2.3 human digestive system
TRANSCRIPT
Sistem Penghadaman Manusia
Alimentary canal
Mouth
Esophagus
Stomach
Duodenum
Small intestine
Large intestine
Rectum
Anus
Food (Rice) in mouth is chewed + Saliva
Food bolus move along esophagus
Arrived stomach-hold food, secretes gastric jus
Liver, released bile to emulsify fat
Duodenum-receive bile and pancreas jus
Small intestine-secretes intestinal juice-absorbed food into blood
Large intestine-formation faeces
Anus-remove faeces from body
Rectum-stored faeces
Process of Digestion
1. The digestive process involves breakdown of food from complex to simple form in the alimentary canal
2. Sequence in the digestive process:
Food
Ingestion
Physical and chemical digestion
Defecation
Absorption
Assimilation
Outside the body
Alimentary canal
Body cells and tissues
IngestionThe process of intake of food in solid/liquid forms into the alimentary canal.
DigestionPhysically and chemically in the digestive system.
Defecation Undigested food will be disposed
Absorption a.blood circulatory system b.lymphatic system
Assimilation In body cells :a.growth b.cellular respiration (to
release energy)
Process of digestion
Physical digestion Chemical digestion
-mechanical process -breaking down food into smaller particles
-using the teeth
-Action of various enzymes -The end products are simpler molecules which are soluble.
Digestion of carbohydrates starts in the mouth
Digestion of proteins starts in the stomach
Digestion of fats starts in the small intestine
Digestion of carbohydrates, proteins and fats ends in the small intestine
Amylase enzyme
Mouth
Starch molecules
Enzymes break down starch molecules
Glucose molecules
1. Digestion begins in the mouth.
2. The teeth chew and grind food into smaller particles
Saliva contains
amylase enzymemaltose, a type of sugar.
Starch
Enzyme amylase
maltoseAlkaline medium
Peristalsis
Inside esofhagus, no food digestion occurs
Peristalsis
Inside esophagus, no food digestion occurs
Peristalsis
Inside esophagus, no food digestion occurs
Peristalsis
Inside esophagus, no food digestion occurs
Peristalsis
Inside esophagus, no food digestion occurs
lumen
Wall constricts
wall dilates Direction of movement of food
food mass
Contraction of the wall of the digestive tract
The digested food is pushed to the stomach by the contraction and relaxation of the walls of the esophagus
The wave-like contraction of the esophagus muscles are known as peristalsis.
Date:
Experiment: 2.4
Aim: To test the action of salivary amylase on
starch
Diagram:
Procedure:
1.My mouth was rinsed with distilled water and
spat out.
2.My mouth was rinsed again with some distilled
and the water was spat into a beaker. The
saliva solution were collected.
3. 5 cm3 of starch solution were poured into a
test tube labeled P.
4. 5 cm3 of saliva solution were added to test
tube P.
5. The mixture was stirred with a glass rod. Test
tube P was placed into a water bath at 370C
and the stopwatch was started.
6. 2 cm3 of the mixture were poured from test
tube P into two separate test tubes immediately
7. The iodine test and Benedict’s test were carried out on the mixtures in the two separate
test tubes.
8. After 30 minutes, 2cm3 of the mixture were
poured from test tube P into two other test tubes and the iodine test and Benedict’s test were carried out on the mixtures again.
9. All my observations were recorded in the table.
Procedure:
1. Rinse your mouth
2. Rinse your mouth again and spit the water into the a beaker.
3. Pour 5cm3 of starch solution into test tube.
4. Add 5 cm3 of saliva solution to test tube.
5. Stir the mixture.
6. Place the test tube into the water bath. Start the stop watch.
7. After 2 minutes, pour 2cm3 of the mixture into two separate test tube.
8. Carry out the iodine test and Benedict’s test.
9. After 30 minutes, repeat steps 6 -7 again.
Food test At the beginning of the activity
At the end of the activity
Observation Inference Observation Inference
Iodine test
Benedict’s test
Observation:
Food test At the beginning of the activity
At the end of the activity
Observation Inference Observation Inference
Iodine test Dark-blue solution
Starch is present
Brown solution
Starch is absent
Benedict’s test
Blue solution
Glucose is absent
Brick-red precipitate
Glucose is present.
Observation:
Conclusion:
The enzyme in saliva breaks down starch to form _________
amylaseStarch maltose
Discussion:
1.Why must you rinse your mouth with distilled water before collecting the saliva solution?
-to ensure that the saliva does not contain sugar
2. Why must you place test tube P into the water bath at 370C?
-The optimum temperature for salivary amylase is 370C.
3. What effect did your saliva have on the starch solution?
- Saliva digested starch by changing it into sugar that gives a positive result to the Benedict’s test.
4. Variables:
i) Fixed : Temperature of water (370C)
ii) manipulated: presence of enzyme
iii) responding : presence of maltose
Digestion of proteins starts in the stomach
Digestion in stomach
1.The stomach - acts as a bag to store food
2. When food enters the stomach, the stomach wall will secrete gastric juice that contains:i) Hydrochloric acid,
ii)Enzyme pepsin
(a form of protease)
Functions of hydrochloric acid:i. Prevent food from decayingii.Kill bacteria that may be found in foodiii.Stop the action of salivary amylaseiv.Prepared an acidic medium
The stomach wall will secrete mucus to protect stomach tissue from corrosion by the hydrochloric acid.
pepsin enzyme
Proteins Polypeptides
Digestion of food in stomach takes about
2 – 4 hours.
Then food is sent from the
stomach to the small intestines in semi-solid form known as chyme.
Date:
Experiment: 2.5
Aim: Action of enzyme in the stomach on proteins
Hypothesis: Enzyme in the stomach can convert proteins into polypeptides (or peptones)
Variables:
i) Fixed : temperature of water bath (370C)
ii)Manipulated: presence of water
iii)Responding: presence of proteins
Procedure:
1.Four test tube were labelled as A, B, C, and D
2.The following mixtures were poured into each test tube:
Test tube Mixtures
A 1cm3 of egg albumin
2cm3 of pepsin solution
2cm3 of dilute hydrochloric acid
B 1cm3 of egg albumin
2cm3 of dilute hydrochloric acid
Test tube
mixtures
C 1cm3 of egg albumin
2cm3 of pepsin solution
2cm3 of distilled water
D 1cm3 of egg albumin
2cm3 of distilled water
3. Four test tube were then immersed in a water
bath at 370C for 2 hours.
4. Then the egg albumin in each test tube was observed.
Observations:
Conclusion:
In acidic state, the enzyme _______ will convert _______to _______(peptones)
-if the temperature of the water bath is too high, the pepsin and protein will be destroyed. This condition is called denaturalisation.
Test tube Observations
A Egg albumin has dissolved
B Egg albumin is still in the test tube
C Egg albumin is still in the test tube
D Egg albumin is still in the test tube