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Questions and Answers
What percentage of body weight does the skin account for?
What percentage of body weight does the skin account for?
- 3 percent
- 7 percent (correct)
- 10 percent
- 5 percent
Which layer of the skin is responsible for temperature regulation?
Which layer of the skin is responsible for temperature regulation?
- Hypodermis
- Epidermis
- Dermis
- All of the above (correct)
Which of the following is NOT a function of the epidermis?
Which of the following is NOT a function of the epidermis?
- Synthesis of vitamin D (correct)
- Mechanical injury protection
- Blood loss protection
- Dehydration prevention
Which of the following substances can be absorbed through the skin?
Which of the following substances can be absorbed through the skin?
What is the primary type of tissue found in the epidermis?
What is the primary type of tissue found in the epidermis?
What percentage of body weight is accounted for by the integumentary system?
What percentage of body weight is accounted for by the integumentary system?
Which of the following is NOT a function of the integumentary system?
Which of the following is NOT a function of the integumentary system?
Which component of the skin is avascular and consists of dead cells?
Which component of the skin is avascular and consists of dead cells?
What role does melanin play in the integumentary system?
What role does melanin play in the integumentary system?
Which layer of the skin contains the arrector pili muscle?
Which layer of the skin contains the arrector pili muscle?
How does the skin help maintain normal body temperature?
How does the skin help maintain normal body temperature?
Which structure is primarily responsible for the sensation of touch?
Which structure is primarily responsible for the sensation of touch?
Which of the following layers of skin contains adipose tissue?
Which of the following layers of skin contains adipose tissue?
What is the primary process occurring in the stratum basale?
What is the primary process occurring in the stratum basale?
Which layer of the skin is known for containing melanocytes?
Which layer of the skin is known for containing melanocytes?
What happens to the cells as they move toward the surface of the skin?
What happens to the cells as they move toward the surface of the skin?
What is the primary function of the stratum corneum?
What is the primary function of the stratum corneum?
Which pigment is produced by melanocytes?
Which pigment is produced by melanocytes?
What type of tissue primarily composes the dermis?
What type of tissue primarily composes the dermis?
What is the role of the hypodermis?
What is the role of the hypodermis?
Which of the following is NOT a component of the epidermis?
Which of the following is NOT a component of the epidermis?
What part of the hair is living and located within the hair follicle?
What part of the hair is living and located within the hair follicle?
Which type of gland secretes sebum to lubricate and waterproof the skin?
Which type of gland secretes sebum to lubricate and waterproof the skin?
What is the primary function of the arrector pili muscle?
What is the primary function of the arrector pili muscle?
What is the scale-like outer layer of the hair called?
What is the scale-like outer layer of the hair called?
Which type of sudoriferous gland is involved in evaporative cooling?
Which type of sudoriferous gland is involved in evaporative cooling?
What secondary function does hair serve besides protection?
What secondary function does hair serve besides protection?
Which component of hair receives nutrients and is located at the base of the hair root?
Which component of hair receives nutrients and is located at the base of the hair root?
What do nails primarily serve to do?
What do nails primarily serve to do?
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Study Notes
Integumentary System
- Composed of skin (integument) and associated structures (hair, glands, nails)
- Accounts for approximately 7% of body weight
- Dynamic interface between body and external environment
Functions of the Integumentary System
- Physical Protection: Skin acts as a barrier against microorganisms, water, and UV light
- Acidic surface (pH 4.0-6.8) inhibits pathogen growth
- Hydroregulation: Prevents excessive water loss and absorption
- Thermoregulation: Maintains body temperature through sweating, shivering, and blood vessel dilation/constriction
- Cutaneous Absorption: Allows absorption of small amounts of UV light for vitamin D synthesis, but also permits entry of toxins and pesticides
- Synthesis: Produces melanin (protective pigment) and keratin (protective protein)
- Sensory Reception: Possesses numerous sensory receptors for touch, temperature, pressure, and pain
- Communication: Interacts with circulatory, immune, and nervous systems
Structure of the Skin
-
Epidermis: Outer layer, composed of stratified squamous epithelium (30-50 cells thick)
- Avascular; outer cells are dead, keratinized, and cornified
- Stratum corneum: Outermost layer, dead cells
- Stratum lucidum: Found only in thick skin (palms, soles), translucent layer
- Stratum granulosum: Granular layer, cells begin to keratinize
- Stratum spinosum: Spiny layer, cells interconnected by desmosomes
- Stratum basale: Basal layer, actively dividing cells (mitosis)
- Melanocytes: Pigment-producing cells found in stratum basale and stratum spinosum, produce melanin
-
Dermis: Inner layer, highly vascularized connective tissue
- Papillary layer: Superficial layer, in contact with epidermis
- Reticular layer: Deeper, thicker layer, in contact with hypodermis
- Blood Vessels: Supply nutrients and oxygen to skin
- Sweat and Oil Glands: Secrete sweat and sebum
- Hair Follicles: Structures that contain hair
- Sensory Receptors: Detect touch, temperature, pressure, and pain
-
Hypodermis (Subcutaneous Tissue): Layer beneath the dermis
- Composed of loose connective tissue, adipose tissue, blood and lymph vessels
- Binds dermis to underlying organs, stores fat, insulates and cushions the body, regulates temperature
Associated Structures of the Skin
- Hair: Composed of dead, keratinized cells
- Hair Follicle: Germinal epithelial layer that grows down into the dermis, responsible for hair growth
- Hair Shaft: Visible portion of the hair
- Hair Root: Living portion of the hair within the follicle
- Hair Bulb: Enlarged base of the root, receives nutrients
- Arrector Pili Muscle: Smooth muscle associated with hair follicles, causes hair to stand on end
- Nails: Hardened, transparent stratum corneum of the epidermis
- Protect digits and aid in grasping objects
- Exocrine Glands:
- Sebaceous Glands (Oil Glands): Secrete sebum, lubricate and waterproof the skin
- Sudoriferous Glands (Sweat Glands):
- Eccrine Glands: Abundant on forehead, back, palms, soles; function in evaporative cooling
- Apocrine Glands: Found in axillary and pubic regions; function at puberty as a sexual attractant
- Mammary Glands: Specialized sudoriferous glands in female breasts; secrete milk under hormonal influence
Physiology of the Skin
- Protection: Against dehydration, mechanical injury, pathogens, UV light, and blood loss
- Synthesis: Of pigments (melanin) and vitamin D
- Temperature Regulation: Via vasodilation, vasoconstriction, sweating, and shivering
- Absorption: Of O2, CO2, fat-soluble vitamins, steroid hormones, and some toxins
- Excretion: Of salts, water, and urea
- Sensory Reception: For touch, temperature, pain, pressure, and stretch
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