Innate Immunity

innate/ natural defenses

present at birth, provide nonspecific resistance to infection

• 1st and 2nd line of defense

adaptive immunities

specific, must be acquired

• 3rd line of defense

White blood cells/Leukocytes (cells) and fluids

the immune system is a large, complex, and diffuse network of…

1st line of defense 

physical/ chemical barriers 

2nd line of defense 

“immune” system cells (leukocytes- WBC) 

Leukocyte

1. recognize self vs. foreign

2. survey the body

3. destroy “foreign”

monocytes

develop into macrophages

lymphocytes

develop in to B- and T-cells

Haematopoiesis

how blood cells develop

mast cells

tissue cells similar to basophils that trigger local inflammatory reactions and allergic symptoms 

• found in tissues, release histimine 

neutrophils

phagocytes; active engulfers and killers of bacteria 

basophils

function in inflammatory events and allergies

• found in blood 

Eosinophils

active in worm and fungal infections, allergy, and inflammation 

Pathogen-associated patterns (PAMPs)

molecules shared by microorganisms

• molecule found on pathogen

Pathogen recognition receptors (PRRs)

receptors on WBCs for PAMPs

• on Leukocyte → detects pathogen

Toll-like receptors

protein receptors within cell membrane of macrophages 

transcription factor (NF-kB)

used to detect foreign molecules and signal the macrophage to produce chemicals to stimulate an immune response 

Reticuloendothelial system

network of connective tissue fibers that interconnects other cells and meshes with the connective tissue network surrounding organs.

• has phagocytic cells

• allows for passageway within and between tissues and organs

blood components

• erythrocytes

• leukocytes

• platelets

• plasma

erythrocytes

carry oxygen via hemoglobin, non nucleated

leukocytes

immunity

platelets

clotting

plasma

liquid containing salts, proteins 

has clotting factor (fibrinogen)

• buffy coat

serum

liquid without clotting factor (fibrinogen) 

artery

• carry oxygenated blood away from the heart 

• thick muscular walls

• blood travels at high pressure in these vessels

vein

• carry deoxygenated blood to the heart

• have valves to prevent reverse blood flow 

• blood travels at a low pressure in these vessels 

capillary

• facilitate gas exchange through their thin walls 

• microscopic and only one cell thick 

• blood travels at a low pressure in these vessels 

lymphatic system

collects fluid (lymph) between cells and returns it to bloodstream (goes only in one direction → towards heart)

• defends body against pathogens 

lymphatic vessels and lymphoid tissues & organs

What does the lymphatic system consist of? 

elephantiasis

blockage by parasitic worms

• lymphatic system not working properly 

primary organs

sites of lymphocytic origin and maturation

secondary organs and tissues

circulatory-based locations

• lymph nodes

• spleen 

• tonsils

• Peyer’s Patches (intestine)

lymph nodes

small, encapsulated, bean-shaped organs stationed along lymphatic channels and large blood vessels

Peyer’s Patches

• found in the wall of intestine

• resemble tonsil in structure

• capture and destroy bacteria in the intestine

thymus gland

generates T-cell lymphocytes

bone marrow

generates B-cell lymphocytes

swollen lymph nodes

caused by expansion in the number of lymphocytes

tonsils

• small masses of lymphoid tissue around the pharynx 

• trap to remove bacteria and other foreign materials 

spleen

• located on the left side of the abdomen

• lymphocytes found on reticulate fibers (white pump) 

• destroys worn out blood cells (red pump) 

• filters blood, blood reservoir, forms blood cells for fetus

actions of 2nd line of defense

1. interferon

2. complement

3. inflammation

4. phagocytosis

complement

includes a combination of innate and adaptive aspects of the immune system 

chemokine

tells leukocytes where to go

cytokine

tells leukocytes what to do & triggers immune response → kill pathogen

inflammation

redness, pain, heat, swelling (edema), chemical signals released, margination and emigration of WBCs (Diapedesis), tissue repair 

histamine

vasodilation, increased permeability of blood vessels

kinins

vasodilation, increased permeability of blood vessels, increased pain

prostaglandins

intensifies histamine and kinin effect

leukotrienes

increased permeability of blood vessels, phagocytic attachment

fever

initiated by circulating pyrogens which reset the hypothalamus to increase body temp; signals muscles to increase head production and vasoconstriction 

exogenous pyrogens

products of infectious agents

endogenous pyrogens

liberated by leukocytes

diapedesis

migration of cells (leukocytes) out of blood vessels into the tissues

phagosome

formed by pathogen engulfed by phagocytosis

phagolysosomes

formed by phagosomes fusing with lysosomes