Lymphatic System I Flashcards
- Carries excess interstitial fluid from tissues back to cardiovascular circulation.
- Provides locations for immune cells to monitor the body.
Lymphatic System
Take in fluids from the extracellular space and carry them through lymph nodes.
Porous Lymphatic Vessels
Where immune cells scan the fluids for foreign particles.
Lymph Nodes
Must be returned to circulation via lymphatics to maintain cardiovascular function.
Fluid
Two parts of lymphatic systems.
- Meandering Network of Lymphatic Vessels
- Various Lymphoid Tissues and Organs
Transport fluids that have escaped from the blood back to the cardiovascular system.
Lymphatic Vessels
House phagocytic cells and lymphocytes which play essential roles in body defense and resistance to disease.
Lymphoid Tissues and Organs
- Fluid that remains behind in the tissue spaces (3L daily) becomes part of the ____.
- This excess tissue fluid and any plasma proteins that escape from the blood must be carried back to the blood to have sufficient blood volume.
Interstitial Fluid
Fluid that accumulates in the tissues.
Edema or Swelling
Impairs the ability of cells to make exchanges with the interstitial fluid and ultimately the blood.
Excessive Edema
- Their function is to form an elaborate drainage system that picks up this excess interstitial fluid now called the lymph (clear water) and returns it to the blood.
- Form a one-way system where lymph moves only toward the heart.
Lymphatic Vessels or Lymphatics
- Weave between the tissue cells and blood capillaries in the loose connective tissues of the body and absorb the leaked fluid.
- Remarkably permeable that once thought to be open at one end.
Microscopic Lymph Capillaries
Edges of the endothelial cells of the lymph capillaries forming the walls loosely overlap one another, forming flaplike ____ that act as one-way swinging doors.
Minivalves
Anchored by fine collagen fibers to surrounding structures.
Flaps
The flaps gape open when the fluid pressure is higher in the ____, allowing fluid to enter the lymphatic capillary.
Interstitial Space
When the pressure is higher inside the ____, the endothelial cell flaps are forced together, preventing the lymph from leaking back out and forcing it along the vessel.
Lymphatic Vessels
Normally prevented from entering blood capillaries but they enter the lymphatic capillaries easily, particularly in inflamed areas.
- Proteins
- Cell Debris
- Bacteria
- Viruses
Cells that travel in lymph and that lymph takes detours through the lymph nodes.
White Blood Cells
Where the WBCs are cleansed of debris and examined by cells of the immune system.
Lymph Nodes
Larger lymphatic vessels where lymph is transported from the lymph capillaries until returned to the venous circulation through two large ducts in the thoracic region.
Lymphatic Collecting Vessels
Drains lymph from the right arm and the right side of the head and thorax.
Right Lymphatic Duct
Receives lymph from the rest of the body.
Large Thoracic Duct
Empty the lymph into the subclavian vein on their own side of the body.
Both Right Lymphatic Duct and Thoracic Duct
Thin walled and the larger vessels have valves.
Lymphatic Vessels
A low-pressure, pumpless system.
Lymphatic System
Transported by the same mechanisms that aid return of venous blood: milking action of the skeletal muscles and pressure changes in thorax during breathing = muscular and respiratory pumps.
Lymph
Contracts rhythmically helping to pump the lymph along.
Smooth Muscle in the Walls of the Larger Lymphatics
- Help protect the body by removing foreign material (bacteria and tumor cells) from the lymphatic stream.
- Provide a place where lymphocytes that function in the immune response can be activated.
Cells in Lymph Nodes
Three regions of the body where large clusters of lymph are found.
- Inguinal
- Axillary
- Cervical
As lymph is transported toward the heart, it is filtered through thousands of ____.
Lymph Nodes
- Located within the lymph nodes.
- Engulf and destroy bacteria, viruses, and other foreign substances in the lymph before it is returned to the blood.
Macrophages
Type of WBC located in the lymph nodes and respond to foreign substances in the lymphatic stream.
Lymphocytes
- Vary in shape and size but most are kidney-shaped, about 1 cm long, buried in the connective tissue that surrounds them.
- Each is surrounded by a fibrous capsule.
Lymph Nodes
Connective tissue strands that extend inward to divide the node into a number of compartments.
Trabeculae
Outer part of the node that contains follicles.
Cortex
Collection of lymphocytes.
Follicles
- Many follicles that have dark-staining centers.
- Enlarge when specific B lymphocytes (B Cells) are generating daughter cells (plasma cells) that release antibodies.
Germinal Centers
Inward extensions of cortical tissue that contain both B and T cells.
Medullary Cords
Where phagocytic macrophages are located.
Central Medulla
- Referred to the Peyer’s patches, appendix, and tonsils that are part of this collection of small lymphoid tissues.
- Act as a sentinel to protect the upper respiratory and digestive tracts from the constant attacks of foreign matter entering the cavities.
Mucosa-Associated Lymphoid Tissues
Two types of mechanisms that defend the body against enemies that make up the immune system.
Innate and Adaptive Defense Mechanisms
- Responds immediately to protect the body from all foreign substances.
- Humans are born with these defenses.
- Reduce the workload of the adaptive defense mechanisms by generally preventing the entry and spread of microorganisms.
Innate Defense System or Nonspecific Defense System
- Fights invaders that get past innate defenses by mounting an attack against one or more particular foreign substances.
- Must first meet an initial exposure to a foreign substance (antigen) before it can protect the body against the invader.
- Remembers which invaders it has fought as it has both specificity and memory.
Adaptive Defense System or Specific Defense System
Resulting highly specific resistance to disease.
Immunity
Refers to the mechanical barriers that cover body surfaces and to the cells and chemicals that act on the initial battlefronts to protect the body from invading pathogens.
Body Defense
Nonspecific response that is triggered whenever body tissues are injured.
Inflammatory Response
Four most common indicators (cardinal signs) of acute inflammation.
- Redness
- Heat
- Pain
- Swelling
Inflammatory chemicals released when cells are damaged that cause:
* Blood vessels in the area to dilate.
* Make capillaries leaky.
* Attract phagocytes and white blood cells to the area.
Histamine and Kinins
Enhances the innate defenses either by attacking microorganisms directly or by hindering their ability to reproduce.
Antimicrobial Proteins
Refers to a group of at least 20 plasma proteins that circulate in the blood in an inactive state.
Complement
- Abnormally high body temperature.
- A systemic response to invading microorganisms.
Fever
Any substance capable of provoking an immune response.
Antigen
- Produce antibodies and oversee humoral immunity.
- Can target specific extracellular antigens.
B Lymphocytes or B Cells
- Constitute the cell-mediated arm of the adaptive defenses and do not make antibodies.
- Can recognize and eliminate specific virus-infected or tumor cells.
T Lymphocytes or T Cells
- Also referred to as immunoglobulins.
- Constitute the gamma globulin part of blood proteins.
- Soluble proteins secreted by activated B cells or by their plasma-cell offspring in response to an antigen.
- Capable of binding specifically with that antigen.
Antibodies
Occurs where antibodies bind to specific sites on bacterial exotoxins or on viruses that can cause cell injury.
Neutralization
A process that causes clumping of foreign cells.
Agglutination
Chemicals released by macrophages and dendritic cells that play important roles in immune response.
Cytokines
Specialized in killing virus-infected, cancer, or foreign graft cells directly.
Cytotoxic T Cells
Release chemicals that suppress the activity of both B and T cells.
Regulatory T Cells
