20 Questions
What is the primary function of hair?
Protection from sunlight
Where are sebaceous glands typically found?
All over the skin except palms and soles
Which type of sweat gland is most numerous in the palms and soles?
Eccrine
Where do apocrine sweat glands open into?
Hair follicles in armpits and genitalia
What is the reason for the differences in hair length between the back of the hand and pubic hair?
Varied growth cycles in those regions
Which type of gland produces sebum, an oily substance rich in lipids?
Sebaceous glands
Which layer of the epidermis contains a translucent substance called eleidin?
Stratum lucidum
What type of keratinocytes are predominantly found in the Stratum spinosum layer of the epidermis?
Polyhedral keratinocytes
Which layer of the epidermis is known as the 'granular layer' due to the presence of keratohyaline granules?
Stratum granulosum
What makes the Stratum corneum so strong according to the text?
Filled with keratin
In which layer of the epidermis does desquamation, or shedding of dead skin cells, occur?
Stratum corneum
Which layer of the epidermis is primarily composed of dead squamous cells filled with keratin?
Stratum corneum
Which enzyme is lacking in individuals with albinism that affects the production of melanin?
Tyrosinase
What is the name for the type of hair that appears during the last trimester of fetal development?
Lanugo
Which hormone contributes to men having more obvious hair growth?
Testosterone
What is the main type of hair that grows to a certain length and then ceases to grow?
Definitive hair
Which type of skin is thick and hairless, found on palms, soles, and flexor surfaces of digits?
Glabrous skin
What is the name of the fine, light-colored short hair found on the body?
Vellus hair
Where does each hair arise from in humans?
Hair bulb
Which hormone is involved in the growth cycle of hair in both men and women?
Estrogen
Study Notes
Hair Function and Types
- The primary function of hair is to protect the body from external damage.
- Lanugo is the type of hair that appears during the last trimester of fetal development.
- Vellus hair is the fine, light-colored short hair found on the body.
- Terminal hair is the main type of hair that grows to a certain length and then ceases to grow.
Glands
- Sebaceous glands, which produce sebum, an oily substance rich in lipids, are typically found in the dermis.
- Apocrine sweat glands open into hair follicles.
- Eccrine sweat glands are the most numerous type of sweat gland in the palms and soles.
Epidermis Layers
- The Stratum corneum, the outermost layer of the epidermis, is strong due to the presence of multiple layers of dead cells.
- The Stratum lucidum, a translucent layer of the epidermis, contains a substance called eleidin.
- The Stratum granulosum, also known as the 'granular layer', contains keratohyaline granules.
- The Stratum spinosum layer of the epidermis contains predominantly prickle cells.
- Desquamation, or shedding of dead skin cells, occurs in the Stratum corneum.
- The Stratum corneum is primarily composed of dead squamous cells filled with keratin.
Hair Growth and Development
- The growth cycle of hair is influenced by testosterone in men and is involved in hair growth in both men and women.
- The difference in hair length between the back of the hand and pubic hair is due to the variation in hair growth rates.
Skin Types
- Palmar skin, found on palms, soles, and flexor surfaces of digits, is thick and hairless.
Genetic Disorders
- Albinism is caused by a lack of the enzyme tyrosinase, which affects the production of melanin.
Explore the primary functions of hair, such as protection, touch sensation, and warmth. Learn about major glands like sebaceous glands and sweat glands, including eccrine and apocrine glands.
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