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Accessory Structures of the Skin: Hair Growth and Types01:20

Accessory Structures of the Skin: Hair Growth and Types

Hair growth begins with the production of keratinocytes by the basal cells of the hair bulb. As new cells are deposited at the hair bulb, the hair shaft is pushed through the follicle toward the surface. Keratinization is completed as the cells are pushed to the skin surface to form the shaft of hair that is externally visible. The external hair is completely dead and composed entirely of keratin. Hair can be cut or shaven without damaging the hair structure because the cut is superficial. Most...
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Accessory Structures of the Skin: Hair and Hair Follicles01:16

Accessory Structures of the Skin: Hair and Hair Follicles

Hair and hair follicles are integral components of the integumentary system. Hair is a filamentous structure composed mainly of a protein called keratin. It is found on the surface of the skin throughout the body, except for areas such as the palms of the hands and soles of the feet.
Hair is a keratinous filament growing out of the epidermis. It is primarily made of dead, keratinized cells. Hair strands originate at the epidermal penetration called the hair follicle. The hair shaft is the part...
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Multipotency and Niche of Bulge Stem Cell01:06

Multipotency and Niche of Bulge Stem Cell

A hair follicle or HF is a small part of the skin that produces the hair shaft. Paul Gerson Unna was the first to observe a bulge in the human hair follicle's outer root sheath (ORS). The bulge is present between the sebaceous gland and the arrector pili muscle and is the niche for hair follicle stem cells (HFSCs). The bulge is also a niche for melanocyte stem cells, and their loss results in graying of hair. The HFSCs express Sox9 and Lhx2, which help them maintain stemness and prevent...
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Antihypertensive Drugs: Vasodilators01:23

Antihypertensive Drugs: Vasodilators

Vasodilators, primarily affecting the smooth muscles within arterial and venous walls, are commonly used for hypertension treatment. Medications such as minoxidil and hydralazine primarily target arteries and arterioles, while sodium nitroprusside acts on arterioles and venules. Minoxidil, functioning as a prodrug, is metabolized by hepatic sulfotransferase into its active form, minoxidil sulfate, after oral administration. This metabolite binds to the sulfonylurea receptor (SUR) component of...
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Local Anesthetics: Common Agents and Their Applications01:23

Local Anesthetics: Common Agents and Their Applications

Local anesthetics (LAs) are commonly used for various applications in medical and dental procedures. Some of the common agents used are cocaine, lidocaine, and bupivacaine.
Cocaine is an ester of benzoic acid and methylecgogine. It is used to anesthetize and vasoconstrict locally. Currently, it is used primarily for topical applications. It is beneficial for surgeries on the upper respiratory tract, providing anesthesia and shrinking the mucosa. Cocaine in the form of cocaine hydrochloride is...
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Folliculogenesis01:20

Folliculogenesis

Folliculogenesis is the development of ovarian follicles, the specialized structures within the ovarian cortex where oogenesis, or egg development, occurs. This process is essential for female reproductive health and begins during fetal development when primordial follicles are formed. Each primordial follicle comprises a primary oocyte in the center, surrounded by a single layer of squamous pre-granulosa cells. These follicles remain dormant in late prophase I of meiosis until triggered by...
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