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Questions and Answers
What is the primary function of the subcutaneous layer?
What is the primary function of the subcutaneous layer?
In which area are apocrine sweat glands primarily located?
In which area are apocrine sweat glands primarily located?
Which type of tissue is predominantly found in the subcutaneous layer?
Which type of tissue is predominantly found in the subcutaneous layer?
How does sweat loss differ during prolonged heavy exercise compared to normal temperatures?
How does sweat loss differ during prolonged heavy exercise compared to normal temperatures?
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What are the two main types of sweat glands found in the skin?
What are the two main types of sweat glands found in the skin?
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What is the primary function of melanocytes in the skin?
What is the primary function of melanocytes in the skin?
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How many layers of epidermis are found in thick skin?
How many layers of epidermis are found in thick skin?
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Which type of cells continuously form in the basal cell layer of the epidermis?
Which type of cells continuously form in the basal cell layer of the epidermis?
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What is the main characteristic of the stratum corneum?
What is the main characteristic of the stratum corneum?
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What distinguishes thin skin from thick skin?
What distinguishes thin skin from thick skin?
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What role does the epidermis play in protecting the body?
What role does the epidermis play in protecting the body?
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Which layer of the epidermis is only found in thick skin?
Which layer of the epidermis is only found in thick skin?
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What is the primary composition of the stratum granulosum?
What is the primary composition of the stratum granulosum?
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What is the primary mechanism for heat loss that involves direct transfer through physical contact?
What is the primary mechanism for heat loss that involves direct transfer through physical contact?
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Which heat loss mechanism is responsible for the evaporation of sweat?
Which heat loss mechanism is responsible for the evaporation of sweat?
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What happens when the temperature at the pre-optic area rises above its set point?
What happens when the temperature at the pre-optic area rises above its set point?
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Which of the following contributes to roughly 15% of the body's heat loss indoors?
Which of the following contributes to roughly 15% of the body's heat loss indoors?
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What effect does vasodilation have on heat loss?
What effect does vasodilation have on heat loss?
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Which mechanism is NOT a method for heat loss described in the content?
Which mechanism is NOT a method for heat loss described in the content?
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What role do sensory thermoreceptors play in temperature regulation?
What role do sensory thermoreceptors play in temperature regulation?
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Which of the following is not a mechanism for heat loss mediated by hypothalamic reflexes?
Which of the following is not a mechanism for heat loss mediated by hypothalamic reflexes?
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What is the primary function of the heat-promoting center?
What is the primary function of the heat-promoting center?
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Which mechanism is NOT involved in heat gain?
Which mechanism is NOT involved in heat gain?
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What hormone released by the adrenal medulla increases glycogenolysis?
What hormone released by the adrenal medulla increases glycogenolysis?
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What occurs during the chill stage of fever?
What occurs during the chill stage of fever?
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Which process involves increased metabolism by the liver and BAT adipose breakdown?
Which process involves increased metabolism by the liver and BAT adipose breakdown?
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What triggers the resetting of the thermostat in the fever mechanism?
What triggers the resetting of the thermostat in the fever mechanism?
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Which of the following is a symptom of fever during the initial stages?
Which of the following is a symptom of fever during the initial stages?
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What usually stimulates the development of fever?
What usually stimulates the development of fever?
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What is the primary function of merocrine glands during thermoregulation?
What is the primary function of merocrine glands during thermoregulation?
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What pigment is responsible for giving skin its yellowish hue?
What pigment is responsible for giving skin its yellowish hue?
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What causes albinism in an individual?
What causes albinism in an individual?
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Which glands are responsible for producing ear wax?
Which glands are responsible for producing ear wax?
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What role do capillaries in the dermis play regarding skin color?
What role do capillaries in the dermis play regarding skin color?
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Which structure synthesizes Vitamin D3 upon UV exposure?
Which structure synthesizes Vitamin D3 upon UV exposure?
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What is the primary function of sebaceous glands?
What is the primary function of sebaceous glands?
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What condition is characterized by patchy absence of melanocyte activity?
What condition is characterized by patchy absence of melanocyte activity?
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Which of the following describes the function of arteriovenous shunts in the skin?
Which of the following describes the function of arteriovenous shunts in the skin?
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What vitamin deficiency is associated with abnormal bone development in children?
What vitamin deficiency is associated with abnormal bone development in children?
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Study Notes
Skin Structure
- Superficial fascia is a layer of connective tissue that connects the dermis to the hypodermis.
- Epidermis has three main types of cells: squamous cells, basal cells, and melanocytes.
- The basement membrane separates the epidermis from the deeper layers of the skin.
- Thick skin is found on the palms of the hands and soles of the feet.
- Thin skin is found on the rest of the body.
- The epidermis is a stratified squamous epithelium layer, composed of keratinocytes.
- It provides water resistance, protection from microorganisms and abrasion, and supports some sensory cells.
- The fingerprint is a pattern of epidermal ridges that increase the surface area for contact between the epidermis and dermis.
Layers of the Epidermis
- Stratum Corneum: outermost layer, composed of 15-30 rows of flat, dead cells filled with keratin. Continually shed and replaced.
- Stratum Lucidum: only found in thick skin, composed of flat, densely packed cells.
- Stratum Granulosum: 3-5 rows of flattened cells with degenerating nuclei.
Subcutaneous Layer (Hypodermis)
- Connects the skin to the underlying tissue.
- Primarily composed of adipose tissue, which serves as an energy store and insulation.
- Contains sensory nerve endings called Pacinian corpuscles, sensitive to pressure and vibration.
Subcutaneous Fat Deposition
- Important for insulation in babies.
- Hormone-dependent, especially during puberty.
- Distribution varies in location with different body shapes like pear or apple shape.
- Adipose tissue can be white or brown.
Exocrine Glands
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Sweat (Sudoriferous) Glands
- Apocrine: Simple branched tubular glands located in axilla, pubic region and areolae of breast. Secretion begins at puberty.
- Merocrine/eccrine: Coiled tubular glands widely distributed in the body. Secretion onto surface, important for cooling, excretion and protection.
- Sebaceous (oil) glands: Holocrine glands that discharge oily lipid secretion called sebum into hair follicles.
Other Integumentary Glands
- Ceruminous glands: Modified sudoriferous glands found in the auditory canal. Excretion onto surface or into sebaceous glands, contributing to ear wax (cerumen).
- Mammary glands: Anatomically related to apocrine glands, development and secretion are controlled by hormones.
Control of Gland Secretion
-
Nervous control:
- Sebaceous and Apocrine glands are turned on/off by the Autonomic Nervous System.
- Merocrine glands are selectively activated by the ANS for specific regions or for thermoregulation.
Skin Color
- Melanin: Produced by melanocytes, responsible for varying skin colors. Found in basale and spinosum layers. Complete absence of melanocyte activity results in albinism, while patchy absence results in vitiligo.
- Carotene: Orange-yellow pigment accumulating in epidermal cells and fatty areas, contributing to a yellowish hue. Also found in vegetables, essential for maintaining epithelia and photoreceptor pigments in the eyes.
- Capillaries: In Caucasian skin, redness is due to blood capillaries in the dermis.
The Epidermis and Vitamin D3
- Limited sunlight exposure is beneficial for Vitamin D3 production in the stratum spinosum and basale.
- UV light converts 7-dehydrocholesterol to cholecalciferol (Vit D3) in the skin.
- Calcitriol, the active form of Vitamin D3, is essential for calcium and phosphate absorption from the gastrointestinal tract.
- Vitamin D deficiency can lead to Rickets in children and Osteomalacia in adults.
Thermoregulation
- Maintained by a balance of heat production and heat loss.
- Sensory thermoreceptors in the skin, mucous membranes, and hypothalamus send information to the hypothalamus.
- The hypothalamus, specifically the preoptic area, regulates body temperature through heat-gain and heat-loss centers.
Heat Loss Center
- Activated when temperature at the pre-optic area rises above the set point.
- Mechanisms include: vasodilation, perspiration, decreased metabolic rate, increased respiration, and behavioral changes.
Heat Gain Center
- Activated when temperature at the pre-optic area drops below the set point.
- Mechanisms include: vasoconstriction, shivering, sympathetic release of adrenaline and noradrenaline, thyroxine release, and behavioral responses.
Thermogenesis
- Shivering Thermogenesis: Increases muscle tone to consume more energy, producing heat.
- Non-Shivering Thermogenesis: Increased metabolism in the liver and breakdown of brown adipose tissue.
Abnormal Body Temperature - Pyrexia (Fever)
- Usually caused by bacterial or viral infections, but also by other factors like heart attack, tumors, surgery, or trauma.
- Phagocytes release interleukin-1, which triggers prostaglandin production in the hypothalamus, resetting the thermostat to a higher temperature.
- Stages of fever: chill, crisis (body temperature falls).
Dermal Circulation and Innervation
- Blood in the skin serves two major functions: nutrition and heat loss.
- Cutaneous plexus: Network of capillaries between the subcutaneous layer and dermis, supplying adipocytes, hair follicles, and sweat glands.
- Papillary plexus: Branches off the cutaneous plexus, forming papillary loops.
Skin Vascularity
- Arteriovenous Shunts: Conserve heat by shunting blood between arteries and veins. Activated by the sympathetic division of the ANS.
- Sensible heat loss: Evaporation of sweat.
- Convection: Heat loss to cooler air that moves across the body surface.
- Conduction: Direct heat transfer through physical contact, less effective than other methods.
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Description
Test your knowledge on the structure and layers of the skin, including the features of the epidermis and its various cell types. This quiz covers key concepts such as thick and thin skin, as well as the layers of the epidermis from the stratum corneum to the stratum lucidum.