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Flashcards in Innate immunity chapter Deck (16):

The first line of defense is composed of?

External physical barriers to pathogens, skin & mucous membranes


The second line of defense

Internal and composed of protective cells, bloodborne chemicals, & the processes that inactivate or kill invaders


The first two lines of defenses (first line and second line) are called?

Innate immunity because they are present at birth prior to contact with infectious agents or their products. Innate immunity is rapid and works against a wide variety of pathogens, including parasitic worms, protozoa, fungi, bacteria, & viruses


The third line of defense is?

Adaptive immunity responds against unique species or strains of pathogens and alters the body's defenses such that they act more effectively upon subsequent infection with the specific strain


The epidermis also contains phagocytic cells called?

Dendritic cells. They have slender, fingerlike processes that extend among the surrounding cells forming a network to intercept invaders. These cells both phagocytize pathogens nonspecifically and play a role in adaptive immunity


What is the role of blood vessels in the dermis layer?

They deliver defensive cells and chemicals


In addition to its physical structure, the skin has a number of chemical substances that nonspecifically defend against pathogens. Describe this

* Dermal cells secrete antimicrobial peptides
* Sweat glands secrete perspiration (contains salt), antimicrobial peptides, and lysozyme
-The salt draws water osmotically from invading cells, which inhibit their growth and kills them


What are antimicrobial peptides? (sometimes called defensins)

They are positively charged chains of 20-50 amino acids that act against microorganisms


Describe the role of lysozyme in sweat secreted by sweat glands

Its an enzyme that destroys the cell walls of bacteria by cleaving the bonds between the sugar subunits of the walls. Bacteria without cell walls are more susceptible to osmotic shock & digestion by other enzymes within phagocytes


Where are the mucous membranes

They line the lumens of the respiratory, urinary, digestive, and reproductive tracts. Like skin they act nonspecifically to limit infection both physically and chemically


Unlike surface epidermal cells, surface cells of the mucous membranes are?

Alive and play roles in the diffusion of nutrients and oxygen (in the digestive, respiratory and female reproductive systems) and in the elimination of wastes (in urinary, respiratory, and female reproductive systems)


How are organisms kept from invading through the thin mucous membranes?

In some cases they are not, which is why some mucous membranes, especially those of the respiratory and reproductive systems, are common portal of entry for pathogens


The epithelial cells of the mucous membranes are?

Tightly packed to prevent entry of pathogens, the cells are continually shed and then replaced via the cytokinesis of stem cells


Dendritic cells reside below the mucous epithelium to phagocytize invaders. These cells are also able to?

Extend pseudopodia between epithelial cells to "sample" the contents of the lumen, which helps prepare adaptive immune responses against particular pathogens that might breach the mucous barrier


What is microbial antagonism?

Our skin and mucous membranes are normally home to a variety of protozoa, fungi, bacteria, and viruses. These "normal microbiota" play a role in protecting the body by competing with potential pathogens in a variety of ways


How does microbial antagonism work?

A variety of activities make it less likely that a pathogen can compete with them & produce disease. Microbiota consume nutrients, making them unavailable to pathogens. They can also change the pH, creating an environment that is favorable to other microorganisms