physiology of digestion - copy

8/7/2019 Physiology of Digestion - Copy

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Introduction

The digestive system is a portal for nutrients from the

environment to gain access to the circulatory system. Before

such transfer can occur, foodstuffs first have to be reduced to

very simple molecules by a combination of physical and

mechanical digestion. The resulting sugars, amino acids,

fatty acids and the like are then transported across the

epithelium lining the intestine into blood.

Physical digestion refers to the grinding of large pieces of

food into tiny particles while chemical digestion describes

use of enzymes released into the digestive system to break

down large biopolymers into monomers or simple forms.


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A. Physical Digestion of Macromolecules


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Methodology

1. Stared and imagined how it tastes like

2. Smelled the aroma and imagined its

flavor

3. Took a bite and observed specific parts

of the mouth that ground the food.

Mouth should be as dry as possible before the experimentObservations from start to swallowing were taken note of


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Results and Discussion

- Salivate (brought by sight, smell,

taste)- Incisors, Canine, Pre-molar, Molar


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B. Chemical Digestion of Carbohydrates


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Methodology

C

1

C

2

C

3

C

4

C1: 3.0 ml distilled H2O

C2: 3.0 ml salivary amylase

C3: 3.0 ml salivary amylase with 10

drops HCl

C4: 3.0 ml salivary amylase

solution & place tube in boilingwater for 5 minutes

Added 5.0 ml of starch solution to each tube

and

incubated at 370C water bath for1 hour.


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Methodology

C

1

C

2

C

3

C

4

C

1

C

2

C

3

C

4

Check for the presence ofstarch.

(Lugols Test)

-Lugols iodine solution

-Blue to black: Starch is

present(+)

-Amber coloration (-)

Check for the presence of

maltose.

-(Benedicts test)

-5.0 ml Benedicts reagent

*place in boiling H2O for10 mins

-Green (small amts), Yellow

(moderate amts), Orange to Red

(large amts)


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Lugols Iodine (Lugols solution, 1829)

a solution of elemental iodine and potassium

iodide in water

consists of 5 g iodine (I2) and 10 g potassium

iodide (KI) mixed with 85 ml distilled water, to

make a brown solution with a total iodine content

of150 mg/mL.

Uses:

As an indicator test for the presence of starch in

organic compounds, with which it reacts byturning a dark blue/black. iodine interacts with

the coil structure of the polysaccharide.

An antiseptic and disinfectant


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Results and Discussion

LUGOLS TEST

C1: ++++

C2: +

C3: ++

C4: +++

*presence of starch in all test tubes; they only varied

with the amount of starch present.


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Benedicts Reagent

(Benedicts solution orBenedicts Test)

C1: + (remained blue)

C2: ++++

C3: ++

C4: +++

used as a test for the presence of reducing sugars, presence of

aldehyde, and alpha-hydroxy-ketones (e.g. fructose)

used to determine how much reducing sugar is present. contains blue copper(II) ions (Cu2+) which are reduced to copper(I)

(Cu+). These are precipitated as red copper(I) oxide which is

insoluble in water.


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EXPERIMENT OBSERVATION INTERFERENCE

Substance in water + 3ml

Benedicts solution, then boil for

few minutes and allow to cool

Red ppt or green ppt or yellow ppt

obtained

Reducing sugar e.g. Glucose is

present

Substance in water + 3ml

Benedicts solution, then boil for

few minutes and allow to cool

Solution remains clear Non-reducing sugar e.g. Sucrose is

present


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C. Chemical Digestion of Protein


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Methodology

P

1

P

2

P

3

P

4

P

5

Added 5 ml of pepsin toeach tube except P4

P1:10 drops of distilled

water

P2:10 drops of HCl

P3:10 drops of HCl and

put in ice bath

P4: 5 ml of distilled water

and 10 drops of HCl

P5:10 drops of NaOHIncubate all except P3 in 37oC

water bath for 90 mins


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Methodology

Examined egg whites slices in incubation.

Took note:

if any digestion occurred

any color change to the solution

* (+) digested with or without color change

* (-) not digested


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Results

Set-up Number Observation

P1 (pepsin and water) + fast (second)

P2 (pepsin and HCl) + fastest

P3 (pepsin and HCl on ice) + fast (third)

P4 (water and HCl) + slowest

P5 (pepsin and NaOH) - no digestion


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Discussion

Just like our stomach, test tube 2 is very acidic.

Therefore, its acidity caused the fastest

breakdown of protein in the egg white. HCl

somehow speeded up the digestive function ofpepsin.


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Temperature also affected the activity of theenzymes as test tube 3 (the one placed in an ice

bath) digested the egg white slower. Too high and

too low temperatures could disrupt an enzymes

function; a moderate temperature is required for

them to work efficiently.


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Test tube 1 followed because it does not contain

HCl that would catalyze pepsin. Test tube 4 ranks

fourth because HCl alone cannot breakdown

covalent bonds. Finally, the basic substance in testtube 5 adversely affected pepsin, completely

stopping its digestive function.


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D. Chemical Digestion of Triglycerides


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Methodology

F

1

F

2

F

3 3.0 ml of cream in each tube

F1: 5.0 distilled H2O + few grains of bile salt

F2: Pancreatin solution

F3: Pancreatin solution + few grains of bile salt

Shook.

Measured INITIAL PHIncubated tubes in 37o C water

bath for1 hour

Measured pH every 20, 40, and 60 minutes


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Results

EXPERIMENTAL

F1 F2 F3

START BASIC BASIC ACIDIC

20 minutes BASIC BASIC ACIDIC

40 minutes BASIC SLIGHTLY ACIDIC ACIDIC


THEORETICAL

F1 F2 F3

START BASIC BAS

IC AC

IDIC

20 minutes BASIC BASIC ACIDIC




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Discussion

Pancreatin

:mixture of digesting enzymes produced by the

pancreas, including amylase, lipase, and trypsin.

Bile salts

:negatively charged cholesterol derivatives

:amphipathic - both hydrophobic (lipid soluble) and

hydrophilic

:emulsification agents


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Lipids aggregate into large droplets minimizingthe surface area of contact between fat and

water.

Digestive enzymes are hydrophilic, only able to

digest molecules on the surface. Amphiphatic molecules break down fats droplets

to tiny emulsification droplets.

Lipases can come contact with the triglycerides

and hydrolyze them into amphiphatic free fattyacids and monoglycerides.


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Conclusion

For food to be utilized by the body, it must

first undergo a series of processes which we

call digestion. After we perform the only

really voluntary actions involved in theprocess of nutritionputting the food into our

mouths, chewing and swallowingthe

balance of the digestive process is the

function of the autonomic or involuntarynervous system.


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THE END.

February 15, 2010

physiology of digestion - copy

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