Integumentary System Histology Flashcards
What are the components of skin?
Skin
Epidermal Derivatives
What are Epidermal Derivatives?
- Hair follicles & hair
- Sweat (sudoriferous) glands
- Sebaceous (oil) glands
- Nails
Functions of Integumentary system
Protective•Immunologic•Homeostasis •Sensory•Endocrine•Exocrine
Two principle layers of skin
Epidermis & Dermis
Superficial layer of skin
Epidermis
What type of epithelium is the epidermis?
Keratinized stratified squamous
Where is the epidermis derived from?
Ectoderm
Is the epidermis vascular?
No, avascular
Deep layer of the skin
Dermis
What is the dermis made of?
Connective tissue
What is the dermis derived from?
Mesoderm
Subcutaneous layer deep to the skin
Hypodermis
What is the hypodermis composed of?
Adipose tissue, vascularized
Where is thick skin found?
Palms of hands and soles of feet
Found in areas subject to the most abrasion
Thick skin
Hairless skin
Thick skin
Thickest epidermal layer
Thick skin
Hair follicles present in
Thin skin
- Found everywhere except palms of hands and soles of feet
- Much thinner epidermis than thick skin
Thin skin
How many layers in thin skin?
4 layers
How many layers in thick skin?
5 layers
Name the layers of epidermis from Deep to superficial
- Stratum Basale
- Stratum Spinosum
- Stratum Granulosum
- Stratum Lucidum
- Stratum Corneum
- Produce keratins
- Participate in formation of water barrier
Keratinocytes (85%)
Pigment producing cells
Melanocytes (5%)
Antigen presenting cells of the immune system
Langerhans’ cells (2%-5%)
Mechanoreceptor cells associated with sensory nerve endings
Merkel’s cells (6%-10%)
Principal cell type of epidermis
Keratinocytes
Major structural proteins of epidermis
Keratins
What do keratins form?
Keratin filaments
Keratin filaments are classified as
Intermediate filaments or tonofilaments
What do keratinocytes help form
Epidermal water barrier
What is the water barrier formed via?
Production of lamellar bodies
- Tubular/ovoid shaped membrane bound organelles
- Lipid-containig structures
Epidermal water barrier
Single layer of basophilic cells
Stratum Basale
How are cells in the Stratum basale?
Small and cuboidal/ low columnar
Mitotically active layer; contains stem cells that give rise to keratinocytes
Stratum Basale
Where does the production of intermediate (keratin) filament begin?
Stratum Basale
Keratinocytes exhibit numerous cytoplasmic processes (“spines”)
Stratum Spinosum
In Stratum Spinosum Cell processes attached to those of adjacent cells via
Desmosomes
What occurs to stratum spinosum during histological prep?
Cells shrink, leaving expanded intercellular spaces between the spines
What contributes to the spiny/ prickly appearance in Stratum spinosum?
Cells shrinking during histological prep
What are intermediate filaments grouped into bundles called
tonofibrils
What is another word for intermediate filaments?
tonofilaments
What production begins in the stratum spinosum?
Production of keratohyalin granules and lamellar bodies
What do keratinocytes contain?
Keratohyalin granules
Intensely basophilic
Stratum Granulosum
Conversion of granular cells into cornified cells
Keratinization
Released within the stratum granulosum
Lamellar bodies
- Basophilic
- Tonofibrils
- Keratinization
- Lamellar bodies
Stratum Granulosum
Layer only found in thick skin
Stratum Lucidum
Thin translucent layer of eosinophilic cells
Stratum lucidum
Nucleus and cytoplasmic organelles becomes disrupted and disappear
Stratum Lucidum
Cells lose nuclei and cytoplasmic organelles
Stratum Corneum
Filled almost entirely (85%) with keratin
Stratum Corneum
Cells of this layer sloughed off at the surface
Statum Corneum
Cells are dead; represented only by flat membranous sacs filled with keratin: Glycolipids in extracellular space
Stratum Corneum
Cells are flattened; organelles deteriorating; cytoplasm full of lamellated granules (release lipids) and keratohyaline granules
Stratum Granulosum
Cells contain thick bundles of intermediate filaments made of pre-keratin
Stratum Spinosum
Cells are actively mitotic stem cells
-Some newly formed cells becomes part of the more superficial layers
Stratum Basale
Produce & secrete the pigment melanin
Melanocytes
Synthesized and stored in melanosomes
Melanin
What type of cells are melanocytes?
Dendritic cells
Rounded cell bodies in stratum basale
Melanocytes
Where are long processes of melanocytes extended upward and between keratinocytes in
Stratum spinosum
Where are melanin-containing melanosomes transferred into?
Adjacent keratinocytes
Why does melanin accumulate over nuclei?
To protect DNA from UV radiation
Possess elongated nuclei surrounded by clear cytoplasm
Melanocytes
Where are antigen presenting cells typically found within?
Stratum Spinosum
What are Langerhan’s cells derived from?
Bone marrow
Encounter and process antigens entering through skin
Langerhan’s cells
What do langerhan’s cells present processed antigen to within nearby lymph node?
T lymphocytes
Mechanoreceptor cells associated with sensory nerve endings
Merkel’s cells
Where are merkel’s cells located within?
Statum basale
What does Merkel’s cells contain?
Neurosecretory granules
Base of Merkel’s cells associate with expanded, plate-like terminal of afferent nerve fibers
Merkel’s Corpuscle
What are the 3 major types of skin cancer
- Basal cell carcinoma
- Squamous cell carcinoma
- Malignant melanoma
- Most common
- Resembles cells of stratum basale
- Slow-growing tumor
Basal cell Carcinoma
- Second most common
* Characterized by highly atypical cells at all levels of epidermis
Squamous Cell Carcinoma
- Most serious form
- Originates from melanocytes
- Presents as irregularly pigmented, multicolor lesion
Malignant Melanoma
2 layers of the dermis
- Papillary Layer
- Reticular layer
What tissue is in the papillary layer?
Loose (areolar) Connective tissue
Finger-like connective tissue protrusions
Dermal papillae
Where do dermal papillae project into epidermis?
Epidermal-dermal junction
What tissue is the reticular layer made of?
Dense Irregular Connective Tissue
Which layer of the dermis is the thickest?
Reticular layer
Which layer of the dermis has the most cells?
Papillary layer
Large Ovoid structures
Pacinian Corposucles
Where are Pacinian corpuscles found?
Dermis and Hypodermis
Where are Pacinian corpuscles found?
Dermis and hypodermis
Myelinated nerve ending surrounded by a capsule?
Pacinian Corpuscle
What does the capsule of the Pacinian corpuscle consist of?
Concentric lamellae
Series of tightly packed, flattened Schwann cell lamellae surrounding unmyelinated axon
Inner core of Pacinian Corpuscles
What do Pacinian Corpuscles do?
Detect pressure and vibration
Tapered, cylindrical structures
Meissner’s Corpuscles
Where are Messner’s Corpuscles located?
Within dermal papillae of hairless skin
What forms lamellae in Meissner’s Corpuscles
Flattened Schwann cells
What follows spiral paths in Meissner’s Corpuscles?
Unmyelinated nerve endings
What do Meissner’s Corpuscles do?
Detect light touch
Derived from down-growths of epidermal epithelium during development?
Epidermal Skin Appendages
- Hair follicles and hair
- Eccrine Sweat glands
- Apocrine Sweat glands
- Secaceous glands
Epidermal Skin Appendages
Eccrine sweat glands
Sudoriferous
Apocrine sweat glands
Sudoriferous
Sebaceous glands
Oil
Elongated filamentous, keratinized structures that project from hair follicles
Hair
Responsible for the production and growth of a hair
Hair Follicle
Where are hair follicles found?
Along the surface of most of the entire body, except thick skin
Smooth muscle extending from connective tissue sheath surrounding hair follicle to papillary layer of dermis
Arrector Pili Muscle
Causes hair to “stand on end” resulting in goosebumps”
Arrector Pili Muscle
- Role in insulation
- Sympathetic innervation
Arrector pili muscle
- Widely distributed
- Simple coiled tubular gland
- Merocrine secretion •Thermoregulatory
- Excretes wastes and excess salts
Eccrine Sweat Gland
- Double layer of epithelial cells
- Secretory cells are larger and appear lighter than the cells of the duct
- Located deep in dermis or upper part of hypodermis
Secretory portion of Eccrine Sweat Glands
- Narrower outside diameter and lumen than secretory portion
- Double layer of small cuboidal cells (i.e., stratified cuboidal epithelium)
- Duct cells are smaller and appear darker than the cells of the secretory portion
- Leads to epidermal surface
Duct portion of Eccrine Sweat Glands
Where are Apocine sweat glands found?
Axillary and perineal regions of the body
- Viscous, protein rich sweat
- Product secreted into hair follicles
Apocrine Sweat Glands
What type of secretion is Apocine Sweat glands
Merocrine secretion
Gland shape in apocrine sweat glands
Coiled tubular glands with very wide lumens
When do apocrine sweat glands become functional?
Puberty
What leads to body odor?
The bacterial breakdown of sweat
Where are the secretory portion of the eccrine sweat glands found?
In the deep dermin or upper part of the hypodermis
What is the difference of secretory cells in the Eccrine sweat glands compared to the ducts
Secretory cells are larger and appear lighter
Epithelium in the duct portion of Eccrine Sweat glands?
Stratified cuboidal
Where does the duct portion of the Eccrine sweat glands lead to?
Epidermal surface
Where is the secretory portion of the apocrine sweat glands found?
Upper part of the hypodermis or deep in dermis
What epithelium is in the secretory portion of the Apocrine sweat glands?
Simple cuboidal
What gland has the widest lumen?
Secretory portion of the Apocrine sweat gland
What epithelium is in the apocrine duct portion
Stratified cuboidal epithelium (2-3 layers)
Where does the duct portion of the apocrine sweat gland empty?
Follicle canal, not surface
Throughout skin of most regions of the body, especially in skin of forehead, palms and soles
Eccrine Sweat Glands
Skin of Axilla, groin, areolas, bearded regions of the face and labia minora
Appocrine Sweat Glands
Secretory portion location of Eccrine
Mostly in deep dermis
Secretory portion of Apocrine
Mostly in subcutaneous layer
Termination of excretory duct in Eccrine
Surface of epidermis
Termination of excretory duct in Apocrine
Hair follicle
Secretion: Less viscous, consists of water, ions, urea, uric acid, ammonia, amino acids, glucose and lactic acid
Eccrine sweat glands
Secretion: More viscous, consists of all the same components of eccrine plus lipids and proteins
Apocrine sweat glands
Regulation of body temp and waste removal
Eccrine Sweat glands
Stimulated during emotional stress and sexual excitement
Apocrine Sweat glands
When is the onset of function of Eccrine Sweat glands?
Soon after birth
When is the onset of function of Apocrine sweat glands?
Puberty
Where are Sebaeous glands found?
Everywhere except thick skin
Type of glands of Sebaceous glands?
Branch acinar
Lipid-containing substance produced and secreted by gland
Sebum
Where does sebaceous gland secrete?
Into hair follicle
What type of secretion does Sebaceous glands do?
Holocrine
Gland that is involved in acne development
Sebaceous Glands
Plates of keratinized cells that rest on nail beds
Nails
