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What's in sweat? (Holocrine, Apocrine, Merocrine Glands)

Video transcript
- So to continue our discussion of appendages I'll come to this palm side right here and so I'll draw this little water droplet to indicate this person has a very sweaty palm and the reason why it's so sweaty is because this guy has a lot of sweat glands so a lot of sweat glands that are on his palm or maybe elsewhere in his body. And as I mentioned in an earlier video our glands are situated in the reticular dermis. They're in the reticular dermis and they have ducts that lead out into the external environment to help coat our skin with their secretions. And now we have three types of glands that exist in our skin. They are called the holocrine gland. There's the apocrine gland and finally the merocrine gland. So I'll kind of compare and contrast them here The first thing to realize is that the way we name these types of glands indicate how they release their secretions. The holocrine gland releases its secretions by disintegrating the whole cell So the entire cell breaks down to release what's called sebum, sebum, and so another name for holocrine glands are sebaceous glands sebaceous because they release sebum. Now apocrine glands release secretions from the apex of the cell or the top of the cell breaks off So the top of your cell breaks off to release a mixture of proteins, lipids, and steroids so proteins, lipids, and steroids so a whole bunch of things right here And finally merocrine secretion or merocrine glands release their secretions which is mostly the watery sweat we think of these are the main sweat glands we talk about they release watery sweat by a process you may be familiar with it's called exocytosis. That's the budding off of the cell membrane with contents from inside the cell which in this case would just be watery salty contents that would be sweat. Now it's got a little more room right here and talk about where each of these types of sweat glands are found. Holocrine sweat glands are found on the face, the chest, and the back, the face, the chest, and the back. It looks like I didn't write it here but I want to make sure you know that sebum is mostly an oily substance so it's more lipid concentrated than say something you're apocrine secretions so it's very oily and now your apocrine glands are mostly concentrated in your armpits, the groin, and around the nipples the armpits, the groin, and around the nipples and the main thing here that's unique about the apocrine sweat glands is that they release their contents into the hair follicle so they release their contents into the hair follicle which is unique from the other types of sweat glands we're talking about and then finally our merocrine glands which are our bread and butter sweat glands, are found literally everywhere else everywhere else in the body and they're mostly concentrated in our palms of our hands like with this guy up here. palms in our hands and even the sols of our feet our palms and our soles and then finally what are the functions of these three types of glands. Well for our holocrine or our sebaceous glands this oily or lipid-rich sebum is meant to lubricate the skin so it lubricates our skin and in doing so that also slows bacterial growth so it slows bacterial growth by making it difficult for bacteria to move around and divide. So slows bacteria growth. Now for apocrine glands the interesting thing about them is that they even don't really begin to release secretions until after puberty hits. until after puberty and the reason why could be better understood when we talk about animals because apocrine glands in animals release things like pheromones and warning signals and even territorial marking signs that we don't really practice as human beings. So the interesting thing about apocrine glands is that they're involved in what's called emotional sweating emotional sweating and they're an ongoing topic of research emotional sweating meaning that these glands are most active during times of great anxiety stress, fear, and even pain. And finally our merocrine glands are actually I'd say our most important glands because they help us cool down through evaporative cooling we talk about that in a separate video so they help us cool down with our sweat. They help us eliminate waste products as well. so any extra nitrogenous waste products that we might have or water or electrolytes we don't need we release through our merocrine glands in our sweat and finally merocrine glands also release things like lysozymes lysozymes which are enzymes that will lyse bacteria and even antibodies which are immunologic proteins so antibodies that will help tag bacteria and other foreign pathogens or bad stuff that could cause damage to our skin and our bodies tag these things for elimination. So your sweat is far more important than just cooling you down. It even helps your livelihood in addition to all the other things we talked about here So there's a lot going on when we talk about our glands and the rest of the appendages we've appreciated here.