Questions and Answers
Where are sebaceous glands not present?
What type of secretion do sebaceous glands produce?
What is the function of myoepithelial cells in eccrine sweat glands?
Where are apocrine sweat glands located?
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What is the characteristic of apocrine secretion?
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When do sebaceous glands become functional?
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Which of the following statements accurately differentiates thick skin from thin skin?
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What primary function do melanin granules serve in the skin?
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What role do Merkel cells play in the skin?
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Which type of cell acts as a macrophage within the epidermis?
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Where are mechanoreceptors located in relation to the skin layers?
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What characterizes thick skin compared to thin skin regarding keratin layers?
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Which of the following statements regarding melanocytes and skin color is true?
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What is the primary function of mechanoreceptors in the skin?
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Which mechanoreceptor is primarily sensitive to light touch?
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Which type of mechanoreceptor is characterized as slow-adapting and found deep in the skin?
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Where are Merkel’s disks primarily located?
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Which mechanoreceptor is sensitive to vibration and pressure?
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What is the primary function of Ruffini corpuscles?
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Which component of the pilosebaceous apparatus causes the erection of the hair shaft?
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What is the primary role of the dermal papilla in the hair follicle?
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What type of epithelial tissue forms the hair follicle?
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Study Notes
Integumentary System 2
Thick vs. Thin Skin
- Thick skin is present on palms and soles, with five cell layers and a thick keratin layer, but no hair follicles and sebaceous glands
- Thin skin is found everywhere else, with no stratum lucidum, and thinner stratum granulosum and corneum, and may contain hair follicles and sebaceous glands
Melanin and Skin Color
- The number of melanocytes per unit area varies from one part of the body to another, but is independent of race
- Differences in skin color are due to differing numbers of melanin granules in melanocytes
- Melanin granules accumulate above keratinocyte nuclei to protect genetic material from UV damage
Langerhans Cells and Merkel Cells
- Langerhans cells are a type of macrophage that arise in bone marrow, migrate to stratum spinosum, and eat foreign substances and present antigen to T cells
- Merkel cells are present in stratum basale and function as touch receptors
Mechanoreceptors
- Mechanoreceptors are a type of somatosensory receptors that relay extracellular stimulus to intracellular signal transduction through mechanically gated ion channels
- They are present in the superficial and deeper layers of skin and near bone
- There are four major categories of tactile mechanoreceptors:
- Meissner's corpuscles (sensitive to light touch)
- Pacinian corpuscles (sensitive to vibration and pressure)
- Merkel's disks (un-encapsulated nerve endings in the epidermis)
- Ruffini endings (slow-adapting, encapsulated mechanoreceptors deep in the skin, ligaments, and tendons)
Pilo-Sebaceous Apparatus
- Hairs: hair follicle and shaft
- Sebaceous glands and ducts: empty into hair follicle
- Arrector pili muscles: cause erection of hair shaft
- Hairs and sebaceous glands derive from ectoderm
Hair Follicle
- The hair follicle is a tubular invagination of the epidermis extending deep into the dermis
- The hair shaft arises from the base of the follicle
- The dermal papilla contains numerous capillaries and maintains the viability of the hair follicle
Skin Glands
- There are three types: sebaceous glands, eccrine (merocrine) sweat glands, and apocrine sweat glands
- They arise from ectoderm and have secretory portions that reside in the dermis
- There are three different types of secretion: holocrine, merocrine, and apocrine
Sebaceous Glands
- Present everywhere except palms and soles
- Secretory portion: peripheral, flattened undifferentiated cells that burst and release sebum (holocrine secretion)
- Duct empties into hair follicle
- Become functional at puberty
Eccrine (Merocrine) Sweat Glands
- Secretory portion has three cell types: clear cells, darker cells, and myoepithelial cells
- Duct is lined by simple cuboidal epithelium and opens onto skin surface
- Secretory cells produce a watery substance and a proteinaceous substance
Apocrine Sweat Glands
- Located only in axilla, areola of breast, and anal canal
- Have larger ducts and secretory units than eccrine sweat glands
- Ducts open into hair follicles
- Apocrine secretion is viscous and contains proteins, carbohydrates, and lipids
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Description
This quiz covers the histology of the integumentary system, including the epidermis, thick and thin skin, mechanoreceptors, and skin glands. It is based on Lecture 10 from Anthony L. Mescher's Basic Histology TEXT & ATLAS.
