The Lymphatic System

• Lymphatic tissue is composed of a large number of lymphocytes and is a specialized form of reticular connective tissue.
• Yellow bone marrow is not a component of the lymphatic system.
• Vitamin C is not transported from the gastrointestinal tract into the blood by the lymphatic system.
• The thoracic duct receives lymph from the left side of the head.
• B-lymphocytes produce antibodies.
• Lymphatic nodules are not surrounded by a connective tissue capsule.
• Common functions of the lymphatic system include:
• Transportation of lipids from the gastrointestinal tract to the blood
• Return of filtered plasma proteins to the cardiovascular system
• Return of excess interstitial fluid to the cardiovascular system
• Carrying out immune responses.
• Large lymphatic vessels closely resemble veins.
• The largest single mass of lymphatic tissue in the human body is the spleen.
• Tissue edema can be caused by:
• An infected lymph node
• Blockage of a lymphatic vessel
• Increased capillary blood pressure
• Lymph nodes are bean-shaped organs scattered throughout the body and are located along lymphatic vessels, used to filter foreign substances out of the lymph.
• Afferent lymphatic vessels carry lymph into lymph nodes.
• Worn-out and damaged red blood cells are destroyed in the spleen.
• Hemopoiesis during fetal life occurs in the red pulp of the spleen.
• The thymus gland is the site of T-cell maturation and selection.
• Red pulp is associated with the spleen.
• After a splenectomy, the liver & red bone marrow carry out the normal functions of the spleen.
• The first line of innate defenses against pathogens is intact skin and mucous membranes.
• Cytotoxic T cells are not components of the second line of innate defenses.
• Gastric juice is considered a chemical factor in the first line of innate defenses.
• Complement proteins are found in blood plasma.
• Macrophages develop from circulating blood cells called monocytes.
• The lungs, brain, liver, and spleen all contain fixed macrophages.
• Numbness is not a sign or symptom of inflammation.
• Bacteria, viruses, pollen, and food can act as antigens.
• Vaccination is an example of artificially acquired active immunity.
• Mother's milk will provide an infant with naturally acquired passive immunity.
• In cell-mediated immunity, infected host cells are directly attacked by cytotoxic T cells.
• Helper T cells release a costimulator needed for the conversion of B cells into antibody-producing plasma cells.
• Memory T cells are most important in preventing a disease from recurring.
• The main class of antibody secreted by plasma cells immediately after the initial exposure to any antigen is IgM.
• A cell infected by a virus will produce interferons that signal neighboring cells to increase production of proteins which interfere with viral replication.
• The initial response to HIV infection is a modest decline in the number of circulating helper T cells.
• An important function of lymph nodes is to filter foreign substances out of the lymph.
• The spleen stores platelets, making it unique among lymphatic organs.
• T cells received their name because they mature in the thymus gland.
• A plasma cell secretes antibodies and circulates as a B cell until it is exposed to its specific antigen.
• Mother passing antibodies to her baby through breast milk is an example of naturally acquired passive immunity.
• Benefits of inflammation at a site of infection include:
• Increased number of phagocytes in the infected area
• Walls off the infection to prevent it from spreading
• Increased temperature in the infected area
• Increased blood flow to the infected area to remove dead cells and toxins
• Delayed hypersensitivity shots are not used as a treatment for HIV infection.
• The Epstein-Barr virus causes infectious mononucleosis.
• People become more susceptible to infections and malignancies with age because:
• T cells are less responsive to antigens
• Fewer T cells are present
• The thymus gland atrophies
• B cells are less responsive
• Cytotoxic T cells destroy infected host cells by releasing granzymes that induce apoptosis.
• Innate immunity acts against all types of pathogens in the same way.
• Lymph is initially collected from the tissues by lymphatic capillaries.
• Increased physical activity would lead to the fastest rate of lymph circulation.
• Decreased availability of iron to microbe is not an effect of the complement system.
• Anaphylactic shock results from vasodilation of blood vessels, along with fluid loss from the blood, triggered by a type I allergic reaction.
• A transplant between genetically different individuals of the same species is called an allograft.
• Interstitial fluid is the fluid that bathes the cells and becomes lymph when it enters lymphatic vessels.
• The thymus gland is a primary lymphatic organ located in the thoracic cavity.
• Edema is an accumulation of fluid (not blood) in tissue spaces.
• Immunity is the ability to use the body's defenses to ward off disease.
• Body cells infected with viruses produce proteins called interferons.
• Phagocytosis is the ingestion of microbes or other particles like cell debris by phagocytes.
• Macrophages that remain in certain tissues and organs are called fixed macrophages.
• An abscess results from excessive accumulation of pus in a confined space.
• Not only pathogenic microbes are considered antigens in the human body.
• Cytotoxic T cells must specifically recognize an antigen on the surface of the infected cell before attacking.
• Cytotoxic T cells destroy target cells by releasing cytotoxic proteins on contact.
• Delayed hypersensitivity reactions occur 12 to 72 hours after exposure to the allergen.
• Memory T cells do not produce antibodies.
• Mosquitoes do not transmit the HIV virus.
• The main difference between antibody-mediated immunity and cell-mediated immunity is not that the former requires a costimulator because they both do.
• Fat-soluble vitamins are transported from their site of absorption in the gastrointestinal tract to the bloodstream using the lymphatic system.
• The tonsils are five large clusters of lymphatic nodules that form a ring at the junction of the oral cavity, nasal cavity, and throat.
• The complement system consists of a group of plasma proteins that help destroy pathogens by creating holes in the plasma membrane of the microbe.
• Histocompatibility for transplant patients refers to the similarity in MHC antigens between the organ donor and the organ recipient.
• Most antibodies aren't made up of 6 polypeptide chains, but a more complex structure.
• After a T cell is activated, it enlarges and produces a population of identical cells called a clone.
• In the war against pathogens, T cells are foot soldiers that travel to the tissues to destroy the enemy, while B cells use chemical warfare and stay in the lymphatic tissue, sending antibodies.
• Monoclonal antibodies are useful diagnostic tools because they only recognize a single antigen.
• Fluid that filters out of capillaries into tissue spaces is returned to the blood by transport in the lymphatic system and reabsorption at the venous end of the capillary network.
• Most lymphocytes that migrate to the thymus gland from the red bone marrow are destroyed by apoptosis before they even reach maturity.
• Increased capillary permeability and vasodilation at a site of inflammation is stimulated by the release of histamine from mast cells, basophils, and platelets.
• Acquired immunodeficiency syndrome (AIDS) is the end stage of infection by human immunodeficiency virus (HIV).
• Dendritic cells, macrophages, and B cells can present antigens to other immune cells.
• Vaccines do not work by stimulating innate immune responses. They work by adaptive immunity and giving the body more tools to fight infections.
• The primary functions of the lymphatic system include:
• Draining excess interstitial fluid from tissues.
• Transporting lipids and lipid-soluble vitamins from the gastrointestinal tract to the blood.
• Protection of the body from foreign cells, microbes, and cancer cells.
• Main components of the physical barriers used as the first line of defense against disease-causing microorganisms include:
• Epidermis of the skin
• Mucous membranes
• Lacrimal apparatus
• Saliva
• Mucus
• Hairs
• Cilia
• Flow of urine
• Defecation
• Vomiting
• Steps in processing and presenting an antigen by an antigen-presenting cell (APC):
• Ingestion of the antigen by the APC using phagocytosis
• Digestion of antigen into fragments
• Synthesis of MHC molecules
• Fusion of vesicles containing antigen fragments with those containing MHC proteins
• Binding of antigen fragments to MHC molecules
• Insertion of antigen-MHC complex into the plasma membrane
• Sequence of lymphatic vessels and tissues used to carry lymph from the tissues back to the blood: Lymphatic capillaries → larger lymphatic vessels → afferent lymphatic vessels → lymph nodes → efferent lymphatic vessels → lymphatic ducts (thoracic or right lymphatic duct) → subclavian vein near the junction with the internal jugular vein.
• The chemical that triggers apoptosis of infected host cells is called granzymes.
• The protein that punches a hole in the plasma membrane of an infected host cell is called perforin.
• The structure labelled A is the palatine tonsil, a secondary lymphatic organ.
• The the labeled structure C is the thymus gland, a primary lymphatic tissue where T-Cells multiply and mature.
• The labelled structure I is the Lymph Nodes, and have the following characteristics: Fibrous capsule, afferent lymphatic vessels, efferent lymphatic vessels, and abundant reticular fibers.

The cell labeled F in the diagram is, and is a plasma cell.

• The cell labeled D in the diagram that releases interleukin-2 is called a helper T cell.
• To activate B cells, an antigen (labeled C) on a microbe binds to a B cell antigen receptor (labeled A) on the surface of a specific population of B cells.
• As humans get older, their immune system has a tendency to produce more antibodies against their own body's tissues called autoantibodies.