Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

45 Cards in this Set

  • Front
  • Back
What is another name for skin?
cutaneous membrane
Define skin.
largest organ of the body in both surface area and weight; covers the external surface of the body; 16% of total body weight; thicknesses from 0.5 mm (eyelids) to 4.0 mm (heels)
Approximately, how much does the skin weigh?
4.5-5 kg (10-11 lbs)
Approximately, how large is the skin?
2 square meters (22 square feet)
What are the two structural layers of the skin?
epidermis (supperficial, thinner portion); dermis (deeper, thicker connective tissue part)
subcutaneous layer
subQ; deep to the dermis, but not part of the skin; also called hypodermis
What does the hypodermis consist of?
this layer consists of areolar and adipose tissues
What is the function of the subcutaneous layer?
serves as a storage depot for fat and contains large blood vessels that supply the skin
What are lamellated (pacinian) corpuscles and where are they found?
nerve endings that are sensitive to pressure; found in the subcutaneous layer
composed of keratinized stratifies squamous epithelium
What are the four principal types of cells found in the epidermis?
1. kerantinocytes
2. melanocytes
3. Langerhans cells
4. Merkel cells
What percentage of epidermal cells are keratinocytes?
How are keratinocytes found and what is there function?
arranged in four or five layers in the epidermis; produce the protein keratin
What is keratin?
a tough, fibrous protein that heps protect the skin and underlying tissues from heat, microbes, and chemicals
In addition to keratin, what do keratinocytes produce?
lamellar granules which release a water-repellent seaalant that decreases water entry and loss and inhibits the entry of foreign materials
What percentage of epidermal cells are melanocytes?
Where do melanocytes form and what is their function?
develop from the ectoderm of a developing embryo and produce the pigment melanin; long, slender projections extend between the keratinocytes & transfer melanin granules to them
a yellow-red or brown-black pigment that contributes to skin color and absorbs damaging ultraviolet (UV) light
How does melanin protect?
Inside keratinocytes, the mielanin granules cluster to form a protective veil over the nucleus, on the side toward the skin surface--sheild the nuclear DNA from damage by UV light
Langerhans cells
arise from red bone marrow and migrate to the epidermis where they constitute a small fraction of the epidermal cells
What do Langerhans cells do?
participate in immune responses mounted against microbes that invade the skin; easily damaged by UV light
Merkel cells
located in the deepest layer of the epidermis, where they contact the flattened process of a sensory neuron (nerve cell) called a tactile (Merkel) disc; least numerous of the epidermal cells
What forms the epidermis?
several distinct layers of keratinocytes in various stages of development
What are the four strata or layers of the the epidermis in most regions of the body?
1. stratum basale
2. stratum spinosum
3. stratum granulosum
4. Thin stratum corneum
What is thin skin?
stratum corneum
Where does the epidermis have five layers?
where exposure to friction is greatest, such as in the fingertips, palms, and soles
What are the five layers of the epidermis?
1. stratum basale
2. stratum spinosum
3. stratum granulosum
4. stratum lucidum
5. thick stratum corneum
What is thick skin?
thick stratum corneum
What is the deepest layer of the epidermis?
stratum basale
stratum basale
composed of a single row of cuboidal or coumnar keratinocytes
What are stem cells?
some cells in the stratum basale that undergo cell division to continually produce new keratinocytes
Describe the nuclei of keratinocytes in the stratum basale.
large and their cytoplasm contains many ribosomes, a small Golgi comples, a few mitochondria and some rough endoplasmic reticulum
What are tonofilaments?
scattered ntermediate filaments in the cytoplasm within the keratinocytes of the stratum basale
The tonofilaments are comoposed of __________________________.
a protein that will form keratin in more superficial epidermal layers
What cells are scattered among the keratinocytes of the basal layer?
Melanocytes, Langerhans cells, and Merkel cells with their associated tactile discs
What is the stratum basale also known as and why?
stratum germinativum--to indicate its role in forming new cells
What is a skin graft?
involves covering the wound with a patch of healthy skin taken from a donor site
When and why are skin grafts used?
if an injury destroys a large area of the stratum basale and its stem cells--new skin cannot regenerate
What is an autograft?
transplanted skin taken from the same individual
What is an isograft?
transplanted skin taken from an identical twin
What is autologous skin transplantation?
a self-donation procedure used if skin damage is so extensive that an autograft would cause harm
What is the procedure for autologous skin transplantation?
small amounts of an individual's epidermis are removed, and the keratinocytes are cultured in the lab to produce thin sheets of skin--transplanted back to the patient
What epidermal layer is superficial to the stratum basale?
stratum spinosum
What is the stratum spinosum?
8 to 10 layers of many-sided keratinocytes fit closely together--keratinocytes have the same organelles as cells of the stratum basale
Why do keratynocytes appear to be covered with thornlike spines under microscopic examination?
when prepared for microscopic examination, they shrink and pull apart--appear rounded and larger in living tissue