Immunity

Question 1

Susceptibility

Immunity

Innate immunity

Adaptive immunity

Answer 1

Lack of resistance to a disease

Ability to fight off a disease

Defense against any pathogens

Resistance to a specific pathogen (immunity)

Question 2

First line of defense vs Second Line

Answer 2

1st line of defense (Innate)

• Intact Skin
• MM/secretions
• Normal microbiota

2nd line of defense (Innate)

• Phagocytes (neutrophil, eosinophils & Macrophages)
• Dendritic cells
• Inflammation
• Fever
• Antimicrobial substances

3rd line of defense (Adaptive)

• Specialized lymphocytes (T-cells & B-cells)
• Antibodies

Question 3

Innate Immune System

Answer 3

aka Nonspecific defense

from birth

Physical Factors - skin, mm, microbiota (prevention of entry)

Cellular Factor - phagocytes (substances in body that inhibits microbial growth)

Does not gain effectiveness with subequent infections

Responds rapidly to infection

Question 4

How does the innate immune system recognize foreign materials such as bacteria?

Answer 4

Toll-like receptors (TLR) attaches to the Pathogen-associated molecular patterns (PAMP)

TLR induces cytokines - regulates intensity and duration of immune responses

Question 5

Skin

Answer 5

Epidermis - Outer layer of skin (Tightly packed epithelial cells)

Upper most layer: Dead cells contain w/ Keratin protein

Keratin Protein: increases hydrophobicity which dries out skin and inhibits microbial growth.

Dermis - Inner layer of skin (Connective tissues)

Question 6

Mucous membrane

Answer 6

Consist of epithelial layer & connective tissue layer except does not have dead keratinized cells

Secretes fluid = mucous, glycoprotein. Prevents tract from drying. Produced in goblet cell of mm.

Mucous linnings

• RI
• GI
• Genitourinary tract

Question 7

Lacrimal apparatus

Answer 7

Manufactures and Drains away tears

Prevents microbes from settling on surface of eye

Question 8

Saliva

Answer 8

Dilutes and washes away number of microbes

Produced in salivary gland

Contains Lysozyme, Urea, Uric acid, antibodies from adaptive immunity

Question 9

Respiratory Tract

Answer 9

Mucus coated nose hairs - filters/trap inhaled air w/ dust, microoraganism & pollutant

Ciliated cells of lower respiratory tract - propels inhaled dust/microbes upwards toward the throat

aka ciliary escalator

Epiglottis - prevents infection in larynx by covering when swallowing

Question 10

GI Tract

Answer 10

Expels microbes via Peristalsis, defecation and vomitting

Gastric Juice in stomach: pH 1.2-3

Destroys bacterias and most toxins

Question 11

Genitrourinary Tract

Answer 11

Prevents microbes from colonization by flow of urine through the urethra

Vaginal Secretion pH: 3.5 (inhibits microbes)

Cervical mucus has antimicrobial activity

Urine: Contains lysozyme, Urea, Uric acid, Hippuric acid and indicant (inhibits growth)

Question 12

Sebum

Answer 12

• Oily substance produced by sebaceous gland in skin
• Unstaurated fatty acid in sebum - inhibit growths of certain pathogenic bacteria and fungi
• Skin pH: 3-5 (discourages growth)
• Perspiration flushes microbes and contains lysozymes which breaks down cell walls

Question 13

Normal Microbiota

Answer 13

Normal Flora: Humans contain 1x10¹³

• Takes permanent residence of our body
• Do not usually cause diseases unless opportunistic
• i.e. Neisseria meningitidis: normally resides in R.I. tract but can cause meningitis
• Not innate immune system
• Prevents overgrowth of pathogens by competiting for nutrients, producing harmful substance for pathogens and altering pH

Bacterial Cells: Humans contain 1x10¹⁴

Question 14

Second line of defense

Answer 14

Activated when microbes passes 1st line of defense

Encounters 1st type of cell: Phagocytic cells

AND stimulates inflammation, fever and antimicrobial substances

Question 15

Blood

Answer 15

Plasma - Fluid component

Formed elements - cellular component (innate & adaptive)

Leukocytes (WBC)

Question 16

Leukocytes

Granulocytes vs Agranulocytes

Answer 16

Granulocytes - Basophil, Neutrophils, Eosinophils

Agranulocytes - Monocyte, Lymphocyte, Dentritic cells

Question 17

Neutrophil

Answer 17

aka polymorphonuclear leukocytes (PMN)

highly phagocytic and motile

Activated in the 1st stage of infection

Question 18

Basophil

Answer 18

Releases histamine stored in granules

important in inflammation and allergic responses

Question 19

Eosinophils

Answer 19

Somewhat phagocytic

motile

Produces toxic proteins against multicellular parasites

Attaches to parasites and discharges Peroxide ions (toxin)

Question 20

Monocytes

Answer 20

Turns into phagocyte when activated

Leaves bloodstream and enters tissues and matures into macrophages - removes microbes via phagocytosis

Question 21

Dendritic cell

Answer 21

Abundant in epidermis, mm, thymus & lymph nodes

Are phagocytic

Initial adaptive response

Question 22

Lymphocytes

Answer 22

Produces antibodies

Natural killer cells (Innate)

• in blood, spleen, lymph nodes, red bone marrow
• Targets infected body cells & Tumor cells by releasing perforin protein or granzymes causing cytolysis or apoptosis

T cells & B cells (Adaptive)

Destroys cells by cytolysis (perforin protein) and infected cells undergo apoptosis (Self destruction)

Question 23

Diapedesis

Answer 23

Phagocytes squeezeing b/t endothelial cells

Question 24

Phagocytic Cells

Answer 24

Fixed macrophages - does not leave tissue

• Kupffer’s cells - liver macrophages
• Alveolar - Lung macrophages
• Microglial Cell - Nervous system

Phases

• Chemotaxis - chemical that attacts phagocytes to microorganism: microbial product, cytokines, complement peptides, microbial products
• Adherence - attachment of PAMP to TLR or Opsonization (mediated by antibodies or complement proteins)
• Ingestion - extends projections (Pseudopods). Then plasma membrane fuses to form phagosome sac where H+ ions are pumped in, reducing pH to 4. Hydrolytic enzymen is now activated.
• Digestion - Phagosome detaches from plasma membrane and enters cytoplasm and combines with lysosome (digestive enzyme) forming phagolysosome.

Question 25

Inflammation

Answer 25

Local defensive response triggered by damaged tissue Redness Swelling (Edema) Pain Heat Loss of Function

Question 26

Histamine & Kinins Prostaglandins Leuktrienes

Answer 26

Vasodilation & Increase permeability of blood vessels Intense histamine and kinnin effect Increase permeability of blood vessels & phagoctyic attachment

Question 27

Complement system

Answer 27

complements immune system defensive system consisting 30+ proteins Produced by liver Circulates throughout body not adaptable nor changeable Proteins destroys by cytolysis, inflammation, phagocytosis "C1, C2, C3...." Inactive until split into fragments Acts as a cascade (one triggers another until all is turned on)