lymphatic and immune Flashcards
what are the functions of the lymphatic system?
- fluid recovery: filters blood capillaries into the tissue spaces (back to venous circulation)
- Immunity: excess filtered fluid picks up foreign cells and chemicals from tissues
- lipid absorption: lacteals in small intestine absorb dietary lipid that aren’t absorbed by blood capillaries
what is lymph?
the recovered fluid
what is lymphatic tissue?
composed of aggregates of lymphocytes and macrophages that populate many organs in the body
what is lymphatic vessels?
transport the lymph
what do lymphatic organs do?
defense cells especially concentrated in these organs
what is lymph?
- clear, colorless fluid, similar to plasma, much less protein
- originally ecf
what are the layer of the lymphatic vessels?
-tunica interna: endothelium and valves
-tunica media: elastic fibers, smooth muscle
-tunica externa: thin outer layer
what are lymphatic capillaries?
- they penetrate tissues
- contain a one-way valve
- made of endothelial cells
what are the 2 collecting ducts that make up lymphatic vessels?
- right lymphatic duct: lymph from right arm to right subclavian
- thoracic duct: lymph from diaphragm to left subclavian
what is the flow of lymph?
- moved along by rhythmic contractions of lymphatic vessels
- flow aided by skeletal muscle pump
- arterial pulsation rhythmically squeezes lymphatic vessels
- thoracic pump aids flow from abdominal to thoracic cavity
what are the different types of lymphatic cells? what do they do?
- natural killer: attack and destroy bacteria
- T cells: mature in thymus
- B cells: proliferation and differentiation into plasma produce antibodies
- dendritic: into APCs, alert immune system
- reticular cells: contribute to stroma
- macrophages: phagocytic, into monocytes
what are the types of lymphatic tissue?
- diffuse lymphatic tissue: scattered, in body passages, open to exterior, MALT
- lymphatic nodules: dense masses of lymphocytes and macrophages
what are aggregated lymphoid nodules?
dense clusters in the ileum, the distal portion of the small intestine
what are the 2 types of lymphatic organs?
- primary lymphatic organs: where T and B cells became immunocompetent (RBM and thymus)
- secondary lymphatic organs: immunocompetent, (lymph nodes, tonsils and spleen)
what do lymph nodes do?
- cleanse the lymph
- act as a site of T and B cell activation
- enclosed with fibrous capsule
- lymph leaves node through one of 3 efferent lymphatic vessels
What does the Thymus do?
it houses developing T-lymphocytes
what is lymphadenitis?
swollen, painful, node responding to foreign antigen
what is lymphadenopathy?
a collective term for all lymph nodes disease
what is metastasis?
cancerous cells break free from original tumor, travel to other sites in the body, and establish new tumors
what are tonsils:
patches of lymphatic tissue located at the enterence to the pharyns
what are the different sets of tonsils?
- pharyngeal
- palatine
- lingual
what ate the function of the spleen?
- Healthy RBCs come and go
- erythrocyte graveyard
- highly vascular and vulnerable to trauma and infection
- white monitors blood
what is MALT?
mucosa-associated lymphatic tissue
What are the types of Internal Defenses?
- immune cells
- antimicrobial proteins
- inflammation
- fever
what is a pathogen?
agents capable of producing disease
What is an innate defense?
- guard equally against a broad range of pathogens
- they lack capacity to remember pathogens
- local, nonspecific, lacks memory
What are the three kinds of innate defenses?
- protective proteins
- protective cells
- protective processes
What is adaptive immunity?
- body must develop separate immunity to each pathogen
what are antimicrobial proteins? and what are the 2 types?
- attack microbes or hinder their ability to reproduce
- interferons
- complement proteins
what are interferons?
Viral infected cells secrete interferons
- induce other cells to secrete Anti-viral proteins
- activate macrophages and mobilize NK cells
what is immunity?
resistance to disease
What is the first line of defense?
skin and mucosa
what is the function of the mucous membranes?
mucus traps, lysozyme
what is the function of the skin?
mechanical barrier; dry, nutrient poor, acid mantle, antimicrobial proteins, mucus with lysozyme
What is the second line of defense?
Cellular and chemical defenses
What is the protection if microorganisms invade deeper in the tissue?
- immune cells: phagocytes, NK cells, mast cells, WBCs
- antibacterial proteins: interferons, complement proteins
- inflammation
- fever
What are phagocytes?
they engulf destroy pathogens that breach epithelial barriers
what are neutrophils?
they become phagocytic on encountering infectious material in tissues
what are macrophages?
they develop from monocytes and become the chief phagocytic cells
what is the process of phagocytosis?
- phagocyte adheres to pathogens or debris
- phagocyte forms pseudopods that eventually engulf the particles, forming a phagosome
- lysosome fuses with the phagocytic vesicle, forming a phagolysosome
- toxic compounds and lysosomal enzymes destroy pathogens
- sometimes exocytosis of the vesicle removes indigestible and residual material
what are natural killer cells and what do they do?
- larger granular lymphocytes
- attack cells that lack “self” cell-surface receptors
- induce apoptosis in cancer cells
What is the action of natural killer cells?
- NK cells release perforins, which polymerize and form a hole in the enemy cell membrane
- granzymes from NK cells enter perforin hole and degrade enemy cell enzymes
- enemy cell dies by apoptosis
- macrophage engulfs and digests dying cell
What are complement proteins?
major mechanism for destroying foreign substances
- enhances inflammation
- promotes phagocytosis
- causes cell lysis
what is margination?
cell adhesion molecule
- made by endothelial cells
- aid in recruitment of leukocytes
What is inflammation? key signs?
a local defensive response to tissue injury, including trauma and infection
- redness
- heat
- swelling
- pain
What are the benefits of inflammation?
- limit spread of pathogens, then destroys them
- disposes of cell debris and pathogens
- alerts the adaptive immune system
- sets stage for repair and healing
what are the three major process of inflammation?
- mobilization of body defenses
- containment and destruction of pathogens
- tissue cleanup and repair
What are inflammatory chemicals?
- get defensive leukocytes to injured site quickly
- by local hyperemia
what are the vasoactive chemicals involved in inflammation?
- histamine, leukoteienes
- causes local vasodilation
what is Diapedesis?
leukocytes crawl through gaps in the endothelial cells and enter tissue fluid
what is chemotaxis?
neutrophils accumulate at the injury site within an hour
- attraction of neutrophils to the injury site
what is platelet derived growth factor?
secreted by blood platelets and endothelial cells in injured area
- stimulates fibroblasts to multiply
- synthesizes collagen
- hyperemia delivers oxygen, amino acids
- increased heat increases metabolic rate, speed mitosis
what is fever?
pyrogenic response caused by endotoxins
what are adaptive immune responses?
- is specific
- is systemic
- has memory
what are the two overlapping arms of defense?
- humoral immunity
- cellular immunity
what is humoral immunity?
mediated by antibodies that do not directly destroy a pathogen but tag it for destruction
- dissolved in body fluids
what is cellular immunity?
lymphocytes directly attack and destroy foreign cells or diseased host cells
- kills cells that harbor them
where do B and T cells mature?
- B cells mature in RBM
- T cells mature in the thymus
what are the two requirements fo immunocompetence?
- they are able to recognize and bind to a specific antigen
- self tolerance
what is an antigen?
any molecule that triggers an immune response
what is an epitope?
certain regions of an antigen molecule that stimulates immune resonses
what are haptens?
can trigger an immune response by combining with a host macromolecule and creating a complex that the body recognizes as foreign
what are the cells and agents of humoral immunity?
- effector B cells
- antibodies
- memory B cells
- regulatory B cells
what do B lymphocytes produce?
they produce antibodies that bind to antigens and tag them for destruction by other means
in what stages does humoral immunity work?
- recognition
- attack
- memory
what do antibodies do?
inactivate and tag antigens
humoral immune response process?
1) Antigen recognition:
Immunocompetent B cells exposed to
antigen. Antigen binds only to B cells
with complementary receptors.
2) Antigen presentation:
B cell internalizes antigen and displays processed epitope.
3) Clonal selection:
Interleukin stimulates B cell to divide repeatedly and form a clone
4) differentiation: some cells of the clone become memory B cells
5) attack:
plasma cells sythesize and secrete antibody
6) memory
what are the defense mechanisms used by antibodies? wha they do?
- neutralization: antibodies block specific sites on viruses or bacterial exotoxins
- agglutination: antibodies bind the same determinant on more than one cell-bound antigen
- precipitation: complexes percipitate and are subject to phagocytosis
- complement fixation: main antibody defense against cellular antigens
what are primary and secondary immune responses?
primary: first exposure
- 3-6 days
- peak 10-15 d
secondary: re-exposure
- sensitized memory cells
- peak 3-5 d
- no illness
What is IgM, IgA, IgD, IgG, and IgE?
IgM: in plasma and lymph (primary immune response, agglutination)
IgA: monomer in plasma
(passive immunity to newborns)
IgD: monomer, B cell antigen receptor
IgG: monomer, 80% circulating antibodies
(placenta to fetus)
IgE: monomer, transmembrane protein on baso and mast
what are the 3 stages in life of T cells?
- born in bone marrow
- educated in thymus
- deployed to carry out immune function
What happens when cells are not immunocompetent in cortez?
they are destroyed
- positive selection
what happens when T cells fail in the medulla?
they are eliminated
- negative selection
leads to self tolerance
what is Naive lymphocyte pool?
immunocompetent T cells that have not yet encountered foreign antigens
what is Deployment?
naive t cells that leave thymus and colonize lyphatic tissues and orgns everywhere in body
what are the major types of APCs?
- dendritic cells in connective tissues and epidermis
- macrophages in connective tissues and lymphoid orgains
- b cells
what are the 4 types of T cells? what they do?
- Cytotoxic: carry out attack
- helper: activate cells
- regulatory: limit immune response
- memory
what are the stages of cell-mediated immunity?
-recognize
-react
-remember
when do T cells initiate immune response?
when T cells encounter a displayed antigen on the MHC protein
what are MHC-1 and MHC-11 proteins?
1- nucleated cells, transported to, on plasma membrane
2 - only on APCs
what are the 3 effects of interleukins?
- attract neutrophils and NK cells
- attract macrophages, stimulate their phagocytic activity and inhibit them from leaving the area
- stimulate T and B cell mitosis and maturation
what is hypersensitivity?
excess immune reaction against antigens that most ppl tolerate
what are the 4 types of immunity?
- acute, immediate and rapid
- histamine (vasod) - subacute, slower onset
- subacute, slower onset
- delayed cell-mediated response
