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Questions and Answers
What is the primary function of Meissner's corpuscles?
What is the primary function of Meissner's corpuscles?
Which of the following is NOT a function of the integumentary system?
Which of the following is NOT a function of the integumentary system?
What is the major cell type found in the epidermis?
What is the major cell type found in the epidermis?
How long does it approximately take for a keratinocyte to travel through the stratum corneum?
How long does it approximately take for a keratinocyte to travel through the stratum corneum?
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What is the function of melanin in the skin?
What is the function of melanin in the skin?
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Which layer of the skin contains blood vessels?
Which layer of the skin contains blood vessels?
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What is the primary role of the hypodermis/subdermis?
What is the primary role of the hypodermis/subdermis?
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What happens to the skin's color during increased vascularity in the dermis?
What happens to the skin's color during increased vascularity in the dermis?
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What primarily constitutes the waterproofing feature of the skin?
What primarily constitutes the waterproofing feature of the skin?
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What type of receptors in the hypothalamus detects changes in blood temperature?
What type of receptors in the hypothalamus detects changes in blood temperature?
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Which layer of hair is the outermost layer that consists of overlapping cells?
Which layer of hair is the outermost layer that consists of overlapping cells?
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Which of the following is NOT a function of the skin?
Which of the following is NOT a function of the skin?
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What happens to muscles at hair follicles when body temperature rises?
What happens to muscles at hair follicles when body temperature rises?
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Which of the following substances is mainly excreted through sweating?
Which of the following substances is mainly excreted through sweating?
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What is a primary component of hair structure that makes it hard?
What is a primary component of hair structure that makes it hard?
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Vasoconstriction is primarily triggered by which condition?
Vasoconstriction is primarily triggered by which condition?
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What is the primary function of sebaceous glands in the skin?
What is the primary function of sebaceous glands in the skin?
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Which structure in the skin is responsible for sensing vibratory pressure and touch?
Which structure in the skin is responsible for sensing vibratory pressure and touch?
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What is NOT a characteristic of the skin?
What is NOT a characteristic of the skin?
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Which layer of the integumentary system lies directly below the dermis?
Which layer of the integumentary system lies directly below the dermis?
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How much of the total body weight does the skin approximately represent?
How much of the total body weight does the skin approximately represent?
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What role does the integumentary system play in homeostasis?
What role does the integumentary system play in homeostasis?
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What causes goosebumps in humans?
What causes goosebumps in humans?
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Which aspect of skin function is primarily associated with protection against pathogens and injury?
Which aspect of skin function is primarily associated with protection against pathogens and injury?
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Study Notes
Integumentary System
- Skin is the integument
- Skin and its appendages make up the integumentary system
- Two distinct regions: epidermis and dermis
- A fatty layer (hypodermis) lies beneath the dermis
Integumentary System Function
- The integumentary system is the body's outer layer, including skin, hair, nails, and glands
- These organs and structures are the body's first line of defense against bacteria and help protect the body from injury and sunlight
- The integumentary system works with other systems in the body to maintain balance
Skin as an Organ
- The skin is the largest organ in the body
- Its surface area can reach up to 2.2 square meters
- It makes up approximately 7% of the total body weight (assuming a body weight of 65 kg)
- It is waterproof, stretchable, washable, and repairs minor damage like cuts, rips, and burns
- It is sensitive to stimuli
Layers of the Skin
- Epidermis: the outermost layer of the skin, composed of four layers of cells. The main cell type is the keratinocyte that produces keratin, a fibrous protein that aids in protection. Millions of dead keratinocytes are regularly shed. It lacks blood vessels.
- Dermis: the middle layer, composed of collagen and elastin. It contains nerve endings, hair follicles, and glands.
- Hypodermis/Subdermis: lies under the dermis, primarily composed of connective tissue and fatty tissue (adipose tissue). It functions for insulation, energy storage, and cushioning, protecting against trauma.
Skin Structure and Function
- Pacinian corpuscles: specialized nerve endings in the subcutaneous tissue that detect vibratory pressure and touch.
- Free nerve endings are unspecialized nerve endings that detect pain.
- Sebaceous glands: microscopic exocrine glands that secrete sebum, oily or waxy material to lubricate and waterproof skin and hair.
- Meissner's corpuscles: mechanoreceptors that are a type of nerve ending in the skin and are sensitive to light touch.
Skin Color
- Skin color is determined by the presence of melanin (skin pigment), vascularity of the dermis (blood flow), and the number of red blood cells. Increased blood flow results in a reddened complexion; decreased blood flow leads to pale or blue/purple complexion.
Functions of the Integumentary System
- Protection: from external factors like bacteria, chemicals, and temperature.
- Waterproof: fatty secretions from sebaceous glands help prevent fluid loss
- Temperature regulation: The hypothalamus acts as the body’s thermostat. It receives signals from thermoreceptors in the skin related to temperature and activates regulating mechanisms like blood flow, sweating, and shivering. Central thermoreceptors in the hypothalamus detect changes in body temperature.
- Waste excretion: The skin eliminates metabolic wastes (urea, lactic acid, salts and water) through sweat.
- Vitamin D synthesis: involves UVB radiation penetrating the epidermal layers of the skin to produce vitamin D.
- Sensation: Detects touch, pressure, pain, and temperature through nerve endings
Hair
- Functions: warmth (less in humans than other mammals), sense light touch of the skin, and protection (scalp).
- Parts: Embedded root in skin and shaft projecting above skin surface.
- Structure: composed of hard keratin. Three concentric layers: medulla (core), cortex (surrounds medulla), and cuticle (single layers that overlap)
Diseases and Injuries
- Possible diseases and injuries include but are not limited to: rash, blisters, athlete's foot (fungal infection), infection, sunburn, skin cancer, albinism, acne, herpes, cold sores, plantar warts.
Maintaining Body Temperature
- Heat retained: When cool, arrector pili muscles contract pulling hair upright and creating a layer of insulating air around the hair.
- Cooling down: When hot, arrector pili muscles relax to flatten the hair and allow air circulation to cool the skin.
- Sweating: evaporation of sweat cools the skin.
- Vasodilation: blood vessels dilate to allow more blood to flow near the skin to dissipate heat.
- Vasoconstriction: blood vessels constrict to keep blood flow away from the skin to decrease heat loss.
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Description
Explore the intricacies of the integumentary system, which includes the skin and its appendages. Learn about the structure, function, and importance of the skin as the body's largest organ and first line of defense against external threats.
