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Questions and Answers
What is the primary function of the medulla in a hair follicle?
What is the primary function of the medulla in a hair follicle?
What type of hair is characterized as fine and unpigmented, usually found on a fetus?
What type of hair is characterized as fine and unpigmented, usually found on a fetus?
Which stage of the hair cycle is primarily responsible for the growth of hair?
Which stage of the hair cycle is primarily responsible for the growth of hair?
What type of sweat glands become active during puberty in response to stress and sexual stimulation?
What type of sweat glands become active during puberty in response to stress and sexual stimulation?
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Which type of hair is known for being larger, coarser, and heavily pigmented?
Which type of hair is known for being larger, coarser, and heavily pigmented?
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What is the characteristic of first-degree burns?
What is the characteristic of first-degree burns?
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During which phase of the hair cycle can hair be easily pulled out?
During which phase of the hair cycle can hair be easily pulled out?
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Which skin cancer type is the most common and least dangerous?
Which skin cancer type is the most common and least dangerous?
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Insensible perspiration is best defined as:
Insensible perspiration is best defined as:
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Which of the following is NOT a characteristic of apocrine sweat glands?
Which of the following is NOT a characteristic of apocrine sweat glands?
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Mammary glands are classified as:
Mammary glands are classified as:
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What is the primary role of sebaceous glands?
What is the primary role of sebaceous glands?
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What is a characteristic feature of malignant melanoma?
What is a characteristic feature of malignant melanoma?
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What distinguishes vellus hair from terminal hair?
What distinguishes vellus hair from terminal hair?
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What is primarily composed of dense irregular connective tissue in the skin?
What is primarily composed of dense irregular connective tissue in the skin?
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What provides thermal insulation and acts as an energy reservoir in the skin?
What provides thermal insulation and acts as an energy reservoir in the skin?
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Which structure within the dermis allows for mobility of leukocytes?
Which structure within the dermis allows for mobility of leukocytes?
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What layer of the skin is primarily responsible for producing melanin?
What layer of the skin is primarily responsible for producing melanin?
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What describes the role of dermal papillae in the skin?
What describes the role of dermal papillae in the skin?
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Which skin color change is a sign of oxygen deficiency?
Which skin color change is a sign of oxygen deficiency?
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What type of graft uses tissue from another location on the same person's body?
What type of graft uses tissue from another location on the same person's body?
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Which layer is primarily responsible for skin sensation due to its nerve endings?
Which layer is primarily responsible for skin sensation due to its nerve endings?
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What is the primary component of hair and nails?
What is the primary component of hair and nails?
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Which skin marking is characterized as a flat, melanized patch?
Which skin marking is characterized as a flat, melanized patch?
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What layer contains the most adipose tissue?
What layer contains the most adipose tissue?
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What term describes patches of discolored skin often referred to as birthmarks?
What term describes patches of discolored skin often referred to as birthmarks?
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Which of the following can indicate increased blood flow to the skin?
Which of the following can indicate increased blood flow to the skin?
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What describes the downward waves of the epidermis in relation to the dermis?
What describes the downward waves of the epidermis in relation to the dermis?
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What is the main function of keratinocytes in the epidermis?
What is the main function of keratinocytes in the epidermis?
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Which layer of the epidermis is characterized by the presence of several layers of living keratinocytes joined by desmosomes?
Which layer of the epidermis is characterized by the presence of several layers of living keratinocytes joined by desmosomes?
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What is the role of melanocytes in the epidermis?
What is the role of melanocytes in the epidermis?
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The thick skin of the palms and soles contains which of the following layers?
The thick skin of the palms and soles contains which of the following layers?
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Which epidermal layer contains dead, scaly, keratinized cells?
Which epidermal layer contains dead, scaly, keratinized cells?
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Which cells are responsible for the immune response in the epidermis?
Which cells are responsible for the immune response in the epidermis?
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In which layer of the epidermis do stem cells primarily reside?
In which layer of the epidermis do stem cells primarily reside?
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Which layer of the epidermis is not found in thin skin?
Which layer of the epidermis is not found in thin skin?
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What structural feature distinguishes the stratum granulosum?
What structural feature distinguishes the stratum granulosum?
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Which function is primarily associated with the stratum corneum?
Which function is primarily associated with the stratum corneum?
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The epidermis is primarily composed of what type of epithelial tissue?
The epidermis is primarily composed of what type of epithelial tissue?
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How thick is the epidermis generally in thin skin?
How thick is the epidermis generally in thin skin?
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What is a unique feature of the stratum lucidum?
What is a unique feature of the stratum lucidum?
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What is primarily found in the layer known as stratum corneum?
What is primarily found in the layer known as stratum corneum?
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Study Notes
Integumentary System
- Dermatology is the study and medical treatment of the skin, hair, nails, and associated glands.
- The integumentary system is the body's largest and heaviest organ.
Skin (Integument)
- Consists of two layers: epidermis and dermis.
- The hypodermis is beneath the dermis but is not part of the skin.
Epidermis
- General Features: Composed of keratinized stratified squamous epithelium. Avascular. Contains sparse nerve endings.
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Cells of the Epidermis:
- Keratinocytes: Majority of epidermal cells, synthesize keratin.
- Stem cells: Undifferentiated cells that give rise to keratinocytes. Located in the stratum basale.
- Melanocytes: Synthesize melanin, protect DNA from UV radiation, located in stratum basale.
- Tactile cells: Touch receptor cells associated with dermal nerve fibers.
- Dendritic cells: Phagocytic immune cells that defend against toxins and microbes. Found in stratum spinosum and granulosum.
Layers of the Epidermis
- Stratum corneum: Dead, scaly keratinized cells. Provides resistance to abrasion, penetration, and water loss.
- Stratum lucidum: Thin layer found only in thick skin. Keratinocytes are packed with eleidin.
- Stratum granulosum: 3-5 layers of flat, living keratinocytes containing keratohyalin granules.
- Stratum spinosum: Several layers of living keratinocytes joined by desmosomes and tight junctions.
- Stratum basale: Single layer of stem cells, keratinocytes, melanocytes, and tactile cells.
Dermis
- General Features: Composed of collagen, elastic, and reticular fibers. Supplied with blood vessels, sweat and sebaceous glands, nerve endings, hair follicles, and nail roots.
- Boundary Between Dermis and Epidermis: Dermal papillae and epidermal ridges.
- Layers of the Dermis: Papillary layer (thin, areolar tissue) and reticular layer (deep, dense irregular connective tissue).
Hypodermis (Subcutaneous Tissue)
- Layer of connective tissue beneath the skin with more areolar and adipose tissue than the dermis.
- Subcutaneous fat: Primarily composed of adipose tissue and serves as an energy reservoir and thermal insulation.
- Pads the body and binds skin to underlying tissues.
- Common site of drug injection due to blood vessel presence.
Skin Grafts
- Third-degree burns often require skin grafts.
- Autograft: Tissue from another location on the same person's body.
- Allograft: Tissue from an unrelated person, typically deceased donors.
Skin Color
- Eumelanin: Brown and black pigment, associated with tan, brown, and black skin.
- Pheomelanin: Yellowish to reddish pigment, found in Asians, Native Americans, and contributes to pinkish tones in white skin.
- People of different colors have the same number of melanocytes but vary in melanin production and longevity.
- Cyanosis: Blueness due to oxygen deficiency.
- Erythema: Redness due to increased blood flow to the skin.
- Pallor: Paleness due to decreased blood flow to the skin.
- Albinism: White skin due to a genetic lack of melanin.
- Jaundice: Yellowing due to bilirubin in the blood.
- Hematoma: Bruising due to clotted blood under the skin.
Skin Markings
- Friction Ridges: Markings on the fingertips that create fingerprints.
- Flexion Lines/Creases: Lines on flexor surfaces of fingers, palms, wrists, and elbows.
- Freckle: Flat, melanized patch.
- Mole (Nevus): Elevated, melanized patch, often with hair.
- Hemangioma (Birthmark): Patches of discolored skin.
Hair (Pilus/Pili)
- Slender filament of keratinized cells growing from the skin.
- Shaft: The visible portion above the skin surface.
- Root: The portion below the skin surface.
- Bulb: Dilated end of the hair root.
- Layers of Hair: Medulla, Cortex, and Cuticle.
- Hair Color: Determined by melanin production.
Nails
- Structure: Composed of hard keratin.
- Parts: Free edge, nail body, lunula, nail root, matrix.
- Nail Growth: Occurs at the matrix.
Hair Structure
- Medulla - The core of the hair fiber, composed of loosely arranged cells.
- Cortex - The bulk of the hair, consisting of elongated cells arranged in layers.
- Cuticle - The outermost layer of the hair fiber.
- Epithelial root sheath - A layer of cells that surrounds the hair follicle.
- Connective tissue root sheath - The outer layer surrounding the epithelial root sheath.
Hair Types
- Downy hair (lanugo) - Fine, unpigmented hair that appears on the fetus.
- Vellus hair - Fine, pale hair that replaces lanugo after birth.
- Terminal hair - Larger, coarser, and more pigmented hair found in areas like the scalp and eyebrows.
Hair Cycle
- Anagen - The hair growth stage, lasting 6-8 years for scalp hair and making up 90% of the hair cycle.
- Catagen - The degeneration stage, lasting 2-3 weeks, where hair can easily be pulled out.
- Telogen - The resting stage, lasting 1-3 months.
Skin
- Skin does not cover palms, soles of fingers and toes, lips, nipples, and parts of the genitals.
Cutaneous Glands
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Sweat glands - Located on the skin, they release sweat.
- Eccrine (merocrine) sweat glands - Most numerous sweat glands, densely located on palms, soles, and forehead.
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Apocrine sweat glands - Become active during puberty, producing sweat in response to stress and sexual stimulation. This type of sweat is milky and contains fatty acids.
- Myoepithelial cells are found in both apocrine and eccrine glands.
- Sebaceous glands - Produce sebum, an oily secretion that keeps the skin and hair from becoming dry.
- Ceruminous glands - Modified apocrine glands found only in the external ear canal. They produce cerumen (earwax).
Mammary Glands
- Modified apocrine sweat glands - Produce milk during pregnancy and lactation.
- Mammary ridges / milk lines - Two rows of mammary glands found in most mammals.
Perspiration
- Insensible perspiration - Not noticeable, does not produce visible wetness of the skin.
- Diaphoresis - Sweating with visible wetness of the skin, in response to heat, exercise, or circulatory shock.
Skin Cancer
- Basal cell carcinoma - Most common type of skin cancer, rarely metastasizes. Arises from cells in the stratum basale.
- Squamous cell carcinoma - Arises from keratinocytes in the stratum spinosum. It can metastasize to lymph nodes.
- Malignant melanoma - Arises from melanocytes and is linked to severe sunburn during childhood.
Burns
- First-degree burn - Only involves the epidermis and heals within days.
- Second-degree burn - Involves part of the dermis, taking 2 weeks to 7 months to heal. It can leave scars.
- Third-degree burn - Involves all of the dermis and sometimes deeper tissues, requiring skin grafts.
- Burns can result in death due to fluid loss, infection, and the toxic effects of eschar (burned, dead tissue).
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Description
Explore the fundamentals of the integumentary system, focusing on the skin's structure and functions. This quiz covers key components such as the epidermis, dermis, and distinct cell types within the skin. Test your knowledge of dermatology and skin health!
