Chapter 12: innate Immune System

This set of flashcards covers key concepts related to the immune system, including its components, responses, and mechanisms of action.

Immune System

A complex network of cells and proteins that defends the body against infection.

Main purpose of immune system

To protect the human body from infectious disease

Pathogen

Organisms that cause infectious diseases, including bacteria, viruses, fungi, and parasites.

Lymphatic System

A network of organs, vessels, and tissues that helps protect the body from infection.

Lymphatic system function

A circulatory system that moves immune cells, fluids(lymph) and proteins between blood and lymphoid organs

Primary lymphatic organs

Produce most immune system cells organs include bone marrow and the thymus

Secondary lymphoid organs

Organs where the cells of immune system mature and meet pathogens for the first time include lymph nodes(~600), spleen, tonsils, specialized tissue mucous membrane layers in the body

Epithelial Barriers

Physical barrier skin is the bodies first defense against infection forms a tough impenetrable barrier of epithelium protected by layers of keratinized cells

Mucosal Surfaces

Epithelial linings of the respiratory, gastrointestinal, and urogenital tracts.

What is the function of Mucus secreted from the mucosal tissue?

Tissue contains enzyme and other proteins that protect the epithelial cells from damage and helps to limit infection

What do mucous membranes protect?

Digestive, urinary & respiratory tracts and the eye, impedes entry and attachment of bacteria

Antimicrobial peptides (AMPs)

Epithelia produce them to kill bacteria, fungi, and enveloped viruses by perturbing their membrane

Lysozyme

In tears and saliva, an enzyme that kills bacteria by degrading their cell walls

Sebum

Substance secreted by sebaceous glands associated with hair follicles that contains fatty acids and lactic acids to inhibit bacterial growth on the surface of the skin.

Unfavorably environment for pathogens

Altering pH to make environments acidic such as the stomach, vagina, and skin

Innate immune response

First to respond, fast and effective in stopping early stage infections, pathogen destruction

Adaptive immune response

Second response to infection, slow and initiated when first immunity fails, pathogen destruction and improved pathogen recognition

Immune response consists of two parts

Detection/recognition and response

Pathogens in human body detected by immune system in two ways

Soluble proteins(ex, complement) and cell surface receptor proteins(pattern recognition receptors) that bind to the pathogen and its products

Complement System

One of the first weapons against pathogens inside human body system of soluble proteins made by the liver that enhances the ability to clear pathogens.

How does the complement system work?

Costs surface of the bacteria and extra cellular virus particles and makes them more easily phagocytosed (“eaten by the cell”)

What makes up the complement system?

More than 30 proteins but the most important is Component 3 (C3) serves to Opsonize, cell lysis, chemotaxis

Pattern Recognition Receptors (PRRs)

Proteins that recognize structural features of pathogens and distinguish microbes from their mammalian components

Antigen

Any substance recognized by the immune system (ex, carbohydrates, lipids, proteins, nucleic acids)

Self antigen

Healthy cells of the human body

Non self antigen

All bacteria, fungi, viruses, and parasites, as well as unhealthy infected human cells

After detection how are pathogens killed?

Involves special cells that engulf bacteria, kill virus infected cells, attack protozoan parasites

Leukocytes

White blood cells that play a key role in the immune response.

Hematopoiesis

The developmental process by which Leukocytes are produced in the body occurs primarily in bone marrow

Where do Leukocytes derive from?

Common progenitor called pluripotent hematopoietic stem cell

Self renewal

Hematopoietic stem cells can divide to give further hematopoietic stem cells

More mature stem cells commit to one of three cell lineages

Erythroid(mostly innate immunity), Myeloid(innate immunity), Lymphoid(mostly adaptive immunity)

The Erythroid lineage of blood cells

The oxygen carrying erythrocytes and the platelet producing ,megakaryocytes

Megakaryocytes

Giant cells that have nuclei containing multiple sets of chromosomes are permanent residence of the bone marrow

Platelets

Small packets of membrane enclosed cytoplasm that break off from megakaryocytes are non uncleared cell fragments of plate like shape, maintain the integrity of blood vessels initiate and participate in the blood clotting reactions

Neutrophils

The most abundant white blood cells, specialized for phagocytosis (eat cell) effector cells of innate immunity rapidly enter site of infections and can work in the anaerobic conditions, short lived die within hours at site of infection forming Pus

Basophils and eosinophils and function

Mast cells defend against helminth worms and other intestinal parasites, important roles in developing allergies

Basophils and eosinophils contain?

Numerous granules rich in histamine and heparin, activation and degranulation of the mast cells at sites of infection make major contributions to inflammation

Macrophages

Scavenger cells that phagocytize microorganisms and dead cell debris as well as invading microorganisms

Macrophage residence

In the infected tissue are generally the first cell to sense invading microorganism

Macrophage response

Secrete the Cytokines that recruit and other immune cells to the infected area

Cytokines

Molecules immune cells use to communicate with each other

Dendritic Cells function

Immune cells that act as messengers sent to activate the adaptive immune response when needed, activate T cells of the adaptive immune system

Dendritic cells resident

Bodies tissue and have a distinctive shaped morphology

Natural Killer Cells (NK Cells)

Defense against viral infections(& cancer) Immune cells that enter infected tissues to prevent spread of infection by killing virus infected cells and secreting cytokines that impede viral replication in infected cells

Natural killer cells(NK) step 1

virus infection of cells trigger release of interferons

Natural killer cells step 2

Interferon drives proliferation of natural killer cells

Natural killer cells step 3

Natural killer cells transform to killing mode

Natural killer cells step 4

natural killer cells cause virus infected cells to undergo self killing(apoptosis)