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Questions and Answers
What is the primary characteristic of the stratum spinosum?
Which epidermal layer is responsible for initiating keratinization?
What is the main function of the stratum corneum?
What unique feature distinguishes the stratum lucidum?
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Which of the following plays a significant role in the structure of the stratum spinosum?
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What happens to cells as they move above the stratum granulosum?
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How many layers of cells can be found in the stratum granulosum?
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What percentage of the epidermal thickness does the stratum corneum account for?
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What is the primary function of keratinocytes in the epidermis?
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Which layer of the skin is primarily composed of adipose tissue?
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What layer of the epidermis is known for containing actively dividing stem cells?
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Which cells in the epidermis play a crucial role in the immune response?
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Which epidermal layer is present only in thick skin?
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What is the primary characteristic of the dermis compared to the epidermis?
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How frequently does the external layer of the skin renew itself?
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Merkel cells in the epidermis are primarily responsible for which function?
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What is the most common type of skin cancer?
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Which factor is NOT associated with an increased risk of skin cancer?
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What is one key characteristic of Melanoma?
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What is the main function of lotions that contain enzymes for skin repair?
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What type of burn involves damage to both the epidermis and the upper dermis?
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What is a common symptom of a First-Degree Burn?
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Which rule is used to evaluate burn severity and estimate fluid loss?
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Which of the following is a characteristic of Squamous Cell Carcinoma?
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What are the two forms of melanin produced in the skin?
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What effect does increased sunlight exposure have on melanin production?
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What condition is characterized by a blue skin hue due to low oxygen saturation of hemoglobin?
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What is the main cause of vitiligo?
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What type of hair is described as soft and unpigmented, typically found on fetuses and newborns?
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Which layer of the dermis is characterized by loose areolar connective tissue?
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Which pigment can be converted to vitamin A, important for vision and epidermal health?
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What is the function of the arrector pili muscle in hair follicles?
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What is the primary structural component that gives the reticular layer its strength and resiliency?
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What condition can excessive sun exposure lead to regarding skin appearance?
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Which clinical condition is indicated by paleness of the skin?
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Which type of cell is primarily responsible for the pigmentation of the skin?
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What type of alopecia results in hair loss across the entire body?
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What is the term for the finger-like projections found in the papillary layer?
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What is the primary function of hair in the integumentary system?
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What type of connective tissue primarily composes the reticular layer of the dermis?
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What is the physiological effect of trauma that can lead to the formation of blisters?
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Which layer of the skin contains hair follicles, sweat glands, and sebaceous glands?
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Which condition is NOT a result of excessive stretching of the skin?
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What adverse effect can occur due to photosensitivity from certain medications?
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Study Notes
Integumentary System
- Consists of skin, hair, nails, sweat and sebaceous glands
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Skin has three main regions:
-
Epidermis
- Superficial layer
- Composed of epithelial tissue
- Avascular
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Dermis
- Lies underneath the epidermis
- Composed of areolar and dense irregular connective tissues
- Vascular
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Hypodermis
- Superficial fascia, subcutaneous layer
- Deep to the skin, but shares function with skin
- Primarily composed of adipose tissue
- Absorbs shock, insulates the body, anchors skin to muscles
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Epidermis
Cells of Epidermis
- Major cell type: Keratinocytes
- Produce keratin, giving skin its protective qualities
- Millions are shed daily, a significant component of household dust
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Melanocytes
- Produce melanin, protecting cell nuclei from UV damage
- Located deep within the epidermis
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Dendritic Cells
- Star-shaped macrophages
- Patrol the deep epidermis, activating the immune response
- Antigen-presenting cells
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Merkel Cells
- Sensory receptors for touch
Epidermal Layers
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Stratum basale (aka stratum germinativum)
- Deepest layer of the epidermis
- Firmly attached to the dermis
- Composed of a single row of actively dividing stem cells
- Constantly renews the epidermal cell population
- Cells die as they move towards the surface, giving us a new skin every 25-45 days
-
Stratum spinosum (prickly layer)
- Several cell layers thick
- Contains pre-keratin filaments, resisting tension and pulling
- Cells appear spiky or prickly
- Contains dendritic cells and melanosomes
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Stratum granulosum (granular layers)
- Contains 1-5 layers of flattened cells
- Cells start to change appearance, becoming flat and losing nuclei and organelles
- Keratinization begins
- Cells above this layer die due to being too far from dermal capillaries
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Stratum lucidum (clear layer)
- Found only in thick skin
- Composed of a thin, translucent band of 2-3 layers of dead keratinocytes
- Cells appear identical to the stratum corneum
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Stratum corneum (horny layer)
- Outermost layer of the epidermis
- Composed of 20-30 layers of flat, keratinized dead cells
- Accounts for 75% of epidermal thickness
- Approximately 18 kg of cells shed/slough off over a lifetime
- Protects deeper layers from the environment, prevents water loss, protects from abrasion and penetration, and acts as a barrier
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Thick Skin
- Found in areas of high wear (e.g., palms of hands & soles of feet)
- Has five layers: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
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Thin Skin
- Has four layers: stratum basale, stratum spinosum, stratum granulosum, stratum corneum
Dermis
- Strong, flexible connective tissue
- Contains fibroblasts, macrophages, mast cells, and white blood cells
- Semi-fluid matrix
- Contains fibers that bind it together
- Two layers: papillary and reticular
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Papillary layer
- Superficial layer composed of loose areolar connective tissue
- Contains collagen, elastic fibers, and blood vessels
- Contains dermal papillae, finger-like projections into the epidermis
- Contains capillaries, free nerve endings (nociceptors), and touch receptors (Meissner’s corpuscles)
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Reticular layer
- Composed of dense irregular fibrous connective tissue
- Elastic fibers provide stretch-recoil properties
- Collagen fibers provide strength and resiliency
- Makes up 80% of dermal thickness
- Composed of dense irregular fibrous connective tissue
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Clinical Connection
- Extreme stretching of the skin can cause dermal tears, leaving silvery white scars called striae or stretch marks
- Acute, short-term trauma to the skin can cause blisters
Skin Color
- Determined by melanin, carotene, and hemoglobin
-
Melanin
- The only pigment made within the skin
- Two forms: red-yellow and brown-black
- Shields the DNA of keratinocytes from UV damage
- More sun exposure leads to more melanin production
- Differences in pigmentation are due to different amounts of melanin produced
- Freckles and moles are local accumulations of melanin
-
Carotene
- Yellow-orange pigment found in palms and soles
- Can be converted to vitamin A
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Hemoglobin
- Provides a pinkish hue to fairer skin
Clinical Significance of Skin Color
- Alterations in skin colour can indicate disease:
- Cyanosis: bluish tint due to low oxygenation of hemoglobin
- Pallor: paleness due to anemia, low blood pressure, fear, or anger
- Erythema: redness due to fever, hypertension, inflammation, or allergy
- Jaundice: yellowness due to liver disorders
Clinical Connection: Vitiligo
- Chronic autoimmune disorder causing patches of skin to lose color
- Destruction of melanocytes results in a milky-white appearance
- Patches usually appear symmetrically on the body, not necessarily the same shape
Hair
- Composed of keratinized cells
- Functions:
- Warning against insects or foreign bodies
- Protection from physical trauma
- Insulation against heat loss
- Protection from sunlight
- Covers the body except for the palms, soles, lips, nipples, and portions of the external genitalia
- Extends from the epidermis into the dermis
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Hair Bulb: expanded area at the deep end of the hair follicle
- Hair Matrix: actively dividing area of the bulb, responsible for hair growth
- Hair Follicle Receptor: sensory nerve endings encasing the bulb, making hair a touch receptor
- Arrector pili: small band attached to the hair follicle that causes goose bumps and "hair standing" sensations
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Hair Pigment: caused by melanocytes in hair follicles
- Different combinations of melanins create different hair colours
- Red hair also contains pheomelanin
- Graying results from a decrease in melanin production
- Different combinations of melanins create different hair colours
Hair Types and Growth
- Lanugo: soft, unpigmented hair found in fetuses and newborns
- Vellus hair: pale and fine body hair found in children and adult females (assigned female at birth)
- Terminal hairs: coarse, long, pigmented hair found on the scalp, eyebrows, and other areas (axillary, pubic, face, and neck during puberty)
- Hair growth is mainly regulated by hormones and nutrition
Clinical Connection: Alopecia
- Alopecia: Hair loss
-
Types of Alopecia:
- Alopecia areata: hair loss in a single body part
- Alopecia totalis: hair loss on all body parts of a single region
- Alopecia universalis: hair loss all over the body
- Androgenic alopecia: genetic/hormonal hair loss
- Telogen effluvium: hair loss triggered by thyroid disorders, stress, diet, etc.
Skin Cancer
- Most skin tumors are benign (non-cancerous) and do not spread
- Risk factors for skin cancer:
- Overexposure to UV radiation (prolonged sun exposure, tanning, tanning beds)
- Frequent skin irritation
- Some lotions contain enzymes to repair damaged DNA, but nothing is foolproof
Major Types of Skin Cancer
-
Basal cell carcinoma
- Most common, least malignant
- Stratum basale cells proliferate and invade deeper layers
- 99% cured with simple excision
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Squamous cell carcinoma
- Second most common
- Can metastasize but has a good prognosis with early treatment
- Involves keratinocytes of the stratum spinosum
- Usually appears as a red papule or “splotch” on the scalp, ears, lower lip, or hands
-
Melanoma
- Highly malignant and highly metastasizing
- Resistant to chemotherapy
- Requires excision and immunotherapy
- Cancer of melanocytes
- Early detection is key, using the ABCD Rule:
- A: Asymmetry: two sides of the pigment do not match
- B: Border irregularity: indentations on the borders
- C: Color: contains several different pigments
- D: Diameter: greater than 6 mm wide
Burns
- Tissue damage caused by heat, chemicals, electricity, radiation, or chemicals
- Damage to cells, resulting in fluid loss and potential for severe consequences like dehydration, electrolyte imbalance, and renal failure
- Classified according to severity:
- First-degree: epidermal damage only, resulting in redness, edema, and pain
- Second-degree: epidermal and upper dermal damage, resulting in blistering
- Third-degree: damage through all layers of the skin including subcutaneous tissue
- Fourth-degree: complete destruction of tissue down to the bone
- Rule of Nines: used to assess the severity of burns by dividing the body into 11 sections, each representing about 9% of the body surface area (except for the genitals, which account for 1%).
Nail Structure
- Composed of hard, keratinized cells
- Nail Body: visible portion of the nail
- Nail Root: portion embedded in the skin
- Nail Bed: epidermal layer beneath the nail
- Nail Matrix: responsible for nail growth
- Lunula: crescent-shaped, white area at the base of the nail.
- Cuticle (Eponychium): epithelial tissue that overlaps the nail.
- Hyponychium: thickened area of skin under the free edge of the nail.
- Nail folds: edges of skin that surround the nail.
Sweat Glands
-
Eccrine glands: release sweat for temperature regulation
- Found all over the body, especially numerous on palms, soles, and forehead
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Apocrine glands: release sweat that mixes with bacteria, resulting in body odor
- Found in the axillae (armpits), pubic region, and around the nipples
- Begin functioning during puberty
- Ceruminous glands: found in the ear canal, release cerumen, earwax
- Mammary glands: modified sweat glands that secrete milk
Sebaceous Glands
- Produce sebum, an oily substance that lubricates the skin and hair
- Usually associated with hair follicles
- Secretion is regulated by hormones.
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Description
Test your knowledge on the integumentary system, focusing on the structure and functions of skin, hair, nails, and glands. This quiz covers the layers of skin and the different types of cells found in the epidermis, including their roles and importance in protecting the body.
