The Integumentary System Quiz or Worksheet - Free Printable

The image you've provided is a labeled diagram of the integumentary system, showing cross-sections of thick (hairless) skin and thin (hairy) skin. The goal is to identify the structures numbered 1–21 in the diagram.

Below is the correct identification of each numbered structure, based on standard human anatomy:

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Labeling Key:

1) Epidermis
→ The outermost layer of the skin; composed of stratified squamous epithelium.

2) Stratum corneum
→ The outermost layer of the epidermis; made of dead, keratinized cells.

3) Stratum lucidum
→ A thin, clear layer present only in thick skin (e.g., palms and soles).

4) Stratum granulosum
→ Layer where cells begin to die and accumulate keratin.

5) Stratum spinosum
→ Spiny layer; contains keratinocytes and Langerhans cells.

6) Stratum basale
→ Deepest layer of epidermis; site of mitosis and new cell production.

7) Dermis (Papillary layer)
→ Superficial layer of dermis with finger-like projections (dermal papillae) that increase surface area.

8) Dermis (Reticular layer)
→ Deeper, dense connective tissue layer of dermis; contains blood vessels, nerves, hair follicles.

9) Epidermis
→ This bracket includes all layers of the epidermis (1–6).

10) Dermis
→ This bracket includes both papillary and reticular layers of dermis.

11) Sebaceous gland
→ Gland that secretes sebum (oily substance) to lubricate skin and hair.

12) Sweat gland (eccrine)
→ Simple coiled tubular gland that produces sweat for thermoregulation.

13) Hair follicle
→ Structure from which hair grows; located in the dermis.

14) Arrector pili muscle
→ Smooth muscle attached to hair follicle; contracts to make hair stand up (goosebumps).

15) Hair shaft
→ Visible part of the hair above the skin surface.

16) Hair root
→ Part of the hair below the skin surface; embedded in the follicle.

17) Hair bulb
→ Expanded base of the hair root where cell division occurs.

18) Hair matrix
→ Region of actively dividing cells that form the hair shaft.

19) Hair papilla
→ Capillary-rich connective tissue projection at the base of the hair follicle; nourishes the hair.

20) Hair cortex
→ Middle layer of the hair shaft; contains pigment and keratin.

21) Hair medulla
→ Central, soft core of the hair shaft (may be absent in fine hair).

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✔ Final Answer:

| Number | Structure |
|--------|-------------------------------|
| 1 | Epidermis |
| 2 | Stratum corneum |
| 3 | Stratum lucidum |
| 4 | Stratum granulosum |
| 5 | Stratum spinosum |
| 6 | Stratum basale |
| 7 | Papillary layer of dermis |
| 8 | Reticular layer of dermis |
| 9 | Epidermis (entire layer) |
| 10 | Dermis (entire layer) |
| 11 | Sebaceous gland |
| 12 | Eccrine sweat gland |
| 13 | Hair follicle |
| 14 | Arrector pili muscle |
| 15 | Hair shaft |
| 16 | Hair root |
| 17 | Hair bulb |
| 18 | Hair matrix |
| 19 | Hair papilla |
| 20 | Hair cortex |
| 21 | Hair medulla |

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🔍 Explanation:

- Thick skin (left side): Found on palms, soles, fingertips — has five layers of epidermis (including stratum lucidum) and no hair follicles.
- Thin skin (right side): Covers most of the body — has four layers of epidermis (lacks stratum lucidum), has hair follicles, and sebaceous glands.
- Both types have sweat glands, blood vessels, nerves, and connective tissue in the dermis.

This diagram illustrates the complexity of the skin as an organ involved in protection, temperature regulation, sensation, and excretion.

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