Histology of Skin and Appendages

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Questions and Answers

What is the main function of tonofilaments in the Stratum Spinosum?

To produce keratinocytes

To regulate skin pigmentation

To form a barrier to pathogens

To connect to desmosomes at the plasma membrane (correct)

Which characteristic is associated with the Stratum Granulosum?

Forms the outermost protective layer of the skin

Consists of maturing cells with keratohyaline granules (correct)

Contains melanocytes that produce melanin

Is the deepest layer of the epidermis

What is indicated by the absence or diminished granular layer in the skin?

Normal aging process

Enhanced melanin production

Increased skin elasticity

Ichthyosis Vulgaris, or fish skin (correct)

What type of granules are accumulated in the cells of the Stratum Granulosum?

Basophilic keratohyaline granules Signup and view all the answers

What protein is found in the membrane surrounding the granular cells of the Stratum Granulosum?

Filaggrin Signup and view all the answers

What characterizes terminal hairs compared to other types of hair?

They are coarse, thick, and usually dark in color. Signup and view all the answers

Which of the following statements is true regarding vellus hair?

Vellus hair is fine, light-colored, and has a narrow hair shaft. Signup and view all the answers

What is the primary type of hair found on the body of a fetus or newborn?

Lanugo Signup and view all the answers

In terms of structure, which statement correctly describes the hair shaft of vellus hair?

It is fine and rooted in the papillary dermis. Signup and view all the answers

Which part of the hair is mainly surrounded by the cuticle?

The cortex and medulla Signup and view all the answers

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

They are flattened, dead cells filled with soft keratin. Signup and view all the answers

In the context of psoriasis vulgaris, what happens to keratinocyte production and differentiation?

They occur at an accelerated rate. Signup and view all the answers

What process describes the continuous replacement of cornified cells in the stratum corneum?

Desquamation Signup and view all the answers

What underlying condition contributes to the thick silver scales observed in psoriasis?

Accelerated keratinocyte production and differentiation. Signup and view all the answers

What leads to the development of nonmelanoma skin cancers like squamous cell carcinoma?

Atypical keratinocytes in the epidermis. Signup and view all the answers

What type of cells primarily compose the structure of the stratum corneum?

Anucleate corneocytes Signup and view all the answers

Which of the following statements about the stratum corneum is incorrect?

It contains active nuclei in its cells. Signup and view all the answers

What main component do the flattened, dead cells in the stratum corneum primarily contain?

Soft keratin filaments Signup and view all the answers

What is the primary purpose of the inner layers of the hair follicle?

To undergo keratinization and form the hair shaft Signup and view all the answers

Which of the following best describes the growth rate of normal hair?

0.37 mm/day Signup and view all the answers

What structure primarily surrounds the hair follicle?

External and internal root sheaths Signup and view all the answers

How many epithelial layers are formed as hair follicles grow?

5 layers Signup and view all the answers

Which of the following is NOT a component of the hair follicle structure?

Sebaceous gland duct Signup and view all the answers

Which statement accurately reflects the anatomical structure of the hair follicle?

It is an invagination of the epidermis into the dermis. Signup and view all the answers

What defines the tubular structure of a hair follicle?

Formation from perifollicular connective tissue and epithelium Signup and view all the answers

Which layers of the hair follicles undergo keratinization?

The inner three layers Signup and view all the answers

What characterizes the structure of apocrine glands compared to eccrine glands?

Apocrine glands have a wider lumen and more myoepithelial cells. Signup and view all the answers

Which part of the nail is responsible for nail growth and distal movement?

Nail matrix Signup and view all the answers

What is a primary characteristic of hyperhidrosis?

It refers to excessive sweating due to eccrine glands. Signup and view all the answers

Which structure is covered by the proximal nail fold?

Nail root Signup and view all the answers

Bromhidrosis is primarily associated with which aspect of apocrine gland function?

Production of an offensive odor due to bacterial interaction. Signup and view all the answers

Which of the following is NOT a feature of eccrine glands?

They produce a thick, viscous secretion. Signup and view all the answers

What is the role of myoepithelial cells in relation to apocrine glands?

To facilitate secretion. Signup and view all the answers

Which of the following correctly distinguishes the nail matrix from the nail bed?

The nail matrix is responsible for nail growth. Signup and view all the answers

Study Notes

Histology of the Skin and Appendages

Intermediate Filaments: Tonofilaments or keratin filaments connect to desmosomes at the plasma membrane in the Stratum Spinosum.

Stratum Granulosum (Granular Cell Layer)

Comprises 3-5 layers of flattened cells that contain dense basophilic keratohyaline granules.
Filaggrin protein forms the membrane surrounding these keratinocyte layers.
Secretory granules are present and are not membrane-bound.
Clinical Correlation: Absence or decrease in the granules leads to Ichthyosis Vulgaris, characterized by hard, rigid skin.

Stratum Corneum (Cornified Layer)

The outermost layer of the skin, consisting of anucleate, flattened cells filled with soft keratin.
Cells in this layer continuously shed (desquamation) and are replaced from the deeper Stratum Basale.
Clinical Correlation: In Psoriasis vulgaris, accelerated production and differentiation of keratinocytes occur, resulting in thickened skin layers and increased keratinization, visible as silver scales. Atypical keratinocytes can lead to nonmelanoma skin cancers like squamous cell carcinoma.

Melanocytes

Specialized pigment-producing cells located in the epidermis.

Anatomy of Hair Follicle

Comprised of five epithelial layers; the inner three layers undergo keratinization to form hair shafts, while the outer two layers create internal and external root sheaths.
Normal hair growth averages 37 mm/day or about 1 cm/month.
Hair follicles consist of a tubular structure formed by perifollicular connective tissue and epidermal invagination, surrounded by external and internal root sheaths.

Types of Hair

Lanugo: Fetal or newborn hair, fine and present on the fetus/body.
Vellus Hair: Fine, light-colored hair; narrow hair shaft with thin inner root sheath located in the upper dermis.
Terminal Hair: Coarse, thick, and dark hair that extends into the dermis and sometimes into the subcutis.

Sweat Glands

Eccrine Glands: Coiled and tubular glands responsible for thermoregulation through sweating.
Apocrine Glands: Less coiled, wider lumen, and more myoepithelial cells; they open into hair follicles and are associated with body odor.

Nail Structure

Nail Bed: The region under the nail plate.
Hyponychium: The area underneath the distal part of the nail.
Nail Root: The proximal part of the nail, covered by the proximal nail fold, extends into the epidermis.
Nail Matrix: Responsible for nail growth and forward movement through epithelial proliferation and differentiation.

Clinical Correlations

Hyperhidrosis: Excessive sweating associated with eccrine glands.
Bromhidrosis: Offensive odor stemming from apocrine gland secretions and associated bacterial activity.

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Description

This quiz covers the histological structure of the skin, focusing on intermediate filaments and their connection to desmosomes. You'll explore the role of tonofilaments, keratin, and their functions within skin appendages. Test your knowledge on the intricate details of skin histology!