in this video we're going to examine salivary glands and saliva so saliva functions uh saliva has four main functions that is it helps to sort of uh lubric lubricate and clean the mouth it's involved in dissolving food chemicals so that you have the ability to taste via the taste buds that are found on the tongue it moistens the food and in conjunction with the tongue it forms this ball of food called a bolus and within the saliva you have several enzymes enzymes which begin the breakdown of polysaccharides like starch into um smaller sugars not necessarily monossaccharides um so we'll talk about those enzymes in a moment so when we look at the salivary glands there are two main groups the first group are known as the major salivary glands because they're involved in the production of the majority of the saliva so these salivary glands tend to lie outside of the oral cavity and there are three main major salivary glands the paritid the submandibular and the sublingual uh keep in mind that these are all sort of uh duplicates on either side of the oral cavity so then you have the minor salivary glands where their main purpose is to sort of augment um saliva secretion but they're not major producers so these all lie within the oral cavity an example would be glands called bucal glands that facilitate this process so when we look at the major salivary glands you have the paritid gland so this is going to be found just anterior to the ear so it has a sort of triangular uh sort of shape it's going to lie between the massitor muscle and the skin so the surface and throughout the paritid gland this is where you have cranial nerve uh your facial cranial nerve so any kind of surgery in and around the paritid gland can impact that particular nerve and lead to facial paralysis so the paritid gland its duct is going to sort of run parallel to the zygomatic process remember that those bone hallmarks and it's going to deposit um the content into the oral vestibule so remember the oral vestibule is between between your lip and your teeth so just in that particular region there uh and then the medical condition MS it's a particular virus uh is an inflammation of the paritid gland and it can be transferred via saliva so next we look at the submandibular gland and as its name implies it's below the mandible so it's actually medial to the body of the mandible and its duct is going to deposit salivary secretions at the base of the lingu frenulum so remember that's little piece of flesh that kind of connects the um tongue to the the floor of the mouth um and then our third major salivary gland is the sublingual gland which is just anterior to the submandibular and it's found under the tongue and there are about uh 10 to 12 ducts that will deposit saliva into uh the floor of the mouth so then when we look at the salivary glands in total there are major two major types of secretary cells found in the salivary glands so here we have hisytological sections of them there are the cirrus cells and the cirrus cells they're primarily involved in the secretion of the watery saliva that contains enzymes ions and a little bit of the protein mucin then you have the mucus cells and as their name implies their major role is to produce mucus so when we look at the three major glands the paritid and the submandibular these are going to be involved uh mostly as cirrus secretary cells so the saliva the watery saliva that you know and then the sublingu gland is going to be mostly mucus so when we examine then the composition of saliva saliva is going to be mostly composed of water its pH is slightly on the acidic side but not overly so so it's just below a pH of 7 so about 6.5ish it's going to contain several electrolytes so a lot of the composition will be similar to extracellular fluid so it's going to contain some sodium potassium phosphate and bicarbonate ion which helps to neutralize materials that are coming in there are two main enzymes that are going to be secreted into saliva the first is salivary amala and this is going to facilitate the breakdown of complex carbohydrates and you have lingu lipase which begins the breakdown of lipids now although these enzymes are secreted into saliva the enzymes become really active in the lower pH environment of the stomach we also contain metabolic waste products in the saliva ura so remember ura is a penetrating solute so all your secretions are going to have ura you have uh antimicrobial uh elements so IgA this is a class of antibbody uh that can promote a what we call an adaptive immune response and then you have the antimicrobial proteins lysosyme this actually targets certain bacteria called gram positive bacteria uh it targets the synthesis of their cell wall so it weakens their cell wall and causes osmotic lis of those particular bacteria and then you have defensins and cyanide containing compounds that facilitate the destruction of certain uh microbial elements keep in mind that in the oral cavity there are actually over 500 different species of bacteria um just a sort of a little side note one of those uh bacteria is strepto caucus mutans and this is the bacteria that's going to coat teeth uh that leads to sort of tartar formation and then all the other bacteria can then adhere to your teeth and of these bacteria they are in the genus lactobacillus so they produce lactic acid and it's that acid that helps to break down tooth enamel so lots of salivation uh helps to flush away bacteria this is why uh for example you might give chew treats to your dog if you're not constantly brushing their teeth that salivation is going to sort of flush away some of these potential um uh tooth destroying uh bacteria so with regards to salivation we produce about one and a half lers of saliva a day and so one of its functions is to sort of keep the mouth moist uh the control systems that are involved are primarily going to be nervous system so again the control systems are primarily going to be nervous system specifically the branch of the nervous system is the parasympathetic nervous system so uh recall we've kind of uh mentioned the parasympathetic in previous videos it's part of the autonomic nervous system and the two main branches of the autonomic nervous system are the sympathetic which is the fightor-flight response usually when you're physically active and then you have the parasympathetic which is usually active when you're kind of just sitting and kind of chilling so it makes sense that sitting and chilling digestion the parasympathetic uh nervous system is going to be the one primarily controlling the salivary glands and so what is the trigger that's going to stimulate um salivation uh certain ingested food items will stimulate chemo receptors so these are certain chemicals uh that will be initiating a signal as well as stretch receptors or what we call mechano receptors so that's for stretch um that's going to uh send signals now within the nuclei in the brain stem so these are clusters of neurons they're going to send impulses along the parasympathetic fibers and specifically it's going to be cranial nerves and although we're not focusing on it in this class but the facial cranial nerve which runs sort of where the paritid glands are and facial uh so that's cranial nerve number seven and then cranial nerve number nine also known as the glossoparangal will control um salivation now to stop salivation or to inhibit salivation that's going to be the sympathetic stimulation if you're overstimulating the sympathetic this can lead to dry mouth