line of defense?
Adaptive immunity
Respond to specific antigens and form memory of them for the future
3-5 days to mount a response but then will be the dominant response
Why is adaptive immunity slower that innate immunity?
One must be exposed to an antigen before the body can develop an immune response
What are the two arms of adaptive immunity?
Cell-mediated immunity- Two types of T cells
Antibody-mediated immunity- B cells and antibodies
Surface barriers in the first line of defense
Cutaneous (skin) membrane
Mucous membranes
Products they secrete
What are Phagocytes
Cells that can eat foreign or damaged cells
Many cells of the immune system can function as them
What are Natural Killer cells and where are they located?
Located in the blood and spleen
Function in innate immunity
Main role is to activate the T cells of adaptive immunity
Can identify cancer cells but not specific antigens
Secrete antimicrobial cytokines to activate macrophages
What are cytokines?
Molecules used for signaling cell to cell communication
Communication about initiating an immune response or triggering cell movement to specific areas of the body
Tumor necrosis factor
Interferons
Interleukins
What is opsonization?
Foreign particles are marked for phagocytosis
Tags infected cells and identifies pathogens with the same antigens
What is chemotaxis?
Attraction and movement of macrophages to a chemical signal
Think of a taxi, transporting macrophages
What is agglutination?
Uses antibodies to bind pathogens together so that immune cells can attack and weaken them as a group
Protein components of the immune system
Antibodies
Complement system
Cytokines
Lymphoid organs where B cells, T cells and macrophages reside
Lymph nodes
MALT
Spleen
How do lymphoid organs and tissues trap pathogens?
Reticular fibers in lymphoid tissues form nets that trap pathogens so that leukocytes can access them easier
What are Dendritic cells and what do they do?
Most important antigen presenting cells
Can identify threats and act as messengers for the rest of the immune system by antigen presentation
Act as a bridge btw the adaptive and innate immune systems
Activate B and T cells
Two main components of innate immunity involved in rapid response?
Complement proteins and a variety of cytokines and several types of cells including neutrophils, macrophages and NK cells
What are complement proteins?
Plasma proteins that can be activated directly by pathogens or by pathogen bound antibodies leading to the complement cascade of reactions on the surface of pathogens
Main effects include: cell lysis, formation of membrane attack complex, enhanced inflammation, neutralization if viruses, enhancing phagocytosis, opsonization and clearance of immune complexes
What are the two types of cells of innate immunity?
Phagocytes and non-phagocytic cells
What are the different types of phagocytes involved in innate immunity?
Macrophages
Neutrophils
Eosinophils
Dendritic cells
Process by which cells ingest particles and other cells
Phagocytosis
Types of non-phagocytic cells of innate immunity
NK cells
Basophils
What are two basic stages of the inflammatory response?
1) release of inflammatory mediator and the cardinal signs of inflammation
2) the phagocytosis response
Basic process of the inflammatory response
Tissue damage initiates response
Activated complement proteins trigger the release of inflammatory mediators such as basophils and mast cells— act as mediators themselves
Injured area becomes red and swollen, feels warm and hurts
What are some inflammatory mediators?
Histamine Serotonin Cytokines Bradykinin Prostaglandins Leukotrienes
4 cardinal signs of inflammation
What are they caused by?
Redness
Heat
Swelling
Pain
Caused by: vasodilation, increased capillary permeability, occurrence of pain, recruitment of other cells (chemotaxis)
What is margination?
When inflammatory mediators make the capillary endothelium in the damaged area sticky so neutrophils adhere to the capillary wall
What is diapedesis?
When inflammatory mediators increase capillary permeability so neutrophils can squeeze between endothelial cells into the damaged tissue
What are the steps of the phagocyte response?
1) local macrophages activated. Neutrophils migrate to damaged tissue and phagocytize bacteria
2) margination occurs and neutrophils enter damaged tissue by diapedesis and begin to destroy bacteria and other cellular debris
3) monocytes migrate to the area and become macrophages which phagocytize pathogens
4) bone marrow increases production of leukocytes leading to leukocytosis
What is fever? How does it occur?
Body temperature above the normal range
A person with fever is referred to as febrile
An innate response to cellular injury that is initiated when pyrogens are released from damaged cells or certain bacteria
Classes of T cells involved in cell-mediated immunity. What do they respond to?
Helper T cells (Th)
Cytotoxic T cells (Tc)
Respond to cells infected with intracellular pathogens (viruses and bacteria)
Where are T cells formed and matured?
Formed in the bone marrow but migrate to and mature in the thymus
What is a clone?
Antigen that each population of T cells can respond to
What does it mean to be immunocompetent?
Able to mount a normal response to foreign antigens
What is self-tolerance?
When self-reactive T cells are destroyed, it ensures that T cells will be prevented from attacking self cells
What are major histocompatibility complex molecules (MHCs)?
Pieces of antigen bound to glycoproteins
Major determinants of compatibility among tissue and organ donors/recipients
Two types of MHC molecules
Class I MHC molecules
Class II MHC molecules
Class I MHC molecules
Found in surface of plasma membrane.
Present endogenous antigens (those synthesized in the cell).
Cytotoxic T cells generally only interact with class I MHCs
Class II MHC molecules
Found only on the surface of antigen presenting cells.
Present exogenous antigens (those the cell takes in by phagocytosis).
Helper T cells generally interact with class II MHCs
Role of helper T cells
Secrete cytokines that activate and enhance versions components of the immune response
Role of cytotoxic T cells
Cytotoxic effects
Kill cells with foreign antigens bound to class I MHC molecules critical for detection of cancer cells
What is perforin?
Released by Tc cells
Forms pores in the target cells plasma membrane
Three phases of antibody-mediated immunity?
1) B cell clone recognizes its specific antigen which triggers it to secrete antibodies
2) antibody levels rise dramatically
3) persistence of B cells that react more rapidly and efficiently if the antigen is encountered again
What are antibodies
Action component of antibody-mediated immunity
Responsible for its actions or effects on mediating the destruction of antigens to which they bind
What two populations do B cells differentiate into?
Plasma cells- secrete antibodies
Memory B cells- respond to antigens upon a second exposure
what is Precipitation?
Similar to agglutination but involves soluble antigens instead of whole cells
What is neutralization?
Antibodies bind to things like viruses and bacteria and prevent them from interacting with our cells, rendering them inactive
What is complement activation?
Several antibodies (IgM and IgG) bind and activate the complement proteins of innate immunity.
When antibodies bind a cell, their complement binding site is exposed. Allows complement to activate and lose the foreign cell with its membrane attack complex
What are the two types of antibody-mediated immunity?
Active and passive
What is active immunity?
The body’s cells actively respond to an antigen.
Results in the production of memory cells and a large number of antibodies which makes it long lasting
What is passive immunity?
When preformed antibodies are passed from one organism to another
Short lived
Three types of immune system disorders
Hypersensitivity disorder
Immunodeficiency disorder
Autoimmune disorder
What is hypersensitivity?
Immune system may overreact and damage tissues
Type 1: Allergies
Type 2: Reactions to antibiotics
What are the five classes of antibodies?
IgG IgA IgM IgE IgD
What is IgG?
Monomer
Makes up majority of antibodies
Only antibody that can cross the placenta
Functions in opsonization, neutralization and complement fixation
Greatly enhances phagocytosis
What is IgA?
Dimer
Found in secretions like saliva and breastmilk
Functions in agglutination and neutralization
What is IgM?
Pentamer
First antibody secreted on exposure to an antigen
Most potent agglutination and precipitating agent
Functions in complement fixation
What is IgE?
Monomer
Binds mast cells and basophils and triggers their degranulation, facilitating inflammation, particularly in the allergic response
What is IgD?
Monomer
Antibody found exclusively on the surface of B cells
Has a role in B cell sensitization and activation
What is stimulation of inflammation?
IgE directly triggers inflammation by initiating the release of inflammatory mediators from mast cells and basophils
What is the primary immune response?
4-5 day lag phase as B cells reproduce and split into plasma cells and memory cells and secrete antibodies.
Antibody levels peak 7-14 days after exposure
Future exposure to the same antigen results in the activation of memory B cells formed during primary immune response
Primary antibody involved is IgM
What is the secondary immune response?
When memory B cells encounter the antigen for which they are specific
Primary antibody involved is IgG
Antibodies are more effective in secondary response
What are immunodeficiency disorders?
Decrease in function of one or more components of the immune system.
Primary: genetic
Secondary:through infection, trauma, cancer and some meds
Primary Immunodeficiency Disorders
Impair either innate or adaptive immunity.
Most common dysfunctions involve deficient complement proteins or abnormalities in phagocytes
Secondary Immunodeficiency Disorders
Many are induced artificially to combat cancers
Most common is virally induced AIDS
Three phases of HIV
Acute
Chronic
Final
