The Lymphatic System and Immunity Flashcards
(162 cards)
1
Q
Pathogens
A
Disease-causing organism
2
Q
Immunity
A
The ability to resist infection and disease
3
Q
Lymphatic vessels
A
Carry lymph from peripheral tissues to the venous system
4
Q
Lymph
A
Interstitial fluid that has entered lymphatic vessels
5
Q
How do lymphatic capillaries differ from blood capillaries?
A
Lymphatic capillaries:
- Closed at one end
- Have larger luminal diameters
- Have thinner walls
6
Q
What lines lymphatic capillaries?
A
Endothelial cells but the basement membrane is incomplete or absent
7
Q
Lymphatic system
A
- Lymph
- Lymphatic vessels
- Lymphoid tissues and organs
- Lymphoid cells
8
Q
Small lymphatic vessels
A
- 3 layers
- Valves that help lymph move since limited pressure
9
Q
Two sets of lymphatic vessels
A
Superficial lymphatics and deep lymphatics
10
Q
Deep lymphatics
A
Larger lymphatic vessels that accompany deep arteries and veins supplying skeletal muscles and other organs of the neck, limbs, and trunk and the walls of the visceral organs
11
Q
Superficial lymphatics
A
In subcutaneous layer
12
Q
Lymphatic trunks
A
Convergence of superficial and deep lymphatics
13
Q
Thoracic duct
A
Collects lymph from the lower body and upper right body
14
Q
Right lymphatic duct
A
Collects lymph from upper right side
15
Q
Cisterna chyli
A
Saclike chamber that receives lymph from the inferior part of the abdomen, pelvis, and lower limbs
16
Q
Lymphedema
A
Obstruction of lymphatic vessels
17
Q
Lymphoid cells
A
Consist of immune cells found in lymphoid tissues and the cells that support those tissues
18
Q
Phagocytes
A
Macrophages and microphages
19
Q
Lymphocytes
A
Respond to specific invading pathogens, abnormal body cells and foreign proteins
20
Q
Classes of lymphocytes
A
- T cells
- B cells
- NK cells
21
Q
Lymphoid tissues
A
Connective tissues dominated by lymphocytes
22
Q
Lymphoid nodule
A
The lymphocytes are densely packed in an areolar tissue
23
Q
Tonsils
A
Large lymphoid nodules in the walls of the pharynx
24
Q
Pharyngeal tonsils, adenoid
A
Lies in the posterior superior wall of the nasopharynx
25
Palatine tonsils
Left and right palatine tonsils are located at the posterior, inferior margin of the oral cavity
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Lingual tonsils
Lie deep to the mucous epithelium covering the base of the tongue
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Tonsilitis
Inflammation of the tonsils, especially palatine tonsils
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Mucosa-associated lymphoid tissue (MALT)
Collection of lymphoid tissue that protect the epithelia of the digestive, respiratory, urinary and reproductive systems
29
Aggregated lymphoid nodules
Cluster of lymphoid nodules deep to the epithelial lining of the intestines
30
Lymphoid organs
Lymph nodes, thymus and spleen
31
What covers each lymph node?
A dense connective tissue capsule
32
Trabeculae
Bundles of collagen fibres that extend from the capsule into the interior of the node
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Hilum
Shallow indentation
34
Afferent lymphatics
- Bring lymph to the lymph node from peripheral tissues
| - Opposite the hilum
35
Efferent lymphatics
- Leave the lymph node at the hilum
| - Carry lymph away from the lymph node towards venous circulation
36
Lymph flow
Subcapsular space > cortex > paracortex > medulla > sinuses > efferent lymphatics
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Subcapsular space
Contains a meshwork of branching reticular fibers, macrophages and dendritic cells
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Cortex
Periphery of cortex contains B cells with germinal centres
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Paracortex
- Dominated by T cells
| - Where lymphocytes leave blood stream and enter lymph node
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Medulla
Contains B cells and macrophages
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Lymph node function
Filters lymph before it reaches veins
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Septa
Fibrous partitions that divide lobes into lobules
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Lobule
Consists of an outer cortex densely packed with lymphocytes and a medulla
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Lymphocytes in the cortex of the lobule
Form thymic corpuscules
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Function of the thymus
- The cortex contains actively diving T cells > medulla > medullary blood vessel > blood stream
- Epithelial reticular cells maintain blood thymus barrier
46
Which organ contains the largest collection of lymphoid tissue in the body?
Spleen
47
Functions of spleen
1. Removing abnormal blood cells
2. Storing iron recycled from RBCs
3. Initiating immune responses by B and T cells
48
Gastrosplenic ligament
Attaches stomach to spleen
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Hilum
Groove marking the border between the gastric and renal areas
50
Red pulp
Contains large quantities of RBCs
51
White pulp
Resembles lymphoid nodules
52
Trabecular arteries
Splenic artery > trabecular arteries > smaller (surrounded by white pulp) > discharge blood into red pulp
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Cell population of red pulp
Normal components of circulating blood
| Fixed and free macrophages
54
Trabecular veins
Reticular fibres > sinusoids > small veins > trabecular veins
55
Why is the spleen difficult to repair?
Sutures tear out before they have been tensed enough to stop bleeding
56
Immune response
The body's reaction to infectious agents and other abnormal substances
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Resistance
The ability of the body to maintain its immunity
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2 types of immunity
1. Innate (nonspecific) immunity
| 2. Adaptive (specific) immunity
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Innate (nonspecific) immunity
- Physical barriers and internal defence processes that we are born with
- Nonspecific: doesn't distinguish
- NK cells
60
Adaptive (specific) immunity
- T cells and B cells
| - Specific/particular
61
What are most lymphocytes?
T cells
62
Lymphocytopoiesis
Hemocytoblasts divide in red bone marrow > lymphoid stem cells produced
Red bone marrow > B cells and NK cells
Thymus > T cells
63
Innate defenses
1. Physical defences
2. Phagocytes
3. Immune surveillance
4. Interferons
5. Complement
6. Inflammation
7. Fever
64
Physical defenses
Epithelia of skin and mucous membrane, secretions and hairs
65
Phagocytes
Remove cellular debris and respond to invasion by foreign substances or pathogens
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Microphages
- Neutrophils: phagocytize cellular debris or bacteria
| - Eosinophils: target foreign substances coated with antibodies
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Macrophage functions
1. Engulf pathogens
2. Binds to or removes pathogen with help
3. Releasing chemicals
68
Fixed macrophages
Reside in specific tissues or organs
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Free macrophages
Travel throughout the body
70
Chemotaxis
Free macrophages and microphages attracted to or repelled to surrounding fluids
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Adhesions
Free macrophages and microphages begin with adhesion
When phagocytes attach to their target
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Immune surveillance
NK cells continual policing peripheral tissues
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NK cells
1. Recognition and adhesion
2. Realignment of golgi apparatus - trans face points towards abnormal cell, golgi appartus creates perforin
3. Secretion of perforin
4. Lysis of abnormal cells
74
Tumour-specific antigens
In the plasma membrane of cancer cells
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Immunological escape
When abnormal cells avoid detection or neutralise body defenses
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Interferons (IFNs)
Small proteins released by activated lymphocytes and macrophages and by tissue cells infected with viruses
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Interferons process
Interferons bind to surface receptors on the membrane of a normal cell and by second messengers, triggers the production of antiviral proteins
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Antiviral proteins
Interferon with viral replication inside the cell
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Interferon alpha
Produced by cells infected with viruses
| Attracts and stimulates NK cells and enhances resistance to viral infection
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Interferon beta
Secreted by fibroblasts and slows inflammation in a damaged area
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Interferon gamma
Secreted by T cells and NK cells and stimulates macrophage activity
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Cytokines
Chemicals that tissue cells release to coordinate local activities
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Classical pathway
Most effective activation of the complement system
1. Antibodies bind to bacterial cell wall
2. Attachment of C1 to 2 antibodies
3. Activation and cascade
4. C3b binds to cell wall and enhances phagocytosis
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Lectin pathway
Activated by protein MBL which binds to carbohydrates on bacterial surfaces
1. Lectin binds to bacterial cell wall
2. C3 activation
3. C3b binds to bacterial surface and enhances phagocytosis
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Alternative pathway
Important in the defence against bacteria, some parasites and virus-infected cells
1. Complement proteins interact in plasma
2. C3b protein binds to the bacterial cell wall
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Complement activation causes
1. Cell lysis (MAC)
2. Opsonisation (enhancement of phagocytosis)
3. Inflammation (histamine release)
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Inflammation
Localised tissue response to injury
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Cardinal signs and symptoms of inflammation
Local redness, swelling, heat and pain
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Mast cells
Release histamine, heparin and prostaglandins
90
Inflammation and steps in tissue repair
1. Tissue damage, chemical change in interstitial fluid
2. Mast cells
3. Cardinal signs of inflammation, phagocyte attraction > release of cytokines
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Nercorsis
Tissue destruction after cells have been injured or destroyed
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Abscess
Accumulation of pus in an enclosed tissue
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Fever
Body temperature greater than 37.2 degrees, 99 F
94
Pryogens
Fever-inducing agents
95
Benefits of fever
Higher metabolic rate
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Adaptive immunity lymphocytes
1. Cytotoxic T cells
2. Helper T cells
3. Regulatory T cells
4. Memory T cells
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Cytotoxic T cells
Involved in direct cellular attack
| Enter peripheral tissues and attack antigens physically and chemically
98
Helper T cells
Stimulate the response of both T and B cells
99
What is largely responsible for the loss of immunity in AIDS?
Reduction in helper T cells
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Regulatory T cells
Subset of T cels that moderate the immune response
101
Memory T cells
Respond to antigens they have already encountered by cloning lymphocytes
102
Cell mediated immunity
Cytotoxic T cells
103
Antibody-mediated immunity
B cells
104
What triggers the immune response?
Specific antigens
105
What are most antigens?
Pathogens, parts or products of pathogens or foreign substances
Usually proteins
106
When does a lymphocyte become activated?
When it has contact with an appropriate antigen
107
What happens to an activated lymphocyte?
It begins to divide, producing more lymphocytes with the same specificity
108
Clone
All the identical cells produced by lymphocyte divisions
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Clonal selection
Process of an antigen selecting particular lymphocytes for cloning
110
Active immunity
Develops after exposure to an antigen
| Body responds to to antigen by making its own antibody
111
Naturally acquired active immunity
Normally begins to develop after birth
112
Artificially acquired active immunity
Stimulates the body to produce antibodies under controlled conditions
113
Passive immunity
Produced by transferring antibodies from another source
114
Naturally acquired passive immunity
A baby receives antibodies from the mother during gestation or through breast milk
115
Artificially acquired passive immunity
Person receives antibodies to fight infection or prevent disease
116
Properties of adaptive immunity
1. Specificity
2. Versatility
3. Memory
4. Tolerance
117
Specific defence
Activated by specific antigens
| The immune response targets that particular antigens and no others
118
Specificity
Results from activation of appropriate lymphocytes and the production of antibodies with targeted effects
119
How does specificity occur?
T cells and B cells respond to the molecular structure of an antigen
120
Versatility
Diversity of lymphocytes present in the body
121
Memory
Lymphocyte divisions produce two groups of cells
One group attacks the invader immediately
Another group remains inactive unless it meets the same antigen at a later date
122
Tolerance
Tolerance towards self-antigens
123
MHC proteins
Membrane glycoproteins
124
Antigen presentation
Occurs when an antigen-MHC protein combination capable of activating T cells appear in the plasma membrane
125
Classes of MHC
Class I: In all nucleated body cells
| Class II: Present only in plasma membranes of antigen-presenting cells and lymphoctes
126
Antigen-presenting cells
Engulf and break down pathogens or foreign antigens
127
Antigen processing
Creates fragments of the antigen which are then bound to class II MHC proteins and inserted into the plasma membrane
128
Antigen recognition
Lymphocytes respond to an antigen bound to either a class I or a class II MHC protein
129
What determines whether a T cell responds to antigens held in class I or class II MHC proteins?
The structure of the T cell plasma membrane: CD markers
130
CD3 markers
Present on all T cells
131
CD8 markers
Present on cytotoxic and regulatory T cells
class I MHC
132
CD4 markers
Present on all helper T cells
class II MHC
133
2 types of CD8 cells
1. Responds quickly to a class I MHC-bound antigen, producing cytotoxic T cells and memory T cells
2. Responds slowly, producing small number of regulatory T cells
134
Cytotoxic T cells
1. Release perforins
2. Release cytokines
3. Secrete lymphotoxin
135
Cell mediated immunity
```
Results from activation of CD8 cells by antigens bound to class I MHCs
T cells divide to generate cytotoxic T cells and memory T cells
```
136
Helper T cells
```
Respond to antigens presented by class II MHC proteins
When activated, helper T cells secrete cytookines
```
137
Cytokines
Chemical messengers coordinated by the immune system
138
Interleukins
1. Increase T cell sensitivity to antigen exposed on macrophage membranes
2. Stimulate B cell activity
3. Plasma cell formation, ant antibody production
4. Enhance innate defenses
5. Moderate immune response
139
Interferons (IFNs)
Slow the spread of the virus making the synthesising cell and its neighbours resistant to viral infection
140
Tumour necrosis factors (TFNs)
Slow tumour growth and kill tumour cells, and act as pyrogens
141
Colony stimulating factors (CSFs)
Factors produced by active T cells, cells of the monocyte-macrophage group, endothelial cells, and fibroblasts
142
B cell sensitisation
Antibody molecules in their plasma membrane bind antigens. The antigens are then displayed on the class II MHC proteins of the B cells which become activated by helper T cells activated by the same antigen
143
What does an active B cell differentiate into?
A plasma cell or they produce daughter cells that differentiate plasma cells and memory B cells. Antibodies are produced by plasma cells
144
Y-shaped antibody molecule
Consists of two parallel pairs of polypeptide chains containing constant and variable segments
145
Classes of immunoglobulins
1. IgG
2. IgE
3. IgD
4. IgM
5. IgA
146
IgG
Responsible for resistance against many viruses, bacteria, bacterial toxins
147
IgE
Releases chemicals that accelerate local inflammation
148
IgD
Located on the surfaces of B cells
149
IgM
First type of antibody secreted after an antigen arrives
150
IgA
Found in glandular secretions
151
Antigen-antibody complex
When antibody molecules bind to an antigen
152
Neutralisation
Antibody binding that prevents viruses or bacterial toxins from binding to body cells
153
Precipitation
Forming of an insoluble immune complex
154
Aggltiniation
Formation of large complexes
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Primary response
Antibodies first produced by plasma cells in humoral immunity
156
Secondary response
Maximum antibody level after second exposure to antigen
157
Immunocompetence
The ability to produce an immune response after exposure to an antigen
158
Hypersensitivites
Allergies, excessive immune responses to allergens
159
4 types of allergies
1. Immediate hypersensitivity
2. Cytotoxic reactions
3. Immune complex disorders
4. Delayed hypersensitivity
160
Anaphalaxis
When a circulating allergen affects mast cells throughout the body
161
Autoimmune disorders
Develop when an immune response inappropriately targets normal body cells and tissues
162
Immunodeficiency disease
The immune system does not develop normally or the immune response is blocked
