Structure/Function of Immune System Flashcards
1
Q
What are the primary lymphatic organs of the immune system?
A
- Red bone marrow (B cells)
- Thymus (T cells)
2
Q
Characteristic of red bone marrow for the immune system
A
- Flat bones and ends of long bones in adults
- Stem cells give rise to mature B cells and immature T cells
3
Q
Characteristics of Thymus for the immune system
A
- Immature T cells migrate to Thymus to mature into functional T cells
- Two lobed organ posterior to sternum
- Contains large number of T cells and macrophages
4
Q
What are the secondary lymphatic organs of the immune system (where most immune responses occur)?
A
- Lymph nodes
- Spleen
- Lymphatic nodules
5
Q
Characteristics of lymph nodes?
A
- Heavily concentrated near axillae, mammary glands, and groin
- Contain mature B cells, plasma cells, T cells, dendritic cells, and macrophages
- Filter lymph and trap foreign substances
6
Q
What destroys trapped foreign substances within lymph nodes?
A
- Macrophages
- Lymphocytes
7
Q
Characteristics of the Spleen?
A
- Largest single mass of lymphatic tissue
- Located between stomach and diaphragm
- Covered by a capsule of dense connective tissue
- Contains two types of tissue
8
Q
What are the two types of tissue in the spleen?
A
- White pulp
- Red pulp
9
Q
What is white pulp within the spleen?
A
Lymphatic tissue where B and T cells carry out immune responses
10
Q
What is red pulp within the spleen?
A
Blood-filled sinuses where worn-out blood cells and platelets are removed
11
Q
Characteristics of lymphatic nodules
A
- Egg-shaped masses of lymphatic tissue not surrounded by a capsule
- Plentiful in connective tissue of GI, Urinary, and Reproductive tracts and respiratory airways
12
Q
What are the two types of immunity?
A
- Adaptive (specific)
- Innate
13
Q
What is included within Innate immunity?
A
- Barriers provided by skin and mucous membranes (first line defense)
- Various internal defenses (second line defense) such as:
- Antimicrobial substances
- Natural Killer cells
- Phagocytes
- Inflammation and fever
14
Q
What is included within Adaptive (Specific) immunity?
A
- Lymphocytes (called B and T cells)
15
Q
What are the two types of Adaptive Immunity?
A
- Cell-mediated immunity
- Antibody-mediated immunity
16
Q
What is innate immunity?
A
Refers to a wide variety of body responses that serve to protect us
- we are born with this type of immunity
17
Q
What are phagocytes?
A
Specialized cells that perform phagocytosis (ingestion of microbes and other particles)
18
Q
What are Antibodies?
A
Belong to a group of plasma proteins called globulins (therefore known as immunoglobulins) - each class has a distinct chemical structure and different functions
19
Q
How many and what are the different classes of Immunoglobulins?
A
5:
- IgG
- IgA
- IgM
- IgD
- IgE
20
Q
Characteristics of IgG
A
- 80% of all antibodies in blood
- Protects against bacteria and viruses
- Only antibody that can cross placenta from mother to fetus
21
Q
How does IgG protect against bacteria and viruses?
A
- Enhances phagocytosis
- Neutralizes toxins
- Triggers the complement system
22
Q
Characteristics of IgA
A
- About 10-15% of all antibodies in blood
- Found mainly in sweat, tears, saliva, mucus, breast milk, and GI secretions
- Levels decrease during stress
- Provides localized protection of mucous membranes against bacteria and viruses
23
Q
Characteristics of IgM
A
- About 5-10% of all antibodies in blood (also in lymph)
- First antibody to be secreted by plasma cells after exposure to antigen
- Activates complement and causes agglutination and lysis of microbes
- Antibody binds to A and B antigens during blood transfusion
24
Q
Characteristics of IgD
A
- About 0.2% of all antibodies in the blood (also in lymph)
- On surfaces of B cells as antigen receptors
- Primarily involved in B cell activation
25
Characteristics of IgE
- Less than 0.1% of all antibodies in blood
- Also located on mast cells and basophils
- Primarily involved in allergic and hypersensitivity reactions
- Provides protection against parasitic worms
26
What type of barriers are found in the skin that covers the body and mucous membranes that line body openings?
- Physical barriers
| - Chemical barriers
27
What provides the physical barrier to the entrance of microbes?
Many layers of closely packed, keratinized cells (i.e. the epidermis)
28
What helps remove microbes from at the skin surface?
- Continual shedding of the top epidermal cells
| - Bacteria rarely penetrate an intact and healthy epidermis
29
What layer secretes mucus and what do they do?
- Epithelial layer of mucus membranes
- It lubricates and moistens the surface of a body cavity
- Is sticky and can trap microbes and foreign substances
30
How does mucus membrane of the nose work?
Has mucus-coated hairs that trap and filter microbes, dust, and pollutants from inhaled air
31
How does mucus membrane of the upper airway work?
Contains cilia (microscopic hair-like projections) which propel inhaled dust and microbes that have become trapped in mucus toward the throat
32
What are the second line defenses once the skin and mucus membrane defense are broken?
- Antimicrobial substances
- Phagocytes
- Natural killer cells
- Inflammation
- Fever
33
Body fluids contain what 4 main types of antimicrobial substances that discourage microbial growth?
- Interferons (IFN's)
- The complement system
- Iron-binding proteins
- Antimicrobial proteins (AMPs)
34
What are the Interferons?
Proteins produced by lymphocytes, macrophages, and fibroblasts that have been infected with viruses
35
How do interferons work?
They stimulate protein synthesis in unaffected, neighboring cells that interfere with viral replication
36
How do viruses cause disease?
Can only cause disease if they can replicate within body cells
37
What makes up the Complement system?
A group of normally inactive proteins in blood plasma and on plasma membranes
38
How do the complement system work?
- Enhance certain immune, allergic, and inflammatory reactions
- Create holes in plasma membrane of the microbe, leading to cytolysis
- Causes chemotaxis
- Some cause opsonization
39
What is Cytolysis?
When extracellular fluid moves into hole in the plasma membrane of the microbe, causing the microbe to burst
40
What is Chemotaxis?
Chemical attraction of phagocytes to a site
41
What is Opsonization?
A process in which complement proteins bind to the surface of a microbe and promote phagocytosis
42
How do iron-binding proteins inhibit the growth of certain bacteria?
Reducing the amount of available iron
43
What are Antimicrobial proteins (AMP's)?
Short peptides that have a broad spectrum of antimicrobial activity
44
How do AMP's work?
- Kill a wide range of microbes
| - Can attract dendritic and mast cells which participate in immune response
45
Do microbes that are exposed to AMP's appear to develop resistance?
No
46
What is the nonspecific defense when microbes penetrate the skin/mucous membranes or bypass the antimicrobial substances in blood?
- Phagocytes
| - Natural Cell Killers
47
How does Inflammation interact with immune response?
- Defensive response
- Events of inflammation:
* Dispose of microbes, toxins, or foreign material at the site of injury
* Prevent their spread to other tissues
* Prepare site for tissue repair
48
What are the four signs of inflammation?
- Redness
- Pain
- Heat
- Swelling
49
Can inflammation cause loss of function in the injured area?
Yes, depending on the site and extent of injury
50
Why does abnormally high body temperature occur?
Because the hypothalamic thermostat is reset
51
How does fever work in relation to immune response?
- Intensifies effects of interferons
- Inhibits the growth of some microbes
- Speeds up body reactions that aid repair
52
What is one common aspect of innate immunity?
They are not specifically directed against a particular type of invader
53
What does adaptive immunity involve?
Production of specific types of cells or specific antibodies to destroy a particular antigen
54
What is an antigen?
Any substance, such as food, microbes, drugs, pollen, that the body recognizes as foreign
55
Does the immune system include cells and tissues that carry out immune responses?
Yes
56
What is self-tolerance?
Lack of reaction to the body's own chemicals and tissues
57
What are the two types of mature T cells that exits the Thymus?
- Helper T cells
| - Cytotoxic T cells
58
What are the two types of Adaptive Immunity?
- Cell-mediated immunity
| - Antibody-mediated immunity
59
How does cell-mediated immunity work?
- Triggered by antigens
| - Cytotoxic T cells attack invading antigens
60
How does antibody-mediated immunity work?
- Triggered by antigens
| - B cells transform into plasma cells, which synthesize and secrete specific proteins called antibodies
61
What are cell-mediated immunity particularly effective against?
- Intracellular pathogens
- Some cancer cells
- Foreign tissue transplants
62
Basics Cell-mediated immunity?
Cells attacking cells
63
Basics antibody-mediated immunity?
Works mainly against extracellular pathogens
64
What is antibody-mediated immunity also called?
Humoral immunity
65
What is clonal selection?
The process by which a lymphocyte proliferates (divides) and differentiates (form highly specialized cells) in response to a specific antigen
66
Where does clonal selection of lymphocytes occur?
In the secondary lymphatic organs and tissues
67
What are the two major types of cells in a clone after a lymphocyte undergoes clonal selection?
- Effector cells
| - Memory cells
68
Which cells in a clone die after the immune response has been completed?
Effector cells
69
What cells do not participate in the initial response to the antigen?
Memory cells
70
How do memory cells respond to an antigen?
By proliferating and differentiating into more effector and memory cells
71
How long of a life span do memory cells have?
They do not die at the end of the immune response and therefore can live for decades
72
What are examples of antigens?
- Microbes or parts of microbes
- Chemical components of bacteriological structures (flagella, capsules, cell walls, bacterial toxins, viral proteins)
- Pollen
- Incompatible blood cells
73
What are major histocompatibility complex (MHC) proteins?
Protein "self-antigens" that are located at the plasma membrane surface of most body cells
74
Are MHC proteins unique?
Yes, unless you have a twin
75
How many MHC molecules mark the surface of your body cells? Except for which one?
- Thousands
| - Except for RBC's
76
What is the normal function of MHC proteins and what else can they do?
- Help T cells recognize an antigen is foreign
| - Reason that tissue transplant can may be rejected
77
What do antigens induce plasma cells to secrete?
Antibodies
78
How many chains does most antibodies contain?
4 polypeptide chains
79
What group of plasma proteins belong to and what are they called?
Globulins and as such are known as Immunoglobulins
