Term
| Physical Barriers to invading organism |
|
Definition
1) secretion
2) mucous
3) cilia of trachea
4) epithelial tight junctions
5) acidic pH of gastric lumen
6) commensal organisms in gut & vagina |
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Term
| Innate, Non-Adaptive Responses |
|
Definition
1) 1st line of defense
2) phagocytosis by granulocytes
3) unspecific response
4) Inflammation |
|
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Term
| Adaptive Immune Response must be able to do what? |
|
Definition
1) Recognize foreign substance
2) Mount a response against it |
|
|
Term
| On first exposure to antigen, is adaptive response slow or fast? |
|
Definition
| Slow, innate response is quicker on first response |
|
|
Term
| What are the two mechanisms of the adaptive immune response? |
|
Definition
1) Humoral immunity - secretion of antibodies by plasma cells (B cells)
2) Cell-mediated immunity
- secretions of cytokines by T helper cells
- action of natural killer cells (large granular lymphocytes – innate, non-immune response as well) and cytotoxic T cells
- plays a major role in defense against foreign organisms (viruses, fungi, bacteria) and transformed (tumor) cells
- responsible for transplant rejection. |
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|
Term
| What are the 3 characteristics of the Lymphatic System? |
|
Definition
1) recognition (non-self) of antigens
2) specificity - each cell or group of cells recognizes one antigen
3) memory - specific immune cells remember the antigen they encounter |
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Term
| What are the primary lymphatic organs? |
|
Definition
1) Thymus
2) Bone Marrow
*lymphocytes genetically programmed to recognize antigen
*Proliferation and differentiation of lymphocytes in primary organs is antigen-independent |
|
|
Term
| What are secondary lymphatic organs? |
|
Definition
*Antigen-dependent
1) Spleen
2) Bone Marrow
3) Lymph nodes
4) Lymph nodules
5) Diffuse lymphatics
6) MALT - mucosa associated lymphatic tissue |
|
|
Term
|
Definition
Mucosa membrane that lines cavities connected to outside the body
1) epithelium
2) underlying CT called lamina propria
3) smooth muscle |
|
|
Term
| What are the cells of the immune system? |
|
Definition
1) B cells
2) T cells
3) Natural Killer Cells/Large Granular
Lymphocytes (LGL's)
4) APC's
5) Macrophages
6) Reticular Cells |
|
|
Term
| What are the functions of B cells? |
|
Definition
1) Differentiate in Bone marrow B = B and possibly GALT
2) 20-30% of circulating lymphocytes
3) membrane bound antibodies serve as antigen binding sites
4) express MHC II
5) humoral immunity |
|
|
Term
| What are the types of T cells? |
|
Definition
1) T-helper cells CD4+
2) Cytotoxic T cells CD8+
3) Gamma/delta T cells
4) T suppressor cells |
|
|
Term
| What are the functions of T cells? |
|
Definition
1) Migrate from bone marrow and differentiate in thymus
2) 60-80% of circulating pop. |
|
|
Term
| What does a CD4+ cell do? |
|
Definition
1) T-helper cell
2) secrete cytokines that stimulate B cells and others to elicit an immune response
3) Sub-divided by cytokine they produce - interferon, interleukins, mitotic agents, chemotactic factors |
|
|
Term
| What is/does a CD8+ cell (do)? |
|
Definition
1) Cytotoxic T cell
2) Destroy host cells infected with virus or transformed
3) recognizes antigen bound to MHC I molecules on cell surface |
|
|
Term
| What do gamma/delta T cells do? |
|
Definition
1) colonize epithelium
2) do not recirculate
3) 1st line of defense of mucosal surfaces |
|
|
Term
| What do T suppressor cells do? |
|
Definition
| 1) Suppress the immune response |
|
|
Term
| What is the mode of entry for HIV? |
|
Definition
| 1) binds CD4+ on T helper cells |
|
|
Term
| What are Natural Killer Cells? |
|
Definition
1) large Lcytes with azurophilic granules
2) Recognize surface changes on tumor cells and virally infected cells
3) non- phagocytic
4) release "perforins" that make PM leaky and causes apoptosis
5) Two classes
- antibody independent
- antibody dependent |
|
|
Term
|
Definition
|
|
Term
|
Definition
1) Expressed on surface of all nucleated cells and platelets
2) involved in elimination of abnormal host cells
- tumor cells
- infected cells
3) CD8+ are MHC I restricted |
|
|
Term
|
Definition
1) Expressed on antigen presenting cells (APC)
2) and cells that interact with T helper cells
- dendritic cells
- B cells
3) present fragments of peptides to T helper cells
- T helper cells are MHC II restricted |
|
|
Term
|
Definition
1) Antigen presenting cells
2) Langerhans cells in skin, B cells, dendritic cells
3) express MHC I & II
4) phagocytize antigens and fragment them to be produced to MHC II and T helper cells |
|
|
Term
|
Definition
1) APC's can be specialized macrophages
2) phagocytosis and ingestion of microorganisms and apoptotic cells
3) secretion of cytokines, acid hydrolases, proteases, lipases |
|
|
Term
|
Definition
1) Antibodies
2) produced by B cells
3) 2 heavy & 2 light chains |
|
|
Term
| What is the structure of an antibody? |
|
Definition
1) Fab portion
- antigen binding
- shows diversity
- 2 branches portion
2) Fc portion
- constant
- binds to Fc receptors on immune cells
- determines Ig class |
|
|
Term
| What are the 5 major Ig classes? |
|
Definition
1) IgG
- 70-75%
- produced during secondary response
2) IgM
- 1st class produced during primary response
3) IgA
- found in milk, saliva, tears
4) IgD
- found on surface of B cells where it acts as an antigen receptor
5) IgE
- Stimulates mast cells and basophils |
|
|
Term
| What is Lcyte activation? |
|
Definition
1) Encountering an antigen
- APC
- macrophage
2) Blast transformation
3) Clonal expansion
4) Differentiation
- effector cells
- memory cells
5) Basis of vaccination
- recognition
- specificity
- memory |
|
|
Term
| How many lobes does the thymus have? |
|
Definition
|
|
Term
| What type of cell differentiates at the thymus? |
|
Definition
|
|
Term
| What is the origin of the thymus? |
|
Definition
|
|
Term
| What is the basic structure of the thymus? |
|
Definition
1) surrounded by a CT capsule that extend septa in thymus forming incomplete lobes
2) Each lobe is divided into:
- cortex (Lcyte rich)
- medulla (epithelium rich)
2) |
|
|
Term
| What is the supporting structure of the thymus? |
|
Definition
1) Cytoreticulum
- epithelioreticular cells
- no fibers in stroma of thymus excluding CT and trabeculae |
|
|
Term
| What are epithelioreticular cells? |
|
Definition
1) cells attached by desmosomes
2) tonofilaments indicate epithelial origins
3) distinguishable from Lcytes by pale-staining nucleus
4) contain membrane bound vesicles containing a # of hormones that function in the maturation of T cells
5) 6 types |
|
|
Term
| 6 Types of Epithelioreticular cells |
|
Definition
1) Type I
- at CT capsule/cortex boundary
- adventitia of BV's
2) Type II
- cortex
- MHC I & II
- connect others via desmosomes
- compartmentalize the cortex
3) Type III
- cortex-medulla boundary
- occluding junctions
- MHC I & II
4) Type IV
- Medulla side of cortex-medulla boundary
- occluding junctions
5) Type V
- medulla
6) Type VI
- Hassal's corpuscles |
|
|
Term
| What is the blood-thymic barrier? |
|
Definition
| Separates developing thymocytes from antigens |
|
|
Term
| What is the blood-thymic barrier made of? |
|
Definition
1) BV endothelium
2) endothelial basal lamina
3) perivascular CT
4) epithelial basal lamina
5) epethilioreticular cells |
|
|
Term
| What are Hassall's Corpuscles? |
|
Definition
1) Type VI epithelial cells form tightly wound structures in MEDULLA
2) inner cells may be keratinized
3) produce hormones
- thymosin
- thymopoietin |
|
|
Term
| What are the functions of the thymus? |
|
Definition
1) Stem cells enter medulla and migrate to cortex
2) active proliferation of pre-T-cells (thymocytes) in subcapsular space and outer cortex
3) Tcyte differentiation facilitated by epithelial nurse cells
4) expression of T cell receptors (TCR or CD's)
- distinguish self & non-self
- cells that recognize self MHC survive first test and migrate to medulla (positive selection)
- others apoptosis
4) in Medulla
- negative selection
- cells recognizing self AG from self MHC are eliminated
5) surviving cells move to cortico-medullary junction to exit
6) 90-95% die in thymus |
|
|
Term
| What are thymic hormones? |
|
Definition
1) Secreted by Type VI epithelioreticular cells
- promote thymic differentiation |
|
|
Term
| What is thymic involution? |
|
Definition
1) Starts in 12 months
2) reduces 3%/year until middle age
3) 1%/year after that
4) Thymus replaced by fatty tissue
5) stress causes accidental involution |
|
|
Term
| What is the effect of thymectomy? |
|
Definition
| If removed at birth, spleen and lymph nodes smaller in size due to lack of T cells |
|
|
Term
| What are the 2 types of functions of the spleen? |
|
Definition
1) Immune functions
2) Hemopoietic functions |
|
|
Term
| What are the immune functions of the spleen? |
|
Definition
1) Removal of AG's from blood
2) AG presentation & initiation of immune response
3) Activ. and prolif. of T & B cells
4) Prod. of antibodies against blood antigens |
|
|
Term
| What are the hemopoietic functions of the spleen? |
|
Definition
1) Removal of old/damaged RBC's
2) Retrieval of Fe from hemoglobin
3) Formation of RBC's (fetal period)
4) Storage of blood in some species |
|
|
Term
| What is the structure of the spleen? |
|
Definition
1) CT capsule
- dense CT
- trabeculae extend from capsule to spleen
- indented hilus where splenic aa & vv enter/leave
2) Supporting network
- trabeculae
- branched reticular cells and fibers (Type III collagen)
3) White pulp
- where most lymphatic-antigen reactions occur (dark staining)
4) Marginal Zone
- concentric layers of reticular cells/fibers at periphery of white pulp
- separates red/white pulp
- receives branches from central artery
- much of blood filtration/processing occurs here
5) Red pulp |
|
|
Term
| What is white pulp and where is it located? |
|
Definition
1) Spleen
2) Contains:
- Central artery
- Periarterial Lymphatic Sheath (PALS)
- Lcytes (T cells) surrounding central canal
- Nodules
- in PALS (B cells)
- If presented with antigen, B cells proliferate forming germinal centers in the center of the nodule (secondary nodule) |
|
|
Term
| What are the functions of white pulp? |
|
Definition
1) prolif. & matur. of B & T cells
2) Antigen presentation
3) AB production |
|
|
Term
| What is red pulp and where is it? |
|
Definition
1) Spleen
- makes up bulk of spleen
2) made of venous sinuses separated by Cords of Bilroth (splenic cords) |
|
|
Term
| What are the Cords of Bilroth? |
|
Definition
1) separate venous sinuses of red pulp
2) macrophages, platelets, RBC's, B cells
3) Functions:
- bring blood from terminal arteriole to splenic sinuses
- store platelets
- destroy RBC's |
|
|
Term
| What are the splenic sinuses? |
|
Definition
1) specialized units of BV's in spleen
2) lined by fusiform epi cells
- junctional complexes common
3) reticular fibers surround epi cells
4) basal lamina discontinuous
- allows RBC's to enter/leave CofB |
|
|
Term
| What are the functions of Red pulp? |
|
Definition
1) removal of old/damaged RBC's
2) Fe retrieval
3) hematopoiesis in fetus
4) blood and platelet storage
5) blood filtration & antigen removal |
|
|
Term
| Describe splenic circulation |
|
Definition
1) Central artery branches into marginal zone & then red pulp
2) In red pulp, arterioles branch into straight penicilli
3) penicilli continue as capillaries
4) Periarterial Macrophage Sheath
- surrounds capillaries
5) Blood from capillaries enters sinuses to be processed
- open circulation theory
- endothelial pores in capillaries |
|
|
Term
|
Definition
| 1) filter AG's from interstitial fluid and lymph |
|
|
Term
| What are the functions of lymph nodes? |
|
Definition
1) filter AG's from interstitial fluid & lymph
2) Lcyte maturation
3) AB/Ig production
4) phagocytosis |
|
|
Term
| Describe the structure of a lymph node |
|
Definition
1) dense CT capsule
- trabeculae extend into node
2) aa, vv, and efferent lymphatic vessel enter/leave at hilus
3) afferent lym. vessel empties into subcapsular space
4) 3 zones:
- cortex
- paracortex
- medulla |
|
|
Term
| Are there sinuses in the lymph node? |
|
Definition
Yes, they serve as channels for lymph fluid.
1) enters through afferent lym. vessel in subcapsular sinus
2) flows through trabecular sinus in cortex
3) enters medullary sinus
4) exits through hilus through efferent lym. vessel |
|
|
Term
| What is the reticular meshwork? |
|
Definition
1) Stroma - Type III collagen & ground
2) Cells
- reticular - synthesize Type III collagen
- dendritic - efficient APC's
- macrophages - APC's
- follicular dendritic cells |
|
|
Term
| What are follicular dendritic cells? |
|
Definition
1) trap antigen-antibody complexes on thin cytoplasmic processes
2) cytoplasmic processes interdigitate between B cells in germinal centers |
|
|
Term
| Describe the cortex of a lymph node |
|
Definition
1) B cells packed into nodules/follicles
- primary or secondary
2) secondary nodules contain germinal centers indicative of B cell prolif. |
|
|
Term
| Describe the paracortex of a lymph node |
|
Definition
1) mostly T cells; macrophages also present
2) T & B cells migrate into node from blood
3) Occurs through High endothelial venules (post-capillary venules)
- cuboidal epi with Lcyte receptors
4) Lcytes cross endo between cells (diapedesis)
5) Devoid of nodules |
|
|
Term
| Describe the medulla of the lymph node |
|
Definition
1) centrally located around hilus
2) made of medullary cords separated by sinuses
3) medullary cords made of:
- reticular cells/fibers
- macrophages
- Lcytes
- plasma cells
- granulocytes
4) sinuses lined by simp. squam. epi.
- lumen bridged by reticular cells
- allows for turbulence |
|
|
Term
| What are Diffuse Lymphatics? |
|
Definition
| 1) accumulations of non-encapsulated lymphatic tissue found in the lamina propria and submucosa of the GI, respiratory and genito-urinary tract (MALT & GALT) |
|
|
Term
| What are Lymphatic Nodules? |
|
Definition
1) concentrations (usually ovoid in shape) of lymphocytes that are not encapsulated
2) lamina propria and submucosa of the GI, respiratory and genito-urinary tract
3) primary nodules contain small Lcytes
4) secondary nodules have germinal centers (sites of actively dividing lymphocytes) and a mantle zone or corona |
|
|
Term
| What are some specific locations for lymphatic nodules? |
|
Definition
1) Ileum
- Peyer's Patches/M cells
- M cells are microfold cells
- APC's
2) Appendix
3) Cecum
4) Tonsils
- partially encapsulated lymph nodes |
|
|
Term
| How many types of tonsils are there? What are they? |
|
Definition
1) 3
2) Pharyngeal (adenoid)
3) Lingual
4) Palatine |
|
|
Term
| Describe a pharyngeal tonsil |
|
Definition
1) roof of pharynx
2) luminal surface lined by strat. squa. or respiratory epi.
-the latter is usually found in crypts |
|
|
Term
| Describe a Lingual tonsil |
|
Definition
1) base of tongue
2) luminal surface lined by strat. squa. epi.
3) Capsular surface
- contains mucous glands
- skeletal muscle of tongue
- mixed glands also |
|
|
Term
| Describe a palatine tonsil |
|
Definition
1) sides of pharynx
2) strat. squa. epi
3) luminal surface has ~ 20 deep crypts
4) capsular region has mucous glands |
|
|
Term
| Are lymphocytes stationary? |
|
Definition
|
|
Term
| Describe Lymphatic vessels |
|
Definition
1) Originate in CT spaces as anastomosing capillaries
2) capillaries flow into collecting vessels that empty into R & L thoracic duct
3) Lymph flows in one direction only:
- to thoracic duct |
|
|
Term
| What are the functions of lymphatic vessels? |
|
Definition
1) return material to blood
2) absorb fat from intestine & protein from liver
3) pick up macrophages from serosal cavity |
|
|
Term
|
Definition
| lymph nodes, tonsils, adenoids |
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