Immunity Flashcards
What are the two arms of the immune system?
The innate and adaptive arms.
What distinguishes the innate defense system from the adaptive defense system?
The innate defenses are always armed and ready to go, but they aren’t specific. They are simply ‘fighting’ anything that isn’t identified as ‘self’ by antigens on the cell surface. The adaptive arm is very specific, forming a defense against the exact thing that has invaded, but this takes some time to mount.
Which is the first line of defense?
Innate.
There are two main types of innate defenses. What are they?
Surface barriers (skin and mucous membranes) and internal defenses, which inhibit the invaders spread throughout the body.
How are the skin and epithelial linings mechanical barriers to microorganisms?
There are demosomes that connect cells of the skin, creating very tight borders between cells. Mucous membranes have mucous that trap debris and foreign bodies (viruses, bacteria, parasites) and then cilia which sweep them back out of the system.
Describe what tissues are acidic and how this helps as a defense mechanism.
The skin has an acid mantle. This is made from the mixture of sweat and sebum (oil). The low pH of this mixture kills foreign bodies. Other tissues that are acidic are the vagina and stomach.
Describe where the enzyme lysozyme is found and how that helps protect the body.
Lysozyme is found in the saliva, respiratory mucus and lacrimal fluid in the eye. This enzyme can destroy foreign bacteria.
Describe where mucin is found and how it acts as a chemical barrier.
Mixed with water, mucin forms mucous. Mucous lines the digestive and respiratory tracts and traps microorganisms and then washes them either back out or into the stomach where they are digested.
Describe what defensins are, where they can be found, and how they act as a chemical barrier.
Definsins are antimicrobial proteins made by the skin and mucous membranes. These increase in number during an inflammatory response. They break or disrupt the cell membrane of microbes, killing them.
Describe how cilia that line the respiratory tract and hair in the nose act as a barrier.
They move with coordinated motion and sweep things out of the tract, once they have been trapped in mucous.
What types of cells act as phagocytes? How do they defend the body?
Macrophages and neutrophils act as phagocytes. They engulf foreign bodies like bacteria, viruses and other microorganisms.
Describe the difference between free and fixed macrophages.
Free macrophages circulate through the body looking for foreign bodies. Fixed macrophages remain in one location/organ.
What are opsonins? Why are they a benefit? What happens without them?
Opsonins can coat a microbe, making it sticky, so that a phagocytic cell like a macrophage or neutrophil can attach to it. These are important because some foreign microorganisms can for a capsule, hiding their antigens. The capsule isn’t ‘sticky’ enough for a phagocytic cell to grab onto. The opsonins allow these cells to function.
Describe what natural killer cells are and how they work.
These circulate through the blood and lymph, looking for foreign bodies. They can kill cancer and virus infected cells even before the adaptive side of our immune system has a chance to mount a response. These are lymphcytes, non-specific (targeting anything foreign), and are not phagocytic. Instead of using phagocytosis, they cause a cell to undergo apoptosis (programmed cell death). They also secrete chemicals that increases the inflammatory response.
Describe the benefits of inflammation as a defense mechanism.
Inflammation prevents the spread of damaging agents to other tissues, disposes of cell debris and pathogens (microorganisms), and turns on the adaptive immune system.
What are the causes of inflammation? What are the beneficial effects for the body? What are the signs you can look for on someone experiencing inflammation?
The causes could be trauma, intense heat, chemicals or infection. The benefits are in question #15. The symptoms are redness, heat, swelling, pain and impaired function.
Describe the chemicals that cause an inflammatory response. Where do they come from? What do they result in?
The chemicals that cause an inflammatory response come from the cells that have been damaged and the immune system cells in that area. The chemicals can include histamine, kinins, prostaglandins and cytokines. They result in vasodilation of the nearby arterioles, an increase in the permeability of the capillaries in that area, and an attraction of phagocytes to that area.
What are the benefits of vasodilation at the site of inflammation?
This causes an increase in blood flow to the area (hyperemia). This aids more cells of the immune system to migrate to that specific area. The benefit of an increase of permeability is that fluid from the blood, carrying immune system cells and nutrients are more easily accessed at the injury site.
