Ch 34-35 FRQ - Sasha Preston Period 4 Chapter 34 35 Free Response Questions 1 a An innate defense is a mechanical barrier Skin acts as a defensive

Ch 34-35 FRQ - Sasha Preston Period 4 Chapter 34 35 Free...

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Sasha Preston Period 4 Chapter 34 & 35 Free Response Questions 1.) a.) An innate defense is a mechanical barrier. Skin acts as a defensive barrier to bacteria and viruses in the external environment. The outermost layer of skin, called the epidermis, acts as a physical barrier between the body and the bacteria outside. Each cell in the epidermis, called a keratinocyte, is tightly connected to its neighbors, so that no bacteria can pass between them. As long as the skin is intact and healthy, bacteria and viruses cannot penetrate the barrier. If the skin is injured, such as from a blister, a splinter, a cut or a burn, bacteria can enter the body and cause an infection. The inner layer of the skin, called the dermis, contains several different types of cells that provide protection from disease. To help keep the skin moist and healthy, sebaceous glands located in the dermis produce sebum. Sebum is a waxy substance that helps the skin retain moisture and prevent drying out. A second innate defense is chemical defence. Among the nonspecific chemical defenses of the body are the secretions of lubricating glands. The tears and saliva contain the enzyme lysozyme, which breaks down the peptidoglycan of the cell wall of Gram-positive bacteria. The extremely caustic hydrochloric acid of the stomach is a barrier to the intestine. A third innate defence is inflammation. Inflammation is a nonspecific response to any trauma occurring to tissues. It is accompanied by signs and symptoms that include heat, swelling, redness, and pain. Inflammation mobilizes components of the immune system, sets into motion repair mechanisms, and encourages phagocytes to come to the area and destroy any microorganisms present. Inflammation can be controlled by nervous stimulation and chemical substances called cytokines. These chemical products of tissue cells and blood cells are responsible for many of the actions of inflammation. The loss of fluid leads to a local swelling called edema. In some types of inflammation, phagocytes accumulate in the whitish mass of cells, bacteria, and debris called pus.
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  • Fall '17
  • Randy Smith
  • inflammatory disease

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