A&P 5 lecture slides Flashcards
What is the Integumentary system is composed of and what do they contain
Cutaneous membrane (skin) with two layers
Accessory Structures: hair, nails, exocrine glands
Subcutaneous Layer: separates the integument above from the organs and muscles, composed of mostly adipose tissue
What are the two layers of Cutaneous membrane (skin)
Epidermis: superficial epithelium; “epi” above the dermis
Dermis: underlying layers of connective tissue
Function of the Integumentary system
Protection
Excretion
Maintenance of normal body temperature
Synthesis of vitamin D
Storage of nutrients
Sensory perception (touch, pressure, pain, temperature)
What is the epidermis composed of
stratified squamous epithelial tissue arranged in 4 to 5 layers, or strata
Features/functions of the epidermis
contains no blood vessels (avascular)
provides mechanical protection
prevents fluid loss
guards against microorganisms (e.g. bacteria, viruses)
What are the 5 layers of the epidermis from uppermost layer to the bottom layer
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum germinativum
Stratum germinativum features/functions
Bottom most (or basal) epithelial layer
Epidermal ridges increase the surface area of contact between epidermis and the underlying dermis
Basal (epithelial) cells produce new cells that replace lost or shed cells at surface
Melanocytes – produce melanin that colors epidermis
Merkel’s cells – cells sensitive to touch
Stratum corneum features
15-30 layers of dead flat epithelial cells that are filled with keratin
Keratinized cells are connected by desmosomes that hold them together ; cells shed in sheets
Skin Color contains variable quantities of 2 pigments: What are the colors of these pigments and vitamins associated with them
Carotene – yellow-orange pigment found in orange vegetables (carrots & squashes); can be converted into Vitamin A
Melanin – brown, yellow-brown or black pigment produced by melanocytes; melanin production is triggered by ultra-violet (UV) light from the sun; melanin protects from skin damage though some UV light is helpful for synthesizing Vitamin D)
Melanocyte cells are found where? What do they produce?
Found in stratum germinativum
Produce melanosomes, these travel to keratinocytes (epidermal cell which produces keratin) where they are broken down and release their pigment melanin
How can blood circulation color the skin?
Blood vessels travel in the dermis and in the tissue below the dermis
When blood is rich in oxygen, blood is bright red and this can influence skin color
When vessels are dilated, skin turns brighter red (e.g. blushing, heat, swollen)
But if blood is low in oxygen, the color of the skin becomes blueish (cyanosis); can appear blue around lips and beneath nails
Cyanosis can occur due
extreme cold, or in respiratory disorders, severe asthma, heart attack
Ultraviolet light stimulates epidermal cells in lower epidermis to synthesize
vitamin D
vitamin D3 (cholecalciferol)
this Vitamin D helps to promote
Calcium and phosphate uptake which keeps bones strong
Two Skin Cancers
Carcinomas- metastasis is rare; treatment is surgical removal of tumor
Melanoma- is more serious; cancerous cells grow rapidly & metastasize through the lymphatic system
Two types of Carcinoma skin cancer
basal cell carcinoma in stratum germinativum
squamous cell carcinoma higher levels of epidermis
Detection of Melanoma
Skin needs to be examined for unusual darkened spots that have:
Asymmetry – tend to be irregular in shape
Border – the border of a melanoma is unclear
Color – generally variable coloring in different areas (tan, brown, black, red, pink, white, blue)
Diameter – spot changes size. bigger than 5mm in diameter is dangerous
The Dermis connective tissue lying beneath the epidermis have two layers, what are the two layers called and what do they contain
Papillary layer consists of areolar tissue (loose connective tissue), capillaries, sensory neurons, various types of cells
Reticular layer contains interwoven meshwork of collagen & elastic fibers (irregular connective tissue) which enable it to withstand tension and physical distortion
What are they lines of cleavage
due to the orientation of bundles of collagen and elastic fibers in dermis
lines are oriented to resist stresses of movement
What are the clinical significance lines of cleavage
incision parallel to lines of cleavage heals quicker
incision perpendicular to lines of cleavage heals slower
Dermal Blood Supply function
Supplies blood to the hair follicles, sweat glands in the dermis
Sends small loops of capillaries to the dermal epidermal border
Nutrients diffuse into the epidermis
We find the subcutaneous plexus of small veins and arteries in
the hypodermis
Sensory receptors the epidermis contains
Merkel’s cells when touched release chemicals that stimulate nerve endings (Merkel’s discs), very sensitive to light touch
Free nerve endings unspecialized and respond to pain
Root hair plexus detect movement of hair
Sensory receptors the dermis contains
Meisner’s (tactile) corpuscles: light touch
Lamellated (pacinian) corpuscles: deep pressure; vibrations
Ruffini’s corpuscles: skin distortion
