Chap 1 Part 2 Flashcards
What kind of epithelium is two or more cell layers thick?
stratified epithelium
What kind of function is shared by all stratified epithelium>?
protection
Stratified Squamous epithelium have multiple layers of cells that tend to flatten out from basal layer to superficial layer. Where can this type of epithelium be found?
esophagus, oral cavity, tongue and vagina
Although stratified squamous epithelium protects against abrasion, is protection is limited. Why? What are its limitations?
limited thickness; no protection from drying
What is the function of Keratinized Stratified Squamous epithelium?
Protection in a dry environment
What are the layers in epithelium of skin?
stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum (Boys Seldom Get Lucky Consistently)
Which layer of the keratized stratified squamous is composed of 1-2 layers of keratinocytes which are mitotic and closest to the dermis?
stratum basale (germinativum)
Which layer of the keratinized stratified squamous is composed of multiple layers of “spiny shaped” keratinocytes? Thickness of this layer can vary.
Stratum Spinosum
Which layer of the keratinized stratified squamous can be described as the uppermost 2-5 layers of flattened living keratinocytes where exocytosis of lipid-filled lamellar granules will occur?
stratum granulosum
Which layer of the keratinized stratified squamous is not easy to see, present only in thick skin, and is a thin layer of recently dead or dying keratinocytes?
stratum lucidum (nucleus and organelles are not present)
Which layer of the keratinized stratified squamous is composed of dead cells, karatin, and lipids? It also has 3 distinct functions.
stratum corneum
What are the 3 functions of the stratum corneum?
prevents water loss, barrier to microbes, and protects against abrasion
T/F: thickness varies in the stratum corneum and stratum spinosum.
True
What is the the Malpighian layer?
stratum basale and stratum spinosum; a way of grouping layers together where cell division can occur
How do epidermal pegs (rete ridges) and dermal papillae contribute to the strength of epithelium?
increase surface area for attachment of the epithelium to the CT below
How long do epithelial cells live?
about 28 days
Melanocytes do what and are found where?
protect against UV radiation; stratum basale
What occurs with increased UV light exposure (with regard to melanocytes)?
skin color greatly influenced; melanocytes increase, increasing melanin
T/F: melanocytes are about equal in all humans.
True
Which type of cell recognizes external foreign antigens, is an epidermal dendritic cell, a resident APC, and is found in the stratum spinosum?
Langerhans Cells
Which type of cell provides touch receptors, is associated with free nerve endings (very numerous in areas of high sensitivity) and is found in the stratum basale layer?
Merkel cells (fingertips and hair follicles)
T/F: Melanocyte numbers decrease with repeated UV exposure.
False; this is true of Langerhans cells, melanocyte numbers increase
What are the 5 types of stratified epithelium?
stratified squamous, keratinized stratified squamous, stratified cuboidal, stratified columnar, and transitional
Which types of stratified epithelium function in protection?
all of them
Where can you find stratified cuboidal? how many layers?
larger in ducts in sweat glands and salivary glands; 2 layers (basal layer is flattened and superficial is cuboid
Wher can stratified columnar be found?
large ducts in pancreas, parts of male urethra and conjunctiva of the eye
T/F: stratified columnar epithelium is very rare, and consists of two layers. The basal layer is flattened and the superficial is columnar in shape.
True
Other than protection, what function does stratified columnar perform?
provides a transition between epithelial types
What/where is transitional epithelium?
Urinary epithelium or urothelium; found in most of urinary tract
Other than protection, what function is transitional epithelium specialized to do?
stretch
What part of transitional epithelium is thin and fenestrated? which part is large and rounded? And which part is well developed?
basement membrane, superficial cells, and zonula occludens/tight junctions (respectively)
Why is it important that transitional epithelium has a well-developed zonula occludens?
prevents wastes (urine) from seeping out; needed because of fenestrated basement membrane
T/F: when transitional epithelium is stretched, distance of diffusion is increased.
False; the distance of diffusion is decreased therefore more oxygen can actually get into the cells
Where do cells accumulate during psoriasis vulgaris (patchy skin lesions)?
in stratum corneum
T/F: Freckles are an increase in melanin and melanocyte numbers.
False; they are an increase in melanin without an increase in melanocyte numbers
What are patches which lack melanocytes called?
vitiligo
What is the term for discolorization due to proliferation of melanocytes?
moles
What is occuring when melanocytes become mitotically active and invade dermis? This is very invasive and metastic requiring surgery/chemotherapy.
malignant melanoma
What condition occurs when melanocytes fail to produce melanin?
albinism
What enzyme is missing from melanocytes in the most common form of albinism?
tyrosinase (a catalyst in the conversion of tyrosine to melanin)
