There are many muscles in our body but the one muscle that controls an entire sense would be the tongue, along with it, the sense taste.
There are many capabilities of the tongue and one of them is to frenchkiss
Ok, that is really besides the point. anyway as I was saying, the tongue has many functions and one of its most important function would be the ability to taste the stuff that we put into our mouth(may be food or may not be...you are what you eat..) Of course there is peristalsis, pushing the food into the gullet, but we're talking about the taste of food, what is better than to learn about how you taste those heavenly foods!
First of all, an introduction to the structure of the tongue!
Majority of the tastebuds sit on PAPILLAE protruding out of the tongue. There are a total of four papillae on the surface of the human tongue.
-FUNGIFORM PAPILLAE:Slightly mushroomed in shape. Present mostly on the apex(tip)of the tongue and at the sides.
-FILIFORM PAPILLAE:Thin, long "V-shaped" cones that don't contain tastebuds but are the most numerous
-FOLIATE PAPILLAE:Ridges and grooves towards the posterior part of the tongue found on lateral margins.
-CIRCUMVALLATE PAPILLAE:Only about 3-14 of these papillae on most people and they are present at the back of the oral part of the tongue. They are arranged in a circular-shaped row at the back of the tongue.
Upclose on the different papillae
There are currently 5 known and recognised taste sensations. The five are - sour(as in like a lemon), salty(like soya sauce or dark sauce) , these two work with ion channels, then there are bitter(like when you eat medicine), sweet(honey and sugar) and lastly umami(which gives a feeling of richness like cheese, also known as savory,these tastes work with a signal through a G-protein coupled receptor.
Each taste bud is flask-like in shape, its broad base resting on the corium, and its neck opening by an orifice, the gustatory pore, between the cells of the epithelium. The bud is formed by two kinds of cells: supporting cells and gustatory cells.Each taste bud is flask-like in shape, its broad base resting on the corium, and its neck opening by an orifice, the gustatory pore, between the cells of the epithelium.
The bud is formed by two kinds of cells: supporting cells and gustatory cells.The supporting (sustentacular) cells are mostly arranged like the staves of a cask, and form an outer envelope for the bud. Some, however, are found in the interior of the bud between the gustatory cells.The gustatory (taste) cells, a chemoreceptor, occupy the central portion of the bud; they are spindle-shaped, and each possesses a large spherical nucleus near the middle of the cell.
Now for the difficult part, how the tongue tells what taste it is tasting.
When a stimulus is detected, the response is triggered and the “resting” potential changes to the action potential.
While in resting potential, pumps in the neuron walls are constantly actively transporting 3Na+ ions out of the cell for every 2K+ ions that are pumped into the cell; this is accomplished by a structure known as a sodium-potassium pump. At the same time, an open ion gate is allowing K+ ions to flow down the concentration gradient back out of the neuron, while the ion gate for Na+ ions is closed.
Thus, more positive ions are leaving the cell than entering, and the inside of the cell has a negative charge.
When an action potential is triggered, Na+ ions start to enter the cell through a separate gate, increasing the charge in the cell. This in turn triggers the voltage regulated Na+ and K+ channels in the cell wall to change shape. This opens the Na+ channel and closes the K+ channel. Sodium ions rush down the concentration gradient into the cell, but potassium ions are unable to escape, thus the potential in the cell rises.
This potential in the cell causes other voltage regulated gates further down the cell to open, and the potential travels as a wave through the neuron.
After the potential has passed, the cell enters into a refractory period, to revert the potential to resting potential.
To travel from one neuron to the next, the action potential must pass through the synapse. As the action potential travels down the axon, it triggers voltage regulated gates which allow Ca2+ ions to flow into the neuron. From this point there are several different routes which can be taken. Sometimes, these ions cause two or more free-floating chemicals within the cell to bond and form a secondary messenger known as a neurotransmitter. This neurotransmitter is then released from the cell into the synapse through exocytosis, when the vesicle (a small bubble containing the neurotransmitter) they are in merges with the pre-synaptic membrane. The neurotransmitter then goes on to trigger the opening of Na+ ion channels in the post-synaptic membrane, which allows Na+ ions to flow into the dendrite of the next neuron, continuing the action potential.
Once the potential has been “passed on”, a different chemical causes the re-uptake of the neurotransmitter, breaking it down and returning it to the pre-synaptic neuron. Some neurotransmitters are acetylcholine, dopamine, serotonin, and GABA. The vesicle system of neurotransmitter release through exocytosis and return to pick up more neurotransmitter is known as the vesicle cycle and it involves, specifically, targeting, tethering, docking, release, membrane recovery and transmitter breakdown and vesicle recycling.
Ok, so that sounds like a mouthful, but it is basically saying that the change of concentration of ions causes gates to open which allow sodium ions to travel as an electrical wave down the sensory neurone. When met with a synapse at the end of the sensory neurone axon, the nerve impulse triggers gates to open which allow calcium to flow in. Sodium and calcium then attach themselves to free floating chemicals and bond as a secondary messenger, also known as a neurotransmitter. The neurotransmitter then triggers another gate to release more sodium ions to flow as electrical impulse to the next neuron and so on.
Thats about all how the tongue works in relation to the nervous system:D
