The Integumentary System Flashcards
What is the integumentary system?
The outer covering of the body, including skin, glands, hair, and nails.
What is the largest organ in the body?
The skin.
What are the main functions of the integumentary system?
Barrier/protection, sensation, temperature regulation, vitamin D production, and water loss prevention.
What are the three main layers of the skin?
- Epidermis (outer layer) 2. Dermis (middle layer) 3. Hypodermis (subcutaneous layer).
What is the function of the epidermis?
Prevents water loss and protects against abrasion.
What is the function of the dermis?
Provides structural strength, elasticity, and contains sensory structures.
What is the function of the hypodermis?
Anchors the skin to underlying tissues and stores fat
Is the epidermis vascular or avascular?
Avascular (lacks blood vessels).
How many layers does the epidermis have?
4-5 layers (strata).
Where are new epidermal cells generated?
Stratum basale.
How long is the epidermal cell turnover cycle?
~35 days.
What are the main cell types in the epidermis?
- Keratinocytes 2. Basal cells 3. Melanocytes 4. Langerhans cells 5. Merkel cells.
What is the function of keratinocytes?
Produce keratin for waterproofing and strength.
What is the function of basal cells?
Precursor cells for keratinocytes (undergo mitosis).
What is the function of melanocytes?
Produce melanin for UV protection.
What is the function of Langerhans cells?
Immune defense (phagocytose bacteria).
What is the function of Merkel cells?
Sensory receptors for touch
What are the layers of the epidermis (deep to superficial)?
- Stratum basale 2. Stratum spinosum 3. Stratum granulosum 4. Stratum lucidum (only in thick skin) 5. Stratum corneum.
What happens in the stratum basale?
Cells divide and migrate upwards (keratinocytes, melanocytes, Merkel cells present).
What happens in the stratum spinosum?
Keratinocytes are connected by desmosomes; Langerhans cells are present.
What happens in the stratum granulosum?
Cells begin producing keratin and start to die.
What happens in the stratum lucidum?
Present only in thick skin (palms, soles); contains dead, flattened cells.
What happens in the stratum corneum?
Dead, keratinized cells (corneocytes) form a waterproof barrier.
What are the two layers of the dermis?
- Papillary layer (superficial) 2. Reticular layer (deep).
What is the main cell type in the dermis?
Fibroblasts (produce collagen and elastic fibers).
What structures are found in the dermis?
Hair follicles, sensory receptors, sweat glands, sebaceous glands, blood vessels, lymphatic vessels.
What is the function of dermal blood vessels?
Supply oxygen and nutrients to the epidermis.
What are the functions of hair?
Protection, sensory input, thermoregulation.
What structure produces hair?
Hair follicle.
What is the function of the arrector pili muscle?
Causes hair to stand (goosebumps) due to cold or fear.
What are the two main types of glands in the skin?
Sweat glands and sebaceous glands.
What is the function of sweat glands?
Produce sweat for cooling and waste elimination.
What is the function of sebaceous glands?
Produce sebum (oily substance) for lubrication and antimicrobial activity.
What is the “surface film” on the skin?
A protective barrier of sweat, sebum, and sloughed epithelial cells.
What are the functions of the surface film?
Antibacterial, antifungal, lubrication, hydration, toxin protection.
How does the epidermis prevent dehydration?
Keratin and lipid layers reduce water loss.
What happens if the epidermal barrier is damaged?
Water loss increases, leading to dry/cracked skin
What determines skin color?
- Melanin 2. Beta-carotene 3. Stratum corneum thickness.
What is the function of melanin?
Protects DNA from UV radiation.
What stimulates melanin production?
UV light, hormones, genetics.
Where is melanin produced?
Melanocytes in the stratum basale
What triggers vitamin D production in the skin?
UV light converts cholesterol into cholecalciferol (Vitamin D3).
Where is Vitamin D3 converted into active vitamin D?
Liver and kidneys.
What are the main functions of vitamin D?
- Calcium and phosphate absorption 2. Bone health.
Why is the stratum corneum important for drug absorption?
Acts as a barrier; drugs must penetrate this layer to be effective.
Why does skin thickness vary in different body regions?
Thicker in high-friction areas (palms, soles) for protection.
What is the role of the skin in thermoregulation?
Sweat glands and blood vessel dilation/constriction regulate temperature
What is the main structural protein in the skin?
Keratin.
What is the deepest layer of the epidermis?
Stratum basale.
What is the main immune cell in the epidermis?
Langerhans cells.
