Histology 232ANAT: The Integumentary System
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Questions and Answers

What is the primary type of cell found in the stratum corneum of thick skin?

  • Langerhans cells
  • Keratinocytes (correct)
  • Melanocytes
  • Merkel's cells

Which layer of the epidermis is characterized by intense mitotic activity?

  • Stratum Basale (correct)
  • Stratum Corneum
  • Stratum Granulosum
  • Stratum Lucidum

What distinguishes thick skin from thin (hairy) skin?

  • Thickness of the epidermis (correct)
  • Types of skin receptors
  • Presence of blood vessels
  • Type of connective tissue

Which cell type is primarily responsible for melanin production in the epidermis?

<p>Melanocytes (B)</p> Signup and view all the answers

What is the main function of Langerhans cells in the epidermis?

<p>Antigen presentation (A)</p> Signup and view all the answers

What is the consequence of albinism in terms of melanocyte function?

<p>Disruption in tyrosinase activity (D)</p> Signup and view all the answers

In psoriasis, what is observed in relation to skin cell proliferation?

<p>Increase in proliferating cells in basal layers (B)</p> Signup and view all the answers

Which epidermal layer is characterized by keratohyalin granules?

<p>Stratum Granulosum (C)</p> Signup and view all the answers

What are Langerhans cells primarily responsible for?

<p>Binding and presenting antigens to T lymphocytes (C)</p> Signup and view all the answers

Which layer of the dermis is formed of areolar connective tissue and contains Meissner's corpuscles?

<p>Papillary layer (B)</p> Signup and view all the answers

What causes the skin to become more fragile and develop wrinkles in old age?

<p>Extensive cross-linking of collagen fibers and loss of elastic fibers (A)</p> Signup and view all the answers

What type of sweat is secreted by apocrine sweat glands?

<p>Unpleasant viscous sweat (B)</p> Signup and view all the answers

Which type of hair is present in infants and is characterized by its fine, soft texture?

<p>Vellus hair (D)</p> Signup and view all the answers

What structural component surrounds the root of each hair?

<p>Hair follicle (D)</p> Signup and view all the answers

Which type of sweat gland is NOT present on the glans penis and nail beds?

<p>Merocrine glands (B)</p> Signup and view all the answers

What is the primary function of Merkel's cells in the skin?

<p>Sensation of touch (A)</p> Signup and view all the answers

What leads to the patchy loss of pigment in vitiligo?

<p>Degeneration and disappearance of melanocytes (B)</p> Signup and view all the answers

Which characteristic is NOT associated with the reticular layer of the dermis?

<p>Presence of Meissner’s corpuscles (C)</p> Signup and view all the answers

What types of cells do merocrine sweat glands secrete?

<p>Watery sweat (B)</p> Signup and view all the answers

Which cells are responsible for mechanoreception in the skin?

<p>Merkel's cells (A)</p> Signup and view all the answers

What contributes to the development of wrinkles in aging skin?

<p>Reduction of elastic fibers due to solar elastosis (A)</p> Signup and view all the answers

Which characteristic defines apocrine sweat glands and their secretions?

<p>Present in specific areas and secrete viscous sweat after puberty (C)</p> Signup and view all the answers

What type of hair is characterized as soft and fine in infants?

<p>Vellus hair (D)</p> Signup and view all the answers

What structure is involved in the obstruction leading to acne development?

<p>Sebaceous glands (C)</p> Signup and view all the answers

What is the main structural difference between the stratum granulosum and the stratum lucidum?

<p>Stratum granulosum is composed of flattened polygonal cells with keratohyalin granules, while stratum lucidum contains homogenous clear cells. (C)</p> Signup and view all the answers

Which factor contributes to the increase in skin cell proliferation specifically observed in psoriasis?

<p>Increased cycle time of cells in the stratum basale and stratum spinosum. (D)</p> Signup and view all the answers

What is primarily responsible for the synthesis of melanin in melanocytes?

<p>Tyrosinase enzyme activity. (B)</p> Signup and view all the answers

In the structure of the thick skin, how are keratinocytes organized?

<p>Layered into five distinct strata with varying cell shapes. (D)</p> Signup and view all the answers

What characterizes the cells of the stratum corneum in thick skin?

<p>They are flattened, non-nucleated cells filled with soft keratin. (D)</p> Signup and view all the answers

What is the primary role of Merkel's cells in the epidermis?

<p>To act as sensory receptors. (B)</p> Signup and view all the answers

What defines thin (hairy) skin as compared to thick skin?

<p>Thin skin has a thinner epidermis and lacks a stratum lucidum. (B)</p> Signup and view all the answers

Which statement is true regarding melanophores compared to melanocytes?

<p>Melanophores obtain melanin by phagocytosis, while melanocytes synthesize it. (D)</p> Signup and view all the answers

Flashcards

Epidermis structure

The superficial, avascular layer of skin, composed of stratified squamous keratinized epithelium.

Keratinocytes function

Make up 85%of the epidermal cells, forming keratin, and are arranged in layers.

Melanocyte function

Melanin-producing cells found in the epidermis, crucial for skin pigment.

Stratum Basale

Deepest epidermal layer, with actively dividing cells.

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Stratum Corneum

Outermost epidermal layer, composed of flattened, dead cells filled with keratin.

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Thick skin location

Found on palms and soles, with five epidermal layers.

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Albinism cause

Hereditary condition preventing melanocytes from producing melanin, impacting skin pigmentation, due to a lack of tyrosinase activity.

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Melanophores characteristics

Melanin-containing cells that acquire melanin through phagocytosis but cannot produce it themselves. They lack tyrosinase.

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Vitiligo

A skin disorder causing patchy loss of pigment due to melanocyte degeneration.

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Langerhans Cells

Star-shaped antigen-presenting cells in the epidermis derived from bone marrow.

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Merkel's Cells

Mechanoreceptors in the skin that detect touch via nerve endings.

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Papillary Layer (Dermis)

Upper layer of the dermis containing touch receptors (Meissner's corpuscles) and capillaries.

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Reticular Layer (Dermis)

Lower layer of the dermis with dense connective tissue, collagen, and elastic fibers.

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Merocrine Sweat Glands

Throughout body (except certain areas), producing watery sweat.

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Apocrine Sweat Glands

Located in specific areas (e.g., armpits), secreting viscous sweat.

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Hair Structure

Composed of shaft (medulla, cortex, cuticle), root, and follicle (outer and inner sheaths).

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What causes Vitiligo?

Vitiligo is a skin disorder caused by the degeneration and disappearance of melanocytes, leading to patches of depigmentation.

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Papillary Layer

This layer of the dermis contains a network of blood capillaries and Meissner's corpuscles, which are responsible for touch sensation.

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Reticular Layer

This dense layer of the dermis contains collagen and elastic fibers, giving skin its strength and elasticity.

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What are the two main layers of skin?

The skin is composed of two layers: the epidermis and the dermis. The epidermis is the superficial avascular layer, made of stratified squamous keratinized epithelium. The dermis is the deeper layer composed of connective tissue.

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What is the difference between thick and thin skin?

Thick skin has all five layers of the epidermis and is found on palms and soles. Thin skin has only four layers and is found on the rest of the body.

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What are keratinocytes?

Keratinocytes are the most abundant cells in the epidermis, making up 85% of the epidermal cells. They are responsible for producing keratin, the protein that gives skin its strength and resilience.

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What do melanocytes do?

Melanocytes are melanin-producing cells found in the epidermis. They are responsible for giving skin its color and protecting it from UV radiation.

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What are Langerhans cells?

Langerhans cells are specialized immune cells found in the epidermis. They act as antigen-presenting cells, helping the immune system recognize and fight off foreign invaders.

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What are Merkel cells?

Merkel cells are sensory receptors found in the epidermis. They are responsible for detecting light touch and pressure.

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What is albinism?

Albinism is a genetic condition that prevents melanocytes from producing melanin. This results in a lack of pigmentation in the skin, hair, and eyes.

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What are melanophores?

Melanophores are cells that contain melanin but do not produce it. They acquire melanin by phagocytosis (engulfing) from other cells.

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Study Notes

Histology 232ANAT

  • Course name: Histology
  • Course code: 232ANAT
  • Institution: King Khalid University

The Integumentary System (Skin)

  • Skin is the largest organ, comprising 16% of total body weight.
  • It comprises skin and its appendages.
  • It consists of epidermis (superficial, avascular) and dermis (deep, connective tissue).
  • Epidermis is made of stratified squamous keratinized epithelium.
  • Dermis is composed of connective tissue.
  • Skin types are classified by thickness:
    • Thick skin (palms and soles)
    • Thin (hairy) skin (rest of the body)

Lecture Objectives

  • Describe the histological features of the epidermis and dermis.
  • Explain the differences between thick and thin skin.
  • Identify skin receptors.

Epidermal Cells (Thick Skin)

  • Keratinocytes (85%): form layers, keratin production

  • Melanocytes: melanin production

  • Langerhans cells: antigen-presenting cells (2-8%)

  • Merkel cells: sensory receptors

  • Keratinocytes are arranged in five layers:

    • Stratum basale (germinativum): single layer, high mitotic activity
    • Stratum spinosum (prickle cell layer): 4-8 polyhedral cells
    • Stratum granulosum (granular layer): 3-5 flattened cells, keratinohyalin granules
    • Stratum lucidum (clear layer): 1-5 rows of acidophilic dead cells, keratohyaline and eleidin granules
    • Stratum corneum (horny layer): 15-20 layers of flattened, acidophilic, non-nucleated cells, soft keratin

  • Psoriasis: increased proliferating cells in basal/prickle layers, decreased cycle time

Melanoctyes

  • Present between stratum basale cells.
  • Derived from neural crest cells.
  • Synthesize melanin using tyrosinase.
  • DOPA-positive
  • Melanophores do not synthesize melanin; they phagocytize it.
  • Albinism: hereditary inability to synthesize melanin (tyrosinase disorder).
  • Vitiligo: loss of pigment due to melanocyte degeneration.

Langerhans Cells

  • Star-shaped, present mainly in stratum spinosum.
  • Antigen-presenting cells.
  • Process antigens and present them to T lymphocytes.

Merkel Cells

  • Derived from bone marrow.
  • Expanded terminal discs at Merkel cell bases.
  • Mechanoreceptors.

Dermis (Layers)

  • Papillary layer: areolar connective tissue, rich in capillaries, Meissner's corpuscles.

  • Reticular layer: dense reticular connective tissue, collagen and elastic fibers, wrinkles due to sun exposure, solar elastosis, acne due to sebum blockage.

  • There are sweat glands, Pacinian corpuscles and Ruffini and Krause end bulbs.

Thin Skin (Hairy Skin)

  • Covers most of the body, excluding palms and soles.
  • Thinner epidermis (fewer layers).
  • Irregular dermal papillae.
  • Contains hairs, sebaceous and sweat glands (distributed differently than thick skin).
  • Sweat Glands: two types
    • Merocrine: all over body (except glans penis/nail beds), clear/dark cuboidal, watery sweat
    • Apocrine: axillae, pubic, perianal regions, clear/dark cuboidal, viscous sweat (starts after puberty).

Hairs

  • Two types (infantile/vellus and adult/terminal).
  • Shaft, root, hair follicle.
  • Shaft: medulla, cortex, cuticle
  • Follicle: inner/outer root sheaths, connective tissue sheath.
  • Hair follicles
  • Sebaceous glands: branched alveolar glands, secrete sebum.

Differences Between Thick and Thin Skin

  • Thickness of the epidermis
  • Presence of a stratum lucidum
  • Density of dermal papillae
  • Distribution and type of glands (merocrine and apocrine sweat glands)
  • Presence of hair follicles and sebaceous glands

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Description

This quiz covers the histological features of the integumentary system, focusing on the structure and composition of the skin, including the epidermis and dermis. Learn about the differences between thick and thin skin, as well as the various epidermal cells and their functions. Test your knowledge on skin receptors and their roles in the body.

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