Digestion Physiology

8/8/2019 Digestion Physiology

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Digestion, involving physical and chemicalbreakdown of food particles, happensthrough the alimentary canal and utilizes

various enzymes from various accessoryorgans to digestion. Such enzymes exhibitsspecificity and works under particulartemperature and pH values; these variables

are critical to maintaining the enzymesstructure which affects the digestion ofspecific food particle.


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High temperature may destabilize the

tertiary to quaternary structure of the

enzyme, or simply called itsdenaturation.

Low temperature, on the other hand,may inhibit catalytic activity for it

reduces the total kinetic energy of the

enzymes.


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The pH levels are critical also for the

enzymes require or work most efficiently

under the certain pH level wherein theycan maintain their tertiary to quaternary

structures.


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Protein receives primary digestion in the

stomach with the gastric juice working

on them pepsin is the more specificenzyme digesting the protein. Protein is

finally broken down into its simplest form

in the small intestine with a long list of

enzymes.


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Lipids or fats are the hardest to digest

because of their nature hydrophobic.

Fat digestion first occurs in the stomachwith lipase. However, same with the

other biomolecules, fats are digested in

the small intestine further into its smallest

simplest form with bile salts released byliver by the action of CCK hormone.


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The materials used in this part of the

exercise were egg white and pepsin.

Egg white was used because itcharacteristically composed of proteinmolecules Albumin making it a good

source of protein in ones diet. Pepsin

was used for it is the enzyme acting onprotein and is produced by chief cells ofstomach and HCl for activation.


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Five test tubes were obtained from thestockroom and labeled P1 to P5. Oneach was placed a small piece of hard-boiled egg white. The followingsubstances were added:

P1: pepsin + water

P2: pepsin +HCl

P3: pepsin + HCl in ice bath

P4: water +HClP5: pepsin + NaOH


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Each test tube, except P3, was

subjected to water bath incubation

under37C for 90 minutes and resultswere recorded as to whether changes in

color occurred or not and whether the

egg white slice was digested or not.


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The materials used in this part of theexercise were cream, bile salts, water,and pancreatin.

Cream was used in experiment for it iscomposed of non-water-soluble lipids or

fats.

Bile salts were used for this is the enzyme

acting on lipids. It is produced in liverand concentrated in gall bladder beforereleasing to the small intestine. Releaseof bile salts is triggered by CCK hormone


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Incubation in water bath was utilized to

inspect digestion as it happens on

certain temperature requirement.Variations in temperature may affect the

total digestive process.


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Three test tubes were obtained from thestockroom and labeled F1 to F3. 3.0 ml creamwas placed in each tube. The followingdesignated substances were added:

F1: 5.0 ml distilled water + bile saltsF2: pancreatin solution

F3: pancreatin + bile salts

Each tube was shook vigorously to mix thecontents. Afterwards, pH of each substance ineach test tube were recorded and served as

initial pH. The tubes were then subjected towater bath incubation under37C for onehour. Recording of pH measurements wasdone at 20-minute intervals. Results weretabulated


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Set-up TheoreticalResults

P1-

P2 ++++

P3 -

P4 +

P5 _


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Theoretically, P1, P3, and P5 will not be

observed to digest the slices of egg

white. In P4, digestion would be

observed, while in P2, digestion would bevery obvious. P2 and P3 contained the

same chemicals, but P3 was put in an

ice bath that inhibited digestion as

opposed to the thorough digestion thathappened in P2.


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Set-up and a

few grains of

bile salts

Initial After 20

minutes of

incubation

After 40

minutes of

incubation

After 60

minutes of

incubation

F1(Distilled water and a few grainsof bile salts)

7.88

7.86

7.8

2 7.86

F2(pancreatin solution)

7.29 6.90 6.77 6.79

F3(pancreatin solution and a few

grains of bile salts)

7.29 7.05 6.63 7.16


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There is a general trend of decreasing

pH through time. Theoretically, the pH

levels in the three test tubes would alldecrease unlike the recorded values in

F1. Moreover, F3 should exhibit the

greatest decrease in pH level and not by

F2. Following F3 would be F2 and then F1which should only exhibit a slight

decrease in pH level.


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Proteins only start to be digested once it

enters the stomach where the gastric

juices are produced resulting in a low pHlevel. Pepsin, along with HCl in the

stomach, are the primary substances

that breaks down Proteins. Further

digestion takes place as the proteins aretransported into the small intestines

wherein various enzymes act upon it.


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In this experiment, the digestive

capacity HCl and Pepsin towards

Protein, represented by the egg white,was tested. Active digestion of the egg

white would be manifested by its color

changes and decrease in overall size

after the activity.


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Digestion of Triglycerides or Fats is usually thelast process to take place. This is due to thehydrophobic property of fats that gives themthe tendency to aggregate in large droplets.The water-soluble property of the digestive

enzymes all the more makes the entire processharder because it lessens the contact betweenfat and water. Thus, the fat molecules shouldbe broken down into monomers or simplerforms in order for its nutrients to be absorbed,

for instance, by the bloodstream. There are alot of substances involved in these processesand their functions are affected by certainfactors such as temperature and pH.


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After the initial pH measurements, thetubes were incubated in a 37C water bathand their pH levels were measured inintervals of 20 minutes. Comparing thevalues gathered after the first interval tothose gathered initially, there is anobservable decrease in the pH levels. Thisdecreasing trend would continue tomanifest as the time of incubation prolongs.This pH level lowering shows the progressivedigestion of triglycerides. It demonstratesthat the more the substances pancreatinand bile salts act on the triglyceride, themore it lowers the pH level of the solution.Also, the combination of the salts and thepancreatin demonstrated the mosteffective breakdown of the triglycerides

thus exhibiting the lowest initial pH and thehighest drop of the succeeding pH levels.

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Digestion Physiology