Integument Flashcards
Integument Composed of…
- Epidermis
- Dermis
- Skin Appendages: Hair (nails)
- Glands
Hypodermis
NOT part of integument
-Fatty cell layer with adipose tissue
Dermis ->
Dermal Scales (denticles)- fish and amphibians
Epidermis->
Terrestrial Vertebrates Epidermal Scales (stratum Corneum)-reptiles, feathers- dinosaurs and birds
Epidermis->
Hair, Nails (mammals)
Sweat Glands
Apocrine
-Mammary Glands (mammals)
Zoological definition of a mammal
Presence of mammary gland in an animal
Epidermis Classification of skin
- Thick Skin
- Thin skin
Thin Skin Characteristics
Covers most of the body
Thick Skin Characteristics
thicker St. Corneum
- Presence of St. Lucidum
- On palms of hands and souls of feet
Cells of the Epidermis
- Keratinocytes
- Langerhan’s Cells
- Merkel’s Cells
- Melanocyte
Keratinocyte
- Filled with Keratin (intermediate) Filaments
- Attached to each other by Desmosomes
5 Layers of Thick Skin
From Top to bottom:
- Stratum Corneum
- Stratum Lucidum
- Stratum Granulosum
- Stratum Spinosum
- Stratum Basale
Stratum Basale (Germinativum)
- living cell layer
- Layer restsing on basement membrane and under the dermis
- most mitotic! Rise up
- Connected by desmosomes
- Hemidesmosomes use integrins
- Desmosomes use Cadherins
Stratum Spinosum
- Tonofibrils Cytokeratin Filaments
- Desmosomes
- Artifact of tissue shrinkage
- Spiny Cell layer
- Spiney occurs from tissue shrinkage
- During preparation of tissue, the cell shrink but held by desmosomes so as cells shrink, the desmosomes rise to spiny apearances because theyre holding on 2 cells together
Stratum Granulosum
- Keratohyalin Granules (no membrane) (flaggrin binds keratin)
- Lamellar Granules (membrane coated)
-Lipid sheets secreted into intercellular space to form intercellular cement and barrier
Stratum Lucidum and Corneum (non-living layers)
- Squames
- St. Granulosum
Layers of Thin Skin
- St. Corneum
- St. granulosum
- St. Spinosum
- St. Basale
Layers of Thick Skin
- St. Corneum
- St. Lucidum
- St. granulosum
- St. Spinosum
- St. Basale
Dermatoglyphics
(finger prints)
-unique to everyone except if you are an identical twin (still some changes from nature and nurture)
Functions of Epidermis
- Abrasion Resistance (loose cells of the stratum corneum)
- Physical- Chemical Barrier- skin is physical barrier to bacteria
- Water Proofing (adaptation to terrestrial environemtn against desiccation)-inhibits evaporative loss
Cells of Epidermis
- Keratinocytes
- Langerhan’s Cells
- Merkel’s Cell
- Melanocyte (originate from neural crest)
Melanocyte
Eumelanin (black)
Pheomelanin (red)
-Tyrosinase converts DOPA into dopaquinone into melanin
PIC
Melanocyte Function
Give rise to melanin and pigmentation
- secreted into cytoplasm of adjacent keratinocytes
- migrate to lcoation above nucleus above of that keratinocyte bc they act as a barrier to sunlight
- Purpose is to protct DNA material from UV light/damage
Skin color is dependent on amount of…
Melanin in Carotene NOT Melanocytes
Albinism
-Albinos lack the enzyme Tyroisnase and they cant make melanin- pinkness is reflection of blood
Langerhan’s Cells
- Dendritic Cells
- APC (from monocytes)
Merkel’s Cell
(sensory)
- Rare type of tumor
- Lean on nerve fiber
3 main types of skin cancer
- Basal Cell Carcinoma
- Squamoud Cell Carcinoma
- Melanoma
Melanocytes
Cells that produce skin coloring or pigment known as melanin (where Melanoma Starts)
Dermal- Epidermal Junction
PIC
Dermis
- Papillary Layer
- Reticular Lyaer
Dermis, Papillary Layer
(Peg and socket) locks epidermis to dermis to lock them together
- Capillaries
- Meissner Corpuscles (light touch)
Dermis, Reticular Layer (arteriovenous shunts)
(leather from animals)
-Animals use leather in reticular layer to keep warm
Dermis (dense irregular connective tissue)
Irregular desposition responsible for wrinkles
- fibroblasts
- bundle of Type I collagen
- Elastic fibers
Arteriovenous (AV) shunts
(thermoregulation)
- Control flow of blood up to papillary layer
- When youre cold , blood vessels clamp and reduces flow of blood into papillary laye– reduces evaporative cooling
When youre hot- start getting pink/ red- blood vessels open up and increase blood flow into
campilalries of papillary layer right underneath the epidermis for more cooling (releasing more water to cool)
Afferent Nerve Fibers and Sensory Structures of Skin
- Free Nerve ending
- Merkel’s Cell
- Meissner’s Corpuscle
- Pacinian Corpuscle
Dermis, Pacinian Corpuscle
Deep Touch/pressure, reticular layer
Nails (epidermal)
Derived from epidermis
-Nail Matrix gives rise to nail plate (part that if hanging above skin)
Hair Follice and bulb (epidermal)
Consists of shaft
Beneath skin is called root
-epidermal in origin
Hair Bulb
- Germinal Matrix (Chemotherapy destroys fast growing cells causing hair loss)
- Melanocytes
- Hair Papila (dermal)
- Blood Vessel
Scalp cooling device
- Reduces hair loss caused by chemo
- Cooling reduces blood flow through the hair papilla by redirecting blood
- Less chemo reaches papila and haird dont fall out
Internal Root Sheath
Epidermal, At level of sebatious gland
External Root Sheath
Epidermal, Continuous beyond the sebatious gland onto the surface of body as epidermis
Hair Shaft
- Medulla
- Cortex
- Cuticle (small barbs)
Structure of Hair follicle
- Hair Shaft Cubicle (small Barbs)
- Internal Root Sheath
- External Root Sheath
- Glassy Membrane
Arrector Pili Muscle
Functions in cold- contracts and pulls to straighten hair shaft, increasing boundary effect to incease boundary layer on surface of skin- contract on fear and fligt reactions
Cause of Graying of hair
Loss of melanin with age
Glands of the Skin
- Sebaceous Gland (secretes onto hair shaft NOT epidermis)
- Eccrine (merocrine) Sweat gland
- Apocrine Sweat Gland
Sebaceous Gland consist of
Simple branched acinar gland
- Holocrine mode of secretion (whole cell reptures and expells)
- Sebum maintains stratum corneum weak antibacterial/fungal activity
Eccrine (merocrine) Sweat gland consist of
- Myopethelial Cells
- Secretory Portion
- Dark Cells: Nucleoid, Antibacterial, Secretory Granules
- Clear Cells: Produce sweat
- Duct is lined by stratified cuboidal epithelium
Eccrine (merocrine) Sweat gland- Excretory Duct
Absorption mainly Na+ and Cl- Ions
Eccrine (merocrine) Sweat gland- Secretory Duct
Secretion mainly protein free filtrate
Apocrine Sweat Gland structure
- Secretes onto hair shaft, larger diamete than eccrine glands
- Only Dark Cells (antibacterial, Pheronomes)
Apocrine Sweat Gland Function
(Name is misnomer, secretes via merocrine mode)
- Restricted to axillary parts of body (armpit and groins)
- -larger luminal diameter
- Secretes via merocrine mode of secretion as well
