white blood cells
What do these white blood cells do at the site of inflammation? The main role of white blood cells is to fight pathogens in the body. There are actually several different kinds of white blood cells. Some white blood cells have very specific functions. They attack only certain pathogens. Other white blood cells attack any pathogen they find. These white blood cells travel to areas of the body that are inflamed. They are called phagocytes, which means eating cells. Neutrophils are a type of phagocyte. In addition to pathogens, phagocytes eat dead cells. They surround the pathogens and destroy them. Sometimes it is said that the phagocyte engulfs the pathogen, and then destroys it. This process is called phagocytosis. White blood cells also make chemicals that cause a fever. A fever is a higher-than-normal body temperature. Normal human body temperature is 98.6 F (37 C). Most bacteria and viruses that infect people reproduce fastest at this temperature. When the temperature is higher, the pathogens cannot reproduce as fast, so the body raises the temperature to kill them. A fever also causes the immune system to make more white blood cells. In these ways, a fever helps the body fight infection.
The bodys second line of defense against pathogens includes the inflammatory response. If bacteria enter the skin through a scrape, the area may become red, warm, and painful. These are signs of inflammation. Inflammation is one way the body reacts to infections or injuries. Inflammation is caused by chemicals that are released when skin or other tissues are damaged. The chemicals cause nearby blood vessels to dilate, or expand. This increases blood flow to the damaged area, which makes the area red and slightly warm. The chemicals also attract white blood cells called neutrophils to the wound and cause them to leak out of blood vessels into the damaged tissue. This little girl just got her first scraped knee. It doesnt seem to hurt, but the break in her skin could let pathogens enter her body. Thats why scrapes should be kept clean and protected until they heal.
the immune systems second line of defense
The little girl pictured below ( Figure 1.1) has a scraped knee. A scrape is a break in the skin that may let pathogens enter the body. If bacteria enter through the scrape, they could cause an infection. These bacteria would then face the bodys second line of defense. The second line of defense is also nonspecific, fighting many types of pathogens.
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the second line of defense is specific to a few types of pathogens.
a. true --> b. false
inflammation begins when the skin or other tissues is damaged or cut.
--> a. true b. false
the dilation of blood vessels during the inflammatory response
--> a) increases blood flow to the damaged area. b) allows the damaged skin to clot and stop bleeding. c) allows the mucous membranes to heal the wound. d) all of the above
what is the main role of white blood cells?
a) to transport oxygen around the body b) to warm damaged blood vessels so they can heal --> c) to fight pathogens d) to raise the temperature of the body
why does temperature increase as part of the second line of defense?
a) damaged blood vessels heal faster at higher temperatures. --> b) pathogens do not reproduce as well at higher temperatures. c) phagocytes destroy pathogens faster at higher temperatures. d) all of the above
how do white blood cells get to site of inflammation?
--> a) they actually leak out of blood vessels into damaged areas. b) blood vessels have many entry and exit valves, where the white blood cells can easily enter and leave the vessels. c) the damaged tissue makes them, so they are already at the site of inflammation. d) they only function inside damaged blood vessels.
what is the goal of a phagocyte?
a) to bring white blood cells to the site of damage b) to eat dead tissue so it can regrow --> c) to engulf foreign pathogens and dead cells d) all of the above
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