L23: Integumentary System Flashcards
1
Q
Two types of skin. Where is each found? How to tell difference between the two?
A
- ) Thick skin: palms and soles, thick epidermis, no hair follicles, no arrector pili muscles, no sebaceous glands
- ) Thin skin: most of body
2
Q
Does thick skin have sweat glands?
A
- Yes
3
Q
List layers of thick skin from superficial to deep. Function of each layer? What is different with these layers in thin skin?
A
- ) Epidermis:
a. ) Stratum corneum: protection
b. ) Stratum lucidum: protection
c. ) Stratum granulosum: waterproofing
d. ) Stratum spinosum: binding, protection
e. ) Stratum basale/germinativum: cell renewal, anchors epidermis to BM
2.) Dermis: CT layer – strength, defense, nutrition, thermoregulation, sensation, stretch The hypodermis (superficial fascia) is not part of skin
Thin skin all strata except for lucidum, granulosum. Also corneum is thinner.
4
Q
Rete ridges?
A
- projections of epidermis projecting into dermis to increase surface area and secure adhesion to dermis
5
Q
Cell types of the epidermis. Function? Location?
A
- Epithelial keratinocytes: most common, skin renewal (20-30 days desquamate), high mitotic activity, keratin accumulates as cells move up strata
- Langerhans/Dendritic cells: DCs travel through bloodstream to take up residence in epidermis as Langerhans, reside mainly in stratum spinosum, process antigens that enter skin and travel to regional lymph node where they are APCs to lymphocytes
- Merkel cells: mechanoreceptors for discriminative touch in stratum basale, numerous in fingertips
- Melanocytes: protect DNA of skin, arise from neural crest cells, synthesize melanin and distribute to keratinocytes, reside between cells in stratum basale and superficial dermis
6
Q
What are Birbeck granules?
A
- “inclusions/granules” found in Langerhans cells, function not well understood – look like tennis racket
7
Q
In what epidermal layer do Langerhans cells reside?
A
- Mainly in stratum spinosum
8
Q
In what epidermal layer do Merkel cells reside?
A
- Stratum basale
9
Q
In what epidermal layer do melanocytes reside?
A
- Between cells of stratum basale and superficial dermis
10
Q
Describe structure, function of stratum corneum
A
- flattened, desiccated, keratinized dead cells that is thick
- protection
- no nuclei or organelles, has keratin filaments, no desmosomes between cells on surface layers to bind cells together, therefore desquamate
11
Q
Describe structure and function of stratum lucidum
A
- light-staining layer
- no organelles or nuclei, non-viable, contains keratin filaments
- technically a subdivision of corneum
12
Q
Describe structure and function of stratum granulosum
A
- cells contain nuclei, but have apoptotic nuclear morphology (fragments of DNA), keratohyalin granules and membrane-coating granules (known as lamellar bodies) containing lipids that are exocytosed to form waterproof material causing cells above to die of starvation
13
Q
Describe structure and function of stratum spinosum
A
- thick prominent stratum
- cells have intercellular bridges with desmosomes that give a prickle/spiny appearance
- contains bundles of tonofilaments (intermediate filament cytokeratin) that form tonofibrils – binding
- contain lamellar granules with lipid substance
- mitosis occurs in deep part of this layer
- layer contains Langerhans cells – protection
14
Q
What would happen if there were a decrease in cytoplasmic processes found in stratum spinosum?
A
- Skin would be vulnerable to abrasion/wear/tear
15
Q
Describe structure and function of stratum basale/germanitivum
A
- single layer of cells with desmosomes that bind cell membrane to all neighbouring cells
- most intense mitotic activity occurs in this layer
- hemidesmosomes bind these cells to basement membrane
16
Q
Malignancy of stratum basale
A
- Basal cell carcinoma: result of chronic sun exposure, lesion = pearly papule with subepidermal blood vessels (its own blood vessels), slow growing and rarely metastasizes
17
Q
What strata does thin skin contain?
A
- Stratum corneum (thin)
- Stratum spinosum
- Stratum basale
18
Q
What does dermis arise from? Epidermis?
A
- Dermis from mesoderm
- Epidermis from ectoderm
19
Q
Describe layers of dermis (include composition, cell types)
A
- Papillary layer: forms dermal papillae that interdigitate with epidermal ridges. Consists of loose CT with type III collagen, elastic fibers and type VII anchoring collagen fibrils. Fibroblasts, macrophages, plasma cells and mast cells reside here. Capillary loops (nutrition and thermoregulation). Meissner corpuscles for sensation, Krause end bulbs (unknown function)
- Reticular layer: composed of dense irregular collagenous CT with type I collagen – forms regular lines of tension (Langer’s lines) for tensile strength, and elastic fibers. Proteoglycans. Contains fibroblasts, macrophage, mast cells, lymphocytes, fat cells. Also contains hair follicles, arrector pili muscles, sebaceous glands and sweat glands. Pacinian corpuscles (detect pressure and vibrations), Ruffini corpuscles (detect tensile forces)
20
Q
In what layer of skin are Meissner’s, Pacinian and Ruffini corpuscles found?
A
- Meissner’s in papillary layer of dermis
- Pacinian and Ruffini in reticular layer of dermis
21
Q
In what layer of skin are hair follicles, sebaceous glands, arrector pili muscles and sweat glands found?
A
- In reticular layer of dermis
22
Q
There are superficial (first degree), partial thickness (second degree) and full thickness (third degree) skin burns. To what layer of skin does each extend?
A
- ) Superficial through epidermis
- ) Partial thickness through either layer of dermis
- ) Full thickness through hypodermis (not part of skin) and also sometimes to muscle (formerly fourth degree burn)
23
Q
Significance of dermal ridges
A
- Genetically unique, found in thick skin, form distinctive pattern of finger and foot prints
24
Q
List glands of skin
A
- ) Eccrine sweat glands
- ) Apocrine sweat glands
- ) Sebaceous glands
25
Eccrine sweat glands. Function? Where are they located? Types of gland/secretory unit? Secretory method? Innervation
- Function: thermoregulation
- Location: deep in dermis (reticular) or hypodermis throughout body
- Type: simple coiled tubular gland with simple cuboidal to low columnar secretory segment surrounded by myoepithelial cells to squeeze out secretion
- Secretory method: merocrine
- Innervation: SNS from arterial vessels (cholinergic)
26
Apocrine sweat glands. Function? Location? Types of gland/secretory unit? Secretory method? Innervation?
- Function: thermoregulation
- Location: deep dermis (reticular) and hypodermis in axilla, areola of nipple and anal region
- Type: larger than eccrine, simple cuboidal to low columnar with larger lumen than eccrine, secretory segment surrounded by myoepithelial cells
- Secretory method: merocrine
- Innervation: SNS fibers, also influenced by hormones that start functioning at puberty
27
Sebaceous glands. Function? Location? Type of gland/secretory unit? Secretory method? Innervation?
- Function: protection
- Location: deep dermis (reticular) through body, more numerous in scalp and face, appendages to hair follicles, emptying sebum into canal of hair follicle
- Type: acinus = small basal cells and larger round cells with stratified squamous epithelial duct
- Secretory method: holocrine
- Innervation: respond to hormones produced at puberty
28
Components of hair follicles
a. ) Hair root: found in dermal papilla
b. ) External root sheath (not part of hair)
c. ) Internal root sheat
d. ) Hair shaft
e. ) Glassy membrane (like BM)
f. ) CT
29
Arrector pili muscles. Type of muscle, where they attach to hair, relationship to sebaceous glands and innervation?
- Smooth muscle
- Attach to hair follicle midway, raise hair with contraction
- Cradles sebaceous glands
- SNS innervation
30
Composition of nails
- Nail plate: hard keratin
- Nail bed: stratum basale and stratum spinosum
- Nail root: nail growth occurs here at the matrix forms keratin which forms the nail plate further out
- Cuticle = eponychium, which consists of stratum corneum
- Lunula = crescent-shaped area at base of nail, white
- Hyponychium = under tip of nail
