Mouth and Associated Organs – Digestive System Organs (Nursing)

00:00 Now, let's take a look at the physiology of the different organs of the digestive system starting with the mouth.

00:08 The mouth is where our food is chewed and mix with enzyme containing saliva that will begin the process of digestion.

00:16 And also where the process of swallowing is initiated.

00:21 Other organs associated with the mouth include the tongue, the salivary glands and the teeth.

00:29 If we start with the tongue the tongue occupies, the floor of the mouth and is composed of interlacing bundles of skeletal muscles.

00:38 Functions of the tongue include gripping, repositioning and mixing of our food during chewing, the formation of a bolus, which is a mixture of food and saliva, and also the initiation of swallowing as well as speech and taste.

00:57 The tongue contains intrinsic muscles which change the shape of the tongue and extrinsic muscles which are responsible for altering the tongues position.

01:08 Underneath the tongue, we have the lingual frenulum, which is the attachment of the tongue to the floor of the mouth.

01:17 The next associated organs of the tongue are the salivary glands.

01:21 There are three major salivary glands found in the mouth.

01:26 We have the parotid gland which is anterior to the ear and external to the masseter muscles.

01:33 The parotid ducts leave the parotid gland and open into the oral vestibule next to the second upper molar teeth.

01:43 Next we have the submandibular gland.

01:47 This one is medial to the body of the mandible and it's ducts open at the base of the lingual frenulum under the tongue.

01:57 Then we have the sublingual gland.

02:00 This is anterior to the submandibular gland under the tongue and opens by way of 10 to 12 Ducks into the floor of the mouth.

02:13 The salivary glands are going to secrete saliva into the mouth.

02:18 The function of that saliva is to cleanse the mouth, dissolve food chemicals for taste, moisten the food and compact it into a food bolus and also begin the breakdown of starches with an enzyme that they release known as amylase.

02:38 Most of our saliva is going to be produced by the major salivary glands that are located outside of the oral cavity.

02:45 The ones that we just discussed.

02:47 But as well, we also have some minor salivary glands scattered throughout our oral cavity that are going to augment the amount of saliva in our mouths just slightly.

03:00 So what is our saliva made of? Most of our saliva contains water.

03:06 So our saliva is extremely hypo osmotic with 97 to 99.5% of it being water.

03:16 The pH of our saliva is slightly acidic with a pH of about 6.75-7.00.

03:24 Within our saliva, we also have some electrolytes including sodium, potassium, chloride, phosphate ions, and bicarbonate ions.

03:36 Another important element of our saliva is the enzymes, salivary amylase as well as lingual lipase.

03:45 Amylase is going to break down carbohydrates while lingual lipase which is mostly found in babies is going to begin the breakdown of some fats.

03:56 Other proteins found in our saliva include mucin, lysozyme and IGA.

04:03 These usually have more of an immune function.

04:07 Also contained in our saliva our metabolic waste including urea and uric acid.

04:14 The lysozyme, the IGA, as well as defensins and nitric oxide from nitrates in our food are going to help us protect ourselves against microorganisms that may try to enter our bodies through the mouth.

04:30 Some of these are found in our saliva.

04:34 So how do we control salivation.

04:38 First we produce about 1,500 milliliters per day of saliva.

04:44 The minor glands those minor salivary glands found all throughout our oral cavity, or going to continuously keep our mouths moist throughout the day.

04:56 Those major salivary glands, however are going to be activated by the parasympathetic nervous system.

05:03 They're activated when food is ingested and this is going to stimulate chemoreceptors and mechanoreceptors in the mouth.

05:13 Also strong sympathetic stimulation is goingto inhibit salivation and is going to result in dry mouth also known as xerostomia.

05:25 The smell or sight of food or an upset GI tract can also act as stimuli for the production of saliva.

05:36 The next associated organ of the mouth are the teeth.

05:41 These lie in sockets and our gum covered margins of the mandible and maxilla.

05:48 The teeth are going to be responsible for the process of mastication or chewing, that tears and grinds our food into smaller fragments.

05:59 The arrangement of the teeth and the mouth is referred to as dentition.

06:05 Primary dentition when you are first born consists of 20 deciduous teeth or milk, or baby teeth, that are going to erupt between the age of six months and 24 months.

06:19 Underneath the deciduous teeth.

06:22 There are 32 deep-lying permanent teeth that enlarge and develop while the roots of the milk teeth are reabsorbed from below.

06:32 Once this happens, this causes the milk teeth to become loose and eventually fall out.

06:38 This process usually occurs between the ages of 6 and 12 years.