Chapter 5 | Tissues and Integumentary System

  1. Figure 5.11 Which of the following statements about types of epithelial cells is false?
    1. Simple columnar epithelial cells line the tissue of the lung.
    2. Simple cuboidal epithelial cells are involved in the filtering of blood in the kidney.
    3. Pseudostratisfied columnar epithilia occur in a single layer, but the arrangement of nuclei makes it appear that more than one layer is present.
    4. Transitional epithelia change in thickness depending on how full the bladder is.
      Illustration shows tall, diamond-shaped cells layered one on top of the other.
      Figure 5.11 Transitional epithelia of the urinary bladder undergo changes in thickness depending on how full the bladder is.
  2. Figure 5.21 State whether each of the following processes are regulated by a positive feedback loop or a negative feedback loop.
    1. A person feels satiated after eating a large meal.
    2. The blood has plenty of red blood cells. As a result, erythropoietin, a hormone that stimulates the production of new red blood cells, is no longer released from the kidney.
      Prior to birth, the baby pushes against the cervix, causing it to stretch. Stretching of the cervix causes nerve impulses to be sent to the brain. As a result, the brain stimulates the pituitary to release oxytocin. Oxytocin causes the uterus to contract. As a result, the baby pushes against the cervix in a positive feedback loop.
      Figure 5.21 The birth of a human infant is the result of positive feedback.
  3. Figure 5.22 When bacteria are destroyed by leuckocytes, pyrogens are released into the blood. Pyrogens reset the body’s thermostat to a higher temperature, resulting in fever. How might pyrogens cause the body temperature to rise?
    Photo A shows the sun. Photo B shows a sweaty person. Photo C shows a lion with its mane blowing in the wind. Photo D shows a person holding a steaming hot drink.
    Figure 5.22 Heat can be exchanged by four mechanisms: (a) radiation, (b) evaporation, (c) convection, or (d) conduction. (credit b: modification of work by “Kullez”/Flickr; credit c: modification of work by Chad Rosenthal; credit d: modification of work by “stacey.d”/Flickr)

  4. The skin consists of two layers and a closely associated layer. View this animation to learn more about layers of the skin. What are the basic functions of each of these layers?

     

  5. Figure 5.26 If you zoom on the cells at the outermost layer of this section of skin, what do you notice about the cells?
    The outer layer of cells in this micrograph is the thinnest layer and stained deep purple due to full keratinization of dead cells. The next layer occupies one quarter of the micrograph, is lightly stained, and is a dense collection of cells. The third layer from the top is mostly white, with lightly stained, loosely-packed strands radiating in random directions. The bottom-most layer is densely-packed, with thick bands of highly organized muscle tissue that are darkly stained.
    Figure 5.26 Epidermis The epidermis is epithelium composed of multiple layers of cells. The basal layer consists of cuboidal cells, whereas the outer layers are squamous, keratinized cells, so the whole epithelium is often described as being keratinized stratified squamous epithelium. LM × 40. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)
  6. Figure 5.28 If you zoom on the cells of the stratum spinosum, what is distinctive about them?

    This micrograph of the epidermis shows stratum corneum as a rough, darkened layer. The next layer, the stratum granulosum, contains white cells with areas of black in their cytoplasm, equal in thickness to the stratum corneum. The third layer, the stratum spinosum, contains large, grayish cells. The stratum spinosum is the thickest layer, occupying half of the micrograph. A hair follicle is embedded in this layer, which is a round structure with black, concentric spots. The fourth layer is the stratum basalis, which contains grayish cells with clear, dark nuclei, similar in thickness to the stratum corneum. The dermis is the deepest layer, and is lightly-colored with interspersed gray cells. A cross-section of a capillary is visible within the dermis.
    Figure 5.28 Cells of the Epidermis The cells in the different layers of the epidermis originate from basal cells located in the stratum basale, yet the cells of each layer are distinctively different. EM × 2700. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)
  7. This ABC video follows the story of a pair of fraternal African-American twins, one of whom is albino. Watch this video to learn about the challenges these children and their family face. Which ethnicities do you think are exempt from the possibility of albinism?

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