Question

Q5. Now we are going to trace the path nutrients take from their ingestion to their destination in the body. Along the way, make sure to include for each: the anatomical pathway taken in the digestive tract, where absorption of that nutrient occurs, the passageway it would take through the body to reach the heart, and the physical/chemical processes that would be used to break down each substance.

1. Trace the path of a cookie, which is composed primarily of carbohydrates, from ingestion to the heart.
2. Trace the path of an egg, which is composed primarily of protein, from ingestion to the heart.
3. Trace the path of greasy fried food, which is composed primarily of lipids, from ingestion to the heart.

Answer 1

A) Carbohydrates : Digestion of carbohydrares begin in the mouth, chewing of food breaks the food particles into smaller units,the saliva secreted from your salivary glands moistens food as it’s chewed, saliva releases an enzyme amylase which breaks down carbohydrates into simpler substance. The food than moves into the stomach, Minimal carbohydrate digestion occurs in the stomach due to the inactivation of amylase in the acidic environment, but however peristalitic movement of stomach mixes and churns the food with acid, at this stage the food is known as chyme, the chyme than enters the small intestine, where majority of digestion and absorption of carbohydrates takes place,Upon entry of the chyme into the small intestine, the pancreas releases pancreatic juice through a duct. This pancreatic juice contains the enzyme, pancreatic amylase, this enzyme breaks down chyme into dextrin and maltose, from there, the wall of the small intestine begins to make lactase, sucrase, and maltase. These enzymes break down the sugars even further into monosaccharides or single sugars.known as glucose.

The glucose is than absorbed from the small intestine into the blood stream, once glucose is in the bloodstream, pancreas release insulin hormone, which acts on glucose to push into the cells so that cells can use glucose as source of energy, some amount of remaining glucose is stored in the liver as glycogen, which releases glucose when the body needs it, for e.g during increased physical activity, some amount of glucose is stored in the skeletal muscles and adipose tissues, through the blood stream glucose is supplied to the heart and brain and all part of the body.

B) Proteins, In the mouth chewing action starts the mechanical breakdown of protein molecules, than moves into stomach, Once a protein source reaches your stomach, hydrochloric acid and enzymes called proteases break it down into smaller chains of amino acids. Amino acids are joined together by peptides, which are broken by proteases,than the food enters the small intestine wher majority of protein digestion takes place, The pancreas secretes digestive juice that contains more enzymes that further break down the protein fragments. The two major pancreatic enzymes that digest proteins are chymotrypsin and trypsin. The cells that line the small intestine release additional enzymes that finally break apart the smaller protein fragments into the individual amino acids. The muscle contractions of the small intestine mix and propel the digested proteins to the absorption sites. Protein absorption happens in your small intestine, which contains microvilli. These are small, finger-like structures that increase the absorptive surface area of your small intestine. This allows for maximum absorption of amino acids,.the amino acids are than released into the bloodstream and transported to different parts of the body.

C) The first step in the digestion of lipids begins in the mouth as lipids encounter saliva.Lipids go undigested in your digestive tract until they reach your small intestine, where they meet bile. Bile contains bile salts, which act as an emulsifier of lipids. This breaks the large fat droplets into smaller droplets that are then easier for the pancreatic lipase to digest, in small intestine lipids are broken down into fatty acids and glycerol molecules, than they are absorbed  by enterocytes via simple diffusion, and then take the same path as monosaccharides and amino acids into the blood stream.