Module 01 — Basics of Anatomy and Physiology · quiz worth 20 pts · 2026-08-25
The lesson becomes manageable when every structure has a home.
Think tightly packed, water resistant, no blood vessels, melanin, immune defense, new-cell production, and touch receptors.
Blood vessels, nerves, follicles, sweat glands, and oil glands make this the layer for sensation and temperature control.
Loose connective tissue and fat cushion, insulate, store energy, and anchor skin.
Which layer has sweat glands?
The dermis.
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The skin, or integument, contains all four tissue groups. Skin plus hair, nails, sweat glands, and sebaceous glands forms the integumentary system. It separates internal tissues from the environment, limits water loss, blocks pathogens, receives sensory information, and helps regulate body temperature.
The epidermis is the outer water-resistant barrier and has no blood vessels. The dermis is the thick middle layer with dense connective tissue, blood vessels, nerves, follicles, sweat glands, and sebaceous glands. The hypodermis lies below the skin and contains loose connective tissue and fat for insulation, cushioning, energy storage, and attachment to deeper tissue.
Keratinocytes build the protective keratin-rich barrier. Melanocytes make melanin, which helps shield nuclear DNA from ultraviolet radiation. Langerhans cells participate in immune defense. Basal cells divide to replace epidermal cells. Merkel cells work with sensory nerve endings for touch.
When temperature rises, sweat evaporates and dermal blood vessels dilate, moving more heat toward the surface. When temperature falls, sweat production decreases and vessels constrict, reducing heat loss. Dermal nerves also report pain, temperature, pressure, texture, and itch.
A first-degree burn affects the epidermis. A second-degree burn reaches epidermis and dermis and often blisters. A third-degree burn destroys both layers, often damages nerves, and may reach the hypodermis. Deep burns raise dehydration and infection risk because the barrier is lost. A shallow cut closes through faster epithelial cell division; a deeper cut breaks dermal vessels, forms a clot and scab, and replaces damaged tissue.
Do not memorize burn labels alone. Ask which normal structures are missing.
Water can escape and microbes can enter, which explains dehydration and infection risk.
Loss of dermal vessels, nerves, and glands adds circulation, sensation, and thermoregulation problems.
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Skin cancer begins with uncontrolled growth after DNA damage; melanoma begins in melanocytes and has high metastatic risk. Psoriasis is an autoimmune acceleration of skin-cell replacement, producing thick scaly plaques. Acne follows clogged follicles involving sebum, dead cells, and bacterial growth. Eczema reflects a weakened barrier that lets moisture escape and irritants enter. The ABCDE melanoma screen stands for asymmetry, irregular border, uneven color, diameter over 6 mm, and evolving change.
Use the structures named in the prompt, not color alone.
Connect each cell or structure to its layer and job.
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