Hair Structure Quiz

Hair Structure

• Composed of three layers: inner medulla, middle cortex, outer cuticle.
• Inner medulla contains large cells and soft keratin; found primarily in thick hair.
• Middle cortex consists of flattened cells and hard keratin, highly structured.
• Outer cuticle is the most superficial layer, composed of overlapping keratinized cells; wear leads to split ends.

Hair Components

• Shaft projects from skin surface; contains dead cells.
• Root is embedded in the dermis, consisting of living hair cells.
• Hair papilla nourishes hair follicles with blood vessels; located at the base of the hair bulb.
• Hair bulb includes the root and papilla, enclosing new hair growth areas.
• Hair matrix, at the bulb's base, produces new hairs through mitosis.
• Hair follicle surrounds the root; contains nerve endings and blood supply.
• Epithelial root sheath has outer and inner components; supports and attaches hair to the dermis.
• Dermal root sheath separates the follicle from the dermis.
• Arrector pili muscles cause piloerection by contracting, making hair stand up.

Epidermis

• Stratum Basale (Germinativum) is the deepest layer; highly mitotic, containing keratinocytes and melanocytes for melanin production.
• Keratinocytes regenerate skin by pushing dead cells upwards; essential due to daily cell loss.
• Stratum Spinosum appears spiky, with several layers of living keratinocytes, Langerhans, and melanocytes; thickest epidermis layer.

Dermis Structure

• Reticular layer is the deepest dermal layer composed of dense irregular connective tissue; contains collagen and elastic fibers.
• Elastic fibers allow skin to regain shape; stretching can lead to permanent stretch marks.
• Rich in receptors, blood vessels, sweat glands, and sensory neurons; contains Pacinian corpuscles sensitive to pressure.

Skin Markings

• Interaction between dermis and epidermis creates skin markings on palms and soles, enhancing grip.
• Epidermal ridges increase gripping ability; contain sweat pores leading to fingerprints.
• Cleavage lines indicate the direction of collagen fiber bundles; deep creases are flexor lines.

Skin Appendages

• Hair or pili consists of dead keratinized cells; produced by hair follicles.
• Nails are bordered by skin folds; contain hyponychium and lunula.
• Exocrine glands include sweat glands and others.
• Types of sweat glands: eccrine (thermoregulation, widespread) and apocrine (located in specific areas, produce body odor).

Burn Classification

• Estimated using the Rule of Nines, dividing body into areas representing 9% of total body surface area.
• Burns categorized by degree:
  • First-degree: impacts the epidermis; red, painful, no blisters.
  • Second-degree: affects epidermis and part of dermis; red, blistered, painful.
  • Third-degree: full thickness, severe damage; requires skin grafts, painless in burned areas.
  • Fourth-degree: extends into deeper tissues; complete loss, may require amputation.

Skin Cancer

• Common disease caused by DNA mutations disrupting cellular control; leads to tumors that may metastasize.
• Basal Cell Carcinoma is the most prevalent, arising from stratum basale keratinocytes; often forms nodules and ulcers in areas exposed to UV radiation.

Test your knowledge on the anatomy of hair, focusing on its three main layers: the inner medulla, middle cortex, and outer cuticle. This quiz covers the characteristics and functions of each layer, including the types of keratin present. Perfect for students studying biology or cosmetology.