Applied Phytotherapeutics I Skin Deep By Terry Willard ClH, PhD; Todd Caldecott ClH Lesson 7 – Integumentary System Skin Deep: The Integumentary System and Botanical Medicine Introduction The Skin is the largest organ in the body and takes up considerable attention by many people. Our skin is the interface between the internal structures of our body and environments. It is also an interface between our consciousness and the world, through expression, and adornments. The psychological relationship a person has with their skin can be quite complex. It is often wrapped up in ones own self-image. When we refer to the skin, we are referring to a group of tissues that make up the integumentary system. Of all the body organs, none is more easily assessed in a clinical environment than the skin. The skin is derived from the embryonic ectoderm, as is the nervous system, and thus many skin conditions are partially influenced by the underlying state of the nervous system. In Ayurvedic medicine skin relates to the sensation of touch (sparsha) and the element of wind (vayu), the latter of which forms the humoral division of vata, which functions to control the nervous system. Thus the correlation between the skin and the nervous system in Ayurvedic medicine bears remarkable similarity to the scientific concept that the skin and nervous tissue are similar tissues. In the formation and ongoing regeneration of skin however, Ayurvedic medicine considers the skin to be derived from blood, in much the same that milk when heated forms a scum on its surface. Blood is primarily a nutrient delivery and waste removal system, and is routed through the spleen and liver to be filtered. Borrowing from the analogy of Ayurvedic medicine, many skin disorders are thus thought to arise from “bad blood,” which is treated by promoting and normalizing spleen and liver function. The skin also tells us about the state of blood circulation and the oxygenation of tissues, and a bluish skin color, for ©2011 Wild Rose College of Natural Healing 1 All Rights Reserved. Applied Phytotherapeutics I Skin Deep By Terry Willard ClH, PhD; Todd Caldecott ClH Lesson 7 – Integumentary System example, may be an indicator of heart failure. As a protection agent the skin has many jobs, from simple mechanical injury, to attacks by bacteria, fungi, viruses and parasites. The skins pigment provides protection from the sun’s ultraviolet radiation. To this we must remind ourselves that it is one of the major elimination organs, with sweating and the sloughing off of dead skin cells. The skin also plays a role in temperature regulations. The skin serves as a primary sensory organ. The five major sensation that the skin (and nerves) can react to are: touch, pain, heat, cold and pressure. There are other sensations, like vibration that can be seen as composites of these basic sensations. I. Anatomy of skin Information on the Integumentary System can be found in previous courses you have taken, or in your mandatory text: Principles of Anatomy & Physiology by Tortora and Grabowski. T h e s k i n c o v e r s a b o u t 2 ©2011 Wild Rose College of Natural Healing 2 All Rights Reserved. Applied Phytotherapeutics I Skin Deep By Terry Willard ClH, PhD; Todd Caldecott ClH Lesson 7 – Integumentary System square meters of body tissue, weighing about 4.5-5 kg, and ranging in thickness from 0.5 to 4 cm. It is comprised of two principle parts, the epidermis and the dermis. Beneath the dermis is the subcutaneous tissue or hypodermis, that in turn is attached to the underlying connective tissue. The epidermis The epidermis is composed of stratified squamous epithelium, and contains four principal cell types: Keratinocytes: protein keratin, waterproofs and protects, desmosomes. Melanocytes: pigment called melanin, protects the underlying tissues from UV radiation. Langerhans cells: arise from bone marrow and migrate to the epidermis, interact with helper T cells, easily damaged by UV radiation. Merkel cell: deepest layer of the epidermis (stratum basale) in hairless skin, make contact with sensory neuron endings, functioning in the sense of touch. There are five layers of epidermis, and from deepest to superficial, they are the: Stratum basale: a single layer cuboidal cells that contain stem cells capable of continued cell division, and melanocytes. Stratum spinosum: containing 8-10 rows of tightly packed polyhedral cells with spine-like projections. Long projections of melanocytes extend among the keratinocytes, which take in melanin by phagocytosis. Stratum granulosum: consisting of 3-5 layers of flattened cells that are undergoing apoptosis (cell death), contain keratohyalin, precursor of keratin, in various stages of degeneration. Stratum lucidum: consisting of 5 rows of flat, clear dead cells that contain intermediate substances between keratohyalin and keratin, thickened skin of palms and feet have this layer. Stratum corneum: consisting of 25 - 30 layers of flat dead cells completely filled with keratin, and are an effective barrier against water, microbes, heat and UV radiation. ©2011 Wild Rose College of Natural Healing 3 All Rights Reserved. Applied Phytotherapeutics I Skin Deep By Terry Willard ClH, PhD; Todd Caldecott ClH Lesson 7 – Integumentary System Epidermal growth factor (EGF) is a protein hormone that stimulates growth of epithelial and epidermal cells during tissue development, repair and renewal. Certain kinds of proto-cancer genes called oncogenes can cause tumors by permanently activating EGF, which then causes epidermal cells to proliferate out of control. The Dermis The dermis is composed of connective tissue containing collagen and elastic fibers, and certain cells such as macrophages, fibroblasts and adipocytes. The dermis is thickest in the soles and palms, and thin in the eyelids, penis and scrotum. Generally it is thicker on dorsal and lateral aspects of the body, rather than on the ventral and medial parts of the body. Outer portion of the dermis is the papillary region: areolar connective tissue, fine elastic fibers, surface area increased by the dermal papillae, fingerlike projections that indent the overlying epidermis, contain loops of capillaries and a few corpuscles of touch, nerve endings sensitive to touch, produces the characteristic ridges seen in fingerprints. Deepest portion of the dermis is called the reticular region: dense irregular tissue, interlaced bundles of collagen and coarse elastic fibers, provides skin with strength, extensibility and elasticity, small tears occur with stretching are called striae, or stretch marks. Subcutaneous layer: lamellated corpuscles, nerve endings sensitive to pressure and cold are located just below the dermal layer, and those that are sensitive to heat are located in the medial and superficial regions of the dermis. Skin Colour There are three pigments found in the skin: melanin, carotene and hemoglobin. Melanin is produced by melanocytes, most abundantly in the mucous membranes, penis, areola, nipples, breasts, face and extremities, number of melanocytes is the same in all people, and the difference in skin colour is relative to the amount of melanin produced synthesized by melanocytes from tyrosine by the enzyme tyrosinase in an organelle called a melanosome, exposure ©2011 Wild Rose College of Natural Healing 4 All Rights Reserved. Applied Phytotherapeutics I Skin Deep By Terry Willard ClH, PhD; Todd Caldecott ClH Lesson 7 – Integumentary System to UV radiation increases the enzymatic activity of tyrosinase, and as a result, stimulates the production of melanin, tanning. Carotene: is a yellow-orange pigment found in such foods as carrots and egg yolks, precursor of vitamin A, Asian descent carotene is also present in stratum corneum, fatty areas of dermis and subcutaneous layer, giving Asian skin its characteristic yellowish hue. Hemoglobin: pigment contained within red blood cells, Caucasian skin is mostly translucent, due to the small amount of melanin, blood within the capillaries of dermis provides the characteristic pinkish-red colour of Caucasian skin. Albinism is an inherited defect, inability to produce the enzyme tyrosinase. Vitiligo is a disease in which there is a complete loss of melanocytes in the areas affected, producing a pattern of white blotches on the skin. Epidermal Ridges Epidermal ridges are ridges and grooves on the digits of fingers and toes, appearing as a series of straight lines or a pattern of loops and whorls. By the third or fourth month of fetal development the developing epidermis conforms to the underlying structure of the dermal papillae. One of the functions of epidermal ridges is to increase grip of the hand and foot by friction, by acting as tiny suction cups. Epidermal ridges are genetically determined and are lifelong: it is thought that each individual has a unique pattern, which is the basis of using fingerprints in criminology. III. Accessory skin structures Accessory structures in skin include hair, nails and glands. Hair: or pili, projections of epidermis, growth and distribution is largely determined by location, sex, genes, and hormonal activity, protects against UV radiation, decreases heat loss, guards against foreign particles. Normal hair loss is between 70-100 hairs per day, rate of replacement is dependent upon illness, surgery, diet, fever, blood loss, emotional stress, severe weight loss, chemotherapy and childbirth. Glands: sudoriferous (eccrine and apocrine), sebaceous (oil glands), mammary glands and cerminous glands. Perspiration: watery substance produced by eccrine glands, water, salts (mostly NaCl), urea, uric acid, ©2011 Wild Rose College of Natural Healing 5 All Rights Reserved. Applied Phytotherapeutics I Skin Deep By Terry Willard ClH, PhD; Todd Caldecott ClH Lesson 7 – Integumentary System ammonia, sugar, lactic acid, and ascorbic acid, cooling mechanism and in the elimination of wastes. Ceruminous glands: modified sweat gland that produces cerumen (ear wax) in auditory canal. Nails: tightly packed keratinized cells, forming a clear covering; nail body, free edge, nail, lanula, or moon, nail matrix, eponychium or cuticle occupies the margin of the nail, ability to grasp objects and for protection shield.