Unit 7: Chapter 51

Question 1

Epidermis

Answer 1

Covers the body
Composed of straightedge squamous keratinized epi

specialized to form the various skin appendages, which include the hair, nails, and glandular structures.
Contains openings for 2 types of glands, sweat glands and sebaceous glands

Question 2

Epidermis Cells

Answer 2

types of cells that arise from its basal layer—melanocytes, Merkel cells, and Langerhans cells.

Question 3

Keratinocytes

Answer 3

Major cell of the epidermis 85% of the cells of this latyter
Produce fibrous protein called keratin, essential for the protective function of the skin

Question 4

Melanocytes

Answer 4

Produce pigment callled melanin
Which is respsonable for skin Cor, tanning and protection against UV radiation at

Question 5

Merkel Cells

Answer 5

Provide sensory information
Clear cells found in the stratum basale of the epidermis.
Connected to other skin cells by desmosomes
Each cells is connectect to a afferent nerve terminal forming Merkel disk

Question 6

Langerhand Cells

Answer 6

Link the epidermis to the immune system

are scattered in the suprabasal layers of the epidermis among the keratinocytes.
They are less numerous (3% to 5% of epidermal cells) than are the keratinocytes.
They are derived from precursor cells originating in the bone marrow and continuously repopulate the epidermis.

Question 7

Sebaceous Glands

Answer 7

Produce an oily secretion called sebum

Question 8

Epidermis Layers

Answer 8

1. Stratum germinativum or stratum basale (deepest)
2. Stratum spinosum
3. Stratum granulosum
4. Stratum lucidum
5. Stratum corneum

Question 9

Keratinization

Answer 9

Keratinocytes change cytoplasmic structure and compositional they are pushed toward the surface of the epidermis.
This transformation from viable cells to the dead cells of the stratum corneum.

Question 10

Albinism

Answer 10

Gentic lack of enzyme tyrosinase which is a precursor of melanin
Lack of pigmentation in the skin, hair and the iris of the eye

Question 11

Vitiligo

Answer 11

Skin problem where the melanocytes are destroyed.
This increased the risk of developing non melanoma skin cancers

Question 12

Langerhans cells and Skin Reactions

Answer 12

Are immunologic cells responsible for recognizing foreign antigens harmful to the body

Are innervated by sympathetic nerve fibers, which may explain why the skin’s immune system is altered under stress.

Question 13

Basement Membrane

Answer 13

is a layer of intercellular and extracellular matrices that serves as an interface between the dermis and the epidermis
It separates the epithelium from the underlying connective tissue, it anchors the epithelium to the loose connective tissue underneath, and it serves as a selective filter for molecules moving between the two layers.
It is also a major site of immunoglobulin and complement deposition in skin disease.
Is involved in skin disorders that cause bullae or blister formation.

Question 14

Basement Membrane Layers

Answer 14

3 distinct zones
1. lamina lucida is an electron-lucent layer where adherence proteins are located. It consists of fine anchoring filaments and a cell adhesion glycoprotein, called laminin, which plays a role in the organization of the macromolecules in the basement membrane zone and promotes attachment of cells to the extracellular matrix.
2. lamina densa contains an adhesive called type IV collagen as well as laminin. It is important in dermal–epidermal attachment.
3. lamina fibroreticularis then completes the basement membrane. This layer contains many anchoring microfibrils. These are short, curved structures that insert into the lamina densa and the superficial dermis, where they are known as anchoring fibrils.

Question 15

Dermis

Answer 15

the connective tissue layer that separates the epidermis from the subcutaneous fat layer
It supports the epidermis and serves as its primary source of nutrition.
two layers: papillary and reticular dermis, are composed of cells, fibers, ground substances, nerves, and blood vessels.
main component: is collagen, a group of fibrous proteins, is enmeshed in a ground substance called hyaluronic acid.
Collagen fibers are loosely arranged in the papillary dermis, but are tightly bundled in the reticular dermis.

Question 16

Epidermis Layers

Answer 16

skin is composed of the following three layers:
1. Epidermis (outer layer)
2. Dermis (inner layer)
3. Subcutaneous fat layer
The basement membrane divides the first two layers. The subcutaneous tissue, a layer of loose connective and adipose connective tissues, binds the dermis to the underlying tissues of the body

Question 17

Sweat Glands

Answer 17

two types of sweat glands:
1. eccrine: simple tubular structures that originate in the dermis and open directly to the skin surface. They are numerous (several million), vary in density, and are located over the entire body surface except the lips and part of the external genitalia
Their purpose is to transport sweat to the outer skin surface to regulate body temperature
2. Apocrine: are less numerous than are eccrine sweat glands. Larger and located deep in the dermal layer. They open through a hair follicle, even though a hair may not be present, and are found primarily in the axillae and groin. Secrete oily substance

Question 18

Stratum Germinativum (Basale)

Answer 18

Deepest layer
Consits sof a single layer of base Al cells that are attached to the Basel lamina
Cells are columnar, undergo mitosis to produce new keratinocytes that move towards the surface of the skin for shedding

Question 19

Stratum Spinosum

Answer 19

Formed as a result of the cell division in the stratum basale
4 layers thick and cells differentiated as they migrate toward the surface of the epidermis.
Because they develop a spiny appearance where their cell borders interconnect, the cells of this layer are commonly referred to as prickle cells.

Question 20

Stratum Granulosum

Answer 20

few cells thick (thickness varies between one and three cells).
It consists of granular cells that are the most differentiated cells of the living skin.
The cells in this layer are unique in that two opposing functions occur simultaneously

Question 21

Stratum Lucidum

Answer 21

which lies just superficial to the stratum granulosum, is a thin, transparent layer found primarily on the thick skin such as over the palms of the hands and soles of the feet
It consists of transitional cells that retain some of the functions of living skin cells from the layers below and provide a barrier to water.

Question 22

Stratum Corneum

Answer 22

Superficial layer

consists of dead, keratinized cells, which shed intermittently.
This layer contains the most cell layers and the largest cells of the epidermis.
This layer blocks microbes from entering the skin and prevents dehydration of tissues

Question 23

Papillary Dermis

Answer 23

a thin, superficial layer that lies adjacent to the epidermis. Rickey vascularized. Contains lymph and nerve tissues.
It consists of collagen fibers and ground substance. This layer is densely covered with conical projections called dermal papillae
The basal cells of the epidermis project into the papillary dermis, forming rete ridges.
Contains capillaries, end arterioles and venules that norms in the epidermal layers of the skin.

Question 24

Sebum

Answer 24

Secreted by sebaceous glands
mixture of lipids, including triglycerides, cholesterol, and wax. This mixture is called sebum, and it lubricates
the hair and skin.
prevents undue evaporation of moisture from the stratum corneum during cold weather and helps conserve body heat.
Sebum production is under the control of genetic and hormonal influences.

Question 25

Immune Cells

Answer 25

Dermal dendrocytes are spindle-shaped cells that have both phagocytic and dendritic properties. Possess antigen-presenting functions play an important part in the immunobiology of the dermis. Dermal dendrocytes may initiate or to respond to immunologic events in the epidermis. Dermal dendrocytes are also thought to be involved in processes such as wound healing, blood clotting, and inflammation.

Question 26

Innervation of Skin

Answer 26

Complex Accessory structures, receiving sensory information from the enviroment . Receptors for touch, pressure, heat, cold, and pain are widely distributed in the dermis. The papillary layer of the dermis is supplied with free nerve endings that serve as nociceptors (i.e., pain receptors) and thermoreceptors. The dermis also contains encapsulated pressure-sensitive receptors that detect pressure and touch.

Question 27

Meissen Corpuscles

Answer 27

Serve as touch receptors Flat, encapsulated nerve endings found on the palmar surfaces of the fingers and hands and planter surfaces of the feet. They are concentrated on the fingertips, palms, soles, lips, tongue, face, and genitalia.

Question 28

Keloids

Answer 28

Benign, firm, rubbery and often raised itchy skin growths caused by excessive collagen production during healing. Form in the dermis layer

Question 29

Arteriovenous Anastomoses

Answer 29

Richly supplied in the skin Blood flows directly between an artery and a vein, bypassing the capillary circulation They can open up letting blood flow through the skin vessles where there is need to dissipate body heat and close off, conversing body heat if the temp is cold.