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What is the function of the thymus?
Produces thymosins (hormones) which stimulate lymphocyte stem cell division and T cell maturation
Functions of the spleen
Same job for blood that lymph nodes do for lymph
Removes abnormal red blood cells and other blood components by phagocytosis
Stores iron from recycled blood cells
Initiates immune response by B and T cells in response to antigens in blood
Which WBCs are Agranulocytes?
Lymphocytes and Monocytes
Which WBCs are granulocytes?
Neutrophils, Basophils, and Eosinophils
Organize the WBC in order of prevalence
Neutrophils(50-70%), Lymphocytes(20-40%), Monocytes(2-8%), Eosinophils (2-4%), Basophils (<1%)
Main functions of Eosinophils
Attack large parasites & antigen coated pathogens
Sensitive to allergens
Control inflammation
Main function of basophils
Accumulate in damaged tissues
Release Histamine -> dilates blood vessels
Release Heparin -> prevents blood clotting
Main functions of Neutrophils
First to attack -> phagocytize pathogens & form pus
Granules contain lysosomal enzymes and bactericides (Hydrogen peroxide & superoxide)
Main functions of Lymphocytes
Migrate in and out of blood (mostly in connective tissues and lymphoid organs)
Specific defense system -> T cells: Cell mediated immunity, B cells: hormonal immunity & synthesize antibodies, NK cels: detect and destroy abnormal tissues (cancers etc.)
Main functions of monocytes
Enter peripheral tissues and become macrophages
Engulf large particles and pathogens
Secrete substances that affect immune system cells and fibroblasts to injured area
What WBCs are phagocytes
Neutrophils and monocytes
What are the 3 functions of the lymphatic system?
1- Immunity
2- Return fluids and solutes to blood
3- Distribute hormones, nutrients, and waste produces from their tissues of origin to the general circulation
What are the two main branches of immunity?
1- Innate (nonspecific) immunity (present at birth and does not distinguish)
2- Adaptive (specific immunity
What are the 7 non specific immunity categories
physical barriers, phagocytes, immune surveillance by NK cells, Interferons, complement, inflammation, fever
Steps of how NK cells target and exert their immune effect
1) NK cell adheres to target cell
2) Golgi apparatus realigns near target cell & perforins (proteins) are produced
3) Perforins are released from NK cell to target cell
4) Perforins create pores in target cells membrane (target cell death)
Explain classical pathway of complement action
most rapid and effective complement activation method
- Antibodies bind to bacterial cell wall
- C1 (complement) must attach to two antibodies for its activation
- C3a diffuses away and activates an inflammatory response
- Activation and cascade
- C3b attachment: C3b binds to bacterial surface and enhances phagocytosis
- Membrane attack complex (MAC) destroys integrity of target cell
Explain alternative pathway of complement action
slower and less effective, occurs in absence of antibody molecules
- Complement proteins interact in plasma (properdin, factor B, factor D)
- C3a activates an inflammatory response
- C3b binds to bacterial surface and enhances phagocytosis
- Membrane attack complex (MAC) destroys integrity of target cell
What are the three results of complement activation
1- Milling of pathogen by cell lysis (MAC)
2- Enhanced phagocytosis (opsonization)
3- Inflammation (histamine release)
What kind of immunity is achieved by vaccines
Artificially induced active immunity
Active immunity
Exposure to antigen
Naturally acquired (antigens in environment)
Artificially acquired (exposure in clinical setting)
Passive Immunity
receiving antibodies
Naturally acquired (maternal antibody transfer to fetus or baby)
Artificially induced (administration of antibodies to a patient)
What are the Four properties of adaptive immunity
Specificity, Versatility, Memory, Tolerance
Explain specificity
B and T cells only have receptors for one specific antigen
Explain Versatility
Millions of lymphocytes, each sensitive to a different antigen and able to produce clones
Explain Memory
Activated lymphocytes produce two groups of cells, one that attack immediately, and memory cells that remain inactive unless exposed to same antigen later
Explain tolerance
ignores self and targets non self (abnormal or foreign cells/toxins). Can develop over time
List the four types of T cells
Cytotoxic T cells, Helper T cells, Memory T cells, Regulatory T cells
What do cytotoxic T cells do
attack foreign cells or body cells infected by viruses commonly by direct contact. Primary cells involved in production of cell-mediated immunity (cellular immunity)
What do helper T cells do
stimulate activation and function of T and B cells. Activated B cells before B cells can produce antibodies
What do regulatory T cells do
AKA suppressor T cells. Moderate immunity by inhibiting T and B cell activity, establish and control sensitivity of immune response
What do memory T cells do?
Respond to antigens they have already encountered. “remember” invaders to fight them off in future
Explain how helper T cells assist with the immune response
· Activating B cells to produce antibodies.
· Stimulating cytotoxic T cells to kill infected cells.
· Enhancing macrophage activity to clear pathogens.
· Coordinating the overall immune response by releasing cytokines.
· Establishing immune memory for faster responses in future infections
Class I Major histocompatibility complex proteins (MHC)
Present in membranes of all nucleated cells, Triggered by viral or bacterial infection of a body cell. “hey im an abnormal cell please destroy me”
Class II MHC proteins
Present in membranes of antigen- presenting cells (APCs). Phagocytic cells engulfs pathogenic material and processes the antigens for presentation; antigen processing. “This is a dangerous antigen floating around, get rid of it”
Process of Class I MHC antigen presentation
1- Viral or bacterial infection of a cell triggers antigen presentation by Class 1 MHC proteins
2- The infection results in the appearance of abnormal peptides in the cytoplasm
3- The endoplasmic reticulum produces Class 1 MHC proteins to which the abnormal peptides are attached
4- After export to the Golgi apparatus, The MCH proteins with their bound abnormal peptides are transported to the plasma membrane
The abnormal peptides are displayed by class 1 MHC proteins on the plasma membrane
Process of antigen presentation by APCs (class II MHC)
1- Phagocytic APCs engulf the extracellular pathogens
2- Lysosomal action produces antigenic fragments
3- The endoplasmic reticulum produces class II MCH proteins
4- Antigenic fragments are bound to class II MHC proteins
5- Antigenic fragments are displayed by class II MHC proteins on the plasma membrane
Explain how B cells become fully activated
- Full activation requires helper T cell
· This prevents inappropriate activation
· Helper T cell must have been activated by exposure to the same antigen
· Helper T cell binds to MHC (Class II) complex of sensitized B cell
· Secretes cytokines to promote B cell activation
Basic configuration of IGs
2 parallel pairs of polypeptide chains, one light and one heavy, each pair contains consistent segments and variable segments
List all 5 Igs
IgG, IgE, IgD, IgA, IgM
what does IgG do
responsible for resistance against many viruses, bacteria, and bacterial toxins
What does IgE do
attaches to basophil and mast cell surface (accelerates inflammation in presence of antigens)
What does IgD do?
on B cell surface, where it binds antigens in extracellular fluid, also plays a role in B cell sensitization
what does IgM do?
first class of antibody secreted after antigen encountered (production declines as IgG production increases)
What does IgA do?
attack primarily before pathogens gain internal access ( found primarily in glandular secretions, such as mucus, tears, saliva, and semen
What is antigenic determination site?
Formed when a specific antibody molecule binds to its corresponding antigen molecule. Binds to specific portions of the exposed surface called antigenic determinant sites on an antigen
List the 7 functions of antigen- antibody complexes
Neutralization of antigen-binding sites
Precipitation and agglutination: formation of immune complex
Activation of complement
Attraction of phagocytes
Opsonization: increasing phagocyte efficiency
Stimulation of inflammation
Prevention of bacterial and viral adhesion.
What do lymphocytes respond to?
Antigens
The attraction or repulsion of certain cells to chemicals in their environment is called
Chemotaxis
Lymphatic vessels are located everywhere but
CNS
Compared to blood capillaries, lymph capillaries
Have no basement membrane
are larger in diameter
have walls of endothelial cells that overlap
are frequently irregular in shape
What do beta cells of the pancreatic islets produce?
Insulin which lowers Blood sugar
What hormone promotes glucose formation in the liver
Cortisol
what are Eicosanoids synthesized from?
Arachidonic acid
Results of thyroid hormones
Thyroid hormones are responsible for increasing cellular metabolism. Therefore, they elevate rates of oxygen consumption and energy consumption, increase heat generation, and assist in the normal development of the skeletal, muscular, and nervous systems in children.
Amino Acid derivatives
Thyroid hormones, Catecholamines, Tryptophan derivatives
Lipid derivative
Eicosanoids, steroid hormones