Gustation: Sense of Taste (Nursing)

00:02 The next sense that we're going to talk about is gustation or our sense of taste.

00:08 Like smell, taste is a chemical sense but it is much simpler than olfaction.

00:16 There are five primary tastes: sour, sweet, bitter, salt and umami which is like a meaty taste.

00:28 The taste buds contain receptors for the sensation of taste.

00:34 Approximately 10,000 taste buds are found on the tongue of a young adult and on the soft palate, pharynx and epiglottis.

00:44 The taste buds contain three different types of epithelial cells.

00:49 We have the supporting cells which are going to surround about 50 gustatory receptor cells.

00:57 These cells contain small hairs referred to as gustatory microvilli that project from the taste pore in the taste bud.

01:08 Within each taste bud, we also have basal cells.

01:12 These are stem cells that produce the supporting cells and these supporting cells will subsequently become our gustatory receptor cells.

01:24 In this image of the taste bud, notice the gustatory receptor cells which contain gustatory taste hairs that protrude from the taste pore toward the oral cavity.

01:37 And this is what is going to come in contact with our tastants.

01:42 Taste buds are located in elevations on the tongue called papillae.

01:47 There are three types of papillae that contain taste buds in our mouth First we had the vallate papillae which are located on the back of the tongue.

01:58 There about 12 of these papillae and each of them contains about 100 to 300 taste buds.

02:06 The other type of papillae is the fungiform papillae.

02:10 These are scattered all over the tongue with about five taste buds each.

02:16 On the lateral trenches of the tongue on the sides, we have our foliate papillae.

02:22 These are going to contain taste buds but most of them are going to degenerate in our early childhood.

02:30 A fourth type of papillae is the filiform papillae.

02:34 This covers the entire surface of the tongue.

02:39 These are going to be tactile papillae that do not contain any taste buds.

02:47 They are responsible for increasing friction which makes it easier for the tongue to move food within the mouth.

02:57 Tastants are going to stimulate the gustatory receptor cells at the microvilli found at the top of the taste pore.

03:07 Receptor potentials can arise from multiple routes.

03:11 One way that we can get a receptor potential is when a tastant enters directly into the receptor cell.

03:20 This is gonna to happen with the salty taste as well as the sour taste where sodium or H+ are able to enter into the gustatory cells.

03:32 Another way we get a receptor potential is when a tastant binds to a G protein-coupled receptor found in the membrane of the gustatory receptor cells.

03:43 This is how we taste taste such as sweet, bitter and umami.

03:50 The gustatory receptor cell can only respond to one type of tastant.

03:56 And each taste bud is going to contain different types of receptor cells so that we can interpret the different taste that come into our mouths.

04:07 In the gustatory pathway, the taste buds are innervated by three cranial nerves.

04:14 This includes the facial nerve which is going to carry taste information from the anterior two-thirds of the tongue.

04:22 The glossopharyngeal nerve is going to carry taste information from the posterior one-third of the tongue.

04:30 And the vagus nerve is going to be responsible for carrying taste information from taste buds located on the epiglottis and in the throat.

04:40 The nerve impulses propagated by these cranial nerves go to the gustatory nucleus of the medulla oblongata.

04:49 From there, some impulses can go to the limbic system in the hypothalamus and lead to our emotional response to certain taste and some go to the thalamus.

05:02 From the thalamus, they go to the primary gustatory area of the cerebral cortex and allows us to perceive and discriminate different tastes.