Where Are Fats Digested?
We really do need to fear the fat. Not only is it bad for cholesterol levels, but can lead to obesity and even diabetes. We’ve all heard of essential fatty acids, but what about the others? More importantly, where are they digested?
Fats come with different numbers of carbon atoms in their chain molecules. Those that have an odd number (like the one shown below) are called ‘odd chain fats’ or simply ‘fatty acids. They are often joined together to make bigger molecules, glycerol (3 fatty acids joined together) and triglycerides (3 glycerols).
The chain can be anywhere from 2-12 carbon atoms long. If there’s only one pair of hydrogen atoms at the end, it’s called ‘monounsaturated’. There can also be two or three pairs of hydrogen atoms attached instead of just one. This makes it ‘polyunsaturated’ (many hydrogens).
Odd chain fats are used in many ways around the body, but not for energy unless all proteins have been used up first. They’re mostly broken down into simpler molecules before being absorbed.
They may be converted into glucose or ketones by cells that need extra energy to survive, such as brain cells. Ketones are also made from the breakdown of odd chain fats when carbohydrate food sources have been exhausted.
Fats are mainly absorbed in the small intestine. Some are also taken up in the stomach when it’s empty, but most get absorbed in the tiny intestine (the part that starts after the stomach).
Some odd chain fats will be used for energy if there isn’t enough carbohydrate around. Most fatty acids may be stored as fat droplets called triglycerides (3 glycerols joined together) inside special cells. Triglycerides stay inside these cells until they’re needed. They can store a lot of fatty acids very compactly.
where does digestion of fat take place in our body:
Mostly the digestion of fat takes place in the small intestine.
-Digestion of fat involves the joining together (fusion) of two smaller molecules to make a larger molecule called a diacylglycerol. The small intestine is the main site for this process, but some fats are digested in other parts of the body as well.
what starts the breakdown of food:
The first step in digestion takes place when our taste buds recognize and respond to certain chemicals (called “substrates”) with which they come into contact. For example, we sense that something is sweet because it triggers receptors that detect sugar molecules.
We know that something has protein because it stimulates chemoreceptors that bind to amino acids and peptides. Other substrates call forth different kinds of receptor activity and induce the brain to undertake a variety of actions, such as the secretion of enzymes and acid in saliva or gastric juice in the stomach.
The overall process begins when we see, smell, taste, or otherwise sense something we put into our mouths. This step is called “sensing” (and is sometimes called “recognition”). The substances involved may be solid (like bread) or liquid (like milk). They can be natural products (like oranges) or they can be man-made ones (like soft drinks), even those that are artificially flavored to resemble natural foods.
These external sensitizers prompt us to start chewing automatically. When the food starts to break down physically under the influence of this mechanical action, its chemical identity is revealed. Digestion begins.
The salivary glands are particularly important because they provide the initial step in digestion. Saliva, a fluid made by the salivary glands, moistens food and makes it easier for us to swallow. It also contains an enzyme called amylase that starts breaking down starches into sugars as soon as we put saliva-moistened food into our mouths.
An acidic fluid secreted by other cells in the gland travels directly through ducts and empties into our mouth to begin neutralizing and washing away any food particles and debris leftover from chewing or biting the tongue or cheeks during eating.
An additional enzyme called lingual lipase is secreted by some of the cells in the gland and travels directly through the second set of ducts to reach our mouth, where it begins breaking down fat.
digestion is the chemical breakdown of food into smaller components that can be absorbed into the blood or lymphatic capillary from the alimentary canal:-
The small intestine is lined with epithelial cells that are responsible for secreting those substances required for digestion. In between those secretions have formed the products of digestion, which must now be absorbed before they can pass out of the intestine—into either a vein or one of its many tributaries (small blood vessels). The large intestine completes this process by collecting whatever remains after absorption and returning it as feces to the anus for elimination from the body.
what breaks down fat in the body:
The cells lining the small intestine are covered with many tiny hairlike projections called villi. The fat in food is absorbed through the walls of these villi, which absorb it into the bloodstream.
This occurs for all other types of macromolecules absorbed by the intestinal wall as well—carbohydrates (starches and sugars), proteins (including amino acids), vitamins, minerals, and water-soluble ions like sodium.
The difference between fats, carbohydrates, and proteins is that fats can be broken down only after they’ve been absorbed; carbohydrates and proteins can begin to be broken down directly via enzymes before they enter the blood or lymphatic capillaries.
Digestion starts outside our body’s cells and continues inside them. The process begins by secreting enzymes that function only in the specific environments provided by our stomach and small intestine; then, once those substances reach their sites of action (the mitochondria), they break down chemical bonds within otherwise indigestible molecules like fats, starches, and proteins.
The digestive tract is composed primarily of smooth muscles located between the sheets of connective tissue septa; these fibers contract under the influence of nerves to propel food along its course and also to mix ingested material with digestive juices secreted from glands scattered throughout this system.
salivary glands secretion mainly contains enzymes:
Saliva itself consists primarily of water mixed with mucus, electrolytes (substances that carry electrical charges), and the enzyme amylase. Amylase begins breaking down starches into sugars as soon as we put saliva-moistened food into our mouths. Although we can’t taste these substances, they’re responsible for the flavor of many foods. Saliva also contains a chemical called lysozyme that inhibits bacterial growth (we’ve all heard stories about people who drowned by swallowing their own saliva).
fat digestion enzyme:
A mixture of lipase and bile is secreted by glands in the small intestine. Fatty acids and monoglycerides are split into glycerol and fatty acids, which pass through the intestinal wall into nearby capillaries (tiny blood vessels). These substances will remain free to pass out of these cells for as long as they’re surrounded by water; but if they happen to encounter a fat-free layer of fluid—as would occur during absorption or filtration—they can be reabsorbed regardless of their chemical properties, including whether they should be absorbed.
digestion:- The first major stage of indigestion occurs when we swallow saliva; we literally bathe our food with this specialized fluid before it enters our stomach. Saliva contains the enzyme amylase, which breaks down large molecules of starch into smaller ones that can be further broken down by hydrochloric acid in the stomach.
other enzymes secreted by salivary glands:
Saliva also contains lysozyme, an antibacterial enzyme. Small numbers of organisms may get past the mouth’s defenses and mingle with food particles to start small colonies, but lysozyme inhibits the growth of these invaders.
There are three steps in fat digestion:
Fat digestion begins outside our body’s cells and continues inside them. The process starts when the surface area of a bolus (chewed mass of food) is greatly increased by grinding between upper and lower teeth—a process we call chewing or mastication. The bolus is then pushed into the mouth by the movement of the tongue and palate, where it’s bathed in saliva containing enzymes that begin to break down fats, starches, and proteins.
A mixture of lipase and bile is secreted by glands in our small intestine. Lipase breaks down large molecules called triglycerides into smaller ones called fatty acids and monoglycerides; these substances pass through intestinal cells into nearby capillaries (tiny blood vessels).
These substances will remain free to pass out of these cells for as long as they’re surrounded by water, but if they happen to encounter a fat-free layer of fluid—as would occur during absorption or filtration—they can be reabsorbed regardless of their chemical properties, including whether they should be absorbed.
A small percentage of triglycerides can pass through intestinal cells on their own, but more often fatty acids and monoglycerides are taken up by the same cells that absorbed dietary fats.
Many triglycerides are too large to fit into these cells; in this case, they must be broken down further before they can enter the bloodstream. Once inside blood vessels, fatty acids are combined with oxygen atoms to create carbon dioxide (which we exhale) and water (which enters our blood).
Monoglycerides are reformed into particles called chylomicrons, which contain some combination of triglyceride, cholesterol, and protein. Chylomicrons pass through intestinal cells and enter larger blood vessels where they’re eventually broken down to release chylomicron remnants and unabsorbed triglycerides into the bloodstream.