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Questions and Answers
What type of secretion do merocrine sweat glands utilize?
What is the primary component of sweat produced by merocrine sweat glands?
Where are apocrine sweat glands primarily located?
What is the primary function of myoepithelial cells in sweat glands?
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What distinguishes sebaceous glands from sweat glands?
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Which type of sweat gland secretion is incorrect when describing apocrine glands?
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Which glands are primarily responsible for temperature regulation through their secretions?
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Which of the following statements best describes the differences between merocrine and apocrine sweat glands?
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Which layer of the skin is primarily responsible for producing melanin?
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What is the main function of the hypodermis?
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Which layer of the epidermis is known as the clear layer and is only present in thick skin?
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What type of connective tissue primarily makes up the papillary layer of the dermis?
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Which cells in the epidermis are responsible for forming a protective barrier?
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What is the primary function of sebaceous glands in the skin?
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Which layer of skin contains hair follicles?
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What type of secretion is produced by holocrine glands like sebaceous glands?
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Which layer contains dead, keratinized cells that form the outermost barrier of the skin?
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What is the primary role of dermal papillae in the skin?
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Which of the following best describes keratinocytes over time?
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What type of glands are responsible for producing sweat?
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Which layer is known for its role in thermoregulation and sensation due to its vascularity?
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Study Notes
The Integumentary System
- The integumentary system includes the skin, which is also known as the cutaneous membrane, and its derivatives: hair, nails, and glands.
- The skin is composed of three layers:
- Epidermis: Outermost layer, providing a protective barrier.
- Dermis: Connective tissue supporting the epidermis, composed mostly of collagen and elastic fibers.
- Hypodermis: Holds the integument to underlying tissues and allows skin movement, containing subcutaneous fat.
Epidermis
- The epidermis is multi-layered epithelium with layers representing different stages of cell maturation.
- The layers of the epidermis from deepest to superficial are:
- Stratum basale: Stem cells that create new epidermal cells; single layer of cells.
- Stratum spinosum: Prickly layer, contains daughter cells from the stratum basale.
- Stratum granulosum: Granular layer containing granules that contribute to keratin formation and water resistance.
- Stratum lucidum: (Thick skin only) Clear layer, a subdivision of the stratum corneum.
- Stratum corneum: Outermost layer, cells lack a nucleus and organelles, cell membranes thicken, filled with keratin filaments. The deepest layer is coated with lipids for water resistance.
Melanocytes
- Melanocytes produce pigment (melanin) in the form of brown, yellow-brown, or black granules called melanosomes which are transferred to keratinocytes.
- Melanin protects DNA from UV radiation.
- Melanin degrades over time and needs to be replaced.
Dermis
- The dermis is connective tissue that supports the epidermis.
- Contains two layers:
- Papillary layer: Closest to the epidermis, loose connective tissue.
- Reticular layer: Closest to the hypodermis, dense irregular connective tissue.
Papillary Layer
- Contains dermal papillae that interlock with epidermal ridges, strengthening the attachment between the epidermis and dermis.
- Contains sensory nerve endings and capillaries.
- The epidermis is avascular, so nutrients and gases are exchanged in the papillary layer.
Reticular Layer
- A network of thick collagen and elastic fibers.
- Contains blood vessels, nerves, hair follicles, glands.
Hypodermis
- Connects the integument to the underlying tissue and allows for skin movement.
- Contains subcutaneous fat that:
- Provides insulation.
- Acts as an energy reservoir.
- Offers protection and padding.
Hair
- Found on most of the body:
- Except: Palms, soles, lips, and portions of the external genitalia.
- Non-living structure produced in hair follicles, surrounded by a connective tissue sheath.
Hair Production
- Hair growth starts at the hair bulb, the base of the hair follicle.
- The hair papilla is the connective tissue that contains blood vessels, supplying nutrients and signals for epithelial (hair) cell growth.
- Epithelial cells divide and push upward, becoming keratinized (hard and dead).
Hair Associations
- Arrector pili: Smooth muscle that causes "goose bumps."
- Root hair plexus: Sensory nerves that sense hair movement.
- Certain Glands: Sebaceous glands, and apocrine glands.
Glands in the Skin
- The skin contains exocrine glands, which have different modes of secretion.
- These are the three main types of glands associated with the skin:
-
Sebaceous glands: Usually associated with hair follicles.
- Holocrine glands releasing secretions as cells burst.
- Produce sebum, an oily secretion that lubricates hair and skin.
- Activity increases during puberty, resulting in oily skin/hair and acne.
-
Merocrine sweat glands: Secrete directly onto the skin surface.
- Use merocrine secretion, releasing secretions by exocytosis.
- Distributed across the body.
- Produce sweat, mostly made of water and electrolytes such as NaCl, metabolites, and waste.
- Important for temperature regulation.
-
Apocrine sweat glands: Merocrine secretion, not apocrine!
- Found in axilla, nipples, pubic, and anal regions.
- Secrete into hair follicles.
- Secretion attracts bacteria, causing body odor.
-
Sebaceous glands: Usually associated with hair follicles.
Key Terms
- Epidermis: Outermost layer of skin.
- Dermis: Connective tissue layer beneath the epidermis.
- Hypodermis: Layer beneath the dermis, containing subcutaneous fat.
- Sebaceous glands: Oil-producing glands associated with hair follicles.
- Merocrine glands: Sweat glands that release secretions by exocytosis.
- Apocrine glands: Sweat glands found in specific areas of the body, secreting into hair follicles.
Key Points
- Epidermal layers: Understand the characteristics and function of each layer (stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum).
- Dermis: Compare and contrast structure and function of papillary and reticular layers.
- Hair structure: Describe the structure of hair and its development from the hair bulb.
- Skin glands: Explain the different types of glands found in the skin (sebaceous, merocrine, and apocrine), and compare and contrast their structure, secretion, and function.
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Description
This quiz covers the integumentary system, focusing on the structure and functions of the skin and its layers: epidermis, dermis, and hypodermis. You will learn about the characteristics of each layer and their roles in protecting the body and maintaining health.
