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Questions and Answers
What is the primary function of keratinocytes in the epidermis?
Which statement accurately describes the dermis?
How do nutrients reach the epidermis?
What role do dendritic cells play in the epidermis?
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What is the subcutaneous tissue primarily composed of?
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Which layer of the epidermis makes up the majority of its thickness?
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Which type of cells in the epidermis are responsible for sensing touch?
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What distinguishes the epidermis from the dermis?
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What does pallor or blanching indicate about blood flow?
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What does erythema usually signify?
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Which condition causes a yellow tint in the skin and eyes?
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What causes the formation of bruises on the skin?
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What is a potential indication of insulin resistance in the skin?
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What is the main component that makes up hair strands?
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What is the medical term for the discoloration resulting from blood leakage below the skin?
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What color change in the skin might indicate decreased oxygenation?
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What is the primary function of the hair papilla?
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What is the primary function of eccrine sweat glands?
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Which part of the hair follicle expands to form the hair bulb?
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What is the primary composition of nails?
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Where are eccrine sweat glands primarily located?
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What is characteristic of the secretions from apocrine sweat glands?
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What does the nail matrix produce?
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What is the role of the hyponychium?
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How are the secretions of eccrine and apocrine glands expelled?
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What can trigger increased activity in apocrine sweat glands?
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What layers make up the epithelial root sheath of the hair follicle?
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Which of the following is NOT a component of eccrine sweat?
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Which structure in hair follicles wraps around the bulb and functions as a sensory nerve ending?
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What is the appearance of the lunule in nails?
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Which statement regarding the structure of eccrine sweat glands is correct?
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What is a unique function of myoepithelial cells in sweat glands?
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What type of skin cancer is considered the most dangerous?
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Which area of the body is commonly affected by squamous cell carcinoma?
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What characterizes a first degree burn?
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Which of the following is a characteristic of melanoma?
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How long does it generally take for a second degree burn to heal?
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What is the defining factor for burns to be considered critical?
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What significant feature distinguishes third degree burns from others?
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In the rule of nines, how much of the total body area does each of the 11 areas represent?
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Study Notes
Integumentary System
- The integumentary system is composed of skin, hair, and nails.
- The skin is the outermost layer of the body and protects underlying structures.
- The skin is composed of three layers: epidermis, dermis, and subcutaneous tissue.
Epidermis
- The epidermis is the outermost layer of the skin.
- It is composed of epithelial cells.
- It is nonvascularized, meaning it does not contain blood vessels.
- Nutrients reach the epidermis by diffusion from the dermis.
- It is constantly being renewed, with new cells being generated every 25 to 45 days.
- The epidermis is responsible for protecting the body from microorganisms and UV radiation.
Dermis
- The dermis is the middle layer of the skin and contains connective tissue, blood vessels, and nerve endings.
- It is tough and flexible, giving the skin its strength and elasticity.
- It is vascularized, meaning it contains blood vessels.
Subcutaneous Tissue
- The subcutaneous tissue is the deepest layer of the skin and lies beneath the dermis.
- It is also known as the hypodermis or superficial fascia.
- It is composed of adipose tissue and areolar connective tissue.
- It anchors the skin to underlying structures, providing insulation and cushioning.
Cells of the Epidermis
- The epidermis is composed of four main types of cells: keratinocytes, melanocytes, dendritic cells, and tactile cells.
- Keratinocytes are the most abundant cell type in the epidermis. They produce keratin, a protein that gives the skin its strength and waterproofness.
- Melanocytes are spider-shaped cells that produce melanin, a pigment that gives the skin its color and protects against UV radiation.
- Dendritic cells are star-shaped cells that arise from bone marrow and migrate to the epidermis. They are responsible for identifying and ingesting foreign substances, known as phagocytosis.
- Tactile cells are sensory receptors that detect touch.
Layers of the Epidermis
- The epidermis is made up of five distinct layers:
- Stratum corneum: The outermost layer of the epidermis, composed of dead, keratinized cells.
- Stratum lucidum: A thin, clear layer found only in thick skin of the palms and soles.
- Stratum granulosum: Contains cells that produce keratin.
- Stratum spinosum: A layer of cells connected by desmosomes.
- Stratum basale: The deepest layer of the epidermis, where new cells are generated.
Skin Color
- Skin color is determined by the amount of melanin produced by melanocytes.
- Other factors that can influence skin color include:
- Pallor or Blanching: Caused by a decrease in blood flow to the skin, often due to stress or illness.
- Redness or Erythema: Caused by increased blood flow to the skin, often due to blushing, fever, inflammation, or allergy.
- Yellowness: Caused by the accumulation of bilirubin in the body, indicating liver dysfunction.
- Cyanosis: Caused by a lack of oxygen in the blood, resulting in a bluish discoloration of the skin.
- Bruses or Ecchymoses/Hematoma: Caused by damage to blood vessels, resulting in bleeding and discoloration.
Hair
- Hair, also known as pili, is produced by hair follicles.
- Hair follicles are invaginations of the epidermis that extend into the dermis.
- Hair is composed mainly of dead keratinized cells.
- The hair root is the portion of the hair that is embedded in the follicle.
- The hair bulb is a swelling at the base of the hair root that contains the hair papilla, a dermal structure that supplies nutrients to the growing hair.
- The hair follicle wall consists of several layers:
- Peripheral connective tissue sheath: Derived from the dermis.
- Glassy membrane: A junction between the fibrous sheath and the epithelial root sheath.
- Epithelial root sheath: Derived from the epidermis and has two components: external and internal.
- Hair color is determined by the amount and type of melanin produced.
- Hair growth is regulated by hormones and nutrition.
Nails
- Nails are composed of hard keratin, a protein that is also found in hair.
- The nail plate rests on the nail bed, a layer of epidermis.
- The nail matrix is located at the base of the nail and is responsible for nail growth.
- The lunula is the white crescent at the base of the nail.
- The hyponychium is the skin beneath the free edge of the nail.
- The cuticle, also known as the eponychium, is the fold of skin at the base of the nail.
Sweat Glands
- Sweat glands are also known as sudoriferous glands and are found all over the body, except for the nipples and parts of the external genitalia.
- There are approximately 3 million sweat glands on the human body.
- There are two types of sweat glands: eccrine and apocrine.
- Eccrine glands are the most common type of sweat gland. They are found all over the body, but are particularly concentrated on the palms, soles, and forehead. Their secretions are watery and odorless.
- Apocrine glands are located in the axillary, anogenital, and areolar areas. They begin functioning at puberty. Their secretions are more viscous and contain fatty substances and proteins. They are often responsible for body odor when bacteria decompose the secretions.
Modified Apocrine Glands
- Ceruminous glands are modified apocrine glands that produce ear wax.
Skin Cancer
- Skin cancer is the most common type of cancer in the United States.
- There are three main types of skin cancer:
- Basal cell carcinoma: The most common type of skin cancer. It usually arises from the stratum basale and is slow-growing.
- Squamous cell carcinoma: The second most common type of skin cancer. It usually arises from the stratum spinosum and is more likely to metastasize than basal cell carcinoma.
- Melanoma: The most dangerous type of skin cancer. It usually arises from melanocytes and is highly metastatic.
Burns
- Burns are injuries to the skin caused by heat, chemicals, electricity, or radiation.
- Burns are classified by their degree, which indicates the extent of tissue damage:
- First-degree burns: Damage only the epidermis. They are characterized by redness, swelling, and pain. They typically heal within 2 to 3 days.
- Second-degree burns: Damage the epidermis and upper dermis. They are characterized by redness, swelling, pain, and blisters. They typically heal within 3 to 4 weeks.
- Third-degree burns: Damage the entire thickness of the skin, including the epidermis, dermis, and subcutaneous tissue. They are characterized by charring, numbness, and a lack of pain. They require skin grafting to heal.
Rule of Nines
- The rule of nines is a method used to estimate the percentage of body surface area that has been burned.
- The body is divided into 11 areas, each representing 9% of the total body surface area.
- The genitals represent 1% of the total body surface area.
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Description
Explore the key components of the integumentary system, including the skin, hair, and nails. This quiz covers the structure and function of the epidermis, dermis, and subcutaneous tissue, providing insights into their roles in protecting the body. Test your knowledge on this essential biological system.
