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Questions and Answers
What is the main function of scalp hair?
What is the main function of scalp hair?
Which type of hair is characterized as fine and unpigmented, typically found on fetuses?
Which type of hair is characterized as fine and unpigmented, typically found on fetuses?
Which gland is responsible for producing sweat with visible wetness?
Which gland is responsible for producing sweat with visible wetness?
What type of cancer is considered the least dangerous?
What type of cancer is considered the least dangerous?
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What does bromhidrosis refer to?
What does bromhidrosis refer to?
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What is the function of guard hairs and eyelashes?
What is the function of guard hairs and eyelashes?
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Which part of the hair follicle is responsible for sensory reception?
Which part of the hair follicle is responsible for sensory reception?
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Which of the following hair types typically signifies sexual maturity?
Which of the following hair types typically signifies sexual maturity?
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What is the primary function of keratinocytes in the epidermis?
What is the primary function of keratinocytes in the epidermis?
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Which layer of the epidermis contains dendritic cells that help protect against pathogens?
Which layer of the epidermis contains dendritic cells that help protect against pathogens?
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What is one major role of the acid mantle on the skin?
What is one major role of the acid mantle on the skin?
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What distinguishes the stratum corneum from the other layers of the epidermis?
What distinguishes the stratum corneum from the other layers of the epidermis?
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Which component is primarily found in the dermis layer of the skin?
Which component is primarily found in the dermis layer of the skin?
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What is the thickness range of the hypodermis?
What is the thickness range of the hypodermis?
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What is a significant function of the dermal papillae?
What is a significant function of the dermal papillae?
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What type of cell is responsible for sensing touch in the epidermis?
What type of cell is responsible for sensing touch in the epidermis?
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What is the primary composition of the hypodermis?
What is the primary composition of the hypodermis?
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Which layer of the epidermis is involved in the synthesis of keratin?
Which layer of the epidermis is involved in the synthesis of keratin?
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Study Notes
Integumentary System Overview
- Largest organ in the body, comprising 15% of body weight
- Composed of three layers: epidermis, dermis, and hypodermis
- Epidermis is a keratinized stratified squamous epithelium
- Dermis is a connective tissue layer
- Hypodermis is the subcutaneous layer, primarily composed of adipose tissue
Functions of the Skin
- Resistance to trauma and infection due to keratin and desmosomes, and an acidic mantle (pH 4-6)
- Barrier to ultraviolet radiation (UV damages DNA)
- Vitamin D synthesis
- Sensory receptors provide tactile information to the nervous system
- Thermoregulation through sweating
- Nonverbal communication through skin expressions
Cells of the Epidermis
- Stem Cells: Undifferentiated cells in the deepest layer of the epidermis, responsible for replacing epidermal cells
- Keratinocytes: Most abundant cells in the epidermis, produce keratin, a tough protein that protects the skin
- Melanocytes: Produce melanin, a pigment that protects the skin from UV radiation
- Tactile (Merkel) Cells: Receptor cells associated with nerve fibers, responsible for touch sensation
- Dendritic (Langerhans) Cells: Immune cells (macrophages) that protect the skin from pathogens
Layers of the Epidermis
- Stratum Basale: Single layer of cells resting on the basement membrane, contains stem cells, melanocytes, and tactile cells
- Stratum Spinosum: Several layers of keratinocytes, contains dendritic (Langerhans) cells
- Stratum Granulosum: 3 to 5 layers of flat keratinocytes, contains keratinohyalin granules (combine with filaments of cytoskeleton to form keratin) and lipid-filled vesicles (release glycolipid for waterproofing)
- Stratum Corneum: Outermost layer, composed of 30 layers of dead, keratinized cells, constantly exfoliating
Dermis
- Thickness varies from 0.6 to 3 mm, composed of connective tissue
- Contains collagen, elastic, and reticular fibers, as well as fibrocytes
- Dermal papillae are extensions of the dermis into the epidermis, forming the ridges of fingerprints
- Composed of two layers: papillary layer (superficial) and reticular layer (deeper)
Hypodermis (Subcutaneous Tissue/Superficial Fascia)
- Primarily composed of adipose tissue, acting as an energy reservoir and thermal insulator
- Highly vascular, making it a suitable site for injections
Hair
- Composed of hard keratin, formed by disulfide bridges between protein molecules
- Present almost everywhere on the body, with variations in texture and color based on individual and sex
- Three types of hair: lanugo, vellus, and terminal hair
Structure of the Hair Follicle
- Epithelial root sheath surrounds the hair shaft
- Connective tissue root sheath anchors the follicle to the dermis
- Hair receptors (sensory) sense hair movement
- Piloerector muscle causes hair to stand erect (goosebumps)
Functions of Hair
- Body hair: provides minimal warmth, alerts to parasites
- Scalp hair: retains heat, protects from sunburn
- Beard, pubic, and axillary hair: signal sexual maturity, distribute sexual scents
- Guard hairs and eyelashes: protect against foreign objects entering nostrils, ear canals, and eyes
- Eyebrows: express emotions
Cutaneous Glands
-
Sweat Glands: Secrete sweat, a filtrate of blood plasma.
- Eccrine (Merocrine) Glands: Most abundant type, responsible for thermoregulation
- Apocrine Glands: Secrete sweat containing fatty acids, found near hair follicles, respond to stress and sex
- Sebaceous Glands: Secrete sebum (oily substance), containing broken-down cells, empties into hair follicles
Skin Cancer
- Caused by UV radiation from the sun
- Basal cell carcinoma: Least dangerous, arises from the stratum basale
- Squamous cell carcinoma: Arises from keratinocytes in the stratum spinosum, can metastasize to lymph nodes
- Malignant melanoma: Most deadly, arises from melanocytes, characterized by ABCD rule (Asymmetry, Border irregular, Color mixed, Diameter over 6 mm)
- Result of oncogene BRAF in men
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Description
Explore the complex structure and functions of the integumentary system, the body's largest organ. This quiz covers the skin's layers, key cellular components, and their essential roles in protection, sensation, and thermoregulation.
