The Sense of Taste
Over the past few months we have looked at the various systems that collectively make up the human body. In the various systems we got a quick look at the various parts and what they do. Starting today, we are going to take a look at some of the different aspects and parts of the human body. As I contemplated on what to start with in the new stage in the series, I figured how best to wet your appetite than to start with the sense of taste.
In The Amazingly Designed Human Body – Part 10, we got a brief look at the tongue and its many parts, so if you need a reminder, please return to this installment.
The proper name for the sense of smell is ‘gustation’. Gustation, works in conjunction with the senses of smell and sight to help prevent us from eating things that are toxic, rotten and spoiled with bacteria.
On the surface of the tongue as well as along the roof of the mouth and top of the throat are a variety of papillae. The papillae vary is size, shape and location of the tongue. Taste receptors, more commonly referred to as taste buds, are clusters of 50 to 150 receptor cells located on the various papillae. Different receptor cells are designed to detect different tastes as chemicals penetrate the pores of the taste buds to reach them.
It is estimated that at birth, a person has about 10,000 taste buds. After you reach the age of fifty, the number of taste buds slowly decreases. In some people, the sense of taste has been so finely developed that they can detect the slightest differences in foods and drinks, such as wine, cheese and gourmet recipes.
There are five basic tastes detected by the receptor cells;
I. Bitter – Bitterness is considered to be the most sensitive of the tastes. It is characteristic of substances like quinine, coffee, unsweetened chocolate, beer, olives and similar type foods. Some people actually like bitter tasting foods while others find them very disagreeable.
A. Index – Quinine is the base standard for the bitterness index with a rating of 1.0. The most bitter substance known is denatonium with a bitterness index of 1,000. It is used as an additive to toxic substances to make them so bitter that they will not be ingested.
B. Mechanism – When someone ingests something that contains quinine, such as a lemon, the quinine binds to what is known as the G-protein in the receptor cells in the taste buds which triggers the bitter stimulus in the T2R taste receptor.
II. Salty – Saltiness is produced by the detection of sodium and potassium ions. There are other alkaline metals that can also taste salty.
A. Index – It is the sodium in table salt (sodium chloride – NaCl) that gives it the salty taste which is why the saltiness index of 1.0 is based upon sodium. Potassium as in potassium chloride (a common salt substitute) has an index of 0.6.
B. Mechanism – When something salty is consumed, the sodium or potassium ions are taken directly into the receptor cells. The influx of ions depolarizes the cells creating an action potential or current across the nerve synapses creating a salty sensation.
III. Sour – Sourness is generally defined as the detection of acids such as lemon juice and hydrochloric acid.
A. Index – Sourness is rated by an index that ranges from 0.1 to 1.0 with hydrochloric acid being 1.0, citric acid being rated at 0.46 and carbonic acid being only 0.06.
B. Mechanism – When you ingest something acidic like a lemon, the hydrogen ions are taken into the receptor cells creating a potential gradient that is interpreted as a sour taste.
IV. Sweet – Sweetness is the detection of the basic sugars such as sucrose and fructose.
A. Index – Sweetness also has a rating index with sucrose being rated at 1.0 and lactose (the sugar found in milk) at 0.3.
B. Mechanism – As you bite into that delicious chocolate bar, the sugar molecules bind to the G-protein coupled with the T1R1 and T1R3 receptors. This triggers a signal that is then interpreted as being sweet.
V. Umami – Umami is a distinctive taste that is described as a meaty or savory taste and comes from the Japanese word for ‘good taste’ or ‘deliciousness’. It can be found in foods like soy sauce, cheese, some grains and aged or fermented foods. It comes from the amino acid glutamate along with some ribonucleotides such inosinate and guarnylate.
A. Index – As far as I could find there is no index for umami taste as there is for the other four tastes.
B. Mechanism – When consuming something that contains glutamate, like a well aged cheese, the glutamate combines to the G-protein coupled T1R2 and T1R3 receptors. The resulting sensation, first described in 1908 by Dr. Kikunae Ideda as being the best taste one could experience.
Indeed, when we bite into a juicy steak, chocolate bar or sip a glass of wine, our taste buds go to work to help us enjoy the experience. At the same time, if you taste something not as pleasing such as the bitter herbs that were used at the time of Passover, your taste buds will help remind you of the bitterness the Hebrews experienced in the hands of their Egyptian masters for so many years.
Taste is something that most of us take for granted and really never think twice about. But when you examine the molecular and chemical make up of taste, it becomes apparent that it’s not just a simple thing after all.
I’ve often wondered how the sense of taste was supposed to have evolved in the first place. Yes it serves a purpose as a safety mechanism for us, but what would cause the first so-called primitive creatures to evolve the receptor cells in their mouths, and then consider that there are different types of receptor cells in the taste buds.
Taste is closely associated with the sense of smell, which will be discussed next week, and we have a number of references in Scripture that connect the two and may give us a clue as why God created the sense of taste and smell:
It is a burnt offering to the LORD. It is a pleasing aroma, a food offering to the LORD. Exodus 29:18
Then you shall take them from their hands and burn them on the altar on top of the burnt offering, as a pleasing aroma before the LORD. It is a food offering to the LORD. Exodus 29:25
The other lamb you shall offer at twilight, and shall offer with it a grain offering and its drink offering, as in the morning, for a pleasing aroma, a food offering to the LORD. Exodus 29:41
From interaction with their peers to the instruction and correction that they receive at home, children interpret their experience from a worldview that seeks to answer their fundamental questions: Who am I? What do I exist for? Where can I find joy?
As parents, we need to be providing our children with a consistent, persuasive, and biblical framework for understanding the world God has made and their place in it. The instruction that we provide for them should not only inform their mind; it should be directed towards persuading their hearts of the wisdom and truthfulness of Gods ways. We must impress truth on our children’s hearts, not to control or manage them, but to point them to the greatest joy and happiness that they can experiencedelighting in God and the goodness of his ways.
Instructing a Childs Heart is an essential follow-up to Tedd Tripp’s previous bestseller, Shepherding a Childs Heart. This book gives practical instruction aimed at helping parents instruct their children in ways that will persuade them of God’s wisdom. Instead of focusing solely on changing a child’s behavior, the authors help us to look at the heart of the child. Point your child toward the happiness they will find from doing things God’s way!
“This book brings the Bible into the parents’ lives in a fresh way. It is one thing to say that parents must use the Bible for parenting. It is another thing to show how that is actually done. Instructing a Child’s Heart provides practical, real life instruction on how to do just that.” John Younts (Author of Everyday Talk)
“Tedd and Margy Tripps Instructing a Childs Heart is a biblical and practical sequel to Shepherding a Childs Heart.” Marvin Olasky (Editor-in-Chief, WORLD Magazine)