Sebaceous Glands and Sweat Glands

‭Sebaceous Glands and Sweat Glands‬ ‭ ‬‭There is the sebaceous gland but‬‭most of the time‬‭these sebaceous glands are attached to the‬ ✪ ‭hair but sometimes we can find sebaceous glands independent of any hair formation. These g‬ ‭sebaceous moors are very variable in number (up to 100 /cm² at the level of the face and up to 400‬ ‭at the forehead, scalp). These sebaceous glands are absent in hairless skin. This sebaceous gland‬ ‭derives from an area, from a bud of the outer epithelial sheath of the follicle and these glands‬ ‭appear early in intrauterine life and are functional in the fetus.‬ ‭ This an acinar alveolar gland which has a secretion modality which is Holocrine, which means‬ ✪ ‭that the entire cell is the product of secretion therefore in the secretory part: the alveoli are made up‬ ‭of so-called sebaceous cells which go accumulate different types of products, which will‬ ‭hypertrophy then burst, so these are the debris from these cells +the product that has been‬ ‭developed which is called sebum and all that forms a secretion which is evacuated at the level of the‬ ‭hair by an excretory canal which is very short so on the diagram, we see the sebaceous gland with a‬ ‭very short excretory canal, there are the alveoli made up of these sebaceous cells which explode and‬ ‭the product goes be routed through this excretory canal of the hair and therefore will serve to‬ ‭lubricate the hair and the skin.‬ ‭ These are lipids, debris cellular, it protects the epidermis, it forms a sort of thread superficial and‬ ✪ ‭sometimes there is a hypersecretion of this sebum (mixture of lipid, debris) and this hypersecretion‬ ‭is the Seborrhea and this secretion is directly linked to sexual hormones, i.e. to testosterone in men‬ ‭and to androgens which are secreted by the ovaries and by the adrenal gland in women, therefore‬ ‭regulation, control by testosterone and androgens.‬ ‭ ‬‭The sweat glands or sweat glands.‬ ✪ ‭There are 2 categories: apocrine glands and eccrine glands.‬ ‭ -‬ 1 ‭The so-called glands‬‭cases‬‭are found on all the surface‬‭of the skin but are much more‬ ‭numerous on the palms of the hands and the soles of the feet and this are tubular glands which‬ ‭produce sweat, tubular because its a tube at the end of which there is a secretory structure which is‬ ‭the glomerulus which is more or less coiled and which contains a united epithelium stratified with‬ ‭dark cells which contain the grains of secretion and clear cells which do not do not contain. A‬ ‭unistratified epithelium and myoepithelial cells which will intervene when they contract to expel‬ ‭cells their content. This glomerulus is located in the dermis and there is an excretory duct which is‬ ‭very long and very narrow.passes through the dermis and the epidermis: when it passes through the‬ ‭dermis it has a wall own therefore an unstratified epithelium with cubic cells but when it crosses the‬ ‭epidermis it loses its own wall and in fact these are the keratinocytes of the epidermis which serve‬ ‭as its wall. If we take the diagram about the hair follicle, we see the sweat gland with the secretory‬ ‭part with the glomerulus and the excretory duct in the dermis with a clean wall which disappears.‬ ‭And this channel will open laughing at the surface level of the epidermis through a pore. The‬ ‭secretion is merocrine so it is secreted by exocytosis. In fact it is an ultrafiltrate containing water,‬ ‭electrolytes which constitute a kind of sweat primitive which is modified in the sense that certain‬ ‭electrolytes are reabsorbed at the level of the epithelial cells of the excretory tube so there is an‬ ‭initial elaboration by the glomerulus which is in fact a simple transfer of water so it constitutes the‬ p‭ rimitive sweat, a dialysis to from the plasma and at the level of the excretory channel reabsorption‬ ‭of certain electrolytes and therefore the result is that the final sweat which contains water, NACL,‬ ‭potassium etc. A definitive sweat which is hypotonic compared to plasma. The secretion of sweat‬ ‭(the sweating) is controlled by thermoregulatory structures located in the hypothalamus and‬ ‭therefore it is these neurons which will control, when the ambient temperature is higher than that of‬ ‭the body, which controls the vasodilation of the capillary networks and this Vasodilation will cause‬ ‭the increase in the production of primary sweat then sweat and the elimination of water through‬ ‭sweat is the only way to reduce body heat. This elimination is important because of the order of‬ ‭600ml/day. All sweat glands, boxes do not operate at the same time but are all under the control of‬ ‭the hypothalamus.‬ ‭ -‬ 2 ‭The other category of sweat glands are the‬‭so-called‬‭apocrine glands‬‭. The term apocrine is‬ ‭improper because in fact they are also glands whose production, secretion is merocrine by‬ ‭exocytosis. They are different from the previous ones because they do not elaborate the sweat but‬ ‭produce a secretion which is milky, opaque, alkaline. The structure is approximately the same with‬ ‭a glomerulus located in the deep dermis or hypodermis and an excretory duct. The difference‬ ‭compared to the previous ones is that they are located in territories particular : anogenital, inguinal,‬ ‭axillary and other than the excretory duct is in the sheath of the hair and not isolated from the hair‬ ‭as was the excretory duct of the eccrine gland. It is also a so-called sweat gland but with a different‬ ‭secretion, a excretory duct with different locations and apocrine glands which are located in‬ ‭different and very specific skin territories.‬