29 Questions
What is unique to each individual, even in identical twins?
Fingerprints
Which layer of the epidermis contains keratohyaline granules?
Stratum granulosum
What is the function of melanocytes in the skin?
To synthesize melanin
In which stage of melanosome development is melanin synthesis initiated?
Stage II
What is the location of melanocytes in the skin?
Epidermis
Which of the following is NOT a layer of the epidermis?
Stratum papillare
What is the function of tyrosinase in melanin synthesis?
To catalyze melanin synthesis
What is the size range of mature melanin granules?
0.5-1 μm
What is the function of the Golgi apparatus in melanin synthesis?
To process and modify tyrosinase
Which layer of the skin is composed of stratified squamous epithelial cells?
Epidermis
Which type of cells play a crucial role in mediating immune response by binding, processing, and presenting antigens to T lymphocytes?
Langerhans cells
What is the primary function of the dermal papillae in the skin?
To provide mechanical support to the skin
What is the primary component of the skin's hypodermis?
Fatty tissue
What is the term for the pattern of accumulation of fatty tissue in the skin?
Sex-dependent pattern
What is the name of the layer of the hair root sheath that is composed of granular cells?
Huxley's layer
What is the term for the phase of hair development characterized by active growth and mitotic activity?
Anagen
What is the function of the sebaceous glands in the skin?
To produce sebum
What is the term for the lines of tension in the skin formed by collagen and elastic fibers?
Langer's lines
What is the term for the phase of hair development characterized by apoptosis and involution?
Catagen
What is the name of the receptor responsible for detecting light touch and vibration in the skin?
Pacinian corpuscules
What is the primary function of eccrine glands?
To produce true sweat
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
What is the characteristic of the telogen phase of the hair follicle?
A period of hair shedding
What is the type of epithelium found in the stratatum germinativum?
Simple cuboidal epithelium
What is the function of myoepithelial cells in the mammary gland?
To contract and expel milk
What is the characteristic of the merocrine way of sweat gland secretion?
Both apocrine and eccrine glands release their products through merocrine secretion
What is the difference between ceruminous glands and mammary glands?
Ceruminous glands secrete earwax, while mammary glands secrete milk
What is the characteristic of the polygonal cells in the hair follicle?
They are polygonal in shape
What is the difference between inactive and lactating mammary glands?
Inactive glands are smaller, while lactating glands are larger
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
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.
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