How much does the skin weigh?
What percent of body weight is the skin?
The surface area of skin is ________ sq. meters.
4 to 5 kilograms = 9 to 11 lbs.
7%
1.2 to 2.2
What region of the skin is composed of epithelial cells and is the outermost protective shield?
Epidermis
What layer of the skin is also called the superficial fascia?
Hypodermis
What makes up the bulk of the skin?
Dermis
What are the two distinct regions of the skin?
Epidermis and Dermis
What is the only region that is vascularized?
The dermis
Which region of the skin thickens markedly when a person gains weight, and why?
Hypodermis, because it is composed mostly of adipose tissue
True or False:
The epidermis is keratinized stratified squamous epithelium.
True
What are the four distinct cell types of the epidermis?
Keratinocytes
Melanocytes
Dendritic cells
Tactile cells
What are the fibrous proteins that help give the epidermis its protective properties?
Keratin
What is the thickening of the epidermis?
Callus
True or False:
Millions of dead keratinocytes rub off every day, giving us a totally new epidermis every 365 days.
False. Every 25 to 45 days.
What is found in the deepest layer of the epidermis?
Melanocytes
What are membrane-bound granules that melanin accumulates in?
Melanosomes
What helps protect from UV radiation in sunlight?
Melanin
What are also called langerhans cells?
Dendritic cells
What ingests foreign substances and are key activators of our immune system?
Dendritic cells
Merkel cells are also called ________ cells.
Tactile
Each tactile cell is intimately associated with a disk-like sensory nerve ending. This combination called a _______ disk, or ________ disk, functions as a sensory receptor for touch.
Tactile...
Merkel
What are the four main layers of the epidermis?
Stratum corneum
Stratum granulosum
Stratum spinosum
Stratum basale
In thick skin, there is also a fifth layer, called ________.
Lucidum
Where is the thickest skin in the body?
Upper back
What is the alternate name for stratum basale?
Stratum germinativum
10 - 25% of the stratum basale are ________.
Melanocytes
How many cell layers are in the stratum granulosum?
4-6
The process in which protein cells fill with keratin is called ________.
Keratinization
What two granules are made in the stratum granulosum?
Keratohyaline
Lamellar
Where is the stratum lucidum located?
Just above the stratum granulosum
What are cable-like parrallel arrays of intermediate filaments?
Tonofilaments
Three quarters of the epithelial thickness is the ________ layer, also called the ________ layer.
Stratum corneum...
Horny
The shingle-like shell remnants of the stratum corneum are referred to as ________ or ________ cells. (Dandruff)
Cornified...
Horny
The average person sheds ________ dead skin cells every minute, and ________ pounds of these skin flakes in a lifetime.
50,000...
40 pounds
The skin region that is strong, flexible, connective tissue is the ________.
Dermis
What part of the skin of animals is used to make leather?
Dermis
What are the two layers of the dermis?
Reticular
Papillary
True or False:
The papillary layer is thinner than the reticular layer.
True
What are peglike projections from the papillary layer surface?
Dermal papillae
What are free nerve endings and touch receptors called?
Tactile or Meissner's corpuscle
In thick skin, papillae lie atop larger mounds called ________, which cause the overlying epidermis to form ________.
Dermal ridges...
Epidermal ridges
________ enhance the gripping ability of fingers, hands, and feet.
Friction ridges
The papillary layer is _______ connective tissue, while the reticular layer is ________ connective tissue.
Areolar...
Dense fibrous
The network of blood vessels that nourishes the reticular layer?
Cutaneous plexus
What lines are important to surgeons because incisions made parallel to these lines makes the skin gape less and heal easier?
Cleavage lines
What are dermal folds that occur at or near joints?
Flexure lines
What three pigments contribute to skin color?
Melanin
Carotene
Hemoglobin
Which pigment is made in the skin?
Melanin
Two forms of melanin range in color from _____ _____ to _____ _____.
Reddish yellow...
Brownish black
Differences in skin color reflect the kind and amount of ________ made and retained.
Melanin
What are local accumulations of melanin called?
Freckles and Moles
What causes the appearance of leathery skin?
Clumped elastic fibers due to excessive sun exposure
True or False:
Sunspots are not caused by the sun, but by a fungus infection.
True
What is a yellow to orange pigment found in certain plant products such as carrots?
Carotene
What is the oxygenated pigment in the red blood cells?
Hemoglobin
Blue appearance of the skin due to poor oxygenation is called ________.
Cyanosis
Reddened skin caused by fever, inflammation, allergy, etc. is called ________.
Erythema
Yellowing of the skin due to liver problems:
Jaundice
________ of the skin occurs during fear, anger, and certain other types of emotional stress.
Blanching
________ reveal where blood escaped and is clotted beneath the skin.
Bruises