Set 8 Flashcards
What are the three types of components of the immune system?
- Lymphoid tissues
- Various types of immune cells
- Chemical signals that coordinate responses
What are the primary functions of the immune system?
- Protects against pathogens
- Protects against foreign molecules
- Removes dead or damaged cells
- Attempts to recognize and remove abnormal cells
What are the three types of immune system pathologies? Give an example for each.
- Incorrect immune response (e.g. autoimmune disease)
- Overactive immune response (e.g. allergy)
- Lack of immune response (HIV-AIDS immunodeficiency)
What are the two lines of body defenses?
1) Physical and chemical barriers
2) Immune defenses
What are physical barriers?
- Skin
- Mucous membranes
- Lacrimal apparatus (ducts secreting tears)
- Saliva
- Epiglottis
What are four chemical barriers?
- Sebum
- Perspiration
- Gastric juice
- Urine
How does sebum inhibit microbial growth?
Sebum, secreted by sebaceous glands, has a low pH, which inhibits microbial growth
How does perspiration inhibit microbial growth?
Flushes skin of microbes and contains lysozyme
What are the four steps in an immune response?
1) Detection and identification of the foreign substance
2) Communication with other immune cells
3) Recruitment of other immune cells, and coordination of the response
4) Destruction or suppression of the invader
What is the lymphatic system?
Vascular system that collects tissue fluid and returns it to the blood
What is the function of the lymphatic fluid?
- Lymph travels through lymphatic vessels
- At lymph nodes, they are screened for pathogens
- Then, they travel back into the venous system
Why are lymph nodes particularly concentrated in extremities?
Screening mechanism for the blood in the extremities prior to their re-entry into the heart
What are the two primary lymphoid tissues?
- Bone marrow
- Thymus
What are the two encapsulated lymphoid tissues?
- Lymph nodes
- Spleen
What are diffuse lymphoid tissues? Give an example.
- Unencapsulated lymphoid tissues and aggregations of immune cells that appear in other organs of the body
- Respiratory and digestive tract
- Ex: gut-associated lymphoid tissue (GALT), and tonsils
What is the structure of the thymus? Where is it located?
- 2-lobed organ
- Located in the thorax just above the heart
What occurs to the thymus during adolescence?
- Reaches its greatest size during adolescence
- Then, shrinks and is replaced with adipose
What occurs in the thymus during development?
Recognition and elimination of self-reactive cells
What peptides does the thymus produce to aid in T-cell differentiation?
- Thymosin
- Thymopoietin
- Thymulin
How do lymphoid nodules differ from lymph nodes?
Lymphoid nodules are NOT surrounded by a fibrous capsule
Where are lymphoid nodules located? How do they differ in size?
- Beneath epithelial lining of organs that have direct contact to the outside world (digestive, respiratory (tonsils), urinary)
- Size increases or decreases depending on the number of dividing lymphocytes
What allows the creation of lymphatic fluid?
- Capillary hydrostatic pressure is greater than blood osmotic pressure, which favours filtration
- Blood colloid osmotic pressure exerts a force to bring fluid back in
How do viruses differ from bacteria?
- Viruses are NOT cells
- Viruses must have a host cell to reproduce
What is the function of glycoproteins on viruses?
Their particular glycoproteins allow them to attach to certain specific types of cells
How do enveloped and non-enveloped viruses differ?
- Viruses with envelopes are very easy to kill with soap (ex: HIV, influenza)
- Non-enveloped viruses are less easy to kill
What are interferons?
Cytokines that inhibit viral replication and modulate the immune response
How are interferons produced? What occurs?
- Virus infected cell triggers the expression of interferons, and subsequently dies
- IFN is released and diffuses to a neighboring uninfected cell, and binds to receptor
- The binding triggers the expression of AVP, which degrade viral mRNA and stop viral replication
In a lymph node, where are B-cells and T-cells located?
- Outside: B-cells
- Middle: T-cells
What are the two functional regions of the spleen?
- Red pulp
- White pulp
What is contained within the red pulp region of the spleen?
- Extensive blood vessels
- Loaded with RBCs
What is contained within the white pulp region of the spleen?
- Resemble the interior of lymph nodes
- Mainly composed of lymphocytes
What are the three granulocytes?
- Neutrophils
- Basophils
- Eosinophils
What are the three agranulocytes?
- Monocytes and macrophages
- Lymphocytes
- Dendritic cells
What is the primary function of basophils and mast cells?
Release chemicals that mediate inflammation and allergic responses
What is the primary function of neutrophils?
- Ingest and destroy invaders
- Most common type of leukocyte
What is the primary function of eosinophils
Destroy invaders, particularly antibody-coated parasites
What are the primary functions of monocytes/macrophages?
- Ingest and destroy invaders
- Antigen presentation
What is the primary functions of plasma cells?
Specific responses to invaders, including antibody presentation
What is the primary function of dendritic cells?
Recognize pathogens and activate other immune cells by antigen presentation
Which leukocyte is specific to tissues? Give an example.
- Macrophages
- Ex: microglial cells in the brain
Are pathogens with capsules or without harder to kill?
Pathogens with capsules are harder to kill (virulence factor)
What must occur for the phagocytosis of pathogens with a capsule?
- The pathogen must be tagged with antibodies first
- Phagocytosis may then occur
What occurs to pathogens following ingestion?
- Phagosome contains ingested pathogen
- Lysosome contains enzymes and oxidants, which digest the pathogen
- Digested antigen
What leukocytes initiate adaptive immunity?
- Dendritic cells and other professional APCs
- They capture, process, and display antigens to the appropriate immune cells
What are the primary functions of natural killer cells?
- Induce apoptosis in infected cells
- Attack some tumour cells
- Secrete interferons
What is the function of IFN-a and IFN-B?
- Prevent viral replication
- At the beginning of a viral infection
What is the function of IFN-gamma?
- Activates macrophages and other immune cells
- At the end of a viral infection
What are three beneficial roles to inflammation?
- Attract immune cells and chemical mediators to sites of infection
- Create physical barriers to prevent infections from spreading
- Promote tissue repair