Immunology and the Lymphatic System Flashcards
What is the function of the lymphatic system? (3)
Drains excess interstitial fluid from fluid spaces and returns it to the blood
Transports dietary lipids and lipid soluble vitamins that are absorbed by the GI tract
Carries out immune response, using highly specific responses directed against particular microbes or abnormal cells
What does the lymphatic system contain? (2)
Lymph (moving fluid)
Lymphatics (group of vessels)
What are the two main branches of the lymphatic system?
Right lymphatic duct
Thoracic duct
What is lymph? (4)
Clear, watery fluid
Results from fluid exiting circulation (3000 ml circulating daily)
Is similar to interstitial fluid, is isotonic to it. Usually contains more proteins
Most comes from the liver and small intestines
What are the lymphatic vessels? (3)
The originate as lymphatic capillaries
The lie side by side of the blood capillaries (Thinner, have more valves, have nodes)
Contines to merge to form major ducts
What area of the body does the right lymphatic duct cover?
The upper right quadrant of the body
What area of the body does the thoracic duct cover?
The rest of the body
What is the function of the lymphatic vessels?
Permits particulate matter that cannot be absorbed into the capillary to be removed from the interstitial space
How does the lymphatic fluid move? (2)
It moves uphill
It is usually attributed to muscular movement
What are lymph nodes?
They have several lymph vessels entering into this ‘filter’ and they have one vessel leaving
What is the function of lymph nodes? (2)
Defence (filtration and phagocytosis)
Hematopiesis (site of maturation of some cells)
What is the immune system?
It is a system that uses many mechanisms to ensure the integrity and survival of the internal environment
What are the two major catergories of the immune system?
Non-specific immunity
Specific immunity
In the immune system, what does non-specific (innate) immunity do?
The external physical and chemical barriers provided by the skin and mucous membranes
In the immune system, what does specific immunity do? (2)
Recognizes specific threatening agents
Slow to recognize targets and overcome the threat (especially first time exposure)
What are the four cells used in non-specific immunity?
Neutrophils
Monocytes
Macrophages
Natural killer (NK) cells
What are the two lymphocytic cells used in specific immunity?
T-cells
B-cells
In non-specific immunity, what does it mean to be species resistant?
Genetic characteristics to protect the body from certain pathogens
What are mechanical and chemical barriers in non-specific immunity? (2)
Skin & mucosa
Secretions
How does the skin and mucosa aid in non-specific immunity?
A continuous wall that separates the internal environment from the external environment
How do secretions aid in non-specific immunity?
Sebum, mucus and enzymes chemically inhibit the activity of pathogens
How does inflammation help in non-specific immunity?
It is an attempt to dispose of microbes, toxins or foreign material at the site of injury, to prevent their spread to other tissues and to prepare the site for tissue repair in an attempt to restore tissue homeostasis
How do neutrophils help with phagocytosis in non-specific immunity?
The granular leukocytes that are usually the first phaocytic cell to arrive due to the inflammatory response
How do macrophages help with phagocytosis in non-specific immunity?
Monocytes that have enlarged to become phagocytic cells (may be called by other names when found in specific tissues)
How do natural killer cells help with non-specific immunity?
They are a group of lymphocytes that kill different types of cancer cells and virus infected cells
How does interferon aid with non-specific immunity?
Proteins produced by cells after they become infected by a virus which inhibits further spread of the viral infection
What is the complement when talking non-specific immunity?
Plasma proteins that produce a cascade of chemical reactions that cause lysis of foreign cells
What is specific immunity?
It attacks specific agents that the body recognizes as not itself
How is specific immunity controlled?
By lymphocytes (a class of WBC)
Where are lymphocytes formed?
In the red bone marrow cells of the fetus from the hematopoietic stem cells
What is the function of B lymphocytes (B cells)?
Produced antibodies (antibody-mediated immunity)
What is the function of T lymphocytes (T cells)
Direct attack of pathogens (cell-mediated immunity)
What are the three lines of defence in the immune system?
First line of defence
Second line of defence
Third line of defence
What is included in the first line of immune defence? (2)
Mechanical barriers
Chemical barriers
What is included in the second line of immune defence? (2)
Inflammation response
Phagocytosis
What is included in the third line of immune defence?
Specific immune response
Natural killer cells
What are antigens? (2)
A substance that introduced to the body that induces the formation of anitbodies
Usually macromolecules located in the membranes of microorganisms or the outer coats of viruses
What are antigenic determinatnts? (2)
Variously shaped, small regions on the surface of the antigen molecule (epitope)
Each kind of antigen has specific and uniquely shaped epitopes
What are combining sites? (3)
Two small concave regions on the surface of the antibody
Like epitopes, have specific and unique shapes
Shaped to allow the epitope of the antigen fit into it and thereby bind to form antigen-antibody complex
What is a clone?
A descendant of a cell
What is a complement?
A group of proteins that work together to destroy foreign cells
What are inactive B cells? (2)
Produced in the yolk sac, then the red marrow or the fetal liver
Circulated to the lymph nodes and spleen
What are active B cells? (4)
When an inactive B cell encounters a specific antigen
This binding triggers a series of mitotic divisions producing clones of B cells
The clones can differentiate into plasma cells and secrete antibodies
Others remain in the lymphatic system as memory cells and will become plasma cells if introduced to the antigen at another time
What are antibodies?
Proteins of the immunoglobulin family
What are antibodies made of?
Large molecules composed of long chains of amino acids (polypeptides)
How many polypeptide chains are in an antibody?
Four
2 heavy
2 light
What shape do the four polypeptide chains take?
A Y shaped appearance
What are the five classes of antibodies?
IgM
IgG
IgA
IgE
IgD
What is an IgM antibody? (2)
It is produced by immature B cells and inserted into plasma membranes
It is the predominate antibody produced after initial contact with an antigen
What is an IgG antibody? (3)
Most abundant circulating antibody (75%)
Predominate in a secondary exposure
Cross the placenta barrier to provide natural passive immunity
What is an IgA antibody?
It is found in the mucous membrane, in saliva and tears
What is an IgE antibody? (2)
It is minor in amount
Can produce major effects (allergies)
What is an IgD antibody?
Found in blood in small amounts (function unknown)
What is a complement of antibodies? (3)
They are a component of blood plasma
They are inactive enzymes that are activated in a definitive sequence to catalyst a series of reactions
Various complement proteins may produce other reactions
What are the two functions of the lymphatic system?
Maintain fluid balance
Immunity
What are the four main types of antimicrobial substances?
Interferons
Complement
Iron-binding proteins
Antimicrobial proteins
What produces interferons? (3)
Lymphocytes
Macrophages
Fibroblasts infected with viruses
What is the function of interferons (IFN)? (3)
Once released by virus-infected cells, IFN’s diffuse to uninfected neighbouring cells
They induce synthesis of antiviral proteins that interfere with viral replication
They do not prevent viruses from attaching and penetrating to host cells, they stop replication
What is the complement system? (2)
A group of normally inactive proteins in blood plasma and on plasma membranes
When activated, these proteins complement certain immune reactions
What are iron-binding proteins?
They inhibit the growth of certain bacteria by reducing the amount of available iron
What are phagocytes?
Specialized cells that perform phagocytosis, the ingestion of microbes or other particles such as cell debris
What are two major types of phagocytes?
Neutrophils
Macrophages
What are the five phases of phagocytosis?
Chemotaxis
Adherence
Ingestion
Digestion
Killing
What are the three stages of inflammatory response?
Vasodilation and increased permeability of blood vessels
Emigration/movement of phagocytes from the blood into interstitial fluid
Tissue repair
What are five other aspects of inflammatory response?
Histamine Kinins Prostaglandins Leukotrienes Complement
What is histamine?
In response to injury, mast cells in connective tissue and basophils and platelets in blood release histamine. Neutrophils and macrophages attracted to the site of injury also stimulate the release of histamine, which causes vasodilation and increased permeability of blood vessels
What are kinins?
These polypeptides, formed in blood from inactive precursors called kininogens, induce vasodilation and incrased permeability and serve as chemotactic agents for phagocytes
What are prostaglandins?
These lipids, especially those of the E series, are released by damaged cells and intensify the effects of histamine and kinins. Prostaglandins also may stimulate the emigration of phagocytes through capillary walls
What are leukotrienes?
Produced by basophils and mast cells, leukotrienes cause increased permeability; they also function in adherence of phagocytes to pathogens and as chemotactic agents that attract phagocytes
What is complement?
Different components of the complement system stimulate histamine release, attract neutrophils by chemotaxis, and promote phagocytosis; some components can also destroy bacteria
What is increased permeability?
Means that substances normally retained in blood are permitted to pass from the blood vessels
What does antigen mean?
Antibody generator
Where do B cells mature?
Red bone marrow
Where do T cells mature?
Thymus
What is immunocompetence?
Before B-cells or T-cells leave their maturation area, they develop immunocompetence which is the ability to carry out adaptive immune responses.
What are cytokines?
Small proteins hormones that stimulate or inhibit many normal cell functions, such as cell growth and differentiation
What is a granzyme?
It is a protein-digesting enzyme that triggers apoptosis
What are five actions of antibodies?
Neutralizing antigen Immobilizing bacteria Agglutinating and precipitating antigen Activating complement Enhancing phagocytosis
What is a neutralizing agent?
The reaction of an antibody with antigen blocks or neutralizes some bacterial toxins and prevents attachment of some viruses to body cells
What is an immobilizing bacteria?
If antibodies form against antigens on the cilia or flagella of motile bacteria, the antigen-antibody reaction may cause the bacteria to lose their motility, which limits their spread to nearby tissues
What is an agglutinating and precipitating antigen?
Because antibodies have two or more sites for binding to an antigen, the antigen-antibody reaction may cross-link pathogens to one another causing agglutination.
What is agglutination?
The clumping together
What is an activating complement?
Antigen-antibody complexes initiate the classical pathway of the complement system
What is enhancing phagocytosis?
The stem region of an antibody acts as a flag that attracts phagocytes once antigens have bound to the antibodies variable region
