Histology of Skin Flashcards
Be able to describe the location, structure, and distinguishing features of the following epidermal layers:
stratum germinativum (stratum basal):
Deepest layer, Basal layer Mitotically active Hemidesmosomes & desmosomes Polyribosomes in cytoplasm Intermediate filaments (keratin type) in cytoplasm
Be able to describe the location, structure, and distinguishing features of the following epidermal layers:
stratum spinosum
cells look like they have spines on them. has LAMELLAR bodies made of LIPIDS
‘Prickle’ cell layer (SPINEY cells)
Mitotically active
Desmosomes hold cells together
Polyribosomes
Intermediate filaments (keratin type) & tonofibrils
Membrane coating granules (keratinosomes) (golgi)
Be able to describe the location, structure, and distinguishing features of the following epidermal layers:
stratum granulosum
No mitotic activity
Keratohyalin GRANULES
Nuclei become pyknotic
Be able to describe the location, structure, and distinguishing features of the following epidermal layers:
stratum corneum
Outermost layer
Cells are dead and flat
Cells are completely ‘keratinized’
PILES OF CELLS
Be able to describe the process of keratinization.
Synthetic phase: Intermediate filaments Membrane coating granules Keratohyalin granules Filaggrin and trichohyalin
Degradative phase:
Membrane coating granule discharge
Lysosomal degradation of organelles
Consolidation of filaments and keratohyalin into a fibrous amorphous mass
What are the hard Keratins
No granular cell layer phase
Hair & nails
What are soft Keratins
Granular cell layer phase
Epidermis and internal root sheath of hair
Be able to describe what the hypodermis is and where it is found?
Loose connective tissue
Frequently contains lots of fat cells
E.g., panniculus adiposus
Be able to describe the location, structure, and distinguishing features of the following dermal layers:
papillary layer of the dermis
- Superficial layer of dermis
a. immediately beneath basement membrane - Composition
a. Loose connective tissue
(1) Thin bundles of collagen fibers
(2) Some reticular and elastic fibers
(3) More cellular than reticular layer - Vascular papillae
a. Papillae contain capillary loop projections
(1) Only source of nourishment for epithelial cells
(2) Thermoregulatory devices - Nervous papillae
a. Contain special nerve terminations
(1) Meissner’s corpuscles (mechanoreceptors)
(2) Krause end bulbs (mechanoreceptors)
Be able to describe the location, structure, and distinguishing features of the following dermal layers:
reticular layer of the dermis
- Deep layer of dermis
a. Between papillary layer of dermis and hypodermis - Composition
a. Dense irregular connective tissue
(1) Coarse, dense, interfacing bundles of collagen fibers (type I collagen)
(2) Some reticular fibers, many elastic fibers
(3) Less cellular than papillary layer
b. Predominant direction of all fibers is parallel to surface
(1) Direction of fibers creates lines of skin tension – Langer lines (specific for surgeons)
(a) These differ in different regions of body
(b) Surgical incisions parallel to these lines gape less and heal with less
scarring
Be able to describe the formation of melanin, the cells involved in melanin formation, and skin pigmentation
Produced by cells called melanocytes, Melanosome formation
Be able to describe the functions of the following cells: Merkel cells
associated with unmyelinated sensory nerves
(1) probably involved in sensory reception
Be able to describe the functions of the following cells: Langerhans cells, (APC)
a. Derived from bone marrow precursors
b. Immunological function
(1) Cell surface Fc (antibody) and C3 (complement) receptors
(2) Phagocytose and process foreign antigens
(3) Migrate to local lymph nodes; present epitopes of processed foreign antigens to T-lymphocytes
Be able to describe the functions of the following cells: melanocytes
a. Produce melanin granules (melanosomes); melanin production dependent upon
the enzyme tyrosinase
b. Donate melanin granules to cells in stratum germinativum and stratum spinosum: cytocrine secretion
Be able to describe the generalized pattern of skin vascularization
Largest arteries reside in subcutaneous tissue
Rete cutaneum
Rete subpapillare
Be able to define and describe the function of what an arteriovenous anastomosis is.
AVA shunts, important in regulation. reduces heat loss. shuts down when in a hot environment. Thermoregulation.
Be able to describe the structure and function of the following associated integumentary structures:
hair
hair shaft, hair follicle and external root sheath
Be able to describe the structure and function of the following associated integumentary structures:
nails
- Nail plate: closely compacted horny scales
a. Hard keratin - Nail bed
a. Stratum malpighian (stratum basale & stratum spinosum) cells only
b. No stratum granulosum
c. Nail plate slowly slides over nail bed - Nail matrix (MITOTIC ACTIVITY)
a. Most proximal portion of nail bed
b. Cells proliferate here – push nail distally - Other terms associated with the nail
a. Nail fold
b. Nail groove
c. Nail wall
d. Eponychium
e. Hyponychium
f. Lunula
Be able to describe the structure and function of the following associated integumentary structures:
eccrine or merocrine sweat glands
Secretory portion
Simple cuboidal epithelium; small lumen
Deep dermis or hypodermis
Clear cells (watery secretion) & dark cells (mucous secretion)
Myoepithelial cells (contractile properties)
Secretions contain: KCl; NaCl; ammonia; urea
Duct portion
Resorbs much of NaCl and KCl
Stratified cuboidal epithelium
Sympathetic innervation
almost no lumen***
Be able to describe the structure and function of the following associated integumentary structures:
arrector pili muscle
Bundles of smooth muscle Sympathetic innervation Anchored in: Hair follicle sheath Papillary layer of dermis Help to: Produce ‘goose bumps’ Move sebaceous gland products
describe sebaceous glands
Usually associated with hair follicles
Exceptions: eyelids; areolae of mammary glands; labia minora; glans of penis; corners of lips
Holocrine secretion (oil rick substance)
Acne: male hormone (androgen) related
Males: testes & adrenal cortex
Females: ovaries & adrenal cortex
Blackheads (blocked up sebaceous glands still open to the surface) white heads, not open to the surface
Be able to describe the structure and function of the following associated integumentary structures:
Apocrine Sweat Glands
Secretory portion Simple cubodial/columnar epithelium Restricted locations: axilla; areolae; anogenital Myoepithelial cells Odorless viscous secretion which becomes odored when acted on by bacteria Duct portion Empty into hair follicles* stratified cuboidal epitheliun Sympathetic innervation visual lumen***
Encapsulated Nerve Endings
Meissner’s corpuscles: touch (penis)
Pacinian corpuscles: pressure (looks like onion), senory nerve fiber in the middle
Be able to describe the process of skin wound healing.
cells increase mitotic rate, fibroblasts migrate to produce collagen.
