PCB 3703 Lecture 5 Integumentary system

Question: What does the integumentary system consist of?

Answer: The skin and accessory tissues including nails, hair, sweat glands, and sebaceous glands.

Question: What is another name for the skin?

Answer: Cutaneous membrane or integument.

Question: What are the primary protective functions of the integument?

Answer: It acts as a barrier to the outside world and protects against injury, microbes, and UV radiation.

Question: What is dermatology?

Answer: The study of skin.

Question: What are the layers of the integument?

Answer: Epidermis and dermis.

Question: What tissue type comprises the epidermis?

Answer: Keratinized, stratified squamous epithelium.

Question: What tissue type primarily comprises the dermis?

Answer: Dense irregular connective tissue.

Question: What tissue types make up the subcutaneous layer or hypodermis?

Answer: Areolar and adipose connective tissue.

Question: Is the subcutaneous layer part of the integumentary system?

Answer: No, it is deep to the dermis.

Question: What are the strata (layers) of the epidermis from deep to superficial?

Answer: Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.

Question: Which epidermal layers are composed of living keratinocytes?

Answer: The first three layers: stratum basale, stratum spinosum, and stratum granulosum.

Question: What is the deepest layer of the epidermis?

Answer: Stratum basale.

Question: What is the cellular structure of the stratum basale?

Answer: A single layer of cuboidal and columnar cells.

Question: What three cell types are found in the stratum basale?

Answer: Keratinocytes, melanocytes, and tactile cells.

Question: What is the function of keratinocytes in the stratum basale?

Answer: They act as stem cells that divide to regenerate new cells and synthesize keratin.

Question: What is keratin?

Answer: A tough, insoluble fibrous structural protein that strengthens the epidermis and makes it water-resistant.

Question: Where are melanocytes located?

Answer: Scattered among keratinocytes in the stratum basale.

Question: What is the function of melanocytes?

Answer: They produce and store melanin pigment and transfer melanosomes into keratinocytes.

Question: Why do melanocytes transfer pigment granules into keratinocytes?

Answer: To shield nuclear DNA from UV radiation.

Question: What are tactile cells also called?

Answer: Merkel cells.

Question: What is the function of tactile cells?

Answer: They are sensitive to touch and release chemicals that stimulate sensory nerve endings when compressed.

Question: What characterizes the stratum spinosum?

Answer: Several layers of polygonal keratinocytes attached by desmosomes.

Question: What are epidermal dendritic cells or Langerhans cells?

Answer: Cells found in the stratum spinosum and granulosum that initiate immune responses.

Question: What characterizes the stratum granulosum?

Answer: 3 to 5 layers of keratinocytes where keratinization begins.

Question: What happens to keratinocytes in the stratum granulosum?

Answer: They fill with keratin while their nucleus and organelles disintegrate, resulting in dead cells.

Question: What characterizes the stratum lucidum?

Answer: A translucent layer, 2 to 3 cell layers thick, found only on thick skin.

Question: Where is thick skin found?

Answer: Palms of hands and soles of feet.

Question: What translucent protein fills the cells of the stratum lucidum?

Answer: Eleidin.

Question: What are the functions of the stratum lucidum?

Answer: Protection from UV and reduction of friction.

Question: What characterizes the stratum corneum?

Answer: 20 to 30 layers of dead, interlocking, anucleate, keratinized cells.

Question: What protection does the stratum corneum provide?

Answer: Protection against abrasion, infection, and antimicrobial defense.

Question: Which epidermal layers are present in thick skin?

Answer: All five epidermal layers.

Question: What glands are found in thick skin?

Answer: Sweat glands (lacks hair follicles and sebaceous glands).

Question: What covers most of the body and lacks a stratum lucidum?

Answer: Thin skin.

Question: What structures are found in thin skin?

Answer: Sweat glands, hair follicles, and sebaceous glands.

Question: What three components determine typical skin color?

Answer: Hemoglobin, melanin, and carotene.

Question: What is hemoglobin?

Answer: An oxygen-binding protein in red blood cells that turns bright red upon binding oxygen.

Question: What are the two types of melanin?

Answer: Eumelanin and pheomelanin.

Question: What shades are associated with eumelanin?

Answer: Brown and black shades.

Question: What shades are associated with pheomelanin?

Answer: Lighter shades including tan, yellow, and red.

Question: What causes albinism?

Answer: Melanocytes are unable to produce melanin due to an enzyme malfunction.

Question: What is carotene?

Answer: A yellow-orange pigment acquired from certain vegetables.

Question: Where does carotene accumulate in the body?

Answer: In keratinocytes of the stratum corneum and subcutaneous fat.

Question: What is beta-carotene converted into in the liver?

Answer: Vitamin A.

Question: What role does vitamin A derived from carotene play?

Answer: A role in eyesight.

Question: What is a nevus?

Answer: A mole, which is a localized overgrowth of melanocytes.

Question: Why should nevi be monitored?

Answer: For changes suggesting UV-induced malignancy.

Question: What are freckles?

Answer: Yellowish or brown spots formed by localized areas of increased melanocyte activity.

Question: What is a hemangioma?

Answer: Skin discoloration due to a benign blood vessel tumor.

Question: What are friction ridges?

Answer: Large folds and valleys of the dermis and epidermis that form fingerprints.

Question: What is the papillary layer of the dermis composed of?

Answer: Areolar connective tissue.

Question: What are dermal papillae?

Answer: Projections of the dermis that interlock with epidermal ridges to increase contact area.

Question: What tissue type composes the reticular layer of the dermis?

Answer: Dense irregular connective tissue.

Question: What do parallel bundles of collagen and elastic fibers in the dermis produce?

Answer: Lines of cleavage.

Question: What causes stretch marks (striae)?

Answer: Tearing of collagen fibers when skin is stretched beyond its capabilities.

Question: What do Meissner corpuscles detect?

Answer: Fine touch discrimination in the ridges of fingerprints.

Question: What do nociceptors sense?

Answer: Tissue injury, damage, or pain.

Question: What do Pacinian corpuscles detect?

Answer: Pressure and vibrations deep in the dermis.

Question: Why do tattoos become permanent?

Answer: Dye is injected into the dermis where scar tissue surrounds dye granules too large for dendritic cells to ingest.

Question: What are some tattoo removal methods?

Answer: Excision, dermabrasion, cryosurgery, and laser removal.

Question: What are the functions of the subcutaneous layer?

Answer: Protection, energy storage, and insulation.

Question: Why is the subcutaneous layer a common drug injection site?

Answer: Its extensive vascular network promotes rapid absorption.

Question: Where does testosterone influence subcutaneous fat distribution?

Answer: Neck, upper arms, abdomen, lower back, and buttocks.

Question: Where do estrogen and progesterone influence subcutaneous fat distribution?

Answer: Mammary region, buttocks, hips, and thighs.

Question: How does the epidermis prevent water loss?

Answer: It is water-resistant, preventing excessive water loss while water is lost through sweat and transpiration.

Question: How is vitamin D synthesized in the skin?

Answer: UV light causes keratinocytes to convert a steroid into Vitamin D3.

Question: What is Vitamin D3 a precursor to?

Answer: Calcitriol.

Question: What is the function of calcitriol?

Answer: It increases absorption of calcium and phosphate from the diet and regulates blood calcium levels.

Question: What waste products are left on the skin through sweat?

Answer: Salt and urea.

Question: What is the function of sebum?

Answer: It lubricates skin and hair and provides water resistance.

Question: How does the skin regulate temperature through blood vessels?

Answer: Through vasoconstriction to conserve heat or vasodilation to release heat.

Question: How do nails and hair initially form?

Answer: As portions of the epidermis.

Question: What are nails and hair primarily composed of?

Answer: Dead keratinocytes.

Question: What are exocrine glands of the skin composed of?

Answer: Living epithelial cells.

Question: What are nails?

Answer: Scalelike modifications of the stratum corneum located on the dorsal edges of fingers and toes.

Question: What are the functions of nails?

Answer: Protecting distal tips of digits and assisting in grasping objects.

Question: What constitutes the nail plate?

Answer: The free edge, nail body, and nail root.

Question: What is the nail bed?

Answer: A layer of living epidermis covered by the nail body.

Question: What is the nail root?

Answer: The part of the nail embedded in the skin.

Question: What causes the pinkish color of the nail body?

Answer: Underlying capillaries.

Question: What happens to Pacinian corpuscles with sustained pressure?

Answer: They shut down with sustained pressure.

Question: What system controls the secretion of sweat and sebaceous glands?

Answer: The autonomic nervous system.

Question: Why is the skin suitable for some drug administrations?

Answer: Because it is selectively permeable, allowing transdermal administration.

Question: Why is the distal free edge of the nail whitish?

Answer: Because there are no underlying capillaries.

Question: What do exocrine glands of the skin initially form as?

Answer: Portions of the epidermis composed of living epithelial cells.

Question: Why can't dendritic cells remove tattoo ink granules?

Answer: Because the tattoo dye granules are too large for dendritic cells to ingest.

Question: Where are epidermal dendritic cells found besides the stratum spinosum?

Answer: The stratum granulosum.

Question: What does the skin serve as in addition to a protective barrier?

Answer: A visual indicator of our physiology and health.

Question: Through what two processes is water lost from the skin?

Answer: Sweat and transpiration.

Question: What is the most common form of carotene and what is it a source of?

Answer: Beta-carotene, which is a source of provitamin A.