integumentuary and dev

skin

external covering of the body .5-5 mm thick

epidermis

epithelium keratiinized stratified squamous

dermis

loose papillary layer and dense reticular layer (vascular)

hypodermis 

deeper looser adipose

epidermal derivatives

hair follicles/hair, sweat glands, sebatioys glands, nails, mamary glands 

list layers of the skin

corneum, lucidium, granulosum, spinosum, basale

basale

basal stem cells w cuboidal/ columnar, constantly dividing to replenish cellular layers

spinosum 

stratified layer of prickle cells  w desmosomes

granulosum

cells flattened somewhat diamond shaped w/ pale indistinct nucleus, -3-5 layers in thick skin, cytoplasm has irregular shaped granules(keratohyalin) 

lucidium

clear, translucent layer that forms homogenous, glassy plate, 3-5 layers of flattened dying cells with indistinct nuclei, cytoplasm filled w semifluid substance (elediun) 

corneum

layer of keratinized cells, proggresively flattened and fuse, cells retainmembrane and cytoplasm replaced with keratin, 

keratin

IF that is fry, shiny, and highly retractable

pigmentation

basic color is yellow(carotene) , blood adds red tint

melanin

from TYr in basale cells granules, degrades as cell move to surface

pigment in lighter skin

only in stratum basale

pigment in darker sin

extends to granulosum

melanocytes

produce pigment that gets transferred to keratinocytes

steps of melanocyte to keratinocyte 

1. premalnosome formation

2. synthesis of melanin in early melansome

3. melanosome secretion

4. melanosome degradtion

two layers of dermis

pappilary and reticular

pappilary layer

LCT, similar to lamina propria of mucous membrane

reticular layer

collagenous DICT, similar to submucous of mucous membrane, thicknes between .3-.4 mm

pappilary layer components

dermal pappilae, tactile, cascular, dermal ridges

dermal papillae

portrude into epidermis, mechanically adventageous

tactile

sensory corspule(meissners)

vascular

bv , made of interwoven mesh of LCT, thin collagenous and elastic fibers, veins and arteries 

dermal ridges (fingerprints)

most prominent in thick skin and run parallel to dermal papillae

pacinian corpsuele

deep dermis or hypodermis, pressure/vibration, near some organs

meissners corpusle

dermal papilla of hairlessmskin low frequency stimuli

reticular layer

collagenous DICT w/elastic fiber network

smooth muscle in reticular layer

found in the arrector pilli muscles, perineum, scrotum, penis, and nipple. in face and neck skeletal muscle involved in skeletal movet terminates in dermis (panniculus carnosus

other structures in reticular layer

hair, sweat glands(LCT cushions), sebatious glands, pacinian corpsules, arteries, veins, nerves 

hypodermis 

superfical fascia seperate from skin but blends with dermis, LCT w bands of septa, spaces occupied by fat lobules, panniculus adiposus when abundant

where does fat never occur

eyelids, scrotum, penis

hypodermis what is present

arteries, veins, and nerves, sometime ssweat glands and pacinian corpsule

nail plate

convex rectangular structure of hard keratin in nail grooce over naile bed, homologus to stratum corneum and lucidium attached to nail bed except at hyponycium

nail bed

continous w basale and spinosum

nail wall

overlaps nail plate and forms groove, shallow latterallu forms deep pocket proximally

lunula

whitish zone partially cocealed by eponycium

hair (dermal) papillae

contains capillaries, nerve fibers, and pigment cells

hair not found

palm, sole, anal or urogenital appetures.

hair

mainly hard keratinized cells, enters skin at an angle, enclosed by tubular hair follicle(d and e), assocated w sebatious glands arrector pilli muscle, epedermal cells of hair shaft in 3 concnenric layer 

3 concnetric layers of hair

medulla, cortex, and cuticles

medulla

2-3 cells thick, loose central axis w shrunken keratinized and cuboidal cells partially seperated by air spaces, in hairs of axilla, beard, and eyebrows, keratin is soft type like epidermis amy have pigment 

cortex

most of hair, long flattened and spindle shaped, keratinized, acidofilic cells,

black hair from what

ox tyr

red hair is from 

ox limited tyr

what can modify color 

air vacoules 

keratin is what kind of type

hard like nails

cuticle

very thin layer of single cell of overlapping anucleate keratinized cells, hard type, compacted cells don’t desquamate 

hair follicle

consistes of compound sheath found in lower 2/3rd of follicle

epidermal root sheath

outer and inner sheath w/subbordanite strata, above sebatous glands lined by normal epidermis

dermal root sheath

fibrous CT sheath mostly coarse hairs scalp

internal epidermal sheath

keratinized cellular sheath surrounding by growing root, epidemris layers are granulosum lucidum and corneum

cuticle layers

henle, huxley, an cuticle 

huxley layer

simple/double layer of transpatent pre-cornified cells

henle

outer single layer cuboidal cells

external epidermal sheath

more cellular appearance, two subbordanate layers that correspond to basale and spinosum 

prickle cell layer

several layers of cuboidal w desmosomes

columnar cell layer: sinlge layer next to glassy membrane of dermal sheath 

dermal root sheath

reticular fibers and amorphus(glassy) ground substance, correspondsw basement membrane

dermal root sheath middle

more cellular layer w/ fine circular fibers, corresponds to papillay layer of dermis

outer dermal sheath

longitudinally directed fibers, correponds to reticular layer of cells

arrector pilli

sm

sebatous glands

one to several always conncects to follicle, between that and musle and duct empties into follicle 2/3-3/4 of the way up, produce oily sebum that has antibacterial properties and moistens skin

eccrine

in most skin, not associated w/hair, ducts to skin surface

appocrine

secretion enter hair follicle and mammillary glands are a modified version, surrounded by myoepitheilial cells and a contractile epithelium w/ expulsion of gland product