Smell V Taste

The sense of smell is important to us.   It helps us decide what foods we want to eat.   It tells us what is a pleasant smell and what maybe is a disgusting smell.
Smell can also help to warn us when there is danger such as gas escaping or of foods that have spoiled.   Smell can also tell us if someone was smoking or drinking.   Smell also makes us hungry when we get the scent of foods like barbeques and apple pie.
We know that dogs are use for tracking because of their high sense of smell.   Do yousometimes wonder if animals without noses are able to smell?   After doing some research the answer is yes in most cases.
Humans have five million olfactory receptor cells.   A rat has 20 million, a rabbit 20 million and a bloodhound 100 million.
Smell receptors deep in the nose bond to gas molecules from the air.   The receptors send electrical signals to the olfactory bulb, which signals the orbit frontal cortex, where the firing pattern reveals to the rest of the brain what smells nice or not so nice.   Different receptors are not required for each smell.
The ability to detect smells is best in childhood, plateaus from the teens through the 50s, and drops starting at about 60 for women, 5 for men.
People can tell the difference between 4000-10000 smells.   Bloodhounds can detect a smell at least 1000 times better than human.
Why do foods taste different?   The tongue and the roof of the mouth are covered with thousands of tiny taste buds.   When you eat something, the saliva in the mouth helps break down the food.   This causes the receptor cells   located in the taste buds to send message through sensory nerves to the brain which tells you what flavors you are tasting.
Taste buds can recognize for tastes: sweet, salty, sour, and bitter.   The salt/sweet taste buds are located near the front of tongue; the sour taste buds line the sides of the tongue; and the bitter taste buds are found at the very back of the tongue.   People have different tastes and tastes changes...