Questions and Answers
What primarily determines the shape of hair?
Which cells in the hair bulb are responsible for synthesizing melanosomes?
What is a characteristic of alopecia areata?
How does the distribution of melanosomes affect hair color?
Signup and view all the answers
What type of hair shape is typically seen in individuals of African descent?
Signup and view all the answers
What phase of hair growth is affected in alopecia areata?
Signup and view all the answers
What is the main function of keratinocytes in the hair bulb?
Signup and view all the answers
Which factor does NOT influence hair color?
Signup and view all the answers
What is the primary function of the epidermis?
Signup and view all the answers
Which of the following processes is involved in keratinization?
Signup and view all the answers
Which type of cells primarily make up the epidermis?
Signup and view all the answers
What happens to keratinocytes as they move upward through the layers of the epidermis?
Signup and view all the answers
What is the thickness range of the outermost layer of the epidermis?
Signup and view all the answers
Which of the following is NOT a role associated with the process of cornification?
Signup and view all the answers
In what origin are keratinocytes derived from?
Signup and view all the answers
What aggregates do keratinocytes form as they differentiate?
Signup and view all the answers
What is primarily produced by the matrix cells in the hair bulb?
Signup and view all the answers
Which segment of the hair follicle houses the arrector pili muscle?
Signup and view all the answers
What key function do stem cells in the hair bulb serve?
Signup and view all the answers
Which characteristic describes the inferior segment of the hair follicle?
Signup and view all the answers
What do melanocytes in the hair bulb primarily contribute to?
Signup and view all the answers
What is the main role of the infundibulum in the hair follicle structure?
Signup and view all the answers
What happens during the cycles of involution and regeneration in the hair bulb?
Signup and view all the answers
What indicates that the inner root sheath (IRS) is fully keratinized?
Signup and view all the answers
What structure is formed at the base of the developing hair follicle as it grows downward?
Signup and view all the answers
What is the collective term for the hair follicle, sebaceous gland, and arrector pili muscle?
Signup and view all the answers
What is the major component of the basal lamina?
Signup and view all the answers
Where do epidermal buds grow after forming the hair follicle?
Signup and view all the answers
Which bud of the fetal follicle develops into the sebaceous gland?
Signup and view all the answers
Which proteins are associated with hemidesmosomes in the basement membrane zone?
Signup and view all the answers
What kind of antibodies are found in Epidermolysis Bullosa Acquisita?
Signup and view all the answers
What function is NOT associated with hair?
Signup and view all the answers
What structural components are found below the lamina densa?
Signup and view all the answers
How does the hair follicle develop in relation to the skin surface?
Signup and view all the answers
Which type of collagen is primarily a component of anchoring fibrils?
Signup and view all the answers
What part of the hair follicle allows for attachment to the arrector pili muscle?
Signup and view all the answers
Which gland is NOT formed from the budding process of the hair follicle?
Signup and view all the answers
In the context of the basement membrane zone, what is a function of dermal microfibrils?
Signup and view all the answers
Which of the following structures is not part of the sublamina densa?
Signup and view all the answers
What is the role of BP230 and BP180 in the skin's structure?
Signup and view all the answers
Study Notes
Epidermis Overview
- Avascular stratified squamous keratinizing epithelium is derived from ectoderm.
- Produces a non-living keratin surface layer, rich in lipids, exposed to the external environment.
- Thickness ranges from 0.4 to 1.5 mm.
- Main function is cornification, leading to the formation of the stratum corneum.
- Keratinocytes make up approximately 80% of epidermal cells and undergo mitosis as they ascend, flattening as they lose their nuclei.
Keratins and Cornification
- Cornification involves synthesis of lamellar granules and specific proteins (keratins, filaggrin, involucrin).
- Structural changes of nuclei, cytoplasmic organelles, plasma membranes, and desmosomes occur during keratinization.
Basement Membrane Zone
- Composed of sublamina densa, anchoring fibrils, dermal microfibrils, and collagen fibers.
- Key collagen types:
- Type IV: Major component of basal lamina.
- Type VII: Major component of anchoring fibrils.
Hemidesmosomal Proteins
- BP230 (Bullous Pemphigoid Antigen 2) and BP180 (Bullous Pemphigoid Antigen 1 or Type XVII) are significant for epidermal adherence.
Epidermolysis Bullosa Acquisita
- Condition is characterized by antibodies against collagen VII.
Hair Follicles and Structure
- Hair and associated structures contribute to body temperature regulation.
- Hair follicles form from epidermal invaginations and develop into the pilosebaceous unit comprising hair follicles, sebaceous glands, and arrector pili muscles.
Components of Hair Follicle
- Hair bulb houses melanocytes and is highly vascularized.
- Stem cells in the hair bulb differentiate to create hair structures.
- Identified in three segments:
- Infundibulum: Opens to sebaceous duct.
- Isthmus: Between sebaceous duct and arrector pili muscle, site for keratinization.
- Inferior Segment: Contains the hair bulb.
Hair Growth and Color
- Melanocytes in the hair bulb produce melanin, influencing hair color.
- Hair undergoes cycles of growth and rest; color is determined by melanization and the distribution of melanosomes in the hair shaft.
Clinical Correlation
- Alopecia areata is an autoimmune condition marked by lymphocytic infiltration causing cessation of hair growth during the anagen phase.
Hair Shape Determinants
- Hair dimensions and the curvature of the inner root sheath influence overall hair shape. Curly hair commonly arises from oval cross-sections, particularly in individuals of African descent.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge on the structure and function of the epidermis, specifically focusing on keratinized stratified squamous epithelium. This quiz covers the cellular composition, thickness, and the process of cornification. Explore the key aspects of how the epidermis interacts with the external environment.