The integumentary unit is short (typically one or two lab sessions) but disproportionately important downstream — nursing programs assume A&P graduates can identify the layers of skin and the structures within them when they reach wound-care competencies.
Skin layers + strata + accessory structures (Page 2)
Same items, paired with function (Page 3)
Thick vs thin skin, distinguishing features (Page 4)
Graded against the standalone Microscopy Practice rubric (cross-cutting protocol)
Standard six-item weekly check (Page 5)
2 stations on the term-end practical (Page 6)
| Canonical answer | Accepted synonyms | Spelling rule / common confusion |
|---|---|---|
| Three principal layers | ||
| Epidermis | (none) | Outermost, avascular, stratified squamous epithelium |
| Dermis | (none) | Connective tissue beneath epidermis; contains accessory structures |
| Hypodermis | Subcutaneous layer, superficial fascia, subcutis | Adipose-rich; not technically part of skin but always graded with it |
| Strata of the epidermis (deep → superficial) | ||
| Stratum basale | Stratum germinativum | Single layer of cuboidal/columnar cells on basement membrane; melanocytes here |
| Stratum spinosum | Spiny/prickle layer | Several layers of polyhedral cells; desmosomes give "spiny" appearance after fixation |
| Stratum granulosum | (none) | Flatter cells with dark keratohyalin granules |
| Stratum lucidum | (none) | THICK SKIN ONLY (palms, soles); thin translucent layer |
| Stratum corneum | Horny layer | Anucleate flattened keratinized cells; outermost |
| Dermal regions | ||
| Papillary dermis | Papillary layer | Loose connective tissue with dermal papillae projecting into epidermis |
| Reticular dermis | Reticular layer | Deeper dense irregular connective tissue; bulk of dermis |
| Accessory structures | ||
| Hair follicle | (none) | Distinguish from sweat gland duct → not yet (follicles contain hair shaft + concentric layers) |
| Hair shaft | (none) | The visible hair within or above the follicle |
| Hair bulb | (none) | Expanded base of follicle in dermis or hypodermis; site of hair growth |
| Sebaceous gland | Oil gland | Holocrine gland opening into hair follicle; foamy cytoplasm of sebocytes |
| Eccrine sweat gland | Merocrine sweat gland | Coiled tubular gland with simple cuboidal epithelium; opens directly to skin surface |
| Apocrine sweat gland | (none) | Larger lumen, opens into hair follicle; axilla, groin only |
| Arrector pili muscle | Erector pili | Smooth muscle bundle from dermal papilla to follicle; goosebump muscle |
| Meissner corpuscle | Tactile corpuscle | Encapsulated mechanoreceptor in dermal papilla; light touch |
| Pacinian corpuscle | Lamellated corpuscle, Vater-Pacini corpuscle | Onion-layered mechanoreceptor in deep dermis or hypodermis; deep pressure / vibration |
| Structure | Acceptable function statement | What does NOT pass |
|---|---|---|
| Epidermis (overall) | Provides waterproof keratinized barrier; first line of defense against pathogens; site of vitamin D synthesis | "Outer skin" alone |
| Stratum basale | Site of mitotic division producing new keratinocytes; contains melanocytes producing melanin and tactile (Merkel) cells | "Bottom layer" alone |
| Stratum corneum | Keratinized barrier providing mechanical protection and resistance to water loss | "Dead skin" alone (must indicate barrier function) |
| Dermis | Provides structural support; houses blood vessels, nerves, glands, and follicles; contains thermoreceptors and mechanoreceptors | "Middle layer" alone |
| Hypodermis | Stores energy as adipose; provides insulation; cushions underlying structures; anchors skin to underlying fascia | "Fat" alone (must indicate function) |
| Sebaceous gland | Secretes sebum (oil) onto hair shaft and skin surface for waterproofing and antimicrobial defense | "Makes oil" alone (must indicate purpose) |
| Eccrine sweat gland | Secretes hypotonic sweat for thermoregulation via evaporative cooling | "Sweats" alone (must indicate temperature regulation) |
| Apocrine sweat gland | Secretes protein-rich sweat at puberty onset; substrate for skin bacteria producing body odor; pheromonal role debated | "Smells" alone |
| Arrector pili | Contracts to elevate hair shaft (piloerection) for thermal insulation in mammals; vestigial in humans, produces “goosebumps” | "Goosebumps" alone (must indicate hair elevation) |
| Meissner corpuscle | Mechanoreceptor for light touch and low-frequency vibration in glabrous skin (fingertips, lips) | "Touch" alone (must specify light/glabrous) |
| Pacinian corpuscle | Mechanoreceptor for deep pressure and high-frequency vibration; rapid-adapting | "Pressure" alone (must indicate deep) |
| Melanocyte (in stratum basale) | Produces melanin pigment; transfers melanin to surrounding keratinocytes for UV protection | "Skin color" alone (must indicate UV protection or transfer mechanism) |
| Slide | Canonical identification | Two features required |
|---|---|---|
| Thick skin (palm or sole) | Thick skin | Stratum lucidum present (diagnostic) · Very thick stratum corneum · No hair follicles · Eccrine sweat glands abundant in dermis |
| Thin skin (general body) | Thin skin | No stratum lucidum · Thin stratum corneum · Hair follicles present · Sebaceous glands associated with follicles |
| Hair follicle in cross-section | Hair follicle | Concentric layers (medulla, cortex, cuticle of hair + internal/external root sheath) · Surrounding connective tissue capsule · Sebaceous gland often adjacent · Arrector pili muscle attached to follicle |
| Eccrine sweat gland | Eccrine sweat gland | Coiled tubular structure in deep dermis · Simple cuboidal/columnar epithelium · Two cell types (clear cells + dark cells) at the secretory portion · Duct portion has stratified cuboidal epithelium |
| Sebaceous gland | Sebaceous gland | Lobular structure with foamy/vacuolated sebocytes · Holocrine secretion (cells disintegrate to release product) · Opens into hair follicle · Found in dermis adjacent to follicles |
For students entering nursing or other allied-health programs, the integumentary unit’s lab notebook should include a side-by-side comparison sketch of thick and thin skin. The structures different between the two (stratum lucidum, follicle presence, gland type distribution) become flashpoints in clinical wound assessment downstream. The drawing forces the noticing.
The integumentary unit contributes 2 stations to the term-end capstone (smaller weight reflecting the smaller unit). Each station is 90 seconds; passes at 3 of 4; excellence at 4 of 4.
Identification: thick or thin skin + indicated layer or stratum. Function: role of indicated layer. Clinical: one wound-healing consideration involving the indicated layer (e.g. partial vs full thickness burns, when scarring occurs). Integration: relate to a different organ system (e.g. blood supply through dermal capillaries, sensory innervation, vitamin D production for skeletal calcium).
Identification: indicated structure (follicle, gland type, muscle, receptor). Function. Clinical: one common pathology or assessment relevance (e.g. acne and sebaceous glands, hyperhidrosis and eccrine glands, neuropathy and Pacinian corpuscles). Integration: relate to autonomic or endocrine input.
| Outcome per station | Counted as |
|---|---|
| 4 / 4 | Excellence (counts toward A bundle) |
| 3 / 4 | Pass (counts toward B and C bundles) |
| ≤ 2 / 4 | Not yet (counts toward D bundle if attempted; no F-bundle credit) |
| No attempt | Not counted toward any bundle |
Student: ______________________________________ Section: _______________ Date: _______________ TA: _______________
| # | Item | ID (R1) | ≥2 features (R3) | Function (R2) |
|---|---|---|---|---|
| 1 | Skin layer (epidermis / dermis / hypodermis) | P / NY | P / NY | P / NY / — |
| 2 | Epidermal stratum | P / NY | P / NY | P / NY / — |
| 3 | Hair follicle component | P / NY | P / NY | P / NY / — |
| 4 | Gland type identification | P / NY | P / NY | P / NY / — |
| 5 | Receptor or arrector pili | P / NY | P / NY | P / NY / — |
| 6 | Thick vs thin skin (whole-slide ID) | P / NY | P / NY | — |
R4 microscopy graded per the Tissues unit’s R4 rubric (5-point checklist); record overall outcome only: P / NY
☐ No ☐ Yes — for item: __________ Tokens remaining: ☐ 3 ☐ 2 ☐ 1 ☐ 0
P = Pass · NY = Not yet · — = Not assessed · Edge cases: circle, bring to coordinator at end of session.