Chapter 5 MCQs and short answers
6. Langerhans cells are commonly found in the ________.
A. Stratum spinosum
18. As you are walking down the beach, you see a dead, dry, shriveled-up fish. Which layer of your epidermis keeps you from drying out?
A. stratum corneum
15. In humans, exposure of the skin to sunlight is required for ________.
A. vitamin D synthesis
Cells of the epidermis derive from stem cells of the stratum basale. Describe how the cells change as they become integrated into the different layers of the epidermis.
As the cells move into the stratum spinosum, they begin the synthesis of keratin and extend cell processes, desmosomes, which link the cells. As the stratum basale continues to produce new cells, the keratinocytes of the stratum spinosum are pushed into the stratum granulosum. The cells become flatter, their cell membranes thicken, and they generate large amounts of the proteins keratin and keratohyalin. The nuclei and other cell organelles disintegrate as the cells die, leaving behind the keratin, keratohyalin, and cell membranes that form the stratum lucidum and the stratum corneum. The keratinocytes in these layers are mostly dead and flattened. Cells in the stratum corneum are periodically shed.
8. Collagen lends ________ to the skin.
B. Structure
13. Sebaceous glands ________.
B. are associated with hair follicles
12. Eccrine sweat glands ________.
B. are present in the skin throughout the body and produce watery sweat
14. Similar to the hair, nails grow continuously throughout our lives. Which of the following is furthest from the nail growth center?
B. hyponychium
23. After a skin injury, the body initiates a wound-healing response. The first step of this response is the formation of a blood clot to stop bleeding. Which of the following would be the next response?
B. increased production of coneective tissue
7. The papillary and reticular layers of the dermis are composed mainly of ________.
C. Connective Tissue
19. If you cut yourself and bacteria enter the wound, which of the following cells would help get rid of the bacteria?
C. Langerhan cells
9. Which of the following is not a function of the hypodermis?
C. Source of blood vessels in the epidermis
21. Bedsores ________.
C. are preventable by eliminating pressure points
20. In general, skin cancers ________.
C. can be reduced by limited exposure to the sun
16. One of the functions of the integumentary system is protection. Which of the following does not directly contribute to that function?
C. folic acid synthesis
24. Squamous cell carcinomas are the second most common of the skin cancers and are capable of metastasizing if not treated. This cancer affects which cells?
C. keratinocytes of the stratum spinosum
The papillary layer of the dermis is most closely associated with which layer of the epidermis?
D. Stratum Basale
22. An individual has spent too much time sun bathing. Not only is his skin painful to touch, but small blisters have appeared in the affected area. This indicates that he has damaged which layers of his skin?
D. epidermis and dermis
Explain the differences between eccrine and apocrine sweat glands.
Eccrine sweat glands - Secrete through pores on the skin. This is a merocrine secretion. Responsible for thermoregulation. Apocrine swear glands - Secrete into the hair follicle. Produce a smelly odor. Mammary, ceruminous, and ciliary glands are all modified apocrine glands. Found in the axillary and anogenital regions. Only active after puberty occurs.
Describe the structure and composition of nails.
Nails are composed of densely packed dead keratinocytes. They protect the fingers and toes from mechanical stress. The nail body is formed on the nail bed, which is at the nail root. Nail folds, folds of skin that overlap the nail on its side, secure the nail to the body. The crescent-shaped region at the base of the nail is the lunula.
Why do scars look different from surrounding skin?
Scars are made of collagen and do not have the cellular structure of normal skin. The tissue is fibrous and does not allow for the regeneration of accessory structures, such as hair follicles, and sweat or sebaceous glands.
Why do teenagers often experience acne?
Sebaceous glands cause acne, these glands produce sebum. Sebum creates blockages, thus resulting in a infection. Sebaceous glands become active when puberty starts. Hormones that are especially active during puberty stimulate the release of sebum, thus giving teenagers more acne.
The skin consists of two layers and a closely associated layer. What are the basic functions of each of these layers?
The epidermis provides protection, the dermis provides support and flexibility highly vascularized, and the hypodermis (fat layer) provides insulation and padding.
Explain your skin's response to a drop in body core temperature.
The errector pilli muscle pushes up this casues hair to stand up closing off the pores of the skin. This helps to hold in the heat of the body.
What determines the color of skin, and what is the process that darkens skin when it is exposed to UV light?
The pigment melanin, produced by melanocytes, is primarily responsible for skin color, carotene(yellow/orange), and hemoglobin(red/pink) are also skin pigments. Melanin comes in different shades of brown and black. Individuals with darker skin have darker, more abundant melanin, whereas fair-skinned individuals have a lighter shade of skin and less melanin. Exposure to UV irradiation stimulates the melanocytes to produce and secrete more melanin, thus causing you to get darker.
If you zoom on the cells of the stratum spinosum, what is distinctive about them?
These cells have desmosomes, which give the cells their spiny appearance.
17. An individual using a sharp knife notices a small amount of blood where he just cut himself. Which of the following layers of skin did he have to cut into in order to bleed?
c. Papillary dermis
10. In response to stimuli from the sympathetic nervous system, the arrector pili ________.
c. are responsible for goose bumps
11. The hair matrix contains ________.
d. a layer of basal cells