Question

Period Name 1. What structures are included in the integumentary systern. 2. Skin may be one of the most underestimated organs in the body. List six functions your skin performs while it is "just lying there" 2. 3. 4. 5. 6. 3. The outer layer of skin is the layer. The inner layer is the layer. Which layer is the thickest? What is the subcutaneous layer? 4. Epidermis contains a few distinct cell types. Fill in the name of the cell type that fits a. Most numerous cell type, this cell produces keratin which helps to b. This type of cell produces the pigments which give skin its color: each description. waterproof skin: 5. The dermis is composed of (connective / epithelial) tissue. Describe the dermis. 6. Answer these questions about glands. a. Where in the body would you most likely find sebaceous glands? b. What are the functions of these glands?

Answer 1

Functions of skin

1. Barrier function-epidermal barrier protects the skin from microbes, chemicals, physical trauma, and desiccation due to tran- sepidermal water loss.1–3 This barrier is created by dif- ferentiation of keratinocytes as they move from the basal cell layer to the stratum corneum. The keratinocytes of the epidermis are produced and renewed by stem cells in the basal layer resulting in replacement of the epidermis approximately every 28 days. It takes 14 days for these cells to reach the stratum corneum and another 14 days for the cells to desquamate.
2. Immunologic function-Epithelial cells at the interface between the skin and the environment provide the first line of defense via the i n n a te i m mu n e s y s te m . 4 – 6 Ep i t h e l i a l ce l l s a re e q u i p p e d to respond to the environment through a variety of structures including Toll-like receptors (TLRs) of which there are at least 10, nucleotide-binding oligomerization domain-like receptors, C-type lectins, and peptidoglycan recognition proteins. TLR-mediated activation of epithelial cells is also associated with the production of defensins and cathelici- dins, families of antimicrobial peptides.
3. Melanin production and protection from ultraviolet light damage
4. Synthesis of vitamin D
5. Sensation-The skin is one of the principal sites of interaction with the environment and many types of stimuli are processed by the peripheral and central nervous systems.9,10 Initially, cutaneous nerves were classified as being either “afferent” controlling sweat gland function and blood flow or “effer- ent” transmitting sensory signals to the central nervous system, but after the discovery of the neuropeptide sub- stance P (SP) and other neuropeptides in sensory nerves, many trophic properties of nerve fibers and neuropeptides have been reported.
6. Temperature regulation-The skin helps to regulate and maintain core body tem- perature through regulation of sweating and varying the blood flow in the skin. Evaporation of sweat contributes to temperature control of the body. Under normal conditions 900 mL of sweat is produced daily. With increased physical activity or increased environmental temperature, 1.4 to 3 L of sweat per hour can be produced.

Outer layer- epidermis(stratum corneum)

Inner layer dermis and sub cut

Thickest layer-dermis

Subcutaneous layer- innermost layer of skin sub cut also called as hypodermis .hypodermis is derived from the mesoderm, but unlike the dermis, it is not derived from the dermatome region of the mesoderm. In arthropods, the hypodermis is an epidermal layer of cells that secretes the chitinous cuticle. The term also refers to a layer of cells lying immediately below the epidermis of plants.

Mainly used for fat storage

Most numerous cell- keratinocytes(basal layer cells)

Pigments and colour to skin -melanocytes

Dermis -

Thickest layer of skin.

primarily consists of dense irregular connective tissue and cushions the body from stress and strain. It is divided into two layers, the superficial area adjacent to the epidermis called the papillary region and a deep thicker area known as the reticular dermis.The dermis is tightly connected to the epidermis through a basement membrane. Structural components of the dermis are collagen, elastic fibers, and extrafibrillar matrix.It also contains mechanoreceptors that provide the sense of touch and thermoreceptors that provide the sense of heat. hair follicles, sweat glands, sebaceous glands, apocrine glands, lymphatic vessels and blood vessels are present in the dermis. Those blood vessels provide nourishment and waste removal for both dermal and epidermal cells

Rest of answers will be cleared from these diagrams