Ch. 21 Lymphatic and Immune System

What is lymph similar to?

Lymph is similar to plasma but contains no plasma proteins.

What is the primary function of lymphatic vessels?

They carry lymph from peripheral tissues to the venous system.

What are the three layers of lymphatic vessels?

1. Tunica interna: endothelium and valves; 2. Tunica media: elastic fibers and smooth muscle; 3. Tunica externa: thin outer layer.

What occurs at the site of interstitial fluid?

Gas exchange occurs with blood, and interstitial fluid is returned to systemic circulation, becoming lymph.

Where are lymphatic capillaries found?

They are blind-ended capillaries found in beds of blood capillaries throughout the body, but not in the skeleton or CNS.

What is the pathway of lymph fluid in the lymphatic system?

Lymphatic capillaries collect lymph, which then travels through collecting vessels, lymphatic trunks, and finally to the collecting duct.

What are the two main ducts that return lymph to systemic circulation?

Right lymphatic duct and thoracic duct.

What areas does the right lymphatic duct drain?

Right side of the head, right thorax, right arm, and shoulder.

What areas does the thoratic duct drain?

The drainage of the left side of the body's lymph, "rest of body"

What is the function of the cisterna chyli?

It receives lymph from the digestive organs and drains into the thoracic duct.

What are neutrophils and their role in the immune system?

Neutrophils are antibacterial cells that help fight infections.

What type of lymphocytes attack and destroy infected host cells and cancerous cells?

Natural killer (NK) cells.

What is the role of T lymphocytes (T cells)?

T cells are involved in cell-mediated immune responses.

What do B lymphocytes (B cells) differentiate into when activated?

Plasma cells that produce antibodies.

What are macrophages and their function in the immune system?

Large phagocytic cells that present antigens to alert other immune cells.

Where are dendritic cells primarily found?

In the skin, mucous membranes, and lymphoid organs.

What is lymphoid tissue?

A collection of lymphocytes in the connective tissues of mucous membranes and many organs.

What are Peyer patches?

Large clusters of lymphoid nodules in the small intestine.

What distinguishes primary lymphoid organs from secondary lymphoid organs?

Primary lymphoid organs (red bone marrow and thymus) are where T and B cells become immunocompetent, while secondary lymphoid organs (lymph nodes, tonsils, spleen) are where these cells populate.

What is the function of the spleen's red pulp?

It disposes of old red blood cells and acts as an erythrocyte graveyard.

What is the role of the thymus in the immune system?

It is where T cells mature, especially active during childhood and adolescence.

What is the first line of defense in the immune system?

Any barrier that blocks invasion at the portal of entry, including skin and mucous membranes.

What constitutes the second line of defense in the immune system?

Protective cells and fluids, including inflammation and phagocytosis.

What is the third line of defense in the immune system?

A specific immune response acquired on an individual basis, providing long-term immunity.

What are the classes of antibodies?

IgG, IgE, IgD, IgA, and IgM.

What is the function of IgG antibodies?

They provide long-term resistance and are involved in subsequent invasions.

What role do IgE antibodies play?

They are involved in allergic reactions and responses to parasites.

What is the significance of IgA antibodies?

They protect mucosal surfaces, such as the nasal and intestinal lining.

What is the function of IgM antibodies?

They are strong antibodies involved in anti-A and anti-B reactions in blood typing.

What is the purpose of vaccines?

Vaccines introduce inactivated or attenuated pathogens to stimulate memory cell production.

What is the mechanism of mRNA vaccines?

They contain mRNA that instructs cells to produce a protein (antigen) without containing the actual protein.

What type of vaccine contains a tiny amount of non-pathogenic virus?

Live attenuated vaccine

What is the purpose of an adjuvant in vaccines?

Enhances immunogenicity and prolongs antigen retention at the injection site

What is the most common adjuvant used in vaccines?

Alum (aluminum hydroxide salts)

Can a vaccine make you sick?

No, but flu-like symptoms may occur due to an active immune response.

What is inflammation?

A tissue response to injury that prevents damage spread, disposes of debris, and prepares for repair.

What causes fever in the body?

Increased body temperature caused by pyrogens released by white blood cells and macrophages.

What are histamines and their role in inflammation?

Histamines are released by mast cells, causing vasodilation and increased permeability.

What is exudate?

Fluid containing clotting factors and antibodies that leaks into tissue during inflammation.

What is purulence?

Technical term for pus, which contains white blood cells, macrophages, debris, and microbes.

What are analgesics?

Drugs that reduce pain.

What are the four types of hypersensitivity?

Type I: Acute, Type II: Antibody-dependent, Type III: Immune complex, Type IV: Delayed.

What happens during a Type I hypersensitivity reaction?

Type I hypersensitivity encompasses reactions such as anaphylaxis, as well as common allergies, including hay fever and asthma.

What is anaphylaxis?

A severe, systemic allergic reaction that can cause respiratory and circulatory disruption.

What happens during a Type II hypersensitivity reaction?

Reaction to mismatched blood transfusion, generating antibodies against A, B, or Rh antigens.

What characterizes rheumatoid arthritis in Type III hypersensitivity?

Immune complex-mediated inflammation leading to joint and tissue damage.

What is Systemic Lupus Erythematosus (SLE)?

An autoimmune disease characterized by a butterfly-shaped rash and autoantibodies against various tissues.

What is the role of cytotoxic T cells in graft rejection?

They recognize foreign MHC markers and initiate an immune response against the transplanted tissue.

What are the classes of grafts?

Autograft, Isograft, and Allograft

What is an autograft?

A graft using a person's own tissue.

What is an Isograft

tissue from an identical twin

What is an allograft?

use of tissue from another person; can be a family member

What is Severe Combined Immunodeficiency (SCID)?

A recessive disorder characterized by low to no B and T cells, requiring patients to live in a 'bubble'.

What is the difference between allergy and hypersensitivity?

Allergy is an exaggerated immune response, while hypersensitivity refers to delayed reactions.

What is edema?

Swelling caused by exudate pressing on nerve endings, leading to pain.

What are interferons?

Proteins released by virally infected cells to protect neighboring cells and interfere with viral replication.