Lecture Exam 2 Study Guide Flashcards
What is the largest organ in the body?
The Skin. Approx 2 sq. meters
What is another term for the skin?
The cutaneous membrane.
What is the cutaneous membrane?
The skin
Skin represents 16% of the total body weight and varies in thickness depending on the proctective functions needed in the particular location. What is the thinnest and thickest area?
Thinnest: eyelids, about 0.5mm thick Thickest: heel, about 4mm thick
Define Term: Epidermis
Epithelial Layer of skin
Define Term: Dermis
connective tissue layer containing blood vessels, beneath dermis
What are the accessory structures for the skin?
hair, nails, exocrine glands (sweat glands, sebaceous glands) , associated muscle and nerves
Define and give relative proportion in the skin: Keratinocyte
Most common skin cell - 90% of the cells in skin. Name comes from the type of intermediate filaments they contain. keratin.
Define and give relative proportion in the skin: Melanocytes
About 8% of the skin. Located in basal layer. Produce the pigment melanin that provides skin color. (Melanin absorbs UV light and helps protect skin from damaging effects of the sun)
Define and give relative proportion in the skin: Langheran’s cells
<2% of the skin. immune cells that migrate into skin from blood. Involved in defense. A type of resident dendritic cell – most tissues have a specialized type fo dendritic cell.
Define and give relative proportion in the skin: Merkel cells
Least numerous cell type in skin. Located in basal layer of skin in contact with sensory neurons. Involved in sense of touch (tactile response)
What is the function of Keratin and where would you find it? What is Keratin?
Keratin is a tough, fibrous protein that helps protect the skin and underlying tissues from abrasions, heat, microbes, and chemicals. Keratin is found in Keratinocytes in the epidermis, hair, and nails.
What are the layers of the epidermis and their locations:
Stratum Corneum, Stratum Lucidum, Stratum Granulosum, Stratum Spinosum, Stratum Basale
Put the layers of the epidermis in layer from apical to basal:
Stratum Corneum, Stratum Lucidum, Stratum Granulosum, Stratum Spinosum, Stratum Basale
Where are dividing cells located in the epidermis?
The basal layer of cells
What direction to keratinocytes migrate in the epidermis?
From the basal layer to the superficial zones.
What is the difference between thin and thick skin?
Thin skin has four layers (stratum basale, stratum spinosum, stratum granulosum, and a thin stratum corneum). Thick skin has five layers in the epidermis (stratum basale, stratum spinosum, statum granulosum, stratum lucidum, and a thick stratum corneum). Thick skin is found where exposure to friction is greatest, e.g. fingertips, pals, soles, etc.
Know the major features of the pathology of Psoriasis
Keratinocytes divide more quickly and migrate more quickly from stratum basale to stratum corneum. The Keratinized layer is abonormal (flaky and sore)
What are the three pigments that contribute to skin color?
Melanin, Hemoglobin, and Carotene
How is hair color determined?
Two forms of melanin, pheomelanin (yellow to red) and eumelanin (brown to black)
Why do we vary in skin color?
The number of melanocytes in similar in all people. It is the amount of melanin that the melanocytes can synthesize and the amount that can be transferred to keratinocytes that varies to alter skin color.
What happens when melanin in unevenly distributed?
moles, freckles, aging spots
What is an albino?
someone with the inherited inability to produce melanin.
Define the area we call the dermis. How would you classify the connective tissue fo the dermis?
The dermis is the connective tissue underlying the epidermis and the specialized structures found there. Dense irricular connective tissue - contains collagens, proteoglycans and glycosaminoglycans, cells, blood vessels, nerves, and exocrine glands.