Ch 5 Terms & Objectives Flashcards
Keratinocytes
Produce a protein mixture (Keratin) which increase the durability of the cells giving the ability to resist abrasion & reduce water loss
Melanocytes
Produce pigment (melanin) contributing to skin color
Langerhans Cells
Part of the Immune System
Merkel Cells
Specialized epidermal cells associated with nerve endings responsible for detecting light touch and superficial pressure
Keratinization
As keratinocytes move from the deepest layer of the epidermis, they fill with keratin, undergo apoptosis, and are sloughed off
Lamellar Bodies
Lipid-filled
Keratohyalin
Protein Granules
Apoptosis
Programmed cell death
Callus
Thickened stratum Corneum layer due to increased friction or pressure
Corn
Thickened skin over boney prominences
Melanin
A group of pigments responsible for skin, hair & eye color
-Protects against UV light from the sun
-Produced by melanocytes
-Packaged into vesicles (melanosomes)
-Melanosomes move into the cell processes of the melanocyte
-Keratinocytes phagocytize the tip of the cell processes and pick up the
melanosomes that are filled with melanin
Melanocytes
Produce pigment (melanin) contributing to skin color
Erythema
Increased blood flow in the skin
-Reddish hue
-Due to an inflammatory response such as infection, sunburn, or allergic
reaction
Body temperature changes due to emotion or the external environment
can also cause this
Cyanosis
Decreased blood flow in the skin
-Bluish hue
Carotene
Yellow pigment found in plants such as carrots and corn
-Excess of the pigment can accumulate in the Stratus Corneum and adipocytes of the dermis and subcutaneous tissue
-Yellowish hue
-Slowly disappears once intake in reduced
Dermal Papillae
Projections into the epidermis
Friction Ridges
formed by the thick skin (palms & soles) that overlies dermal papilla
Cleavage Lines
Formed by elastic & collagen fibers oriented in the same direction
-Incisions are made along these lines rather than across them for better healing
Hair Shaft
Protrudes above the surface of the skin
Hair Root
Located below the surface of the skin
Hair Bulb
Expanded portion at the base of the Hair Root
Hair Follicle
Tube-like invagination of the epidermis that extends into the dermis
Hair Matrix
Mass of undifferentiated epithelial cells that produce the hair & internal epithelial root sheath
Hair Papilla
Portion of the dermis that projects into the hair bulb
-Blood vessels provide nourishment to the matrix cells
Arrector Pili Muscle
Smooth muscle cells that make the hair “stand on end” when contracted
-Humans produce goosebumps
-Other mammals important for warmth and communication
Sebaceous Glands
Produce sebum
-Mostly associated with hair
-Sebum prevents drying and protects against some bacteria
Sebum
Oily white substance rich in lipids
Sweat (Sudoriferous) Glands
-Eccrine (merocrine ) sweat glands
-Apocrine Sweat Glands
Eccrine (Merocrine) Sweat Glands
Helps regulate body temperature by secreting sweat onto the sins surface which evaporates & cools the body
Apocrine Sweat Glands
Become active during puberty as a result of sex hormones
-Secrete smelly sweat (body odor) into hair follicle
-Location, armpits & genitalia
Sweat
Fluid or moisture secreted from the sweat gland to the surface of the skin
Ceruminous Glands
Modified eccrine sweat glands located in the ear canal
Cerumen
Ear wax that protects the tympanic membrane from dirt & small insects
Mammary Glands
Modified apocrine sweat glands located in the breasts
-Produce milk
Nail Matrix
Epithelial tissue was a stratum Basale that gives rise to the cells that form the nail
Nail Root
Covered by skin
Nail Body
Visible portion of the nail
-Free edge, portion that hangs over the phalanx
Hyponychium
Thickened region of the stratum Corneum beneath the free edge
Nail Folds
Skin that covers the lateral & proximal edges of the nail body
Cuticle
Stratum Corneum of the nail fold that grows onto the nail body
Nail Bed
Just below the nail body and appears pink through the nail body
Lunula
Small white part of the matrix that is seen through the nail body
Functions of Skin
-Protection- acts as barrier from ultraviolet light and microorganisms while preventing dehydration by reducing water loss (waterproofing)
-Sensation- Sensory receptors that detect heat, cold, touch, pressure & pain
-Temperature Regulation- Through modulation of Blood flow through the skin & the activity of sweat glands
-Vitamin D production- When exposed to UV light the skin produces a molecule that can be transformed into a hormonal form of vitamin D
-Excretion- Small amounts of waste products are excreted from skin & glands
Keratinization
As Keratinocytes move from the deepest layer of the epidermis, they fill with keratin, undergo apoptosis and are sloughed off
Steps of keratinization
1) Keratinocytes anchored to the basement membrane by hemidesmosomes and to each other by desmosomes
2) Stem cells undergo mitotic division pushing through the daughter cells toward the surface
3) Keratinocytes flatten as they are pushed to the surface
4) Accumulate keratin fibers & lamellar bodies (lipid filled)
5) Accumulate keratohyalin (protein granules)
6) lamellar bodies release lipids into the extracellular space
7) Cells undergo programmed cell death (Apoptosis)
-Nucleus and other organelles degenerate
-Keratin fiber & keratohyalin granules remain
8) Keratohyalin disperses around keratin fibers and appears clear
9) As cells continue to be pushed to the surface, they are sloughed off
10) Cells filled with keratin mixture (keratin and Keratohyalin) and surrounded by lipids
11) Keratin mixture provides the strong barrier
12) Lipids play a role in waterproofing the skin
3 Skin Layers
Epidermis
Dermis
Subcutaneous Layer
Epidermis
Superficial Layer of stratified squamous epithelial cells
-No Blood vessels
-Living Cells receive nutrients & excrete waste products between
epidermis & capillaries of the dermis
Epidermis Cells
- Keratinocytes
- Melanocytes
- Langerhans Cells
- Merkel Cells
5 stratum layers of the epidermis (listed deep to superficial)
-Stratum Basale
-Stratum Spinosum
-Stratum granulosum
-Stratum Lucidum
-Stratum Corneum
Stratum Basale
Single layer of cuboidal or columnar cells (keratinocytes)
-Anchored to the basement membrane by hemidesmosomes & to each other by desmosomes
-Stem cells undergo mitotic division pushing the daughter cells toward the surface
Stratum Spinosum
8-10 cell layers
-Keratinocytes flatten as they are pushed to the surface
-Accumulate keratin fibers & lamellar bodies (lipid-filled)
Stratum granulosum
2-5 cell layers
-Accumulate keratohyalin (protein granules)
-Lamellar bodies release lipids into the extracellular space
-Cells undergo programmed cell death (apoptosis)
-Nucleus & other organelles degenerate
-Keratin fibers and Keratohyalin granules remain
Stratum Lucidum
Thin, clear layer of dead cells
-Only found in thick skin
-Keratohyalin disperses around keratin fibers and appears clear
Stratum Corneum
25+ layers of dead, overlapping squamous cells
-as cells continue to be pushed to the surface these cells are sloughed off
-Cells filled with keratin mixture (keratin and Keratohyalin) surrounded by lipids
-Keratin mixture, provide strong barrier
-Lipids, play a role in waterproofing the skin
Difference between thick skin and thin skin and location of each
Thick skin- Have all 5 strata layers
-Location- areas subject to friction (palms of hands & soles of feet)
-No hair
Thin Skin- Lacks the stratum lucidum layer and the rest of the strata have fewer layers
-Location- covers the rest of the body
-Hair
Steps involved in the production of skin color
Melanocytes produce melanin
Melanosomes (vesicles) package melanocytes
Melanosomes move into the cell processes of the melanocyte
Keratinocytes phagocytize the tips of the cell processes and pick up the melanosomes that are filled with melanin
Characteristics and tissue types of the Dermis
Connective tissue layer deep to the epidermis
-Papillary Layer
-Reticular Layer
Papillary layer vs the reticular layer
Papillary Layer- Loose Connective tissue layer
Reticular Layer- Dense irregular connective tissue that are resistant to stretching in many directions
Papillary Layer
Lose connective tissue layer
-Dermal papillae
-Blood vessels supply the epidermis with oxygen & other nutrients
removes waste products and helps regulate body temperature
-Friction Ridges, formed by the thick skin (palms and soles) that overlies
dermal papilla
Reticular layer
Dense irregular connective tissue that are resistant to stretching in many directions
-Cleavage lines, formed by elastin & collagen fibers
-Also contains nerve endings, hair follicles, smooth muscle, glands &
lymphatic vessels
Characteristics of the subcutaneous layer (Hypodermis)
Hypo=Below Dermis=Skin
-Layer below the sin that attaches to the underlying muscle and bone
-Loose connective tissue with collagen & elastic fibers
-Cells, fibroblasts, adipocytes & macrophages
-Half of the body’s lipid are stored here for insulation and a source of
energy
Organization and components of the hair and its follicle
-Shaft (above skin)
-Root (below skin)
-Hair Bulb (base of hair root)
-Hair
-Medulla
-Cortex
-Cuticle
-Arrector Pili (smooth muscle)
-Sebaceous Gland
-Hair Follicle
-Dermal Root Sheath
-External Epithelial soot sheath
-Internal Epithelial root sheath
-Matrix
-Hair Papilla
Different glands associated with the skin and what they produce
-Sebaceous Glands
-Sweat (sudoriferous) Glands
-Ceruminous Glands
-Mammary Glands
Organization and component of nails
-Nail matrix
-Nail Roots
-Nail Body
-Hyponychium
-Nail Folds
-Nail Bed
-Lanula
Physiological functions of skin
-Protection
-Sensation
-Temperature regulation
-Vitamin D
-Excretion
How skin helps in body temperature regulation
-Body temperature increases- Blood vessels dilate allowing heat to be lost through the skin
-Body temperature decreases- Blood vessels constrict preventing heat loss from the skin