Lymphatic System (ch. 22) Flashcards
1
Q
What are pathogens?
A
Pathogens are disease-producing microbes.
2
Q
What is immunity?
A
Immunity (resistance) is the ability to ward off damage or disease through defenses.
3
Q
What does susceptibility mean?
A
Susceptibility refers to vulnerability or lack of resistance.
4
Q
What is innate immunity?
A
Innate immunity (nonspecific resistance) is present at birth and includes defense mechanisms that provide general protection against invasion by a wide range of pathogens.
5
Q
What is adaptive immunity?
A
Adaptive immunity (specific resistance) involves activation of specific lymphocytes that combat a particular pathogen or other foreign substance.
6
Q
What body system carries out immune responses?
A
The lymphatic system.
7
Q
What does the lymphatic system consist of?
A
Lymph, several structures and organs that contain lymphatic/lymphoid tissue, and red bone marrow.
8
Q
What is one function of the lymphatic system?
A
It assists in circulating body fluids.
9
Q
How does fluid pass into lymphatic vessels?
A
After filtering from plasma through capillary walls to the interstitial fluid (IF), it can then pass into lymphatic vessels.
10
Q
What is Blood Hydrostatic Pressure (BHP)?
A
The pressure exerted by the blood pushing against the capillary walls. At the arterial end, it is 35 mmHg.
11
Q
What is Colloid Osmotic Pressure (COP)?
A
The pressure due to proteins (like albumin) in the blood that pulls water back into the capillaries. At the arterial end, it is 26 mmHg.
12
Q
What is Interstitial Fluid Hydrostatic Pressure (IFHP)?
A
The pressure exerted by fluid in the surrounding tissues, which opposes fluid entering the capillaries. It is approximately 0 mmHg.
13
Q
How is Net Filtration Pressure (NFP) calculated at the arterial end?
A
NFP = (BHP) - (BCOP + IFHP) = (35) - (26 + 0) = 10 mmHg.
14
Q
What does a positive Net Filtration Pressure (NFP) indicate?
A
It indicates net filtration, meaning fluid is pushed out of the capillaries into the surrounding tissue.
15
Q
What is the Blood Hydrostatic Pressure (BHP) at the venous end?
A
BHP drops to 16 mmHg.
16
Q
How is Net Filtration Pressure (NFP) calculated at the venous end?
A
NFP = (BHP) - (BCOP + IFHP) = (16) - (26 + 1) = -9 mmHg.
17
Q
What does a negative Net Filtration Pressure (NFP) indicate?
A
It indicates net reabsorption, meaning fluid is being pulled back into the capillaries.
18
Q
What happens at the arterial end of the capillary?
A
Fluid is pushed out of the capillaries due to high blood pressure (net filtration).
19
Q
What happens at the venous end of the capillary?
A
Fluid is drawn back into the capillaries due to lower blood pressure and higher osmotic pressure (net reabsorption).
20
Q
What is lymph?
A
A fluid called lymph is usually a clear, pale-yellow fluid that flows within lymphatic vessels.
21
Q
How does lymph differ from interstitial fluid?
A
Lymph is different from interstitial fluid in that it is found in lymphatic vessels and tissue, as opposed to between cells.
22
Q
What is lymphatic (lymphoid) tissue?
A
Lymphatic (lymphoid) tissue is specialized reticular connective tissue containing a large number of lymphocytes (T cells and B cells).
23
Q
What is one function of the lymphatic system?
A
Drain interstitial fluid – lymphatic vessels drain excess interstitial fluid and return it to the blood.
24
Q
How does the lymphatic system contribute to blood volume?
A
Makes maintenance of blood volume possible.
25
What dietary components does the lymphatic system transport?
Transport dietary fats – transport lipids and lipid soluble vitamins (A, D, E and K).
26
What role does the lymphatic system play in immune responses?
Carry out immune responses – initiates highly specific responses directed against particular microbes or abnormal cells.
27
What are lymphatic capillaries?
Tiny, closed-ended vessels that begin the lymphatic system.
28
Where are lymphatic capillaries located?
They are found between the cells of various tissues, collecting excess interstitial fluid.
29
How are lymphatic vessels formed?
Lymphatic capillaries merge together to form larger lymphatic vessels.
30
What are the characteristics of lymphatic vessels?
They have thin walls and contain many valves to prevent the backflow of lymph.
31
What is the function of lymphatic vessels?
They ensure lymph flows in one direction toward lymph nodes and eventually back to the circulatory system.
32
What are lymph nodes?
Bean-shaped organs filled with lymphatic tissue.
33
What is the function of lymph nodes?
They contain large numbers of B cells and T cells, crucial for the immune response, filtering lymph and helping fight infections.
34
What are avascular tissues?
Tissues that do not have lymphatic capillaries, such as cartilage and the epidermis.
35
Which other areas lack lymphatic capillaries?
Portions of the spleen and red bone marrow also lack lymphatic capillaries.
36
What is the overall function of the lymphatic system?
It starts with lymphatic capillaries collecting fluid between cells, forming vessels with valves that carry lymph to lymph nodes, where immune cells filter and respond to pathogens. Certain tissues like cartilage and skin lack these capillaries.
37
Where are lymphatic vessels located in the skin?
Lymphatic vessels are located in the subcutaneous tissue, the layer of tissue just under the skin.
38
How do lymphatic vessels follow blood flow?
They follow the same pathways as veins, accompanying the veins closely as blood flows.
39
Where do lymphatic vessels run in the internal organs?
In the internal organs, lymphatic vessels generally run alongside arteries.
40
What are plexuses in relation to lymphatic vessels?
Plexuses are structures formed by lymphatic vessels around arteries, helping distribute lymphatic fluid.
41
How do lymphatic capillaries compare in permeability to blood capillaries?
Lymphatic capillaries are more permeable than blood capillaries, allowing larger molecules and fluids to pass through more easily.
42
What are lacteals?
Lacteals are specialized lymphatic capillaries in the intestines that absorb dietary fats.
43
What is the role of blood capillaries?
Blood capillaries carry blood, allowing fluids and molecules to move into the interstitial fluid.
44
What happens to interstitial fluid in relation to lymphatic capillaries?
Interstitial fluid enters the lymphatic capillaries as lymph, which is then transported through lymphatic vessels.
45
What is the interaction between blood, interstitial fluid, and lymphatic capillaries?
This interaction occurs at tissue cells, enabling nutrient and waste exchange.
46
What is the size and structure of lymphatic capillaries?
Lymphatic capillaries are slightly larger in diameter compared to other capillaries. They are designed to allow interstitial fluid to flow into them but not out.
47
What happens to fluid that enters lymphatic capillaries?
Once fluid moves into the lymphatic capillary, it cannot flow back out. This helps ensure that excess interstitial fluid can be collected and returned to the bloodstream.
48
What are anchoring filaments?
Anchoring filaments are elastic fibers that connect the lymphatic capillaries to surrounding tissues, helping maintain the structure of the capillaries.
49
What occurs when there is too much interstitial fluid?
When tissues swell, anchoring filaments pull on the capillary walls, creating larger openings between cells in the capillary, allowing even more fluid to enter.
50
What is the pathway of lymph after leaving lymphatic vessels?
Lymph passes through lymph nodes and then into lymph trunks.
51
What do lymph trunks include?
Lymph trunks include lumbar, intestinal, bronchomediastinal, subclavian, and jugular.
52
What does the lumbar trunk drain?
The lumbar trunk drains the lower limbs, walls and viscera of pelvis, kidneys, adrenal glands, and abdominal wall.
53
What does the intestinal trunk drain?
The intestinal trunk drains the stomach, intestines, pancreas, spleen, and part of the liver.
54
What does the bronchomediastinal trunk drain?
The bronchomediastinal trunk drains the thoracic wall, lungs, and heart.
55
What does the subclavian trunk drain?
The subclavian trunk drains the upper limbs.
56
What does the jugular trunk drain?
The jugular trunk drains the head and neck.
57
What do lymph trunks merge to form?
Lymph trunks merge to form either the thoracic duct or the right lymphatic duct.
58
What do lymphatic ducts connect to?
Lymphatic ducts connect to major veins in the body, allowing lymph to return to the bloodstream.
59
What does the Right Lymphatic Duct drain?
It drains lymph from the right side of the head, neck, and right arm.
60
Where does the Right Lymphatic Duct join?
It joins the right internal jugular vein and the right subclavian vein at their junction.
61
What does the Thoracic (Left Lymphatic) Duct drain?
It drains lymph from the left side of the body, including the left arm, left side of the head and neck, and lower parts of the body.
62
Where does the Thoracic Duct merge?
It merges with the left subclavian vein at its junction.
63
What does the left bronchomediastinal trunk collect?
It collects lymph from the thoracic cavity.
64
Where does the left bronchomediastinal trunk drain?
It drains into the left subclavian vein.
65
What is the ultimate return of lymph to blood?
Ultimately, the lymph drains into major veins, such as the superior vena cava, which returns the lymph back to the general circulation in the blood.
66
What is the summary of lymphatic fluid return?
Lymphatic fluid is collected in ducts that connect to veins, facilitating the return of lymph into the bloodstream.
67
What is the pathway of lymph flow?
Lymph forms when interstitial fluid enters lymph capillaries, flows through lymph vessels, merges into larger lymph trunks, moves into lymph ducts, and drains into subclavian veins.
68
What is the role of the respiratory pump in lymph flow?
During inhalation, changes in pressure within the chest help draw lymph into the lymphatic system.
69
How does the skeletal muscle pump assist in lymph flow?
As muscles contract during movement, they squeeze nearby lymph vessels, pushing lymph through the system.
70
What prevents backflow in lymphatic vessels?
Valves within the lymphatic vessels ensure that lymph flows in only one direction.
71
What is the function of lymph nodes?
Lymph nodes filter out foreign substances, such as bacteria and viruses, from the lymph via immune responses.
72
What is the role of the lymphatic system?
The lymphatic system ensures that excess interstitial fluid is returned to the bloodstream, maintaining fluid balance in the body.
73
What are primary lymphatic organs?
Primary lymphatic organs are organs where stem cells divide and where immune cells become immunocompetent.
74
What is the role of red bone marrow in the immune system?
Red bone marrow produces immunocompetent B cells and pre-T cells.
75
What happens in the thymus?
In the thymus, T cells become immunocompetent.
76
What are secondary lymphatic organs and tissues?
Secondary lymphatic organs and tissues are sites where most immune responses occur.
77
What are examples of secondary lymphatic organs?
Examples of secondary lymphatic organs include lymph nodes, spleen, and lymphatic nodules.
78
Where do T cells migrate after leaving the thymus?
T cells migrate to lymph nodes, the spleen, and other lymphatic tissues.
79
What is the color of T cells and why?
T cells are red in color due to a rich blood supply.
80
Do T cells continue to divide in the thymus throughout life?
Some T cells continue to divide in the thymus throughout life, although the number decreases with age.
81
What are the two layers of the thymus?
The thymus consists of the cortex and the medulla.
82
What types of cells are found in the thymus?
The thymus contains T cells, dendritic cells, epithelial cells, and macrophages.
83
What is the function of T cells?
T cells are important for the immune response.
84
What role do dendritic cells play in the thymus?
Dendritic cells help in the maturation of T cells.
85
What do epithelial cells provide in the thymus?
Epithelial cells provide structure and support for T cells and produce hormones for their maturation.
86
What is the function of macrophages in the thymus?
Macrophages clear out debris and dead cells, maintaining a clean environment for T cell development.
87
What occurs in the cortex of the thymus?
The cortex is where immature T cells migrate from red bone marrow.
88
What is the function of epithelial cells in the cortex?
Epithelial cells create a supportive framework for T cells and produce hormones necessary for their maturation.
89
What is the role of macrophages in the cortex?
Macrophages help keep the cortex clean by removing dead cells and other debris.
90
What happens in the medulla of the thymus?
The medulla is where T cells become more mature.
91
What is the structure of the medulla?
The medulla contains epithelial cells arranged in concentric layers.
92
What are thymic corpuscles?
Thymic corpuscles are structures found in the medulla that may play a role in T cell regulation and function.
93
What is the summary of thymus function?
The thymus is essential for T cell development, containing T cells and supporting cells.
94
Where do immature T cells migrate for maturation?
Immature T cells move from the red bone marrow into the cortex for growth and maturation.
95
What assists T cell maturation in the cortex?
Dendritic and epithelial cells assist in T cell maturation in the cortex.
96
Where do mature T cells progress after the cortex?
Mature T cells progress to the medulla, where they further mature and can pass into the bloodstream.
97
Where are lymph nodes usually located?
Lymph nodes are usually found in clusters throughout the body.
98
What covers each lymph node?
Each lymph node is covered by a dense connective tissue capsule that protects and supports it.
99
What divides the internal structure of a lymph node?
The inside of the lymph node is divided into compartments by trabeculae, which are small, supportive tissue extensions from the capsule.
100
What are the two layers of the cortex in a lymph node organized for?
The two layers of cortex are organized for immune cells.
101
What immune cells are found in the medulla of a lymph node?
The medulla contains B cells, plasma cells, and macrophages.
102
What is the function of B cells in the lymph node?
B cells produce antibodies.
103
What do plasma cells represent in the lymph node?
Plasma cells are activated B cells.
104
What role do macrophages play in the lymph node?
Macrophages clean up debris and pathogens.
105
How does lymph flow through a lymph node?
Lymph moves through the node in one direction, ensuring efficient filtering.
106
How are the vessels arranged in a lymph node?
Several afferent vessels enter the node from one side, and there are two efferent vessels that exit from the opposite side through the hilum.
107
What is the summary of lymph node structure and function?
Lymph nodes filter lymph and house immune cells, featuring a dense outer capsule, compartments separated by trabeculae, and defined areas for B cells and macrophages. They allow lymph to flow in one direction, with multiple entry points and two exit points.
108
What do the outer cortex of lymph nodes contain?
The outer cortex contains lymphatic nodules (follicles).
109
What are primary lymphatic nodules primarily composed of?
Primary lymphatic nodules are mostly composed of B cells.
110
What are secondary lymphatic nodules and what do they form in response to?
Secondary lymphatic nodules form in response to an antigen and are sites of plasma cell and memory B cell formation.
111
What is found in the inner cortex of lymph nodes?
The inner cortex contains T cells and dendritic cells.
112
What is the role of dendritic cells in lymph nodes?
Dendritic cells present antigens to T cells, causing proliferation and migration to the body where there is antigenic activity.
113
What is the function of lymph nodes?
Lymph nodes function as a filter, trapping substances by reticular fibers in the sinuses.
114
How do macrophages and lymphocytes contribute to the immune response?
Macrophages destroy foreign substances through phagocytosis, while lymphocytes are involved in the immune response.
115
How does lymph flow through lymph nodes?
Lymph flows through multiple nodes, providing multiple points of filtration before returning to the blood.
116
What is the stroma?
The framework for functional spleen cells made from capsule, trabeculae, reticular fibres, and fibroblasts.
117
What are the two tissues of the parenchyma?
White pulp and red pulp.
118
What is the function of white pulp?
B cells and T cells carry out immune functions like lymph nodes; macrophages destroy blood pathogens.
119
What is the function of red pulp?
Removal of defective, ruptured, or worn-out blood cells (and platelets) and storage of platelets.
120
What is fetal hematopoiesis?
The process of blood cell formation in the fetus.
121
What are lymphatic nodules?
Lymphatic nodules are masses of lymphatic tissue that are not surrounded by a capsule.
122
Where are lymphatic nodules located?
They are scattered throughout the lamina propria of mucous membranes lining the gastrointestinal, urinary, and reproductive tracts and the respiratory airways.
123
What is another term for lymphatic nodules in certain areas?
Lymphatic nodules in these areas are also referred to as mucosa-associated lymphatic tissue (MALT).
124
How can lymphatic nodules be categorized?
Some are solitary, while others are aggregated, such as tonsils and Peyer’s patches in the small intestine.
125
What is the function of tonsils?
Tonsils (ring of 5) respond to inhaled or ingested foreign substances.
126
What is innate immunity?
Innate immunity refers to a wide variety of body responses that serve to protect us against invasion of a wide variety of pathogens and their toxins.
127
What does innate immunity include?
Innate immunity includes external physical and chemical barriers and internal defenses.
128
Are we born with innate immunity?
Yes, we are born with this kind of immunity.
129
What are the two lines of defense in innate immunity?
The two lines of defense are skin and mucous membranes (first line of defense) and internal defenses.
130
What is innate immunity?
Innate immunity includes both physical and chemical defenses that protect the body from pathogens.
131
What is the role of skin (epidermis) in physical defenses?
Acts as a protective barrier that prevents pathogens from entering the body.
132
What do mucous membranes do?
Line body cavities (like the respiratory and digestive tracts) and help trap and eliminate germs.
133
What is the function of mucus?
Lubricates and moistens surfaces while trapping microbes to prevent them from causing infections.
134
What are tears and saliva's role in physical defenses?
Wash away pathogens from eyes and mouth.
135
How do cilia and hairs contribute to physical defenses?
Tiny structures that help move mucus and trapped particles out of the respiratory tract.
136
What is the function of the epiglottis?
A flap that prevents food and liquids from entering the windpipe during swallowing.
137
How does urine flow help in physical defenses?
Helps flush out microbes from the urinary tract.
138
What is the role of defecating and vomiting in physical defenses?
Processes that expel harmful substances from the body.
139
What is sebum?
An oily substance on the skin that inhibits the growth of microbes and fungi.
140
What is lysozyme?
Enzymes found in tears and saliva that break down bacterial cell walls, helping to destroy bacteria.
141
What does perspiration do?
Sweat that contains antimicrobial properties to protect the skin.
142
What is gastric juice?
Acidic fluid in the stomach that destroys bacteria and other pathogens that enter the gastrointestinal tract.
143
What is the summary of physical and chemical defenses?
Physical defenses like skin and mucous membranes prevent pathogen entry, while other mechanisms like mucus, tears, and cilia help eliminate germs. Chemical defenses, including sebum and lysozyme, work to inhibit microbial growth and destroy pathogens, providing additional protection for the body.
144
What are antimicrobial substances?
They discourage microbial growth.
145
What are interferons (IFNs)?
Proteins that interfere with viral replication.
## Footnote
Types include ∝, β, and ɣ types.
146
What is the complement system?
Activated plasma proteins causing cytolysis.
147
What are iron-binding proteins?
They inhibit bacterial growth by limiting available iron.
148
What are AMPs?
Short peptides that kill microbes.
149
What is fever?
Abnormally high body temperature occurring during infection and inflammation, from bacterial toxins.
## Footnote
It intensifies interferons, inhibits microbial growth, and speeds up repair.
150
What are natural killer cells?
Natural killer cells kill a wide variety of infected body cells and some tumor cells that lack or have abnormal plasma membrane proteins.
151
What do natural killer cells release into infected cells?
Natural killer cells release granules containing toxic substances into infected cells.
152
What is perforin?
Perforin is a protein that is inserted into the membrane of target cells, causing them to burst.
153
What are granzymes?
Granzymes are protein-digesting enzymes that induce target cell apoptosis.
154
What are phagocytes?
Phagocytes include neutrophil cells and macrophages.
155
What are wandering macrophages?
Wandering macrophages are migrating enlarged monocytes.
156
What are fixed/resting macrophages?
Fixed/resting macrophages are tissue-specific macrophages.
157
What is phagocytosis?
Phagocytosis is the process by which immune cells engulf and destroy pathogens.
158
What is the first step of phagocytosis?
Chemotaxis: Phagocytes are attracted to the site of infection or damage by chemical signals.
159
What occurs during the adherence step of phagocytosis?
Phagocytes attach to the pathogen or foreign substance, facilitated by complement proteins.
160
What happens during ingestion in phagocytosis?
The phagocyte extends pseudopods to surround and engulf the pathogen, enclosing it in a phagosome.
161
What is formed during the digestion step of phagocytosis?
The phagosome merges with lysosomes to form a phagolysosome, which contains enzymes and lethal oxidants.
162
What is the role of enzymes and oxidants in phagocytosis?
They kill many types of microbes within the phagolysosome. Undigested material is stored in residual bodies.
163
What are the five steps of phagocytosis?
1. Chemotaxis 2. Adherence 3. Ingestion 4. Digestion 5. Killing
164
What does 'P' stand for in the context of tissue response?
P stands for pain from the release of chemicals.
165
What does 'R' represent in tissue response?
R represents redness due to an increase in blood flow to the affected area.
166
What does 'I' indicate in the context of tissue response?
I indicates immobility due to loss of function.
167
What does 'S' refer to in tissue response?
S refers to swelling from accumulated fluids.
168
What does 'H' signify in the context of tissue response?
H signifies heat due to increased blood flow to the area.
169
What are the three basic stages of the inflammatory response?
The three basic stages are vasodilation and increased blood vessel permeability, emigration of phagocytes, and tissue repair.
170
What is vasodilation?
Vasodilation is the widening of blood vessels, particularly arterioles, in the area of tissue damage.
171
What effect does vasodilation have?
It increases blood flow to the affected area, delivering necessary substances to help heal the tissue.
172
What is increased permeability in the context of inflammation?
Increased permeability refers to blood vessels, particularly capillaries, becoming more leaky, allowing substances to exit the bloodstream and enter surrounding tissue.
173
What are the symptoms produced by increased blood flow during inflammation?
Symptoms include heat, redness, swelling (edema), and pain.
174
What are some chemical mediators that cause vasodilation and increased permeability?
Chemical mediators include histamines, kinins, prostaglandins, leukotrienes, and complement proteins.
175
What is the role of neutrophils in the inflammatory response?
Neutrophils are the first type of white blood cells to respond, effectively killing and digesting bacteria and fungi.
176
What is the process of emigration in the inflammatory response?
Emigration is the movement of neutrophils out of blood vessels to the damaged area, guided by chemical signals.
177
What leads to pus formation during inflammation?
Pus forms from the accumulation of dead neutrophils, dead bacteria, and damaged tissue.
178
What occurs during the tissue repair stage of inflammation?
The tissue begins to repair itself, which may involve regeneration of cells or formation of scar tissue.
179
What is acute inflammation?
Acute inflammation is a short-term response that occurs immediately after injury and usually resolves quickly.
180
What is chronic inflammation?
Chronic inflammation is a prolonged response that can result from persistent infections or autoimmune diseases, potentially leading to tissue damage.
181
What is the summary of the inflammatory response?
The inflammatory response involves vasodilation and increased vessel permeability, migration of phagocytes to eliminate pathogens, and tissue repair, which can be acute or chronic.
182
What is adaptive immunity?
Adaptive immunity is the body's way of defending itself against specific pathogens that invade. It adapts and improves over time.
183
What are antigens?
Antigens are substances that the immune system recognizes as foreign. They trigger an immune response.
184
What is a key feature of adaptive immunity?
Specificity: Adaptive immunity targets specific pathogens.
185
What is another key feature of adaptive immunity?
Memory: Once the body encounters a specific pathogen, it remembers it, allowing for a faster and stronger response if it invades again.
186
What is cell-mediated immunity?
Cell-mediated immunity targets intracellular pathogens, some cancers, and transplanted tissues.
187
What are the main players in cell-mediated immunity?
Cytotoxic T cells are the main players in this type; they directly attack infected or abnormal cells.
188
What is antibody-mediated immunity?
Antibody-mediated immunity focuses on extracellular pathogens.
189
What do B cells transform into in antibody-mediated immunity?
B cells transform into plasma cells, which produce antibodies.
190
What are antibodies also called?
Antibodies are also called immunoglobulins.
191
What is the function of antibodies?
Antibodies bind to pathogens to neutralize them or mark them for destruction by other immune cells.
192
What is the summary of adaptive immunity?
Adaptive immunity is a specialized defense mechanism that targets specific invaders, using antigens to trigger responses.
193
What are the two main types of lymphocytes in the adaptive immune system?
B cells and T cells.
194
Where do B cells mature?
B cells mature in the red bone marrow.
195
Where do T cells develop?
T cells develop in the thymus.
196
Where does activation of lymphocytes occur?
Activation occurs in secondary lymphatic organs like lymph nodes and the spleen.
197
What are the two main types of mature T cells?
Cytotoxic T cells and Helper T cells.
198
What is the function of Cytotoxic T cells?
They directly attack and destroy cells that are infected with viruses or have become cancerous.
199
What is the function of Helper T cells?
They assist in activating other immune cells, including B cells and cytotoxic T cells.
200
What happens when a B cell encounters an antigen?
It can differentiate into Plasma B cells and Memory B cells.
201
What do Plasma B cells produce?
They produce antibodies that target pathogens in body fluids.
202
What are Memory B cells?
They stay in the body to provide long-term immunity against future infections from the same pathogen.
203
What is Cell-Mediated Immunity?
This involves T cells attacking infected or unhealthy cells.
204
What is Antibody-Mediated Immunity?
This involves B cells producing antibodies against pathogens found outside cells.
205
What is the summary of adaptive immunity?
Adaptive immunity relies on B and T lymphocytes, which develop in the bone marrow and thymus and are activated in secondary lymphatic tissues.
206
What is immunogenicity?
The ability to invoke an immune response by stimulating the production of specific antibodies, the production of specific T cells, or both.
207
What is reactivity?
The ability of the antigen to react specifically with the antibodies or cells it provoked.
208
What can act as antigens?
Entire microbes or just parts of microbes may act as antigens.
209
What typically triggers immune responses?
Certain small parts of a large antigen molecule act as the triggers for immune responses.
210
What are small parts of antigens called?
Epitopes.
211
What must occur for an immune response to take place?
B cells and T cells must recognize that a foreign antigen is present.
212
How do B cells recognize antigens?
B cells can recognize and bind to antigens in lymph, interstitial fluid, or blood plasma.
213
How do T cells recognize antigens?
T cells only recognize fragments of antigenic proteins that are processed and presented in a certain way.
214
What is unique about T cells?
There are millions of T cells, and each has its own unique T cell receptor (TRC).
215
What happens when an antigen enters the body?
There are only a few T cells that have TRCs that recognize and can bind to it.
216
What additional proteins are involved in T cell recognition?
Recognition also involves other surface proteins (CD4 or CD8).
217
What is the first step for helper T cells to respond to an antigen?
Helper T cells must recognize and bind to an antigen presented by an antigen-presenting cell (APC). This process is called costimulation.
218
What happens after helper T cells recognize an antigen?
A small number of T cells undergo proliferation (they multiply) and differentiate (they develop into specific types) to form a clone of effector cells.
219
What do activated helper T cells secrete?
Activated helper T cells secrete cytokines (like IL-2), which are signaling molecules that help regulate and enhance the immune response.
220
What is the outcome of the helper T cell response?
The specific antigen is targeted and ultimately eliminated from the body.
221
What is the summary of cell-mediated immunity involving helper T cells?
In cell-mediated immunity, helper T cells recognize an antigen with the help of antigen-presenting cells. They then multiply and become active cells that secrete important signaling molecules (cytokines) to help eliminate the antigen.
222
What is a neutralizing antigen?
A reaction of the antibody that blocks or neutralizes some bacterial toxin and prevents attachment of some viruses to body cells.
223
What is the effect of immobilizing bacteria?
The antigen-antibody reaction can cause a loss of motility, making it less easy for bacteria to spread.
224
What happens during agglutinating and precipitating antigens?
Binding sites can create cross-links, causing clumping or precipitating out of solution.
225
What role does activating complement play?
Antigen-antibody complexes initiate the classical pathway of the complement system.
226
How does enhancing phagocytosis work?
The stem of the antibody acts as a flag to attract phagocytes once bound to antigens.
227
What is an antigen?
An antigen is a foreign substance, like a microbe, recognized and bound by an inactive B cell.
228
What role do Helper T cells play in antibody-mediated immunity?
Helper T cells provide additional signals (co-stimulation) to the B cell, allowing it to fully activate.
229
What happens during clonal selection and differentiation of B cells?
Activated B cells undergo clonal selection, multiplying and differentiating into a clone of plasma cells.
230
What do plasma cells do?
Plasma cells produce and secrete antibodies that specifically target the recognized antigen.
231
How do antibodies help eliminate antigens?
Antibodies bind to the antigens, marking them for destruction and helping eliminate the infection from the body.
232
What is the summary of antibody-mediated immunity?
In antibody-mediated immunity, B cells recognize an antigen and become activated with help from helper T cells. They then proliferate and differentiate into plasma cells that produce antibodies to eliminate the antigen.
