Procedure 3 Time to Trace! Now its time to put all of the digestive anatomy and

Question

Procedure 3 Time to Trace! Now its time to put all of the digestive anatomy and physiology together to get a "big picture" view of the digestive system. In this procedure you will trace the pathways of three different nutrients from their ingestion at the mouth to their arrival in the blood or lymph. You will trace a cookie (primarily carbohydrates), an egg (primarily protein), and greasy fried food (primarily lipids). Along the way, detail the following for each: 1. The anatomical pathuwy cach takes from ingestion through its passage through the alimentary canal to its absorption into the blood or lymph. 2. The physical and chemical processes that break down each substance, including enzymatic breakdown, churning chewing, and emulsification. Some bints: 1 Remember that digestion and absorprion are quite different for lipids. For exampl fats are not absorbed into the same structures as proteins and carbohydrates. 1 Use the text in this exercise for reference about the enzymes involved in the chemical digestion of cach nutrient. Tracing Steps 1 Cookie: Start: mouth - bloo

Explanation / Answer

1) Cookie / Carbohydrate

ANATOMICAL PHYSICAL CHEMICAL mouth mastication salivary amylase breaksdown starch (cookie) /polysaccharides into oligosaccarides

esophagus peristalsis no digestion

stomach churning movement of stomach digestion inhibited by acidic gastric juice

small intestine ------ digestion occurs by enzymes pancreatic amylase and salivary amylase

oligosaccharides into trisaccharides ( maltotriose ) + disaccharides ( maltose ) + dextrins

Sucrase acts on sucrose and breaksdown into glucose and fructose

Lactase acts on lactose and breaksdown it into glucose and galactose

These smallest by products of carbohydrate digestion are then assimilated and transported across the intestinal mucosa into the blood cappilaries and hence blood .

2) EGG

protein digestion begins in the stomach

stomach : gastric juice contains pepsin which cleaves protein into polypeptides .

small intestine : polypeptide is digested by proteolitic enzyme of pancreas and intestinal mucosa .

trypsinogen is activated by enterokinase into trypsin enzyme .

trypsin further activates chymotrypsinogen into chymotrypsin and carboxypeptidases enzyme . they break smaller peptides into amino acids whiuch is the transported to blood .

3)fat digestion starts in mouth by lingual lipase . most digestion occurs in duodenum .

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