Lymphatic System II Flashcards
- Starts when a pathogen penetrates the surface of the body as it enters.
- Limit the spread of pathogens through the body by taking an approach for pathogen elimination.
- Fast acting and nonspecific.
- Provide crude protection against any and all pathogens that enter the body.
- Second line of defense.
Immune System
Five lines of innate internal defense.
- Phagocytic Cells
- Natural Killer Cells
- Antimicrobial Proteins
- Inflammation
- Fever
Primarily neutrophils and macrophages.
Phagocytic Cells
- Kill body cells that have turned crater: either become virus-infected or cancerous.
- Contains granules in cytoplasm.
- AKA “Large granular lymphocytes.”
- Unusual as these are types of lymphocytes but involved in innate immunity.
- Make up 10% to 15% of lymphocytes circulating in the blood.
- Attack transplanted tissues.
- Plays the role of the rejection of transplanted organs.
Natural Killer Cells
Natural killer cells as similar to T Cells: Kill the body’s own cells under two circumstances.
- Cells have been invaded by intracellular pathogens.
- Cells have become cancerous.
Natural killer cells as similar to macrophages: They become more effective in killing if there is.
- An activation by the cytokines from certain T cells.
- Coating of cells with antibody making them a better target for phagocytes.
Recognizes abnormal cells by looking into different characteristics.
Immune Surveillance
- Does not involve cells.
- Complement and interferons.
Antimicrobial Proteins
- Members of a larger group of cytokines that modulate the immune system.
- Interfere with viral replication.
- Modulate inflammation.
- Activate immune cells.
- Binds to plasma membrane receptors on nearby cells as warning signals for the virus penetration.
Interferons
- Viruses must enter cells to ____.
- Penetrates the target’s membrane then releases ____ to make more copies of the virus.
- The presence of the virus inside the cell causes the ____.
- Replicate
- Nucleic Acids
- Secretion of Interferons
Uninfected cells produce proteins that inhibit viral replication by.
- Degrading viral RNA
- Preventing the synthesis of viral proteins
Three types that are distinct proteins but have common and unique functions.
- Alpha Interferon
- Beta Interferon
- Gamma Interferon
Act in a variety of ways to signal other immune and non-immune cells.
Gamma Interferon
- Complements or enhances other components of both innate and adaptive defenses.
- Complex cascade of interdependent plasma proteins.
Complement System
As a protein is activated, it becomes an enzyme to activate the next proteins until the final product is formed. These proteins can:
- Mark cells for phagocytosis.
- Promote inflammation.
- Kill some bacteria all by themselves.
When innate defenses are overwhelmed with pathogen invasion, it sends chemical messages along the ____.
Adaptive Immune System
- Ingest pathogens.
- Use special membrane receptors to recognize pathogens.
Phagocytes
When phagocytes recognize a pathogen, two events are triggered:
* Ingestion of ____.
* Release of ____ that mobilize other cells of innate and adaptive immunity.
- Pathogen
- Chemical Alarm Signals
Enhances phagocytosis.
Opsonization
Factors that can act as opsonins.
- Antibodies
- Complement
Pathogens escape destruction by phagocytes through:
* Secreting molecules that block the ____ with the phagosome.
* Developing resistance to the effects of ____ and ____.
* Finding ways to escape the phagosome, take up residence, and replicate within the ____ of the phagocyte.
- Fusion of Lysosomes
- Lysosomal Enzymes and Reactive Oxygen Intermediates
- Cytoplasm
- Bacterium that causes Tuberculosis.
- Known for its ability to hide out and replicate inside macrophages.
Tuberculosis Bacterium
- Can enhance the entire killing process inside the macrophage.
- This enhancement only happens when the macrophage presents antigen from such bacteria.
T-Cells
Example of an interaction between innate and adaptive defenses.
Interaction between Phagocytes and T-Cells.
Distributed throughout the body points where pathogens can most easily gain entry.
* Particular points: respiratory and digestive tract mucosae.
Immune System
Two major anatomical parts of the immune system.
- Specialized Immune Cells
- Lymphoid Tissues and Organs
Mostly leukocytes (WBCs) and their close relatives.
Specialized Immune Cells
- Including bone marrow, lymph nodes, spleen, and thymus.
- Sites where lymphocytes are produced, reside, and come in contact with pathogens.
Lymphoid Organs and Tissues
- Originates in the bone marrow.
- Some cells migrate to tissues or circulate through the blood and lymphatic system and enter tissues when needed.
Cells of Immune System
- Term for immune cells that travel in the blood.
- Traditionally classified according to their shape and the colors of their granule (if stained with histological dyes).
Leukocytes
Types of leukocytes (from most to least common).
- Neutrophil
- Lymphocyte
- Monocyte
- Eosinophil
- Basophil
- Has a multi-lobed nucleus.
- Pale-staining granules.
- Most common leukocyte.
- Use the process of phagocytosis which destroys pathogens.
Neutrophil
- Has rounded nucleus and no prominent granules.
- Smaller than monocytes.
- Includes B Cells and T Cells.
Lymphocyte
- Turn into macrophages when entered into a tissue.
- Large cells that have a U-shaped nucleus and do not have prominent granules.
Monocyte
- Has bi-lobed nucleus.
- Has prominent red-staining cytoplasmic granules containing enzymes.
- Fight parasites (worms) by releasing digestive enzymes to them.
- Contribute to allergies (asthma).
Eosinophil
- Has blue-staining granules.
- Make up less than 1% of circulating leukocytes.
- Contain chemicals that mediate inflammation (histamine).
Basophil
- Eating cell.
- Engulf and destroy pathogens, dead cells, and debris.
Phagocytes
- Process and present antigens to T Cells.
- Commonly found in lymphoid organs and tissues.
Antigen-Presenting Cells (APCs)
Three types of cells that can present antigens.
- Dendritic Cells
- Macrophages
- B Cells
- Capture antigens in the periphery.
- Migrate to lymph nodes.
- Present these antigens to T cells.
Dendritic Cells
In adaptive community: B cells and T cells.
Effector Cells
Mostly leukocytes and some non-leukocytes.
Other Cells
Perform other functions in host defenses.
Mast Cells
- Key component of adaptive immunity.
- Originates in the bone marrow.
Leukocytes
Cells that mature in the bone marrow.
B Cells
Cells that mature in the thymus.
T Cells
Two primary lymphoid organs.
Bone Marrow and Thymus
- Where lymphocytes contact pathogens and the site for activation.
- Located at potential sites of invasion.
- House macrophages and other immune system cells.
Secondary Lymphoid Organs
Five secondary lymphoid organs.
- Lymph Nodes
- Spleen
- Peyer’s Patches (small intestine)
- Appendix
- Tonsils
Overlaps in structure and functions with the immune system.
Lymphatic System
Three parts of the lymphatic system.
- Lymphatic Vessels: One-way system of vessels
- Lymph: Fluid in lymphatic vessels
- Lymph nodes
Collect excess interstitial fluid that leaves capillaries and accumulates in tissues.
Lymphatic Capillaries
- Drained by lymphatic capillaries into larger lymph vessels.
- Filtered through lymph nodes to remove antigens.
- Returned to the circulatory system.
Interstitial Fluid
- If not functioning properly, fluid builds up in tissues (Lymphedema) resulting in an inefficient delivery of antigens to the lymph nodes.
- Affected tissues are at increased risk of uncontrolled infection.
Lymphatic Vessels
- The ____ weave through the blood capillary beds of loose connective tissue.
- They are blind sacs (closed tubes) formed by overlapping endothelial cells.
- The overlapping endothelial cells are supported by collagen filaments that anchor the cells to the surrounding matrix.
Flow of Lymph
Lymph Capillaries
- As fluid builds up in the tissue, the ____ of the endothelial cells open and the fluid enters the capillary.
- Overlapping endothelial cells act as one-way valves.
Flow of Lymph
Overlapping Flaps
____ can also enter the lymphatics from the tissues and be transported to nearby lymph nodes.
Flow of Lymph
- Plasma Proteins
- Pathogens
- Antigens
- Dendritic Cells
- Lymph capillaries lead into ____ which contain one-way valves.
- Interspersed between segments of larger lymph vessels are the lymph nodes.
- Lymph filters through the nodes and is cleansed of antigens and pathogens by phagocytes.
Flow of Lymph
Larger Lymph Vessels
Lymph is funneled into successively larger lymphatic vessels until it finally drains into the circulatory system at the ____.
Flow of Lymph
Large Neck Veins
____ excess tissue fluid and any leaked proteins to the blood.
Functions of lymphatic vessels
Return
Transport pathogens, antigens, and dendritic cells from the tissues to the ____.
Functions of lymphatic vessels
Lymph Nodes
Transport absorbed fat to the blood via special lymphatic capillaries in the intestine called ____.
Functions of lymphatic vessels
Lacteals
Together with the ____ and the ____ form the lymphatic system, important for body defenses.
Functions of lymphatic vessels
Lymph and Lymph Nodes
Small, oval or bean-shaped secondary lymphoid organs arrayed along lymphatic vessels.
Lymph Nodes
Clusters of lymph nodes are found where several lymphatic vessels converge.
- Inguinal Region
- Axillary Region
- Cervical Region
Filter the lymph by removing ____ and other ____.
Functions of Lymph Nodes
Antigens and Debris
- Provide sites for the activation of ____ cells by antigens.
- These interactions generate immune responses.
Functions of Lymph Nodes
B and T Cells
- Carry lymph into a lymph node.
- Carry antigen-containing lymph from the tissues into the node.
- Several of these feed into a single node on its convex side.
Afferent Lymphatic Vessels
- Carry lymph away from a lymph node.
- There are fewer of these vessels per node.
- Stows the flow of lymph through the node, allowing for more thorough cleansing as lymph percolates through passages lined with dendritic cells, lymphocytes and macrophages.
- Lymph is filtered by several nodes before it is emptied into the venous circulation.
Efferent Lymphatic Vessels
- Covered by a dense connective tissue capsule.
- Separated into sections by the bundles of collagen fibers that extend from the capsule into the node.
Structure of Lymph Node
Trabeculae
- First of a series of sinuses, interconnected dilated channels, through which the lymph flows as it passes through the lymph node.
- Lymph from the afferent lymphatic vessels empties here and then flows into sinuses in the outer cortex.
Structure of Lymph Node
Subcapsular Sinus
B cells are found organized into oval-shaped lymphoid follicles in here.
Structure of Lymph Node
Outer Cortex
Follicles that contain lighter-staining central areas; formed by B cells proliferating in response to antigen.
Structure of Lymph Node: Outer Cortex
Germinal Center
Where lymphocytes exit blood vessels and enter lymph nodes.
Structure of Lymph Node
Deep Cortex
Encounter antigens presented by dendritic cells.
Structure of Lymph Node: Deep Cortex
T Cells
Shaped into elongated masses of cells called medullary cords.
Structure of Lymph Node
Central Medulla
- Elongated masses of cells.
- Contain both types of lymphocytes as well as macrophages and plasma cells, which are derived from B cells.
Structure of Lymph Node
Medullary Cords
Shallow indentation where efferent lymphatic vessels and blood vessels are found.
Structure of Lymph Node
Hilum
- High vascular organ because it cleans the blood.
- Fist-sized, blood-rich organ located to the left of and dorsal to the stomach.
- Performs the same cleansing function for the blood as the lymph nodes do for the lymph.
- Removes pathogens, aged erythrocytes, and platelets from the blood.
- Stores platelets and breakdown products of erythrocytes.
- Provides a site for the interaction of lymphocytes with antigens.
- Allows intimate contact between blood and lymphocytes.
Spleen
Multiple branches of the splenic artery and vein enter and leave the spleen at the ____.
Hilum
Just like the lymph nodes, the spleen is surrounded by a ____.
Fibrous Capsule
Fibrous capsule has extensions of connective tissue called ____.
Trabeculae
Most of the spleen is made of ____, which looks dark in fresh splenic tissue.
Red Pulp
Sites where filtering and processing of red blood cells and pathogens occur.
Areas of Red Pulp
Lighter colored islands of white pulp surround the ____.
Central Arteries
Made up of collections of lymphocytes.
White Pulp
A red blood cell through the spleen.
- Blood enters the spleen through multiple branches of the splenic artery.
- The branches divide further, eventually forming central arteries surrounded by white pulp.
- The central arteries divide further into smaller arterioles that carry blood deeper into the red pulp of the spleen.
- Blood leaves the arterioles and filters directly into the red pulp.
- The red pulp consists of a network of reticular fibers studded with fibroblasts and macrophages, called the splenic cords.
- Blood trickles through the spaces within these cords and squeezes into the venous sinusoids, thus returning to the venous circulation.
- Macrophages recognize and remove aged erythrocytes and platelets. In addition, older erythrocytes often break into fragments while squeezing into the sinusoids.
- These fragments are then cleaned up by the splenic macrophages.
In stained splenic tissue, the white pulp actually looks ____ than the red pulp because of the many darkly staining nuclei of densely packed lymphocytes.
Darker
The white pulp consists of ____ cells.
B and T Cells
Mostly in follicles, some of which have lighter-staining germinal centers.
B Cells
B and T cells wander through the white pulp where they encounter their ____.
Antigens
Primarily responsible for removing old erythrocytes.
Red Pulp
Site of immune interactions between antigens and lymphocytes.
White Pulp
- Guards the mucosae.
- Collections of lymphoid tissue.
- Distributed throughout the mucosa.
- Inclusion: tonsils, appendix, and Peyer’s Patches (small intestine).
- Includes diffuse collections of cells in respiratory and other mucosae.
- Consists of unencapsulated or partially encapsulated collections of lymphocytes.
- Contains both B cells (in follicles) and T cells.
Mucosa-Associated Lymphoid Tissues (MALT)
The ____ of the digestive tract, respiratory tract, and genitourinary systems are vulnerable to invasion by pathogens because they are exposed to the external environment.
Mucosal Surfaces
____ tonsils found at the posterior end of the oral cavity.
Two Palatine
Embedded in the wall of the nasopharynx.
Pharyngeal Tonsil (Adenoids)
Collection of lymphoid nodules at the base of the tongue.
Lingual Tonsil
- Trap microorganisms that enter the body through the oral or nasal cavities.
- Can become overwhelmed by bacteria, becoming sites that harbor, rather than kill the organisms.
Tonsils
Carried deep into the tonsils via the crypts, stimulate an immune response and lead to the formation of abundant germinal centers.
Microorganisms