Chapter 5
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toxic_paroxysm on March 4, 2011
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61 terms
Terms | Definitions |
|---|---|
 2 distinct Regions of the Skin | Epidermis & Dermis |
| Epidermis is made up of | Keratinized, stratified squamous epithelium |
| 4 Cells of the Epidermis | Keratinocytes, Melanocytes, Langerhans' Cells ( Epidermal Dendritic Cells), & Merkel Cells |
| Keratinocytes | Most numerous, Connected by desmosomes, Produce Keratin, arise from the stratum Basale and constantly undergo Mitosis |
| How do Keratinocytes undergo mitosis from the stratum Basale Layer? | They are pushed upward by newly dividing cells and produce keratin as they move upward. By the time they reach the apical surface they are dead, flattened cells filled with keratin. |
| Keratin | Protective protein that give durability and toughness |
| Melanocytes | Found in the stratum Basale, produce melanin that accumulates in melanosomes and then they are taken up by the Keratinocytes |
| Melanosomes | Membrane bound granules, accumulate on the superficial side of the keratinocyte's nucleus and protect the nucleus from damaging UV radiation in sunlight |
| Melanin | Pigment |
| Langerhans' Cells | Arise from bone marrow and migrate to the epidermis, are macrophages that help activate the immune response. |
| Merkel Cells | Always associated with a sensory nerve ending |
| Merkel disc | Merkel Cells with a sensory nerve, functioning as a sensory receptor for touch. (most receptors in finger tips) |
| 5 layers of the Epidermis | Stratum Basale, Stratum Spinosum, Stratum Granulosum, Stratum Lucidum, Stratum Corneum |
| Stratum Basale | Deepest layer, attached to dermis, cells always originate here |
| Stratum Basal has a single layer of cells (3 types) | Keratinocytes, Melanocytes, Merkel Cells |
| Stratum Spinosum | Several cell layers thick |
| Cells of the Stratum Spinosum | Keratinocytes containing thick bundle of immature keratin, langerhans' cells |
| Stratum Granulosum | 3 to 5 layers cell layers |
| Cells of the Stratum Granulosum | Primarily flattened Keratinocytes and their nuclei/organelles have begun to disintegrate. |
| Granules in the Stratum Granulosum | Keratohyaline Granules and Lamellated Granules |
| Keratohyaline Granules | help to form keratin in the upper layers |
| Lamellated Granules | Contain waterproof glycolipids, released from the granule and coat the surface of the cells making them tough and waterproof |
| Stratum Lucidum | Found in thick skin (palms, fingertips, and soles of feet), consists of a few layers of flat, dead keratinocytes |
| Stratum Corneum | 20 to 30 cell layers, dead flattened Keratinocytes with thickened plasma membranes and are filled with keratin, Glycolipids that act as a waterproof agent, serves for protection of the underlying layers. |
| fiber types of the Dermis | Collagen, Elastin, Reticular |
| Dermis | More supportive, tougher layer, contains blood/lymphatic vessels and nerve fibers, contains sweat/oil glands and hair follicles |
| Layers of the Dermis | Papillary Layer and Reticular Layer |
| Papillary Layer | Upper layer (just under epidermis), looser areolar CT, Superior surface contains projections that contain pain receptors and touch receptors |
| Projections of the superior surface of the Papillary Layer | Dermal Papillae |
| Pain Receptors | Free nerve ending |
| Touch Receptors | Meissner's Corpuscles |
| Reticular Layer | 80% of the dermis, consisting of thick/tough Dense Irregular Connective tissue |
| Hypodermis | Subcutaneous layer below the dermis (not formally part of the skin but has some skin properties), composed of adipose tissue |
| Hypodermis is also called superficial Fascia because | Its superficial to the tough CT membrane of the underlying skeletal muscles |
| Functions of Hypodermis | Stores fat, anchors skin to skeletal muscle, insulation |
| 2 types of sweat glands | Eccrine (Merocrine) Sweat Glands and Apocrine Sweat Glands |
| Eccrine Sweat Glands | Most numerous; the secretory part lies coiled in the dermis and the duct extends into and opens as a funnel shaped pore at the skin surface, Known as True sweat |
| What is true sweat? | Hypotonic filtrate of the blood composed of 99% water, NaCl, Vitamin C, antibodies, lactic acid, waste products (urea, uric acid, ammonia), Small amounts of any ingested drugs |
| Apocrine Sweat glands | Found in Axillary and anogenital areas, larger and empty into hair follicles, have same components as true sweat but also contain fatty molecules/proteins. When its organic molecule are decomposed by bacteria - this becomes the basis of body odor.. Begins functioning at puberty |
| Oil (Sebaceous) glands | found all over the body - except at the palms and soles of the feet, Secretes an oily substance called sebum, begins functioning at puberty |
| Functions of Sebum | Softens/lubricates the hair and skin, slows water loss from the skin during times of low humidity, and high content of fatty acids which are antibacterial. |
| Nails | Modification of the epidermis, clear protective covering on the dorsal finger/toe, composed of hard Keratin |
| 3 basic parts of a Nail | Free edge, body, Proximal root |
| Body of Nail | Over lies the nail bed |
| Nail Bed | Deeper layers of the epidermis under the body of the nail |
| Nail Matrix | Proximal part of the nail bed which is responsible for growth |
| Nail folds | folds of skin that overlap at the lateral and proximal borders of the nail |
| Eponychium (Cuticle) | Extension of the proximal nail fold extending over the nail body |
| Structure of a Hair | Flexible strands of hard Keratin produced by hair follicles |
| Hair has 3 layers of Keratinized cells | Medulla, Cortex, Cuticle |
| Medulla | Central part |
| Cortex | Surrounds the medulla |
| Cuticle | Outermost/most heavy keratinized layer |
| Hair Pigment | Made by melanocytes at the base of the hair follicle and transferred to the cortical cells which pick up the color |
| Hair follicle | Houses the hair |
| Hair Bulb | Deepest end of the hair follicle, sensory nerve endings wrap around this, bending of the hair stimulates these nerve endings. |
| Hair Matrix | Composed actively dividing epithelial cells (in the hair bulb) that produces the hair |
| Root hair plexus | Collection of sensory nerve endings |
| Hair Papilla | Contains capillaries that supplies nutrients tot he hair, sends chemical signals to stimulate cell division and production of new hair cells |
| 3 pigments that contribute to skin color | Melanin, Carotene, Hemoglobin |
| Functions of the Integumentary System | Protection, body temperature regulation (sweat glands), Cutaneous Sensation (sense of feeling), Metabolic functions (producing vitamin d), Reservoir for blood (by sweating), Execretion |
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