Integumentary System Flashcards
Functions of the skin
- thermoregulation
- blood reservoir
- protection
- cutaneous sensations
- excretion and absorption
- synthesis of vitamin D
Types of barriers
chemical
- skin secretions’ low pH retards bacteria
- sebum and defensis kill bacteria
- melanin defends against UV damage
physical
- flat, dead cells of stratum corneum w/ lipid
- keratin and glycolipids = water proof
- drugs, drug agents, heavy metal salts, organic solvents, plant oleoresins, and lipid solubles have limited access
biological
- dendritic cells bring stuff to WBCs
- macrophages bring stuff to WBCs
- DNA electrons absorb UV radiation and convert it to heat
How much water does a person loose in a day? What is this kind of sweat called
- 500 ml
- insensible perspiration
How does the body respond to high or low temperatures?
High: dermal vessels dilate and sweat gland activity increases
Low: Dermal vessels constrict and skin temp drops to slow passive heat loss
Explain cutaneous sensations
- cutaneous sensory receptors
- detect temp, touch, pain, etc…
- deepness of receptor determines deepness of sensation
- deep ones sense pressure
Metabolic functions
- Synthesis of Vit D precursor and collagenase
- chem. conversion of carcinogens and activation of some hormones
Blood reservoir
- up to 5% of body’s blood in skin
- used to raise blood pressure when needed
- that’s why you go pale before fainting
Excretion
nitrogenous waste and salt
Dimensions of skin
area = 2 m^2 = 22 ft^2 weight = 4.5-5.5 kg = 10-11 lbs thickness = 0.5-4 mm
2 types of skin
thin/ hairy skin
- covers almost all of body
- contains hair follicles
thick/hairless skin
-palms and soles of hands, feet, and digits
3 layers of skin
Epidermis
-keratinized, stratified, squamous epithelium
Dermis
-areolar and dense irregular connective tissue
Subcutaneous/hypodermis layer
- attaches skin to underlying connective tissue
- not part of cutaneous membrane
4 types of cells in epidermis
- Keratinocytes
- 90% of epidermal cells
- produce keratin = tough fibrous protein that provides protection - Melanocytes
- produce melanin for UV protection - Langerhans cells (dendritic)
- involved in immune response
- arise from bone marrow - Merkel cells
- function in the sensation of touch along with adjacent tactile discs
Stratum Basale
- firmly attached to dermis
- single row of mitotically dividing, stem cells
- takes 25-45 days for cell to reach top
- Layer is aka as stratum germinativum
- 10-25% of layer is melanocytes
Stratum Spinosum
- “prickly layer”
- several cell layers thick
- cells have web-like system of intermediate prekeratin filaments attached to desmosomes
- keratinocytes look spikey
- lots of melanosomes and dendritic cells
Stratum Granulosum
- 4-6 cells thick (cells are flat though)
- organelles disintigrate
- keratination begins (cells accumulate keratohyaline granules which help form the fibers)
- cells accumulate lamellar granules = water resistant glycolipid
- Cells above this layer die
Stratum lucidum
- only in thick skin
- thin, clear band of 2-3 rows of flat, dead keratinocytes
Stratum Corneum
- 20-30 rows of flat, anucleated, keratinized, dead cells
- 3/4 epidermal thickness
- cells protects deeper cells, prevent water loss, and act as barrier
Outer dermal layer
- areolar ct
- dermal papillae
- cappilary loops
- corpuscles of touch
- free nerve endings
Deeper dermal layer
- dense irregular ct
- adipose cells
- heir follicles
- nerves
- sebaceous glands
- sudiferous glands
3 sensory structures in the deep dermal layer
- lamellated (pucinian) corpuscles
- deep pressure, high frequency vibrations - bulbous (ruffini) corpuscles
- deep pressure and skin distortion - Root hair plexus
- light touch
Striae
- stretch marks
- appear if skin is stretched too much and the dermis breaks
Lines of cleavage
- “tension lines”
- indicate the predominant direction of underlying collagen fibers
- cut parallel to reduce scarring
Epidermal ridges
- reflect dermal papillae
- along with sweat glands form fingerprinds
- increase friction/grip
Dermatoglyphics
study of epidermal ridges
tattoos
- permanent because they penetrate dermis
- red ones are bad
what causes different skin colors
- variations of the three pigment: melanin, carotene, and hemoglobin (mostly melanin)
- number of melanocytes is about the same for everyone, but the amount of pigment produced is different
Melanin
- yellow-red or brown-black pigment produced by melanocytes in epidermis
- secrete melanin which is taken up by keratinocytes to protect their nuclei
Nevus
- a mole
- benign overgrowth of melanocytes
albinism
-inherited inability to produce melanin
vitiligo
-condition where there’s partial or complete loss of melanocytes from patches of skin
carotene
yellow-orange pigment in stratun corneum, dermis, and subQ layers
-carotene is increased by eating more yellow-orange veggies
hemoglobin
- red color
- in erythrocytes flowing through capilaries
- causes you to turn red when exercising or embarrased
Subcutaneous layer
- attaches skin to underlying tissues and organs
- has lamellated (pacinian) corpuscles which detect external pressure applied to skin
hair functions
-protection, reduce heat loss, sense light touch
what is hair
dead keratinized epidermal cells
define hair shaft, root, follicle
- shaft = above skin
- root = penetrates into dermis
- follicles = tissues that house the root (epithelial root sheath (inner and outer) and dermal root sheath)
Hair matrix
mitotic cells at the root bulb which divide and push the hair up
arrector pili muscle
-at hair follicle –> makes hair stand upright when it contracts
hair papillae
dermal tissue with a knot of capillaries to nourish your hair
3 types of hair
- Languo = hair of fetus and newborns
- vellus = fine hair covering most of body
- terminal = course hair
Hair color and grey hair
- caused by melanin
- caused by lack of melanin and air bubbles in shaft
Sebaceous glands
- secrete oily sebum –> prevents dehydration of hair and skin and inhibits bacterial growth
- stimulated at puberty by sex hormones (acne)
- acne is when sebaceous glands get blocked by oil, dead skin, or bacteria
Sudiferous glands
- Eccrine
- pores near surface of skin all over body
- temperature regulation and disposal of waste
- merocrine - Apocrine
- not active til puberty
- pits, groin, areola, bearded faces
- merocrine
- open into hair follicles when stressed or aroused
- cause body odor when mixed with skin flora
Ceruminous glands
- modified sweat glands in ear canal
- secretions mix with sebum to form cerumen (earwax)
- earwax keeps stuff out of ear
Nails
- hard, keratinized epidermal cells
- free edge, body and root/ matrix
Eponychium
cuticle
hyponychium
nail bed
Epidermal wound healing
- cells in strutum basale migrate across would til theyre stopped by contact inhibition
- cells divide to fill gap
- little to no scarring
Deep wound healing
- Inflammatory phase: attract cells for repair
- Migration of cells: epithelial tissue needs to meet before fibroblasts scar tissue fills space
- Regeneration of blood vessels, formation of scar tissue, and growth of epithelial tissue
- maturation with epidermal healing and scar ejection
First degree burn
- sun burn
- epidermal
- lasts a few days
Second degree burn
- upper region of dermis
- blisters
- causes the most discomfort
Third degree burns
- goes through the dermis
- need skin grafts to protect from fluid loss
- destroys nerves
keloid
abonormal healing of a would which causes an overflow of scar tissue
Aging skin
- wrinkles bc of less collagen and elastic
- lowered immune response
- dehydration and cracking
- less sweat
- less melanocytes
- less subcutaneous fat
- more succeptible to pathogens
- growth of hair and nails declines
- brittles
