Skin Flashcards
3 major layers of the skin and what’re they made of?

1) epidermis: stratified squamous epithelium 2) dermis: connective tissues 3). hypodermis of subcutaneous layer. composed of areolar and adipose CT.
T/F: epidermis is avascular
true
5 dif layers of epidermis from base to top
1) stratus basale 2) stratum spinosum 3) stratum granulosum 4) stratum lucidum 5) stratum corneum
4 types of epidermal cells and locations
1) keratinocyte, found in all cll layers
2) melanocytes; found in stratum basale
3) tactile merkel cells; found on the stratum basale basically on basement membrane. raeches down into dermis by sensory nerve ending
4) epiderma dendritic cell/langerhaan cell: involved in immunity and found in stratum basale

Where is the stratum lucidum present?
only found in the epidermis of THICK SKIN - palms of hands
the stratum basale is a SINGLE LAYER of epidermis made of ___ ___ cells. How are these cells attached to the basement membrane? Function of stratum basale?
made of cuboidal/columnar cells. the keratinocytes are attached to each other and to the basement mebmrane by desmosomes and hemidesmosomes. Major function:
1) to attach the skin to the basement membrane
2) to reproduce by mitosis.
thickest layer of the epidermis. function? How are these cells held together?
stratum spinosum is the thickest layer and provides strength and flexibility to the epidermis. 8-10 layesr are held together by demosomes. You can find langerhans and melanocytes in the spinosum layer.
What layer of the epidermis is nuclear degeneration apparent in? What do these cells in this layer contain?
in the stratum granulosum, nuclear degeneration is apparant. the cells contain lamellar granules AND dark-staining keratohyaline granules. Both granule types promote dehydration of cells.
in the stratum spinosum, keratin filamnets form bundles known as:
tonofibrils
purpose of the stratum corneum. what is its purpose?
its 15ish layers of flat dead squamous cells. Its composed of keratin and surrounded by lipids. it acts as a barrier to light, heat, water, chemicals and bacteria
keratinocytes produce ___ and ___ granules
lamellar and keratohyaline granules
two major regions of the dermis
1) papillary region
2) reticular region
the top 20% of the dermis is the ___ region. What is it made of? What is it’s function? What specialized cells/structures does it contain
PAPILLARY REGION. it is made of loose connective tissue and contains TYPE 7 COLLAGEN to anchor the epidermis to the dermis. It contains:
1) capillaries that feed the epidermis
2) meissner’s touch corpsucles and free nerve endings for senations of heat, cold, pain and tickle.
the majority of the dermis is the ___ region. It contains ___ ___ ___ CT with collagen, elastic and reticular fibers. What specialized structures are located in this region? What is the purpose of this region?
RETICULAR REGION because it contains reticular fibers. made of DENSE IRREGULAR FIBROUS CONNECTIVE TISSUE. Purpose is to provide strength, extensibility and elasticity to skin. Contains:
1) oil glands
2) sweat gland
3) fat
4) hair follicles
5) cells and bloodvessels
6) pacinian corpuscles,
7) nerves.
stretch marks are dermal tears to the ___ region
tears in the reticular region
3 accessory structures of the ksin that are dervied from the epidermis
1) hair
2) oil and sweat glands
3) nails
two portions of the hair. Also, what type of muscle surrounds the hair?
the hair consists of the shaft and root, and they are surrounded by arrector pili muscle, which is smooth muscle. the hair is also associated with sebaceous oil glands.
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what is the arrow pointing to?

arrector pili muscle surrounding a hair follicle
type of secretory system of sebaceous oil glands. What does it produce? Function?
HOLOCRINE. produces sebum that moistens hair and waterproofs and softens skin
type of gland

sebaceous holocrine gland
sweat glands can either be ___ or____
eccrine(merocine) or apocrine
where can you find ceruminous glands?
produces a waxy substance, found in the external AUDITORY MEATUS
epithelium of sweat glands
simple cuboidal. Eccrine or merocrine

where can you find apocrine sweat glands? How can you differentiate between eccrine and apocrine sweat glands histologically?
aprocrine sweat glands are foudn in ubic and auxillary regions. they can be distinguished because they have a clean and large lumen, whereas eccrine sweat glands have messy lumens

structure of apocrine sweat gland
simple coiled tubular
___ skin covers all parts of the body, where as ___ skin covers palms and soles of feet.
thin skin, thick skin
T/F: thick skin has hair follicles and sebaceous glands
false. thick skin lacks hair follicles, arrector pilli muscles, and sebaceous glands
What type of skin has more sweat glands?
thick skin contains more sweat glands
5 functions of the skin
1) thermoregulation
2) blood resvoir
3) protection
4) sensory functions: touch, pressure, vibration
5) synthesis of Vit D
a first degree burn affects the ___
epidermis
a second degree burn destroys:
entire epidermis and part of dermis. results in fluid filled blisters
a full thickness burn destroys:
1) epidermis
2) dermis
3) hypodermis
- damaged area is numb because nerves are destroyed. causes scarring
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note the hypodermis is made of primarily adipocytes. just on top of the skeletal muscle

meissner corpuscles are located ___ and pacinian corpuscels are located in the ____ and ____
meissner loctaed in dermal papillae just under the epidermis. but pacinian is located in deeper regions in the HYPODERMIS and DERMIS.
two types of hairs
1) vellus: microscopic around the entire body
2) terminal hairs. larger and coarser hairs that everyone recognizes as hairs
center of the shaft of the hair
medulla. typically cornified or completely absent in bleached hair
the cortex of the hair is made of ___ cells, but in the shaft the cells are flattened and keratinized. What produces hair color?
made of cuboidal cells. pigment granules and air spaces between the cortical cells produce hair color.
the ___ of the hair is made of hard keratin and surrounds the cortex
the CUTICLE
what is the internal root sheath of hair? what three portions are there?
the internal root sheah is the part of the hair follicle and extends from its base to where the sebaceous gland enters.
3 layers:
1) curcile of the internal root sheath
2) huxley’s layer
3) henle’s layer.
purpose of the external root sheath.
1) columnar region of sheath is in contact with connective tissue in the sheath.
2) polygonal cells are seaprated from the connective tissue of the sheath by a glassy membrane, which is an extension of the stratum basale and stratum spinosum of the epidermis.
3) external root sheath houses a population of epidermal stem cells capable of division. Serves as a source of sebaceous gland and follicle cells.
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external root sheath (A) is continuous with the stratum germinativum of the epidermis
internal root sheath (B) is continuous with the stratum corneum.
C & D are the cortex and medulla ( of the hair, respectfully
the “hair” is loccated in

the cortex.
T/F apocrine sweat secretion terminates at the skin surface
false. they terminate at the hair follicle and combine with bacteria to create a characteristic smell. merocrine/eccrine sweat secretions terminate at the sruface however, and they are present in regions that do not have hair at all, such as palms of hands.