Skin and its Appendages saq

Questions and Answers

What are the three main layers of the integumentary system?

The three main layers of the integumentary system are the epidermis, dermis, and hypodermis.

What are the specific functions of the skin?

The specific functions of the skin include protection, sensory perception, thermoregulation, metabolism, and sexual signaling.

What are the skin appendages?

The skin appendages include hairs, nails, sebaceous glands, and sweat glands.

What are the functions of the dermal vasculature?

1- Nutritive function 2- Thermoregulatory function Signup and view all the answers

What are the types of sensory receptors present in the skin?

Unencapsulated receptors and encapsulated receptors Signup and view all the answers

What are the functions of Meissner corpuscles?

Stimulated by light-touch or low-frequency stimuli against skin temporarily deform their shape Signup and view all the answers

Where are Ruffini corpuscles primarily found?

Primarily found in the skin of the penis and clitoris where they sense low-frequency vibrations Signup and view all the answers

What is the role of melanin in the skin?

Melanin absorbs and scatters sunlight, protecting DNA of the living cells from the ionizing, mutagenic effects of UV radiation. Signup and view all the answers

How do keratinocytes transport melanosomes?

Keratinocytes transport melanosomes toward their nuclei. Signup and view all the answers

What is the function of Langerhans cells?

Langerhans cells are antigen presenting cells (APCs) that trigger an immune response when microorganisms try to penetrate the epidermis. Signup and view all the answers

What is the thickness of the dermis and where does it reach its maximum?

The thickness of the dermis varies with the region of the body, reaching its maximum of 4 mm on the back. Signup and view all the answers

What are the two major types of cells found in the epidermis?

The two major types of cells found in the epidermis are keratinocytes and non-keratinocyte cells (including melanocytes, Langerhans cells, and Merkel cells). Signup and view all the answers

What is the major distinction between thick skin and thin skin?

The major distinction between thick skin (found on the palms and soles) and thin skin (found elsewhere on the body) is the thickness of the epidermal layer. Thin skin has a thickness of 75 to 150 μm, while thick skin has a thickness of 400 to 1400 μm (1.4 mm). Signup and view all the answers

How many layers does the epidermis consist of in thin skin? How many layers does it consist of in thick skin?

The epidermis consists of four layers of keratinocytes in thin skin, and five layers in thick skin. The layers are: 1) Basal layer (stratum basale), 2) Spinous layer (stratum spinosum), 3) Granular layer (stratum granulosum), 4) Stratum lucidum (only in thick skin), and 5) Stratum corneum. Signup and view all the answers

What are the characteristic features of the cells in the stratum corneum?

The cells in the stratum corneum are squamous, keratinized cells filled with filamentous keratins. The keratin filaments are synthesized during cell differentiation in the immature layers and become heavily massed with filaggrin and other proteins in keratohyaline granules. Signup and view all the answers

What is the function of lamellated (Pacinian) corpuscles?

Lamellated (Pacinian) corpuscles sense coarse touch, pressure, and high-frequency vibrations. Signup and view all the answers

Where are hair follicles not found on the skin?

Hair follicles are not found on the palms, soles, lips, glans penis, clitoris, and labia minora. Signup and view all the answers

What is the structure that contains the dermal papilla and capillary network necessary for the hair follicle?

The hair bulb contains the dermal papilla and capillary network necessary for the hair follicle. Signup and view all the answers

What are the three major types of exocrine glands in the skin?

The three major types of exocrine glands in the skin are sebaceous glands, eccrine sweat glands, and apocrine sweat glands. Signup and view all the answers

Study Notes

Structure and Function of Skin and its Appendages

Lamellated (Pacinian) corpuscles are large oval structures found deep in the dermis and hypodermis that sense coarse touch, pressure, and high-frequency vibrations.
Hair follicles are elongated structures that form within epidermal invaginations and are found on almost all parts of the skin except the palms, soles, lips, glans penis, clitoris, and labia minora.
The hair bulb is a terminal dilation in the growing hair follicle that contains a dermal papilla and a capillary network required to sustain the hair follicle.
Keratinocytes in the hair bulb matrix proliferate, take up melanin granules, and undergo keratinization to differentiate into the three concentric layers of the hair.
The hair root is covered by the internal and external root sheaths, along with the connective tissue sheath, and is surrounded by the arrector pili muscle.
Nails are hard plates of keratin on the dorsal surface of each distal phalanx that are produced by a similar process of keratinization as the hair.
The nail root is the proximal part of the nail covered by a fold of skin, and it forms from the nail matrix in which cells divide, move distally, and become keratinized to form the nail plate.
The nail plate is bound to the nail bed, which contains only the basal and spinous epidermal layers, and it grows forward over the nail bed.
There are three major types of exocrine glands in the skin: sebaceous glands, eccrine sweat glands, and apocrine sweat glands.
Sebaceous glands secrete oily sebum into the space around the hair root and are more abundant in the face and scalp.
Eccrine sweat glands develop as long epidermal invaginations embedded in the dermis and are most numerous on the foot soles, serving thermoregulatory and excretory functions.
Apocrine sweat glands are found in the axillary and perineal regions, and their secretion is protein-rich and mixed with sebum, potentially acquiring a distinctive odor due to bacterial activity.