skin

layer of skin in order

basale, spinosum, granulosum, lucidium and corneum

basale

stem cells, melanocytes, merkle cells (sensory, cell division, UV protection)

spinosum

langerhans cells, keritanocytes bound by desmosomes (strength +immunity)

granulosum

keratinocytes surrounded by extracellular lipids, keratinocytes form keratohyalin. (waterproofs skin, strength, durability)

lucidium

clear layer for toughness and protection in thick skin, found on soles of feet and hands. has dead keratinocytes called eldium

corneum

outer skin layer, composed of dead flattened keratinocytes. surrounded by lipids ( waterproofs skin, prevents dehydration and damage)

adipose tissue function

energy and insulation - stores fat as triglycerides and provides cushioning, hormone regulation, buyoancy

where is adipose tissue found

hypodermis (subcutanous layer) beneath dermis

hormones adipose tissue regulates

leptin, adiponectin. influence metabolism, appetite, insulin sensitivity.

extracellular lipids

secreted by granulosum, surround corneum

epidermal derivatives

nails, hair, sweat glands, sebaceous glands

hair shaft is in what layer

epidermis

sweat gland layer

dermis

Sebaceous gland layer

dermis

pressure and touch found in what layer

dermis, epidermis

arrector pilli

dermis

blood vessels

dermis and hypodermis, (epidermis has no blood supply)

role of sweat glands

cool body and rid waste

role of sebaceous glands

lubricate and waterproof skin, prevents dehydration

which cells detect light touch

merkle cells

which cells detect pressure and vibration

pacinian corpuscles

defense/immune cells?

langerhans cells

parts of hair

shaft, root, bulb, papilla, arrector pilli, follicle, matrix

hair shaft

visible part of hair

root

part of hair in skin

bulb

base of follica, contains living cells that divide for hair growth

papilla

blood vessels, nerve endings. nutrients for hair growth ( think capillaries)

follicle

tube like structure, anchors hair to skin

matrix

above papilla, actively diving basale cells, . as cells divide and push upward, they are keratinized,

medulla

inner layer of hair, loose packed keratin

cortex

middle layer in hair, thickest layer, keratin, melanin, strength, elasticity, flexibility

cuticle

thin protective layerof overlapping cells on the hair shaft.

nail bed part of what layer of skin?

epidermis

anagen

2-7 years, active growth phase of hair, cells divide rapidly in matrix. 0.3 mm a day. 85% of scalp hair in this phase

catagen

2-3 weeks. transition phase where growth slows down, follicle detatches from capillaries

telogen

2-4 months resting phase of hair growth, hair falls out and new hair begins to grow.