Integument Flashcards
Integument layers
Epidermis Epithelial layer-ectoderm Dermis Layer of CT- mesoderm Hypodermis
Epidermis is what type of tissue
Stratified squamous keratinized
Thin skin
Four layers
Glands and hair follicles
Thick skin
Palms and soles Five layers (w/stratum lucidum) Fingerprints
Layers of epidermis
Stratum corneum Stratum lucidum (thick skin) Stratum granulosum Stratum spinosum Stratum basale
Keratinocytes
Predominant cell type of epidermis
Participate in epidermal water barrier
Stratum basale
Single layer of keratinocytes with stem cells interspersed
Mitotically active, cuboidal/low columnar cells
Contains melanin
Bound apically by desmosomes and basally by hemidesmosomes
Stratum spinosum
Typically thickest layer
Keratin filaments assemble into tonofibrils here
Associate with desmosomes and result in spiny appearance of cells
Stratum granulosum
Filled with keratohyaline granules, lamellar granules-help protect against water loss with keratin
Stratum corneum
Anucleate cells coated by EC layer of lipids
15-20 layers of squamous, keratinized cells that shed as desmosomes break down
Stratum lucidum
Only found in thick skin
Thin, translucent, no organelles or nuclei
Melanocytes
Produce melanin which protects nuclei from UV radiation
One melanocyte maintains an association with around 1- keratinocytes
Langerhans cell
Macrophage of epidermis
Identifiable in stratum spinosum
Pale cytoplasm with long processes
Dermal papillae
Finger-like projections of the dermis at the dermal-epidermal junction
Increased in size/number at sites of mechanical stress
Layers of the dermis
Papillary layer- loose CT below epidermis with vasculature and nerve endings
Reticular layer- dense irregular CT with coarse elastic fibers
Hypodermis
Loose CT that binds skin loosely to subjacent organs
Adipocytes vary in number and size based on area
Extensive vasculature promotes rapid uptake of insulin or drugs
Merkel cells
Function as low threshold mechanoreceptors essential for sensing gentle touch
Contain small, Golgi-derived granules near basolateral surface
Merkel cell carcinoma
Rare, aggressive and difficult to treat
40 times less common that malignant melanoma but 2x mortality rate
Free nerve endings
Located in the papillary dermis and extending into lower epidermal layers
Respond mainly to high/low temperatures, pain, itching
May also function as tactile receptors
Meissners corpuscle
Encapsulated receptors responsive to light touch or low frequency stimuli
Numerous in fingertips, palms and soles
Lamellated (Pacinian) corpuscle
Large, encapsulated, oval structures found in the reticular dermis and hypodermis
Specialized for sensing course touch, pressure and vibration
Also found in CT of visceral organs and wall of rectum/bladder
Merocrine
Secretion delivered via membrane bound vesicles and undergo exocytosis
Holocrine
Secretion accumulates within and then cell undergoes apoptosis and releases
Sebaceous glands
Produce lipid mixture via holocrine secretion
Lubricate/soften skin and hair
Abundant on face and scalp
Eccrine sweat glands
Simple coiled gland with a stratified cuboidal duct
Myoepithelial cells facilitate expulsion of secretions
Merocrine secretion
Apocrine sweat glands
Large lumen, tubular glands
Duct is stratified cuboidal
Much larger lumen than eccrine sweat glands
Myoepithelial cells facilitate expulsion of secretions
Become functional at puberty
(stupid powerpoint says they use merocrine secretion?)
What forms the hair matrix
Keratinocytes, divide and differentiate for hair growth
Follicular bulge
Contains epidermal stem cells near insertion of erector pili muscle
How do hair get nutrients
Dermal papilla inserts into hair bulb and provides nutrients via capillaries
Arrector pili muscle
A small bundle of smooth muscle that extends from midpoint of hair root to papillary layer of dermis
