Non-Specific Host Defense

What are the 3 lines of defense

• Physical barriers

• Generalized attack

• Specialized attack

What is the first line of defense

• Physical barriers

• Any barrier that blocks invasion

  • limits access to internal tissues

  • Not an immune response because it does not involve recognition

• Physical

• Chemical

• Senses/reflexes

What is the second line of defense

• Internal system of protective cells and fluids

• Includes inflammation and phagocytosis

• Acts rapidly at both the local and systemic levels once the first line of defense has been circumvented

What is the third line of defense

• Acquired as each foreign substance is encountered

• The reaction w/each different microbe produces unique protective substances

• Provides long-term immunity

What is skin

• Physical or anatomical barrier

  • Tough outer layer that is impervious and waterproof

  • Constant sloughing

  • Hair shaft is periodically shed

  • Sweat

    • flushing effect

    • increases salinity

1st line of defense: Respiratory tract

• Nasal hair traps larger particles

• Copious flow of mucus and fluids

• Ciliated epithelium

• Sneeze reflex expels

• Foreign matter in the bronchi,trachea, and larync triggers coughing

Genitouninary tract in 1st line

• Continuous trickle of urine through ureters

• Periodic bladder emptying

• Vaginal secretions provide

  • cleansing

  • lower PH

Nonspecific Chemical Defenses

• Sebaceous secretions

• Tears

• Lysozyme: found in tears and saliva

• High lactic acid and electrolyte content of sweat

• Acidic pH and fatty acid content of the skin

• Hydrochloric acid in the stomach

• Digestive juices and bile

Immunology

• The study of

  • features of the body 2nd and 3rd lines of defense

  • The body's response to infectious agents

  • Allergies

What is immunology

• The study of features of the body 2nd and 3rd lines of defense

• The body response to infectious agents

• Allergies

What is a healthy functioning immune system is responsible for

• Surveillance of the body

• Recogintion of foreign material

• Destruction of entities deemed to be foreign

What are white blood cells

• 2nd and 3rd line defense

• Constantly move throughout the body, searching for potential pathogens

Second and third lines jobs

• Recognize body cells (self)

• Differentiate them from any foreign material (nonself)

What does the immune system evaulate

Antigen

What is antigen

• any molecule that elicits an immune response

• Consists of proteins and sugar

• aid non-self differentiation

• Self-proteins should be generally left alone

What is the mononuclear phagocyte system (MPS)

• Monocytes,macrophage, and dendritic cells

• Blood vessels and capillaries

What is the reticulum (aka extracellular matrix)

• A support network of connective tissue fibers

• Interconnects nearby cells with peritoneum

• Provides a passageway within and between tissue and organs

What is mucosa-associated lymphoid tissue (MALT)

• Bundles of lymphocytes or just beneath the mucosal surfaces

• Effective first-strike potential against invaders

  • Appendix

  • Peyers patches

  • Tonsils

What is The lymphatic system

• Network of vessels, cells, and specialized organs

• Transports lymph through vessels and lymph nodes to drain back to the circulatory system

• Act as a drain-off system for response

• render surveillance, recogniiton, and protection against foreign material

What is the Thymus

• The site of T-cell Maturation

• Thymus cells develop specificity and are released into circulation as mature T cells

• T cells migrate to and settle in the lymph nodes and spleen

What are lymph nodes

• Small, encapsulated, bean-shaped orga

• Stationed in clusters

  • The armpit (axillary nodes)

  • Groin (inguinal nodes)

  • Neck (cervical nodes)

• Enlargement can provide clues to patient’s condition

What is Spleen

• Surveys blood

• Recycles red blood cells

• houses B and T cell

• monocyte reservoir

What is blood

• Whole blood consists of

  • blood cells: formed elements

  • Plasma: clear yellowish fluid

  • Serum: used in immune testing and therapy

The second line of defense

• Generalized and nonspecific defenses that support and interact with specific immune responses

  • Phagocytosis

  • Inflammation

  • Fever

  • Antimicrobial proteins

What is a fever

An adjunct to inflammation

• Abnormally elevated body temperature

  • A nearly universal symptom of infection

What is normal body temp

37C (98.6)

• regulated by the hypothalamus

What are pyrogens

• Reset the hypothalamic thermostat to a higher setting

What are the benefits of a fever (3)

• Inhibits the multiplication of temperature-sensitive microorganisms

• Impedes the nutrition of bacteria by reducing the availability of iron

• Increases host metabolism and stimulates immune reactions

  • speeds up hematopoiesis, phagocytosis, and specific immune reactions

What are the side effects of a fever

• Tachycardia: rapid heart rate

• Tachypnea: elevated respiratory rate

• Lowering of seizure threshold

What are three types of phagocytes

• Neutrophils

• Monocytes

• Macrophages

What are the general activities of phagocytosis are

• Survey tissue compartments

• Ingest and eliminate these materials

• Extract immunogenic information

What are neutrophils

• general purpose is phagocytes

• React early in the inflammatory response

• POWERFUL

  • one and done 3 day lifespan

• High neutrophil= common sign of bacterial infection

• Main component of pus

What are dendritic cells

• Antigen-presenting cells

• Found in tissue and blood

• Release activating cytokines

What is the nickname for monocytes and macrophages

King of the phagocytes

What are monocytes

• Macrophage precursors

• outside of blood and in tissues become macrophage

What are macrophages

• Differentiated and localized in tissues

  • Eat a large number of microbes

  • Present antigens

  • Activate further immune responses

What is a phagocyte

An eating cell

What is phagocytosis

• Physical process of engulfment

• Attack and dismantling of foreign cells

What are the events of phagocytosis

1. Chemotaxis

2. Ingestion

3. Phagolysosome formation

4. Destruction

5. Excretion

What are pathogen associated molecular patterns (PAMPS)

• Signal molecules on microbial surfaces are recognized by phagocytes and other defensive cells

• Shared by many organisms but not in mammals

• Serve as “red flags”

What are pattern recognition receptors

• Used by host cells in the second line of defense

• Recognize PAMPS

What are PAMP examples

• Viruses

• Gram-positive bacteria

• Gram-negative bacteria

Where are pattern recognition receptors found

• Found on phagocytes, dendritic cells, endothelial cells, and lymphocytes

• Recognize and bind PAMPS

• Cells possess PRRs whether they have encountered PAMPS before or not

What is cytoknes

• Small molecules secreted to regulate, stimulate, suppress and otherwise control immune responses

• Produced by monocytes, macrophages,lymphocytes,fibroblasts,mast cells, platelets, and endothelial cells

• Effects are local or systemic

What are chemokines

• Attract phagocytes and other immune cells

What are the major functional types of cytokines

• Mediate nonspecific immune reaction such as inflammation and phagocytosis

• Activate immune reactions during inflammation

• Regulate the growth and activation of lymphocytes

• Hematopoiesis factors for white blood cells miscellaneous inflammatory mediators

What are the signs of a inflammatory response

• Rubor

• Calor

• Tumor

• Dolor

What is rubor

• Redness caused by increased circulation and vasodilation in the injured tissue

What is Calor

• warmth caused by the heat given off by the increased flow of blood

What is a tumor

• Swelling caused by flud escaping into the tissues

What is dolor

• Pain caused by the stimulation of nerve ending

What factor elict inflammation

• Trauma from infection

• Tissue injury or necrosis due to physical or chemical agents

• Specific immune reactions

What chronic diseases are caused by chronic inflammation

• Congestive heart disease

• Chrons disease

• IBS
  diabetes

• Rheumatoid arthritis

What are the reactions from an inflammatory response

• Powerful defensive reaction

• Has the potential to cause tissue injury, destruction, and disease

What is pus

• The accumulation of a whitish mass of cells, liquefied cellular debris, and bacteria

What stimulates the formation of pus

• bacteria such as streptococci, staphylococci, gonococci, and menigococci

What is chemotaxis

• Migration of WBC in response to chemical stimuli

What is diapedesis

• Migration of WBCs out of blood vessels into tissue

What is sepsis

• Systemic inflammatory response

• If untreated, it leads to organ failure and death within hours

• Treated with IV fluids, antibiotics and vasopressors

What are the signs and symptoms of sepsis

• Probable or confirmed infection (high WBC)

• Fever

• Heart rate

• low blood pressure

• Rapid breathing

• Elevated blood lactate

• Markers of specific organ failure

What is septic shock

• Multiple organ failure

• Dramatic drops in blood pressure that can’t be recovered

• 50-75% fatality rate

What is interferon

• Small protein produced naturally by some white blood and tissue cells

• Effective regulator and communicator of immune response

What are interferon alpha and beta

• Produced by lymphocytes, fibroblasts, and macrophages

What is interferon gamma

Produced by T cells

How does interferon work

• Bind to cell surfaces and induce changes in genetics expression

• Can inhibit the expression of oncogenes and have tumor suppressor effects

• Some stimulate phagocytes, regulate lymphocytes

What do interferon do in viral infections

• Binding of pathogens to receptors signals interferon productio

  • rapidly secreted

• Binding of interferon induces cell changes that inhibit viral multiplication

  • degrade viral RNA

  • prevent translation of viral protein

• NOT microbe-specific

What is a complement

• Named for its property of “complementing” immune reactions

• 26 blood proteins that work to destroy bacteria and certain viruses

What is cascade reaction

• Sequential physiological response

• First substance activates the next substance which activates the next

What are the stages of the complement cascade (1-4)

1. Initiation

2. Amplification and cascade

3. Polymerization

4. Membrane attack

What is the initiation stage

• C1 components bind to an initiator bound to a foreign cell

  • Cascade to cleave and activate C3

What is amplification and cascade

• C3 leads to C5 being cleaved and bound to the membrane

  • Components cleaved into a and b

  • a activates phagocytes

  • b opsonization continues the cascade

What is the polymerization stage

-C5 products becomes the site of the assembly of the membrane attack complex (MAC)

What is the membrane attack stage

• C5-C9 form the membrane attack complex that punctures pores in the cell membrane; leading to lysis

What is the pathway for complement cascade

Immune complexes—→classical pathway

Bacterial carbohydrate—→ lectin pathway