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Questions and Answers
Which of the following is NOT a function of the skin?
Which of the following is NOT a function of the skin?
What is the main role of the epidermis in the skin structure?
What is the main role of the epidermis in the skin structure?
How does the skin help in heat regulation?
How does the skin help in heat regulation?
Which layer of the skin is referred to as the 'true skin'?
Which layer of the skin is referred to as the 'true skin'?
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Which of the following statements about melanin is true?
Which of the following statements about melanin is true?
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What primarily differentiates the hypodermis from the other layers of skin?
What primarily differentiates the hypodermis from the other layers of skin?
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In which layer of the skin are sebaceous glands located?
In which layer of the skin are sebaceous glands located?
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Which of the following is a part of the skin's protective functions?
Which of the following is a part of the skin's protective functions?
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What role do fibroblasts play in the skin's structure?
What role do fibroblasts play in the skin's structure?
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What is the main function of collagen in the skin?
What is the main function of collagen in the skin?
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As we age, what happens to the production of collagen and elastin?
As we age, what happens to the production of collagen and elastin?
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What substance do mast cells release in response to tissue damage?
What substance do mast cells release in response to tissue damage?
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Which type of sweat gland is responsible for secreting a thicker fluid containing urea and fats?
Which type of sweat gland is responsible for secreting a thicker fluid containing urea and fats?
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What is primarily found in the subcutaneous layer of the skin?
What is primarily found in the subcutaneous layer of the skin?
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What is the role of the dermal papilla in the hair follicle?
What is the role of the dermal papilla in the hair follicle?
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What is the primary function of the stratum corneum?
What is the primary function of the stratum corneum?
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How do arrector pili muscles function when a person is cold?
How do arrector pili muscles function when a person is cold?
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Which layer of the epidermis is primarily responsible for the production of keratin?
Which layer of the epidermis is primarily responsible for the production of keratin?
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Which protein allows the skin to stretch, providing elasticity?
Which protein allows the skin to stretch, providing elasticity?
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What sensation is NOT detected by sensory nerve endings in the skin?
What sensation is NOT detected by sensory nerve endings in the skin?
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What effect does rapid weight loss have on facial appearance?
What effect does rapid weight loss have on facial appearance?
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In which layer are melanocytes primarily found?
In which layer are melanocytes primarily found?
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What is the role of phagocytes in the skin?
What is the role of phagocytes in the skin?
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Which of the following statements about sweat glands is true?
Which of the following statements about sweat glands is true?
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What is the thickness of the prickle cell layer?
What is the thickness of the prickle cell layer?
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What type of cells make up about 90% of the epidermis?
What type of cells make up about 90% of the epidermis?
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What is the primary function of blood capillaries in the skin?
What is the primary function of blood capillaries in the skin?
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What is the main characteristic of the stratum lucidium layer?
What is the main characteristic of the stratum lucidium layer?
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Where are eccrine glands primarily found?
Where are eccrine glands primarily found?
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Which function is NOT performed by blood vessels in the skin?
Which function is NOT performed by blood vessels in the skin?
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Which layer of the dermis is composed of loose connective tissue?
Which layer of the dermis is composed of loose connective tissue?
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What is the role of Langerhans cells in the epidermis?
What is the role of Langerhans cells in the epidermis?
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Study Notes
Skin Functions and Structure
- The skin has seven main functions: sensation, heat regulation, absorption, protection, excretion, secretion, and vitamin D production.
- Sensation: The skin acts as a sensory organ, detecting changes like heat, cold, touch, pressure, and pain.
- Heat regulation: The skin regulates body temperature (37°C) through dilation (widening) and constriction (narrowing) of blood vessels, and sweat evaporation. Subcutaneous fat also insulates the body.
- Absorption: The skin has limited absorption properties, absorbing small particles like hormones, nicotine, and ingredients in lotions.
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Protection: The skin acts as a waterproof barrier against dirt, bacteria, and chemical attack.
- The acid mantle (pH 5.5) discourages bacteria and fungi growth.
- The epidermis' horny layer filters bacteria.
- Melanin protects against UV damage.
- Excretion: Waste products (lactic acid, urea, salts) are eliminated through perspiration, though this is a minor function.
- Secretion: Sebaceous glands secrete sebum.
- Vitamin D production: Sunlight triggers a chemical reaction in the skin, leading to vitamin D production.
Layers of the Skin
- The skin has three main layers: epidermis, dermis, and subcutaneous layer/hypodermis.
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Epidermis: The outermost layer, visible part, doesn't have a direct blood supply. It is made up of five layers.
- Stratum corneum (horny layer): Outermost, dead, scaly cells.
- Stratum lucidum (clear layer): Only in thick skin (palms, soles). Small, transparent cells.
- Stratum granulosum (granular layer): Keratin production; cells become flatter and die.
- Stratum spinosum (prickle cell layer): Cells are dividing constantly, interconnected.
- Stratum germinativum (basal layer): Single layer of actively dividing cells; contains melanin (pigment).
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Dermis: True skin, thickest layer. Made up of two layers: papillary and reticular.
- Papillary layer: Loose connective tissue with blood vessels and nerve endings supplying the epidermis and waste removal.
- Reticular layer: Dense connective tissue; collagen and elastin providing strength and elasticity; connects to subcutaneous layer.
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Cells of the dermis: Fibroblasts, mast cells, and phagocytes.
- Fibroblasts: Produce collagen and elastin for skin strength and elasticity; involved in tissue repair.
- Mast cells: Release histamine in response to injury or infection, causing blood vessels to dilate to facilitate healing.
- Phagocytes: White blood cells engulfing pathogens and debris.
- Subcutaneous layer/Hypodermis: Located under the dermis, primarily composed of fat cells (adipose tissue). Provides insulation, protection, and contour to the body.
Appendages
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Sweat glands: Produce sweat for thermoregulation; two types:
- Eccrine glands: Found all over the body, produce watery sweat.
- Apocrine glands: Found in specific areas (armpits, groin), become active during puberty, produce thicker sweat, and may cause body odor.
- Hair follicle: Indentation of the epidermis housing the hair.
- Hair shaft: Visible part of the hair.
- Dermal papilla: Blood supply for hair growth.
- Sebaceous glands: Produce sebum (oil) throughout the body (excluding palms and soles) to prevent drying and infection.
- Arrector pili muscle: Attached to hair follicles; contracts to cause goosebumps.
- Sensory nerve endings: Detect environmental changes like heat, cold, touch, pressure, and pain.
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Description
Explore the seven essential functions of the skin, including its role in sensation, heat regulation, absorption, protection, excretion, secretion, and vitamin D production. Understand how the skin acts as a barrier and its significance in maintaining body temperature and health.
