Histo 1 Flashcards by Alyanna Agunos

Functions of the integumentary system

Body temp regulation
Protection from external environment
Cutaneous sensations
Excretion and absorption
Vitamin D synthesis

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Group of soluble SERCOSTEROIDS
responsible for enhancing intestinal absorption of CALCIUM AND PHOSPHATE
Body can synthesize vit D in the skin from cholesterol when expose to the sun

VIT D

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Largest organ of the body

Skin

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Two principle parts of the skin

Epidermis
Dermis

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Superficial portion of skin with 5 layers

Epidermis

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Inner portion of skin with 2 regions

Dermis

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KERATINIZED STRATIFIED SQUAMOUS EPITHELIUM
Forms major distinction between thick and thim skin

Epidermis

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Principle types of cell in the epidermis

Keratinocytes
Melanocytes
Lagerhans cells
Merkell’s cells

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Consist 90% of epidermal cells
Produce protein KERATIN and LAMELLAR GRANULES

Keratinocytes

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Consist of 8% of the epiderma cells
Located at the basal layer of epidermis
Produce the pigment MELANIN

Melanocytes

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Types of melanin produced by melanocytes

Eumelanins
Pheomelanin

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Brown/black pigments

Eumelanins

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Pigment found in red hair

Pheomelanin

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Arises from RED BONE MARROW and migrate to the EPIDERMIS
Constitute a small portion of the epidermal cell
Participate in immune responses: RECOGNIZE,PHAGOCYTIZE and PROCESS FOREIGN ANTIGENS and present them to T LYMPHOCYTES for an immune response thus function in ANTIGEN PRESENTING CELLS (APC)
found in stratum spinosum

Langerhans cells

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The least numeruous in epidermal cells
Located in the deepest layer of epidermis where they contact the sensory neuron aka MERKEL OR TACTILE DISC

Merkel cells

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Essential for light touch sensation
Most abundant in highly sensitive skij such as fingers and at the bases of hair follicles

MERKEL CELLS AND TACTILE DISC

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Layers of epidermis

Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale

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Corne-hard or hooklike
Consists od 20-30 layers of dead flat keratinocytes
Contain KERATOHYALIN
Cells continuosly shed and replaced by cells from the deeper strata

Stratum corneum

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Densely packed intermidiate filaments and lamellar granules

Keratohyalin

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These are from the lamellar granules that are effective water repellant barrier and also protects against injury and microbes

Lipids

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Due to constant exposure of skin to friction causes abnormal thickening of the epidermis

Callus

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Means clear
Present only in thick skin of the finger tips, palms and soles
Consist of 2-3 layers of clear, flat deaf keratinocytes that contain densely packed intermidiate filaments and thickened plasma membrane

Stratum lucidum

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Means little grains
Consists of 3-5 layers of flattened keratinocytes
Nuclei and other organelles of keratinocytes begin to degenerate thus granulosum marks the transition between deeper and superficial strata
Contains basophilic granules

Stratum granulosum

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Basophilic granules of stratum granulosum

Keratohyalin
Lamellar

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Darkly stained granules of a protein Organizes intermidiate filaments into even thicker bundles thus becomes more apparent

Keratohyalin

Distinctive granules of the layer Lipid rich impermeable layer around the cell Skins barrier against water loss Provides sealing effect in the skin forming barrier to penetration by most foriegn material

Lamellar

Superficial tonstratum basale Thickest layer especially in epidermal ridges 8-10 layers of POLYHEDRAL KERATINOCYTES fit closely together Apper to be covered with thornlike spinesn Bundles of intermidiate filament of the cytoskeletom tightly join the cells to one another to provide strenght and flexibility to the skin LANGERHANS CELLS AND MELANOCYTES appear in this stratum

Spinosum

Deepest layer of the epidermis Sometimes referred to as startum germinativum Characterized by intense MITOTIC activity Single row basophilic cuboidal or columnar keratinocytes HEMODESMOSOMES join this layer to the basal lamina DESMOSOMES binds the cells of this layer together in their lateral and upper surfaces MELANOCYTES, MERKEL CELLS and TACTILE DISCS are scattered among the keratinocytes of the basal layer Human epidermis is renewed about 15 to 30 days depending on age

Basale

Important feature of all keratinocytes in basale which increase during differentiation as cell moves upward

Cytoskeletal keratins

Second deepest part of the skin Composed of connective tissue containing collagen and elastic fibers Include cells such as fibroblast, macrophages and some adipocytes Blood vessels, nerves, glands and hair follicles are embedded in dermal tissue

Dermis

Superficial portion of dermis Consists of areolar tissue with elastic fibers and small fine typen1 and 3 collagen fibers, fibroblasts, macrophages and other WBC Contain dermal papillae Contain: meissner's corpuscle Free nerve endings

Papillary region

Finger like projections that indent the epidermis and contains loops of capillaries

Dermal papillae

For touch sensation

Meissner's corpuscle

Dendrites that initiates signals that are felt as warmth, coolness, pain, tickling and itching

Free nerve endings

deeper portion of dermis consists of DENSE IRREGULAR CONNECTIVE TISSUE containing more coarsely textured bundles of collagen and some elastic fibers combination of collagen and elastic fibers provides the skin with extensibility and elasticity between collagen and elastic fibers are abundant proteoglycans rich in dermatan sulfate spaces between fibers contain some adipose cells, hair follicles, nerves, sabaceous glands and sudoriferous glands

reticular region

functions of the connective tissue of the dermis

tough collagen fibers and resilient elastic the ground substance of the dermis mast cells, lymphocytes and macrophages in the connective tissue dermis together with its associated blood vessels and nerves

fibers provide meachanical strength for skin lines of tension in the dermus, called LANGER'S LINES, affect healing after surgical incision

tough collagen fibers and resilient elastic

serves as the substrate for diffusion of nutrients and waste to and from various other tissue components

the ground substance of the dermis

carry out substrate for diffusion for the immune system

mast cells, lymphocytes and macrophages in the connective tissue

capable of active response to injury, yielding the defensive reaction of inflammation, followed by the healing processes of growth and repair

dermis together with its associated blood vessels and nerves

types of skin

thin skin thick skin

covers all parts of the body except palms, palmar surfaces of the digits and soles epidermis is thin lack stratum lucidum, spinosum and corneum are thin has fewer dermal papilla, lacks muscle and oil glands but fewer sweat glands than thick sparse distribution of sensory receptors

thin skin

covers palms, palmar surfaces of digits and soles thick epidermis with stratum lucidum, spinosum and corneum more numerous dermal papillae, thus has epidermal ridges lacks of hair follicles, arrector pilli, sabaceous glands has more sweat glands than thin skin also display blood vessels and adipose tissues sensory receptors are more densely clustered

thick skin

types of mechanoreceptors

unencapsulated - tactile - free nerve endings - root hair plexus encapsulated - meissner's corpuscle - pacinian corpuscle - krause end bulbs - ruffini corpuscles

type 1 cutaneous mechanoreceptor for tonic receptors, for light touch and for sensing an objects texture

tactile/merkel disc

in papillary dermis respond to high and low temperature, pain and itching function also as tactile receptors

free nerve endings

sorrounds bases of hair follicles in reticular dermis detects movement of hair

root hair plexus

are encapsulated endings in dermal papillae, most common in palmar and palmar skin, especially in fingertips

meissner's corpuscle

located deeper in dermis also found in tissue organs deep in the body including wall of rectum and unirnary bladder avoid structures resembling small onions respond to deep pressure, vibration and coarse touch

pacinian corpuscle

found in skin of penis and clitoris where they sense low frequency vibration

krause and bulbs

have collagenous fusiform capsules with sensory axons stimulated by stretch or twisting in the skin

rufinni corpuscle

under the skin contains the superficial fascia and adipose tissue mainly for fat storage injection into the subcutaneous tissue is a route of administration used for drugs such as insulin, bc it is highly vascular, the tissue absorbs drugs quickly subcutaneous injection is believed to be the most effective manner to administer some drugs such as human growth hormones can store fat, can also provide good storage space for drugs that need released gradually because there is limited blood flow

subcutaneous layer

produced by melanocytes and stored in basal keratinocytes contributes a yellow/brown color to the epidermis if the epidermis is not heavily pigmented, light readily penetrates into the dermis

melanin

scatter light from the dermis without altering its color, hence the whiteness of white skin primarily a reflection of collagen

collagen

HEMOGLOBIN in rbc scatters lights and is responsible for the pinkness of unpigmented skin. the relative amount of pink in any given patch of skin reflects how closely blood approaches the base of epidermis

blood

skin color

melanin collagen blood

affect the thickness and smoothness of the epidermis, by the quality of fibers in the dermis and by the amount of fluid in dermal connective tissue

skin texture

composed of column of dead, keratinized cells bonded together by extracellular proteins

hairs

parts of hairs

shaft roof hair follicle bulb arrector pilli hair root plexuses

superficial portion of hair

shaft

penetrates into the dermis

roots

concentric layers of shaft and root

medulla cortex cuticle

inner portion of inner layer of shaft and root 2 or 3 rows of polyhedral-shaped cells containing pigment granules and air spaces

medulla

middle portion of shaft and root forms the major part of the shaft and pigment granules in dark hair but mostly air in gray or white hair

cortex

outermost layer of shaft and roof single layer of thin, flat cells that are most heavy keratinized

cuticle

tubular invaginations lined by stratified squamous epithelium similar to epidermis surrounds the roots of the hair

hair folicle

hair follicle is made of

external root sheath internal root sheath

downward continuation of epidermis contains str. basale

external root sheath

hair follicles are associated with

sebaceous gland nerve ending smooth muscle

secrete oil into the hair follicles as well as nerve endings and smooth muscle to form the pilosebaceous apparatus

sebaceous glands

detects deflection of the hair shaft and also controls PILOERECTION OR GOOSEBUMPS

nerve endings

with a small bundle of smooth muscle cells called ARRECTOR PILI attached to the connective tissue sheath around each hair follicle affect PILOERECTION

smooth muscle

the base of hair follicle onion shaped structure

bulb

bulb houses

papilla of the hair matrix

nipple shaped indentation contains areolar connective tissue contains many blood vessels that nourish growing hair follicle

papilla of the hair

germinal layers of cells w/c arise from stratum basale responsible for the growth of existing hairs and producing new hairs when old hairs are shed

matrix

smooth muscle cells stimulated by autonomic nerve endings to contact pulling the hair shaft perpendicular to the skin surface during cold or fright produces goose bumps

arrector pilli

glands of the integumentary system

sebaceous gland sudoriferous glands

lined with STARTIFIED EPITHELIA WITH COLUMNAR OR CUBOIDAL CELLS known as BASAL CElls are associated with hair follciles they are HOLOCRINE GLANDS which means that the whole cell is secreted produce sebum

oil gland

mixture of fats, cholesterol, protein, inorganic salts and pheromones coats the surface of hairs and helps keep them from drying and becoming brittle prevents excessive evaporation of water from the skin keeps skin soft and pliable inhibits growth of certain bacteria

sebum

3-4 m sweat glands release their secretions by exocytosis and empty them onto the skin surface

sudoriferous glands

2 types of sudoriferous or sweat glands

eccrine apocrine

simple coiled tubular glands much more common numerous in skin of plams and soles for regukation of body temperature and waste removal, excrete water, sodium salts, ammonia, uric acid and urea sweat is a physiologic response to increase body temperature

eccrine

types of eccrine cells

clear cells - dark cells - myoepithelial cells

pale staining no secreting granules watery secretion

clear cells

with stringly eosinophillic secreting granules line most the lumen mucous secretion

- dark cells

sorrounds basal portion of sceretory portion contracts to expel the secretion from sweat gland -

myoepithelial cells

simple coiled tubular glands stimulated during emotional stress and sexual excitement secretions are commonly know as COLD SWEAT larger than eccrine limited to axillary, anus and areolar region of breast ducts open into hair follicle and produce viscous secretions that acquire a distinct odor following bacterial decomposition

- apocrine

plates of tightly packed, hard, keratinized epidermal cells cells from a clear, solid covering over the dorsal surface of the distal portions of the digits

nails

parts of nails

nail body free edge nail root lunula hyponychium eponychium

portion of nail that is visible

nail body

part of nail body that may end past the distal end of digits

free edge

proximal edge of the nail plate that is buried in a fold

nail root

whitish cresent shape covered by the portion of nail bed

hyponychium

cuticle, horny epidermal extension of the tip of the nail fold -

eponychium