Term
| What are the derivatives of skin? |
|
Definition
| Hair, nails, sweat glands, and sebaceous glands. |
|
|
Term
| What are the functions of skin? |
|
Definition
| Protection (Uv light, dessication, physical injury), temp regulation (sweating and vascularity), synth of vit D, perception of external environment, and wound healing. Also functions as a source of iPS cells. |
|
|
Term
| What are the four types of cells found in epidermis? |
|
Definition
| keratinocytes, melanocytes, langerhans cells, and Merkel cells. |
|
|
Term
|
Definition
| It varies from .07mm to 1.4 mm in thickness. |
|
|
Term
| Where is thick skin located? |
|
Definition
| Palms of hands and soles of feet. |
|
|
Term
| What are the five layers of thick skin? |
|
Definition
| stratum basalis, stratim spinosum, stratum granulosum, stratum lucidum, stratum corneum. |
|
|
Term
| Describe the stratum basalis and when it is most active. |
|
Definition
| Also known as the germinativum, it is a single layer of columnar or cuboidal cells that are attached to the basement membrane by hemi-desmosomes and desmosomes. It is most mitotically active at night. site of stem cells |
|
|
Term
| What two elements does thin skin have that thick skin doesn't? |
|
Definition
| sebaceous glands and hairs. |
|
|
Term
| What is the stratum spinosum? Describe it. |
|
Definition
| It is several layers of polyhedral cells connected by desmosomes. There are bundles of cytokeratin filaments called tonofibrils. Can be mitotic by the basal aspect of this layer. lamellar granules (membrane coating granules)can be observed here. Spiny connections between cells. |
|
|
Term
| What is the stratum granulosum? Describe it. |
|
Definition
| It is the darkly pigmented layers of cells just above the stratum spinosum. There are 3-5 layers of cells with two types of granules. One is the keratohyalin granules that are not membrane-bound and are associated with tonofibrils. The other is membrane-coating granules which are more abundant in this type of cell. |
|
|
Term
| What happens at the s. granulosum layer to the cells and their surroundings? |
|
Definition
| They release lipid-rich content of membrane-coating granules and they start to destroy all organelles, including the nucleus. |
|
|
Term
| Where is the stratum lucidum found and what is it? |
|
Definition
| It is found in thick skin and is several layers of anucleate, flattened, eosinophilic cells located just above the s. granulosum layer. It is densely packed keratin filaments. |
|
|
Term
| What is the stratum corneum and where is it found? |
|
Definition
| It is the outer most layers of dead cells filled with keratin. These cells still have desmosomes located basally and the plasma membrane is thickened. |
|
|
Term
| What are the defining characteristics of thin skin? |
|
Definition
| Located everywhere else on body, has hair, sebaceous glands and eccrine glands. Usually has s. granulosum and no s. lucidum. |
|
|
Term
| What cell type produces pigment? Where are they located? |
|
Definition
| Melanocytes, derived from neural crest. Located in the basal layer of the epidermis and in hair follicles. |
|
|
Term
| What hormones are responsible for the process of melanization? |
|
Definition
| Tyrosinase is essential. Absence results in albinism. ACTH, beta-MSH, catecholamines, progesterone, estrogens, and thyroxine all affect pigmentation. Sunlight darkens existing melanin and melanin production increases. |
|
|
Term
| What three factors contribute to skin color? |
|
Definition
| carotene- yellow, oxyhemoglobin- reddish color in underlying dermal vascular bed, melanin- brown and black skin color and variation in size and shape of melanosomes. |
|
|
Term
| What are the two types of melanin? |
|
Definition
| Eumelanin- black and brown. Pheomelanin- red and yellow. |
|
|
Term
| What are langerhans cells, where are they, and what do they do? |
|
Definition
| They are macrophages found in the s. spinosum layer. They process and present antigens to T lymphocytes after migrating to lymph nodes. |
|
|
Term
| What types of cell junctions are in skin? |
|
Definition
| Desmosomes and hemidesmosomes in the basal lamina. Desmisomes and tonofibrils made of cytokeratin filaments. Desmosomes even in the s. corneum layer. |
|
|
Term
| What are Merkel cells? Where are they located? |
|
Definition
| located near strum basalis,thought to function as mechanoreceptors. they receive myelinated sensory nerve endings forming an expanded terminal disk and look like chromaffin cells of adrenal medulla. Attached to adjacent keratinocytes by desmosomes. |
|
|
Term
| How are the dermis and epidermis connected? |
|
Definition
| basal and reticular lamina, which form basement membrane. |
|
|
Term
| What are epidermal ridges (rete ridges)? |
|
Definition
| They are finger-like projections down into the dermis |
|
|
Term
| What are dermal papillae? |
|
Definition
| They projections of dermis into the epidermis. |
|
|
Term
| Where are keratohyalin granules and membrane-coating granules located? |
|
Definition
| in the stratum granulosum. |
|
|
Term
| What is the defining characteristic of stratum corneum? |
|
Definition
| keratin embedded in matrix derived from keratohyaline granules. |
|
|
Term
| what is bullous pemphigoid? |
|
Definition
| a disease that affects epidermal attachment to the dermis creating blisters. |
|
|
Term
| What is toxic epidermal necrolysis? |
|
Definition
| the entire epidermis is lost from a hypersensitivity reaction to a drug. |
|
|
Term
| Other types of blistering diseases? |
|
Definition
| antibodies specific to desmosome proteins cause a disruption of desmosomes. also there are diseases from mutations in epidermal cytokeratin genes. |
|
|
Term
| What embryologic layer is the dermis derived from? |
|
Definition
|
|
Term
| What is the dermis made of? |
|
Definition
| irregularly arranged, collagenous connective tissue with elastic fibers. Has lots of blood and lymphatic vessels and nerves. Hairs, sebaceous glands, and eccrine sweat glands arise from epidermis and and reside here. |
|
|
Term
| What are the functions of the dermis? |
|
Definition
| Wound healing, a barrier to infection, and mechanical strength. |
|
|
Term
| What are the two layers of the dermis? |
|
Definition
| papillary layer and reticular layer. |
|
|
Term
| What are some characteristics of the papillary layer of the dermis? |
|
Definition
| Composed of loose connective tissue with reticular fibers and elastic fibers. it also has anchoring fibrils made of type 7 collagen. capillary loops, nerves and sensory receptors are present. |
|
|
Term
| What are some of the characteristics of the reticular layer of the dermis? |
|
Definition
| dense, irregular ct, type 1 collagen and elastic fibers. The ground substance has glycosaminoglycans, - dermatan sulfate. |
|
|
Term
|
Definition
| Production of extra collagen and elastic fibers due to sun exposure. Makes skin look old and leathery. |
|
|
Term
| What vasculature is there in the dermis? |
|
Definition
| arterioles form subpapillary arteriolar network, which give rise to extensive papillary capillary network. Each hair follicle receives blood from the arteriole-capillary loop-venule system. Venules descend from papillary layer to form a sub-papillary venous network, in the papillary layer. Lots of arteriovenous shunts present for thermoregulation. Also has lots of lymphatic vessels. |
|
|
Term
| Dermis has lots of nerves located where? |
|
Definition
| sub-epithelial, papillary dermis, dermis, and sub cut layers. |
|
|
Term
| Dermis has lots of nerves located where? |
|
Definition
| sub-epithelial, papillary dermis, dermis, and sub cut layers. |
|
|
Term
| Where are Meissner's corpuscles found? |
|
Definition
|
|
Term
| Where are Pacinian corpuscles found? |
|
Definition
| deep dermis and hypodermis, vibration and pressure. |
|
|
Term
| What do the free nerve endings that terminate in the epidermis do? |
|
Definition
| perception of pain and temperature. |
|
|
Term
| Describe eccrine sweat glands |
|
Definition
| simple, unbranched, coiled, tubular glands- not found in lips, glans penis, clitoris, labia minora, and in the nail bed. Merocrine gland that secretes by exocytosis. Not associated with hair. Found in dermis or hypodermis. |
|
|
Term
|
Definition
Skin-specific autoimmune, chronic inflammatory
disease
• Excessive production and defective differentiation of
keratinocytes |
|
|
Term
| Where are melanocytes derived from? |
|
Definition
| Neural crest cells )similar to chromaffin cells) |
|
|
Term
| Describe the anatomy of an eccrine sweat gland. |
|
Definition
| secretory portion of gland is in dermis or hypodermis. The cuboidal secretory cells are surrounded by a prominent basement membrane. There are myoepithelial cells between basal lamina and secretory cells. Electrolyte content of secretion is similar to blood plasma, but most of the sodium, potassium, and chloride ions are absorbed by the cells in the duct. |
|
|
Term
| What are sweat glands innervated by? |
|
Definition
| Sympathetic cholinergic fibers. |
|
|
Term
| Where are apocrine sweat glands found? |
|
Definition
| They are found with hair follicles in the axilla, anogenital region, and areola. |
|
|
Term
| What type of secretion mode does an apocrine sweat gland use? |
|
Definition
|
|
Term
| Describe the secretion of an apocrine sweat gland (mmm... yummy) |
|
Definition
|
|
Term
| describe the anatomy of an apocrine sweat gland. |
|
Definition
| The secretory portion is a single layer of cuboidal or columnar epithelium resting on myoepithelial cells and a basement membrane. The lumen of the secretory unit is wide, but there is a narrow lumen in the secretory duct. The secretory duct is lined by stratified cuboidal epithelium and opens on to the hair follicle, just above the sebaceous duct. |
|
|
Term
| Where are glands of Moll found and what are they? |
|
Definition
| they are specialized apocrine sweat glands found in the eyelids. |
|
|
Term
| What are ceruminous glands and where are they? |
|
Definition
| Specialized apocrine sweat glands found in the ear canal. |
|
|
Term
| Where are sebaceous glands and what do they do? |
|
Definition
| Found in association with hair. They secrete oily substance via holocrine secretion. These bad boys cause acne when blocked. They are not found on the hands, soles, and dorsum of feet. |
|
|
Term
| Describe the anatomy of a sebaceous sweat gland. |
|
Definition
| simple, branched, acinar glands whose ducts are lined with stratified squamous eptithelium that is continuous with the external root sheath of the hair follicle. Analogous to preen glands on birds. |
|
|
Term
| What is a Meibomian gland? |
|
Definition
| specialized sebaceous gland in the eyelid. |
|
|
Term
| What is a pilosebaceous unit? |
|
Definition
| It consists of a hair, a sebaceous gland, and an erector pili muscle. Hair is fused keratinocytes produced in follicles. |
|
|
Term
| What is the process of melanin formation? |
|
Definition
| Tyrosine + (tyrosinase)> dopa> dopaquinone> Eumelanin and pheomelanin |
|
|
Term
|
Definition
| It is when melanocytes are lost due to stress of damage and cannot regenerate. Leads to white spots in skin. |
|
|
Term
| Where are Langerhans cells found? |
|
Definition
|
|
Term
| What is innervated by sensory nerves and what is innervated by sympathetic nerves? |
|
Definition
|
|
