Chapter 14: Host defenses and innate immunity

What are innate, natural defenses?

Defenses present at birth that provide nonspecific resistance to infection.

What are adaptive immunities?

Specific defenses that must be acquired.

What cells make antibodies

plasma cells

Where do b cells differentiate in

In a plasma cell

What is the first line of defense?

Physical barriers that block invasion at the portal of entry.

What is the second line of defense?

Protective cells and fluids; inflammation and phagocytosis.

What is the third line of defense?

Acquired immunity with exposure to foreign substances; produces antibodies and memory cells.

How do the lines of defense work?

They overlap and are redundant in their effects.

What does the immune system rely on to protect the body against pathogens?

A multilevel network of physical barriers, immunologically active cells, and various chemicals.

What is the purpose of the first line of defense?

To block invasion at the portal of entry.

What are examples of physical barriers in the first line of defense?

Skin, mucous membranes, and secretions.

What are examples of protective cells and fluids in the second line of defense?

Phagocytes, natural killer cells, and antimicrobial proteins.

What are the mechanisms of the second line of defense?

Inflammation and phagocytosis.

What is acquired immunity in the third line of defense?

Immunity that develops after exposure to foreign substances.

What is the role of antibodies in the third line of defense?

To provide specific protection against pathogens.

What are memory cells in the third line of defense?

Cells that remember specific pathogens for faster and stronger immune responses in the future.

In the 1st line of defenses, what are the three categories of defense?

1. Physical or anatomical barriers at the body surface

2. Chemical defenses

3. Genetic resistance to infection

They block the entry of not only microbes but any foreignagent (living or not)

Physical barriers

skin and mucous membranes

What are the built-in defenses in skin?

Outermost layer of skin with epithelial cells cemented together, and impregnated with keratin. Flushing effect of sweat.

What are mucous membranes?

Coating of digestive, genitourinary, and respiratory tracts. Blinking and tear production. Flow of saliva. Flushing effect of urination, defecation, vomiting.

How do mucous membranes act as a physical barrier?

Mucous coat impedes attachment and entry of bacteria.

How does the respiratory tree defend against pathogens?

Ciliary defense: nasal hair traps larger particles.

Two classes of T cells

CD4 (helper) and CD8 (cytotoxic)

Defensin

Proteins made by out immune system that kills bacteria

What does Lysozyme do in defense?

Breaks outer peptidoglycan layer

pertussis

Damage cilia and cause whooping cough

Nonspecific Chemical Defenses

mechanisms include the skin, mucous membranes, secretions, excretions, enzymes, inflammatory responses, genetic factors, hormonal responses, nutritional status, behavior patterns, and the presence of other diseases.

What are the nonspecific chemical defenses from skin and mucous membranes?

Sebaceous secretions, antimicrobial secretions from specialized glands (meibomian glands)

What are the other defenses in tears, saliva, and skin?

Lysozyme, defensins, high lactic acid and electrolyte concentration in sweat, skin's acidic pH

What is the role of lysozyme?

It hydrolyzes the cell wall of bacteria

What are defensins?

Peptides that lyse bacteria and fungi

What are the nonspecific chemical defenses in the stomach and intestines?

Hydrochloric acid in stomach, digestive juices and bile in intestines

What antimicrobial chemical is present in semen?

Semen contains an antimicrobial chemical

What maintains the acidic pH in the vagina?

The microbiota

What are genetic differences in susceptibility?

Variations in susceptibility to pathogens among individuals.

What is sickle-cell anemia?

A genetic disorder causing abnormal red blood cells.

How are humans with sickle-cell anemia resistant to malaria?

The gene for sickle-cell anemia provides protection against malaria.

What are reticulocytes?

immature RBCs

-Lose nucleus

What is immunology?

Study of body's defense mechanisms

What are the primary functions of a healthy immune system?

Surveillance, recognition, attack and destruction of foreign material

What cells have MHC classes

Every cell in body except for erythrocytes

What are white blood cells?

Cells with innate capacity to recognize and differentiate foreign material.

What is the difference between nonself and self?

Nonself refers to foreign material, while self refers to normal cells of the body.

What are pathogen-associated patterns (PAMPs)?

Molecules shared by microorganisms. (LPS)

What are pathogen recognition receptors (PRRs)?

Receptors on white blood cells for PAMPs. (LPS receptor)

What is the innate capacity of white blood cells?

To recognize and differentiate any foreign material.

What is nonself?

Foreign material.

What is self?

Normal cells of the body.

When did the innate immunity begin?

Began in sponges

When did adaptive immunity appear

Appeared in vertebrae's, specifically in sharks

What is whole blood?

Plasma and formed elements (blood cells)

What is serum?

Liquid portion of blood after a clot has formed (minus clotting factors)

What is plasma composed of?

92% water, metabolic proteins, globulins, clotting factors, hormones, and other chemicals and gases to support normal physiological functions

Where do thrombocytes comes from

megakaryocytes

Why shouldn't you eat before getting blood drawn?

Fat can appear in blood and makes it hard to read

-Grossly lipemic blood (the plasma becomes filled with lipids)

What is hemopoiesis?

Production of blood cells.

What are stem cells?

Undifferentiated cells, precursor of new blood cells.

What are the primary cell lines in blood?

Platelets, Red blood cells (RBCs), Leukocytes (WBCs).

What are granulocytes?

White blood cells with lobed nucleus.

What are considered agranulocytes?

White blood cells with unlobed, rounded nucleus.

Granulocytes

neutrophils, eosinophils, basophils

Agranulocytes

lymphocytes and monocytes

What is diapedesis's

Inflammation that opens up epithelial cells for cells to move towards the site of infection

What WBC is the first line of defense?

neutrophils

What are neutrophils?

Phagocytes with lobed nuclei and lavender granules.

What is the function of neutrophils?

To engulf and destroy pathogens.

What are eosinophils?

Cells with orange granules and bilobed nucleus.

What is the function of eosinophils?

To destroy eukaryotic pathogens.

What are basophils?

Cells with constricted nuclei and dark blue granules.

What is the function of basophils?

To release potent chemical mediators.

What are mast cells?

Nonmotile elements bound to connective tissue.

What makes up puss?

Dead neutrophils

Who created the gram staining for WBC?

Paul Urlick

Other name for Neutrophils

polymorphonuclear leukocytes (PMNs)

What are agranulocytes?

White blood cells without granules in their cytoplasm.

What are lymphocytes?

White blood cells responsible for specific immune responses.

What is the role of B cells in humoral immunity?

Producing antibodies to fight against pathogens.

What is the role of T cells in cell-mediated immunity?

Modulating immune functions and killing foreign cells.

What are monocytes and macrophages?

Largest white blood cells with phagocytic abilities.

What is the function of macrophages?

Final differentiation of monocytes and phagocytosis.

What are dendritic cells?

Cells that trap pathogens and participate in immune reactions.

Neutrophils function

general-purpose; react early to bacteria and other foreign materials, and to damaged tissue

-Perform phagocytosis

Eosinophils function

Destruction of parasitic worms; mediators of allergy

Basophils function

Active in allergy, inflammation, parasitic infections

Monocyte functions

Phagocytosis ,followed by final differentiation into macrophages and dendritic cells

Lymphocytes function

Specific (acquired) immunity

What are erythrocytes?

Red blood cells that develop from bone marrow stem cells and lose their nucleus, becoming simple biconcave sacs of hemoglobin.

What are platelets?

Formed elements in circulating blood that are not whole cells.

What is the function of the lymphatic system?

Provides an auxiliary route for return of extracellular fluid to the circulatory system

What is the role of the lymphatic system in the inflammatory response?

Acts as a drain-off system for the inflammatory response

What does the lymphatic system do in terms of foreign material?

Renders surveillance, recognition, and protection against foreign material

What is lymphatic fluid?

Plasma-like liquid carried by lymphatic circulation.

How is lymphatic fluid formed?

When blood components move out of blood vessels into extracellular spaces.

What is lymph made up of?

Water, dissolved salts, and 2-5% proteins.

What does lymph transport?

White blood cells, fats, cellular debris, and infectious agents.

What parts of the body do lymphatic capillaries not permeate?

CNS, bone, placenta, and thymus

How are lymphatic capillaries moved through the body?

Contraction of skeletal muscles

What is the function of lymphatic vessels?

Return lymph to circulation - flow is one-directional towards the heart eventually returning to the bloodstream

What are primary lymphoid organs?

Sites of lymphocytic origin and maturation: Thymus gland, Bone marrow

What are secondary lymphoid organs and tissues?

Circulatory-based locations: Lymph nodes, Spleen