A&P Chapter 20

What are the functions of the lymphatic system?

Maintains fluid balance, absorbs dietary fats, and provides immune defense

What structures make up the lymphatic system?

Lymphatic capillaries, vessels, trunks, ducts, lymph nodes, spleen

How is lymph formed?

Interstitial fluid enters lymphatic capillaries and becomes lymph

How does lymph move through the body?

Muscle contractions, smooth muscle in vessels, and valves prevent backflow

What is the function of lymph nodes?

Filter lymph and trap pathogens

What is the function of the spleen?

Filters blood, removes old RBCs, and fights pathogens

What is innate immunity?

Fast, nonspecific defense present at birth

What is adaptive immunity?

Slow, specific defense involving T and B cells

How do innate and adaptive immunity work together?

Innate presents antigens to activate adaptive immunity

What happens when a pathogen enters the body?

Inflammation occurs, WBCs migrate, phagocytosis happens, and adaptive immunity is activated

What is humoral immunity?

B cells produce antibodies to fight pathogens

What is cell-mediated immunity?

T cells destroy infected or abnormal cells

What are the basic parts of an antibody?

Two heavy chains, two light chains, variable and constant regions

What are surface barriers in immunity?

Skin and mucous membranes that block pathogen entry

What are phagocytic cells?

Macrophages, neutrophils, eosinophils

What are nonphagocytic cells?

NK cells, dendritic cells, basophils

What are cytokines?

Signaling proteins that regulate immune responses

What is the complement system?

A protein cascade that enhances inflammation, phagocytosis, and pathogen destruction

What are the signs of inflammation?

Redness, heat, swelling, pain

Why is inflammation important?

Brings immune cells to infection and promotes healing

What is an antigen?

A substance that triggers an immune response

What is MHC I?

Found on all nucleated cells; presents internal antigens

What is MHC II?

Found on antigen-presenting cells; presents external antigens

What are the steps of T cell activation?

Clonal selection, activation, proliferation, differentiation

What do helper T cells do?

Activate immune cells and interact with MHC II

What do cytotoxic T cells do?

Kill infected cells and interact with MHC I

What are the steps of B cell activation?

Bind antigen, present it, get activated by helper T cells, proliferate

What do plasma cells do?

Produce antibodies

What do memory B cells do?

Provide faster response upon re-exposure

What are the five antibody classes?

IgG, IgA, IgM, IgE, IgD

What does IgG do?

Most common antibody; crosses placenta

What does IgA do?

Found in secretions like saliva and breast milk

What does IgM do?

First antibody produced in response

What does IgE do?

Involved in allergic reactions

What does IgD do?

Involved in B cell activation

What are the functions of antibodies?

Neutralization, agglutination, opsonization, inflammation

What is the primary immune response?

First exposure; slow with lag time

What is the secondary immune response?

Faster, stronger response using memory cells

How do vaccines work?

Introduce antigens to create memory cells for faster future response

How does the immune system respond to cancer cells?

NK cells and cytotoxic T cells destroy abnormal cells

How do pathogens evade the immune system?

Hide in cells, mimic host cells, or suppress immune responses

Why does HIV target specific cells?

It targets CD4 helper T cells

What effect does HIV have on the immune system?

Weakens immune response and can lead to AIDS

What are the steps of WBC movement during inflammation?

Margination, diapedesis, and positive chemotaxis

What specific cytokines are involved in inflammation?

Histamine, leukotrienes, prostaglandins, and bradykinin

What is vasodilation and what does it cause?

Widening of blood vessels causing redness and heat

What is increased vascular permeability?

Capillaries become leaky allowing fluid to exit, causing swelling

What is a phagosome?

Vesicle inside a phagocyte containing an ingested pathogen

What chemicals do macrophages use to destroy pathogens?

Hydrogen peroxide and hypochlorous acid

What is the difference between red pulp and white pulp in the spleen?

Red pulp removes old RBCs; white pulp fights pathogens

What is clonal selection?

Process where specific lymphocytes recognize and bind to an antigen

What is proliferation in immune cells?

Rapid cloning of activated lymphocytes

What is differentiation in immune cells?

Cells become effector or memory cells

What is an antigen-presenting cell (APC)?

A cell that displays antigen on MHC II (ex: macrophages, dendritic cells, B cells)

What is opsonization?

Process where pathogens are marked to make phagocytosis easier

What are interferons?

Antiviral cytokines that protect neighboring cells from infection

What is a naïve lymphocyte?

A T or B cell that has not yet encountered its antigen

What is the lag phase in primary immune response?

Delay before antibodies are produced after first exposure