Which epidermal cell type is most numerous

Definition It is not responsible for the toughness of the skin. Term Skin surface markings that reflect points of tight dermal attachment to underlying tissues are called? Definition Flexure Lines. Term Which of the following is not a epidermal derivative? Definition Sensory Receptor. Term An arrector pili muscle? Definition Can cause hair to stand up straight. Term The product of this type of a sweat gland includes protein and lipid substances that become odoriferous as a result of bacterial action?

Definition Apocrine Gland. Term Define Sebum? Definition Lubricates the surface of the skin and hair, Consist of cell fragmentand fatty sudstance, In excess may cause seborrhea. Term The rules of nine is helpful clinically in?

Definition Estimating the extent of a burn. Term Which is a function of the skeletal system? Definition Support, hempatopoitic site, storage, amd providing levers for muscle activity. Term A bone with approximately the same width, length and height is most likely. Definition A short bone. Term Sites of hematopoiesis include all but:.

Definition Medullary cavities in bones of a healthy adult. Term An osteon has:. Definition Concentric lamellae, osteocytes in lacunae, and canaliculi that connect lancunae to the central canal. Term The organic portion of martrix is important in providing all but. Definition Hardness. Term The flat bones of the skull develop from. Definition Fibrous connective tissue. Term The remodeling of bone is a function of which cells? Definition Osteoblast and osteocytes.

Term Bone remodeling in adults is regulated and directed mainly by:. Definition Thyroid Hormones. Term Where within the epiphyseal plate are the dividing cartilage cells located? Definition Nearest the shaft. Term Wolff's law is concerned with:. Definition The electrical charge on bone surfaces.

Term Formation of the bony callus in fracture repair is followed by:. Definition Fibrocartilaginous callus formation. Term The fracture type in which the bone ends are incompletely separated is:. Definition Greenstick. Term The disorder in which bones are porous and thin but bone composition is normal is:. Definition Osteoporosis.

Definition Frontal and Parietal. Term What structure is the keystone of the cranium? Definition Sphenoid. Term What structure is the keystone bone of the face? Definition Maxillary. Term Which structures form the hard palate? Definition Maxillary and Palatines.

It is the layer we see with our eyes. It contains no blood supply of its own—which is why you can shave your skin and not cause any bleeding despite losing many cells in the process. The epidermis is itself divided into at least four separate parts.

A fifth part is present in some areas of our body. In order from the deepest layer of the epidermis to the most superficial, these layers strata are the:. Skin overview : Skin layers, of both hairy and hairless skin. Human skin: This image details the parts of the integumentary system. The stratum basale, also called the stratum germinativum, is the basal base layer of the epidermis.

This layer is one of the most important layers of our skin. This is because it contains the only cells of the epidermis that can divide via the process of mitosis, which means that skin cells germinate here, hence the word germinativum.

In this layer, the most numerous cells of the epidermis, called keratinocytes, arise thanks to mitosis. Keratinocytes produce the most important protein of the epidermis. This protein is appropriately called keratin. Keratin makes our skin tough and provides us with much-needed protection from microorganisms, physical harm, and chemical irritation. Millions of these new cells arise in the stratum basale on a daily basis. The newly produced cells push older cells into the upper layers of the epidermis with time.

As these older cells move up toward the surface, they change their shape, nuclear, and chemical composition. These changes are, in part, what give the strata their unique characteristics. The stratum basale is primarily made up of basal keratinocyte cells, which can be considered the stem cells of the epidermis. They divide to form the keratinocytes of the stratum spinosum, which migrate superficially. From the stratum basale, the keratinocytes move into the stratum spinosum, a layer so called because its cells are spiny-shaped cells.

From there the keratinocytes move into the next layer, called the stratum granulosum. This layer gets its name from the fact that the cells located here contain many granules. The keratinocytes produce a lot of keratin in this layer—they become filled with keratin. This process is known as keratinization. The keratinocytes become flatter, more brittle, and lose their nuclei in the stratum granulosum as well.

Once the keratinocytes leave the stratum granulosum, they die and help form the stratum lucidum. This death occurs largely as a result of the distance the keratinocytes find themselves from the rich blood supply the cells of the stratum basale lie on top off. Devoid of nutrients and oxygen, the keratinocytes die as they are pushed towards the surface of our skin. This layer is only easily found in certain hairless parts of our body, namely the palms of our hands and the soles of our feet.

Meaning, the places where our skin is usually the thickest. From the stratum lucidum, the keratinocytes enter the next layer, called the stratum corneum the horny layer filled with cornified cells. This the only layer of skin we see with our eyes. The keratinocytes in this layer are called corneocytes. They are devoid of almost all of their water and they are completely devoid of a nucleus at this point. They are dead skin cells filled with the tough protein keratin.

In essence, they are a protein mass more so than they are a cell. The corneocytes serve as a hard protective layer against environmental trauma, such as abrasions, light, heat, chemicals, and microorganism. The cells of the stratum corneum are also surrounded by lipids fats that help repel water as well.

These corneocytes are eventually shed into the environment and become part of the dandruff in our hair or the dust around us, which dust mites readily munch on. This entire cycle, from new keratinocyte in the straum basale to a dead cell flaked off into the air, takes between 25—45 days. The dermis consists of a papillary and a reticular layer that serve to protect and cushion the body from stress and strain.

Lying underneath the epidermis—the most superficial layer of our skin—is the dermis sometimes called the corium. The dermis is a tough layer of skin. It is the layer of skin you touch when buying any leather goods. The dermis is composed of two layers. They are the papillary layer the upper layer and the reticular layer the lower layer.

The nuclei and other cell organelles disintegrate as the cells die, leaving behind the keratin, keratohyalin, and cell membranes. The stratum lucidum is a thin, transparent band consisting of a few rows of flat, dead keratinocytes. These cells are densely packed with eleidin , a clear lipid-rich protein derived from keratohyalin, which gives these cells their transparent appearance and provides a barrier to water.

Its functions include waterproofing, protection from abrasion and biological and chemical assaults. What cell is the most abundant in the epidermis? Ernest Z. Dec 7, Keratinocytes are the most abundant cells in the epidermis. Explanation: The epidermis consists of four or five layers of cells.

Epidermal layers From courses. It consists of a single layer of the youngest, rapidly-dividing keratinocytes.