Lymphatic and Immune System

A comprehensive set of practice flashcards reviewing the lymphatic pathways, fluid dynamics, organs, leukocytes, and innate versus adaptive immune responses from Lesson 6.

What is the definition of the lymphatic system?

A vast collection of cells and biochemicals that travel in lymphatic vessels, along with the organs and glands that produce them.

What are the three important functions performed by the lymphatic system?

1. Return of interstitial fluid to the bloodstream
2. Lipid absorption
3. Defense against disease

Why is the immune system closely linked with the lymphatic system?

Because many cells that belong to the lymphatic system provide defense against disease as well as immunity against future infection.

What are lymphatic capillaries, and what role do they play in lymphatic pathways?

Microscopic, closed-ended tubes extending into interstitial spaces that receive tissue fluid through their thin walls.

How are lymphatic vessels formed, and what feature prevents the backflow of lymph?

They are formed by the merging of lymphatic capillaries; they resemble thin-walled veins and possess valves that prevent backflow.

What is the function of lymphatic trunks?

They drain lymph from large regions of the body.

Into which major veins do the two lymphatic collecting ducts empty?

The subclavian veins (the right lymphatic duct drains into the right subclavian vein, and the thoracic duct drains into the left subclavian vein).

Based on the drainage map, which body areas are drained by the right lymphatic duct versus the thoracic duct?

The right lymphatic duct drains the upper right quadrant of the body (right side of head, neck, thorax, and right arm). The thoracic duct drains the rest of the body (entire left side and both lower extremities).

Where does tissue fluid originate, and what is its general composition?

It originates from plasma that has filtered through blood capillary walls; it contains water and dissolved substances, generally lacking large proteins but containing smaller filtered proteins.

What physiological mechanism drives tissue fluid into lymphatic capillaries to become lymph?

Increasing hydrostatic pressure in the interstitial spaces forces tissue fluid through the thin walls of lymphatic capillaries.

What are the three sequential fluid compartments that represent the formation of lymph?

Plasma (in blood vessels) $\rightarrow$ Interstitial Fluid (in interstitial/intercellular spaces) $\rightarrow$ Lymph (in lymphatic capillaries).

What external forces help drive lymph flow under low hydrostatic pressure?

Contraction of skeletal muscles, contraction of smooth muscle in the walls of large lymphatic trunks, and low thoracic pressure created by breathing movements.

What condition results when the normal flow of lymph is obstructed or interfered with?

Edema (swelling due to the accumulation of excess tissue fluid).

What are three major functions of lymph?

1. Absorbing and transporting lipids via lacteals in the small intestine
2. Returning small protein molecules and fluid to the bloodstream
3. Transporting foreign particles to lymph nodes

Which white blood cells are classified as granulocytes, and which are classified as agranulocytes?

Granulocytes include neutrophils, eosinophils, and basophils. Agranulocytes include monocytes and lymphocytes.

What is the primary role of neutrophils in the immune defense?

They are the first responders to bacterial or viral infections and actively participate in phagocytosis.

What are the specific roles of eosinophils and basophils?

Eosinophils fight against parasitic infections and participate in allergic symptoms; basophils produce inflammatory and allergic reactions and play a role in asthma.

What are the primary functions of monocytes in the body?

They clean up dead cells, fight off bacteria, viruses, and fungi, and differentiate into macrophages.

What is Mucosa-Associated Lymphoid Tissue (MALT)?

A diffuse system of small concentrations of lymphoid tissue found in various submucosal membranes, including the gastrointestinal tract, nasopharynx, thyroid, breast, lung, salivary glands, eye, and skin.

What are Peyer's patches and where are they situated?

Small masses of lymphatic tissue found throughout the ileum of the small intestine that monitor intestinal bacteria and prevent pathogenic bacterial overgrowth.

What role does bone marrow play as a lymphatic tissue/organ?

It serves as a primary lymphoid organ that generates lymphocytes from immature hematopoietic progenitor cells.

What is the structural organization of a lymph node?

Bean-shaped structures enclosed in connective tissue that extends inward to subdivide them into nodules containing masses of lymphocytes, macrophages, and spaces for lymph flow.

What are the primary functions of lymph nodes?

Filtering harmful foreign particles from lymph before it re-enters the blood, and providing lymphocytes and macrophages to destroy or engulf foreign substances.

What organ is shown here, and what hormone does it secrete to stimulate T cell maturation?

The thymus; it secretes thymosin, which stimulates the maturation of T lymphocytes.

Where is the spleen located, and what are its primary functions?

Located in the upper left portion of the abdominal cavity; it filters foreign particles and damaged red blood cells from blood via its rich population of macrophages and lymphocytes.

Identify the two pharyngeal lymphatic structures shown and explain how they protect the body.

The tonsils (located at the back of the mouth on both sides of the throat) and the adenoid (located behind the nasal cavity above the roof of the mouth); they trap airborne and ingested germs entering through the mouth and nose.

What constitutes the first, second, and third lines of defense against infection?

First line (Innate): skin, mucous membranes, and their secretions. Second line (Innate): phagocytic leukocytes, antimicrobial proteins, inflammatory response, and fever. Third line (Adaptive): lymphocytes, antibodies, and memory cells.

What is species resistance in the context of innate defenses?

A phenomenon where a particular species is inherently resistant to certain diseases affecting other species because its tissues fail to provide the environment required by the pathogen.

What chemical barriers contribute to innate immunity?

Enzymes in gastric juice and tears, low pH in the stomach, high salt in perspiration, interferons, defensins, collectins, and activated complement proteins in plasma.

According to the diagram, what are the four classic cardinal signs of inflammation and their underlying physiological causes?

1. Heat and Redness: caused by increased blood flow to the site of inflammation
2. Swelling: caused by accumulation of fluid and cells
3. Pain: caused by stimulation of sensory neurons by inflammatory mediators
4. Loss of function: caused by tissue damage

Which cells constitute the mononuclear phagocytic system?

Monocytes, mobile macrophages, and fixed phagocytes lining blood vessels and situated within the liver, spleen, and lymph nodes.

How do Natural Killer (NK) cells destroy infected and abnormal cells?

They secrete cytolytic proteins called perforins that lyse cell membranes of cancer cells and virus-infected cells.

How does a fever enhance the body's defense mechanisms?

Infection triggers lymphocytes to release IL-1, elevating body temperature; this elevated temperature lowers blood iron levels (hampering pathogen growth) and increases phagocytic activity.

What is a hapten?

A small molecule that cannot stimulate an immune response by itself, but can become antigenic when combined with a larger carrier molecule.

What distinguishes a primary immune response from a secondary immune response?

A primary response occurs upon the first encounter with an antigen (slower, building memory); a secondary response occurs upon subsequent exposures, where memory cells mount an immediate, rapid defense.

What is the primary difference in operational targets between B cells and T cells?

B cells drive humoral immunity by producing antibodies that attack invaders outside cells; T cells drive cell-mediated immunity by attacking infected cells directly.

What are three common immune system disorders mentioned in the lecture?

1. Allergies: overly strong immune response to harmless substances (e.g., pollen, food)
2. Autoimmune diseases: immune system mistakenly attacks healthy tissues (e.g., lupus, rheumatoid arthritis)
3. Immunodeficiency: underactive immune system caused by genetics or infection (e.g., HIV)

What are the three direct actions antibodies use to neutralize antigens?

Agglutination (clumping), precipitation (insoluble complexes), and neutralization (covering toxic or binding sites).

What are the five immunoglobulin classes and their primary functions?

1. IgA: secreted in mucus, tears, saliva, colostrum; tags pathogens
2. IgD: B-cell receptor; stimulates IgM release
3. IgE: binds mast cells and basophils; mediates allergies and antiparasitic defenses
4. IgG: major circulating blood antibody; crosses placenta; mediates secondary responses
5. IgM: fixes complement; main antibody of primary response; functions as B-cell receptor

Based on the acquired immunity chart, what are the four classifications of immunity and their definitions?

1. Naturally acquired active: antibodies made after natural exposure to an infection
2. Artificially acquired active: antibodies made after getting a vaccination
3. Naturally acquired passive: antibodies transmitted from mother to baby (e.g., via breast milk)
4. Artificially acquired passive: antibodies acquired from an immune serum medicine