Lab#4 Integumentary System Flashcards
Layers of the epidermis
-Thin skin: has hair
-Thick skin: hairless areas subject to abrasion
Ex: Palms, fingertips, soles of feet.
- stratum basale
- stratum spinosum
- stratum granulosum
- stratum Lucidum
- stratum corneum
Functions of integumentary system
The largest system of the body “skin”
Two parts:
- Cutaneous membrane “skin”
- Outer epidermis: epithelial tissue
- Inner dermis: connective tissue - Accessory structures: start in dermis
- Extend->through epidermis to skin surface
- ex: hair, nails and exocrine glands
Stratum Germinativum
Germinating layer– Basal layer
- Deepest epidermal layer
- single row of actively mitotic stem cells
- continually renewing cell population with youngest keratinocytes
Stratum Corneum
A.k.a. Horny layer (Cornu=horn)
- Dead-anucleate (no nucleus) cells
- 20-30 cell layers thick
- durable/protective top layer for abrasion
- flat ingredients socks filled with keratin
Characteristics/locations of thick skin
Hairless skin w/additional layers of cells
Palms of hands and soles of feet.
Has skin ridges/ friction ridges for gripping / sense of touch
Characteristics/location of thin skin
Skin with hair
20-30 layers of keratinocytes
Description of Microscopic view of thin and thick skin
Thick skin - epidermal ridges
Thin skin- hair follicles
Both have eccrine sweat glands
Reasons for differences in skin color
Evolutionary Variations in three pigments
- melanin (reddish yellow / brownish black) - carotene (yellow to orange) - hemoglobin (red blood cells)
Describe microscopic view of pigmented nonpigmented skin
Melanocytes of darker skinned people, produce many more and darker melanosomes than those of fair skinned individuals and their keratinocytes retain it longer.
Recognize papillary dermis
Areolar connective tissue
- fine interlacing collagen and elastic fibers - very invested with small blood vessels
Reticular dermis
- Reticular layer made up of dense irregular connective tissue
- Majority of the dermis layer
- Irregularly arranged dense fibrous connective tissue
- Contains the cutaneous plexus (blood vessel network)
Recognize sweat glands
(AKA) Eccrine glands
(Coiled/knotted) gland within rerticular layer
Describe the distribution in the body of: Sebaceous glands, Sudoriferous glands and Pili follicles
All within the reticular layer of the dermis
Keratin
Fibrous proteins that helps give the epidermis it’s protective properties
-kera = horn in Greek
Keratinocytes
- Makes keratin (protective protein)
- most epidermal cells are keratinocytes
- Millions of dead keratinocytes rub off every day giving us a new epidermis every 25 to 45 days
Basal lamina
A layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. It is often confused with the basement membrane.
Functions of the skin
- Protects us (against bacteria)
- Agent against excretion (water/ salts/organic wastes)
- Maintenance of body temperature (insulation/evaporation)
- Production -Melanin and Keratin (lubrication)
- Synthesis -vitamin D3
- Storage -lipids
- Sensory -touch, pressure, pain, temperature
Sudoriferous glands
Sweat glands
- Eccrine/Merocrine Glands
- Apocrine glands (odored sweat)
- Abundant on palms and soles of feet and forehead
- Coiled tubular glands that secretes sweat to pore on skin surface
Sebaceous glands
Oil glands
- secrete Subum (oily substance)
- All over the body except in the thick skin of the palms and soles
- Attached to hai follicle
Pili and follicles
Hair and hair follicles
-Consist largely dead hard keratinized cells
-connected to follicle is the hair root, the arrector pili muscle, Sabaceous oil gland
Most and I couldn’t sweat
-External Hair = hair shaft
Epidermis
- Keratinized stratified squamous epithelium
- Outermost protective shield of the body
- Contains four cell types:
- Keratinocytes
- Melanocytes
- Dendritic cells
- Tactile cells - Contains four/five layers:
- stratum basale
- stratum spinosum
- stratum granulosum
- stratum lucidum (thin only)
- stratum corneum
Dermis
Contains Papillary and Reticular layers
Below Epidermis above Hypodermis
Hypodermis
Subcutaneous (below blood vessels)
AKA superficial fascia
Mainly adipose cells (fatty)
Technically not part of the skin
Arrector pili muscle
Tiny smooth muscles connecting hair follicle to papillary layer
Contracts to pull hair upright when cold, scared, amazed!
Dermal papilla
Peg-like projections from papillary layer
Indent the overlying epidermis
Epidermal ridge
Epidermal ridge lies above dermal ridges within thick skin of palms and soles of feet.
These are skin ridges/ friction ridges… For grip and sense of touch
Germinative/stem cells
Actively mitotic stem cells within Stratum Basale
Newly formed cells with rapid devision.
Melanocytes
- Site of melanin synthesis
- Deepest layer of epidermis
- Forms on top of keratinocytes (UV Protection)
Melanin
- Pigment found only in deeper layers of epidermis
- A polymer made of tyrosine amino acids
- ranges in color from reddish yellow to brownish black
Dendritic cells
Star shaped cells that come from bone marrow and migrate to the epidermis
They ingest find substances and are key activators to our immune system
Tactile cells
A.k.a. Merkel cells
Present at epidermal/dermal junction
Associated with a sensory nerve ending
Functions as a sensory receptor for touch
