Integumentary System (Ch 5) Flashcards
Skin
- largest organ in body (different tissues working together)
- 7% of body weight
Functions of skin
- protection against mechanical damage
- barrier to fluid loss/pathogens
- Vit D production
- sensory reception
- body temp regulation
- excretion of salts/wastes
Epidermis
- ->keratinized stratified squamous epithelium
- four cell types
- avascular
- regenerates often
- 4/5 cell layers (thin vs. thick)
What are the four cell types of the epidermis?
- keratinocytes: product keratin, most abundant
- melanocytes: produce melanin –> helps shield nuclei of keratinocytes from UV radiation)
- merkel cells: sensation
- dendritic cells: immune cells
What is the structure of the epidermis?
- Stratum Corneum (sup)
- Stratum Lucidum
- Stratum Granulosum
- Stratum Spinosum
- Stratum Basale (inf)
- -> “Come Let’s Get Sun Burnt”
Stratum Corneum
*layer of epidermis (most superior)
dead cells full of keratin, shed regularly
Stratum Lucidum
*layer of epidermis (2nd layer)
“clear” layer, only in THICK skin, consists of a few rows of flat/dead keratinocytes
Stratum Granulosum
*layer of epidermis (3rd layer)
1-5 layers of cells, granules in this layer help waterproof skin
Stratum Spinosum
*layer of epidermis (4th layer)
multiple cells layers of keratinocytes, only layer with DENDRITIC cells
Stratum Basale
*layer of epidermis (most inferior)
attached to dermis, mostly keratinocytes with rapid division, melanocytes/merkel cells
Dermis
- underlies epidermis
- strong/flexible CT
- highly vascularized
- innervated (= sensation)
- 2 cell layers: papillary and reticular
Papillary Layer
- layer of dermis
- 20% of dermis
- areolar CT
- provides nutrients to epidermis
- dermal papillae increase SA for transport of materials into epidermis
Reticular Layer
- layer of dermis
- mostly dense irregular
- network of collagen + elastic fibers provide stretch/strength
Hypodermis
- supports skin (dermis/epidermis)
- areolar + adipose loose CT (mostly adipose)
What are the functions of the hypodermis?
- stores fat
- provides insulation
- anchors skin to muscles
- allows movement of skin over muscle and bones
Fingerprints
- increase friction for grasping
- have dermal papillae which push up/elevate the overlying epidermis
- patterns are unique
Hair
- flexible strands made of KERATIN
- pigment comes from MELANOCYTES
What are the functions of hair?
- sensation (light touch)
- protection (ex. eyelashes)
- insulation
Structure of Hair
- Basic
- shaft (exposed)
- root (embedded into dermis/epidermis) - Hair Follicle
- bulb (innervated)
- papilla (blood supply) - Arrestor Pili muscle
- -> contraction raises hair/causes goosebumps
Eccrine Sweat Glands
- -> secreted onto skin surface
- allows for evaporative cooling
- development: invaginate from skin surface
- product: 99% water, 1% salts/wastes
- acidic/antibacterial properties
Apocrine Sweat Glands
- -> discharge into hair follicles
- development: outgrowths from hair follicles
- product: complex molecules, odorous
- found in armpits/genitals
Ceremonious Glands
line external ear canal, produce earwax
Mammary Glands
secrete milk
Sebaceous Glands
multicellular exocrine glands (secrete onto hair follicles)
- secrete sebum (oil) –> holocrine secretion (cells accumulate sebum then burst to release)
- moisturizes hair/skin
- blocked hair follicle = acne
Melanin
- acts as natural sunblock against UV radiation
- determines skin tone
- # of melanocytes among individuals does not vary, but activity level does (ex. pale = less active)
Why is some exposure to sunlight necessary?
production of Vit D –> calcium absorption
What are the dangers of too much exposure to sunlight?
reduction in folate levels needed for embryonic development
-promotes skin cancer
Basal Cell Carcinoma
- most common form of skin cancer
- originates from stratum basale (a.k.a. stratum germinativum)
- metastasis is rare
Melanoma
- potentially life threatening
- cancerous melanocytes grow rapidly and spread throughout lymphatic system
How to detect skin cancer
A: asymmetry- irregular shape B: border- indistinct C: color- mottled D: diameter- >5mm is dangerous E: elevation- not flat
