Cosmetics – Human Skin and Function

Comprehensive flashcards covering cosmetics definitions, skin anatomy (Epidermis and Dermis), pigmentation, and gland functions based on the lecture notes.

According to the FDA, what categories of products are included in the definition of cosmetics?

Any product applied to the body for cleansing, beautifying, promoting attractiveness, or altering appearance, as well as the ingredients used to manufacture these products.

What are the common uses of cosmetic products?

To clean the body, beautify the appearance, protect the skin, improve attractiveness, and change appearance without affecting normal body functions.

Which products fall under the 'Skin Care Products' classification?

Cleansers, Astringents, Toners, Moisturizers, Face masks, Night creams, Bath products, and Shaving products.

What are examples of 'Make-up Products' mentioned in the lecture notes?

Foundation, Eye shadow, Eyeliner, Mascara, Blusher, Lipstick, and Nail polish.

What types of products are categorized as 'Toiletries'?

Soap, Shampoo, Conditioner, Hair styling products, Hair dyes, Hair straighteners, Deodorants, Antiperspirants, and Sunscreens.

What are the four examples provided for 'Fragrance Products'?

Perfumes, Cologne, Aftershave, and Bath powders.

What are the primary functions of human skin?

Protects the body from injury, acts as a barrier to the environment, prevents water loss, blocks harmful substances and microorganisms, regulates body temperature, and helps in communication (color, texture, odor).

What is the typical surface area range of adult skin?

$$2500 - 18000\,cm^2$$

What are the two types of skin found on the human body?

Hairy skin and Glabrous (hairless) skin.

What are the specific characteristics of skin on the palms and soles?

They have no hair follicles, no sebaceous glands, a thicker epidermis, and many sensory receptors.

What is the specific role of the Dermis in skin protection?

It provides mechanical strength and support.

What is the specific role of the upper Epidermis in skin protection?

It forms the main barrier against water loss and the penetration of harmful substances.

What are the characteristics of the Stratum Basale?

It is the deepest layer of the epidermis, produces new keratinocytes through continuous cell division, and contains cells with large nuclei.

What is the function of the Stratum Spinosum?

It connects skin cells together and gives strength to the epidermis.

What biological event begins in the Stratum Granulosum?

Keratin formation begins.

Where is the Stratum Lucidum typically present?

Mainly in thick skin such as palms and soles.

What are the hallmarks of the Stratum Corneum?

It is the outermost main protective layer consisting of dead flat cells with no nuclei that are filled with keratin.

Which three pigments determine skin color and what colors do they represent?

Hemoglobin (Red color), Carotene (Yellow color), and Melanin (Main pigment).

How do differences in skin color occur between individuals?

Differences are due to the amount of melanin produced, not the number of melanocytes (the cells that produce melanin).

What factors cause an increase in skin pigmentation?

Sun exposure and hormonal changes such as pregnancy.

What are the functions of Melanin?

Protects against ultraviolet (UV) radiation, increases in production in areas with strong sunlight, and helps remove damaged cells caused by sunlight.

What structures and substances are found within the Dermis?

Strong connective tissue, blood vessels, lymph vessels, nerves, hair follicles, and sweat glands.

What are the main protein components of the Dermis?

Collagen ($75\%$), Elastin, and Reticulin.

What is the distribution of sensory nerve fibers in the skin?

The skin contains about one million fibers; most endings are in the face and extremities, while the back contains fewer sensory nerves.

What is the function of Sebum and where is it produced?

Sebum is produced by sebaceous glands to lubricate the skin and hair.

Where are sebaceous glands most abundant and where are they absent?

Most abundant in the scalp, face, upper chest, and shoulders; absent in the palms and soles.

How do hormones affect sebaceous gland secretion?

Androgens increase secretion, while estrogens and anti-androgens decrease secretion.

Where are Apocrine Glands primarily located?

Axilla, anal region, genital region, and around the nipple.

When do Apocrine Glands become active and how is their secretion characterized?

They become active at puberty, are controlled by androgens, and produce a thick milky secretion that develops an odor after bacterial action.