Skin Histology (MCQS)

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Questions and Answers

What is unique to each individual, even in identical twins?

Toe prints

Hand shape

Foot shape

Fingerprints (correct)

Which layer of the epidermis contains keratohyaline granules?

Stratum basale

Stratum corneum

Stratum lucidum

Stratum granulosum (correct)

What is the function of melanocytes in the skin?

To synthesize melanin (correct)

To regulate skin temperature

To protect the skin from UV radiation

To produce keratin

In which stage of melanosome development is melanin synthesis initiated?

Stage II Signup and view all the answers

What is the location of melanocytes in the skin?

Epidermis Signup and view all the answers

Which of the following is NOT a layer of the epidermis?

Stratum papillare Signup and view all the answers

What is the function of tyrosinase in melanin synthesis?

To catalyze melanin synthesis Signup and view all the answers

What is the size range of mature melanin granules?

0.5-1 μm Signup and view all the answers

What is the function of the Golgi apparatus in melanin synthesis?

To process and modify tyrosinase Signup and view all the answers

Which layer of the skin is composed of stratified squamous epithelial cells?

Epidermis Signup and view all the answers

Which type of cells play a crucial role in mediating immune response by binding, processing, and presenting antigens to T lymphocytes?

Langerhans cells Signup and view all the answers

What is the primary function of the dermal papillae in the skin?

To provide mechanical support to the skin Signup and view all the answers

What is the primary component of the skin's hypodermis?

Fatty tissue Signup and view all the answers

What is the term for the pattern of accumulation of fatty tissue in the skin?

Sex-dependent pattern Signup and view all the answers

What is the name of the layer of the hair root sheath that is composed of granular cells?

Huxley's layer Signup and view all the answers

What is the term for the phase of hair development characterized by active growth and mitotic activity?

Anagen Signup and view all the answers

What is the function of the sebaceous glands in the skin?

To produce sebum Signup and view all the answers

What is the term for the lines of tension in the skin formed by collagen and elastic fibers?

Langer's lines Signup and view all the answers

What is the term for the phase of hair development characterized by apoptosis and involution?

Catagen Signup and view all the answers

What is the name of the receptor responsible for detecting light touch and vibration in the skin?

Pacinian corpuscules Signup and view all the answers

What is the primary function of eccrine glands?

To produce true sweat Signup and view all the answers

What is the difference between apocrine and eccrine glands in terms of their ducts?

Apocrine glands have ducts that open into hair follicles, while eccrine glands have ducts that open into pores Signup and view all the answers

What is the characteristic of the telogen phase of the hair follicle?

A period of hair shedding Signup and view all the answers

What is the type of epithelium found in the stratatum germinativum?

Simple cuboidal epithelium Signup and view all the answers

What is the function of myoepithelial cells in the mammary gland?

To contract and expel milk Signup and view all the answers

What is the characteristic of the merocrine way of sweat gland secretion?

Both apocrine and eccrine glands release their products through merocrine secretion Signup and view all the answers

What is the difference between ceruminous glands and mammary glands?

Ceruminous glands secrete earwax, while mammary glands secrete milk Signup and view all the answers

What is the characteristic of the polygonal cells in the hair follicle?

They are polygonal in shape Signup and view all the answers

What is the difference between inactive and lactating mammary glands?

Inactive glands are smaller, while lactating glands are larger Signup and view all the answers

Study Notes

Dermatoglyphics (Fingerprints)

Certain areas of the human skin show ridges and grooves, arranged in distinctive patterns, which are unique for each individual (even differing in identical twins)

Skin Layers

The epidermis consists of:
- Stratum corneum
- Stratum lucidum
- Stratum granulosum
- Stratum spinosum
- Stratum basale
The dermis consists of:
- Papillary layer
- Reticular layer

Epidermal Cells

Produce keratin, the major structural protein of the epidermis
Melanocytes:
- Derived from neural crest
- Round cells with cytoplasmic (dendritic) projections scattered among the basal cells of the stratum basale
- Synthesize tyrosinase in rough ER, processed through the Golgi apparatus, and accumulate in vesicles (stage I melanosomes)
- Melanin synthesis begins in ovoid stage II melanosomes, and accumulates in stage III
- Mature melanin granules (stage IV) have lost tyrosinase and other activities and have an internal matrix completely filled with melanin
Langerhans cells:
- Bind, process, and present antigens to T lymphocytes, mediating immune response

Skin Types

Thick skin (e.g. palms, soles)
Thin skin (e.g. limbs, torso)

Dermal Papillae

Formed by collagen (type I) and elastic fibers regularly oriented, forming lines of tension in the skin (Langer's lines)

Skin Receptors

Pacinian corpuscles
Meissner's corpuscles
Merkel cells
Ruffini's corpuscules

Hypodermis

Also called "superficial fascia"
Fatty tissue which stores fat and anchors skin (areolar tissue and adipose cells)
Different patterns of accumulation (male/female)

Hair

Pilosebaceous unit
Hair follicles and hairs
Phases of hair development:
- Anagen (active phase)
- Catagen (apoptosis-driven involution)
- Telogen (resting phase)

Sebaceous Glands

Associated with hair follicles
Produce sebum, an oily substance that lubricates hair and skin

Sweat Glands

Types:
- Eccrine (merocrine)
- Apocrine
- Modified apocrine (e.g. ceruminous, mammary)
Eccrine glands:
- Most numerous
- True sweat: 99% water, some salts, traces of waste
- Open through pores
Apocrine glands:
- Confined to axillary, anal, and genital areas
- Ducts open into hair follicles
- Organic molecules in it decompose with time, causing odor

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Description

This quiz covers the structure and composition of human skin, including the unique patterns of ridges and grooves, and the different layers of the skin.