Ch. 5: Integumentary System Flashcards
What are some functions of the subcutaneous tissue just deep to the skin?
The hypodermis 1) Stores fat 2) Anchors skin to underlying structures (mostly muscle), but loosely enough that the skin can slide relatively freely over those structures 3) Absorbs shock (due to fatty composition) 4) Insulates body (mitigates heat loss)
Histologically, what is the epidermis?
The epidermis is keratinized stratified squamous epithelium–consisting of 4 distinct cell types and 4-5 layers or strata.
What are the 4 categories of accessory skin structures?
1) Sweat/Sudoriferous Glands 2) Oil/Sebaceous Glands 3) Hair/Hair follicles 4) Nails
Which part(s) of the skin are vascularized?
Only the dermis is vascularized; Nutrients reach the epidermis by diffusing through the tissue fluid from blood vessels in the dermis.
How long does it take for epidermis to completely renew itself?
About 25-45 days, though areas with more friction encountered may slough off keratinocytes faster.
What is a melanocyte?
1) Spider-shaped epithelial cells 2) Present (only) in s. basale. 3) Synthesizes the pigment melanin inside; it accumulates as melanosomes 4) Melanosomes get conveyed via actin filaments in to the processes (“spider-arms”) of the melanocyte; there they are transported to the superficial side of the nucleus of a keratinocyte.
What type of cell is most common in the epidermis?
Keratinocyte
Name the 4 cell types of the epidermis.
1) Keratinocytes 2) Melanocytes 3) Dendritic/Langerhans cells 4) Tactile cells
What tissue lies just deep to the skin? Describe its composition.
The Hypodermis, aka Superficial Fascia is a subcutaneous tissue consisting mainly of adipose tissue; it shares some of the skin’s protective functions.
In terms of composition, how would you describe the skin?
It is composed of the superficial epidermis, itself divided into several strata, and the deeper dermis, composed of a superficial papillary and a deeper reticular layer.
What is the average surface area of the integument, or cutaneous membrane? What is its weight, and proportion of body mass?
1.2-2.2 sq. meters; 9-11 lbs (4-5 kg), 7%
In terms of composition, what is the integumentary system?
The skin/integument/cutaneous membrane and the accessory skin structures, or skin appendages
How does the skin range in thickness?
1.5-4.0 mm
What is the function of the pigment melanin?
After translocation to the superficial side above a keratinocyte’s nucleus, it protects this nucleus by shielding UV radiation.
What are keratinocytes? What is their function?
A keratinocyte 1) They are held tightly together by desmosomes. 2) They originate from continually mitotic keratinocyte cells (prompted by epidermal growth factor) in s. basale; one daughter cell gets pushed upward by the production of new cells below, while the other stays in s. basale. 3) As they move superficially, they produce and store keratin, the intermediate filament which gives the epidermis its protective properties. 4) By the time they reach the superficial strata, they are dead, filled with keratin, and squamous/scale-like, flattened in shape.
