Digestive enzymes Starch Protein s PROTEASE Lipids/ Fats AMYLASE LIPASE fatty acids glycerol amino acids maltos e
Jan 01, 2016
Digestive enzymes
Starch
Proteins PROTEASE
Lipids/ Fats
AMYLASE
LIPASE fatty acids &
glycerol
amino acids
maltose
identify and describe the main regions of alimentary
canal describe the functions of the
parts of the human gut and the associated organs
Pathway of Digestion in Alimentary Canal
Mouth ↓
Oesophagus↓
Stomach↓
Small Intestines↓
Large Intestines↓
Rectum↓
Anus
• Digestion is the process of breaking down complex, large molecules (food) into simple, soluble and diffusible molecules so that it can be absorbed by the body and be used to build and nourish cells and to provide energy.
Functions of digestive system:
(1) Ingestion: taking food into the body.(2) Digestion: breakdown of food materials
into smaller amounts (i) Mechanical digestion (ii) Chemical digestion
(3) Absorption(4) Assimilation(5) Egestion
Types of digestion:(i) Mechanical digestion• Break down particles into smaller pieces so as
to increase the surface area for the action of enzymes.
(ii) Chemical digestion• Involves enzymatic reactions which digest the
food into simpler chemical forms.• Hydrolysis splits the large molecules by addition
of water.
How is Food Digested? Mouth • Ingestion is the process of taking food
into the body. • The tongue rolls and lubricates food with
mucus and saliva. • Chemical digestion of starch starts here
by salivary amylase.
Oesophagus• It takes food down from the throat and
into the stomach. Moving food by waves of muscle contraction called peristalsis.
The oesophagus
Circular muscles contract to push the food ball down.
Circular muscles relax, and the tube widens for food to move.
The partially digested food is pushed to the stomach by wave-like contractions known as
peristalsis.
The stomach
stomach
Stomach• The stomach lining produces mucus and gastric juices
which contains:i) hydrochloric acid (acidic medium of pH 2 for
enzymes and kills micro-organisms in food)ii) Pepsin: hydrolyze protein to polypeptides.iii) Rennin: hydrolyze milk caseinogen to casein.
Quick Revision: What is the function of hydrochloric acid?
1) Provides an acidic medium for activation of gastric enzymes.
Inactive formsProrennin HCl RenninPepsinogen HCl Pepsin
2) Kills germs and potential parasites.3) Stop the action of salivary amylase.
Active forms
Dr. Jones, I am suffering from stomach cancer & half of my stomach was
removed. What should I do?
You should:• take multiple small meal at regular intervals, • take less protein per meal• clean and cook the food thoroughly……
Inflamed oesophagus This condition is due to
the irritation of the oesophagus that is
caused by too much stomach acid.
The Liver & Gall Bladder
A small pear-shaped organ that is greenish-yellow in colour.
Temporarily stores bile secreted by liver.
QUESTION:
Will bile secretion be hindered if the gall bladder is removed?
Liver and Gall Bladder
Pancreas
Small intestines
Large Intestines
Rectum and Anus
THE STRUCTURE & FUNCTIONS OF …
LIVER:
Largest gland in the body.
Lies below diaphragm, on right side of body.
Secretes bile.
QUESTION: Can bile digest food?
Bile is not an enzyme, so it cannot digest food but it aids in digestion of lipids.
The Pancreas
Connected to duodenum by pancreatic duct
Secretes pancreatic juice that contains digestive enzymes.
• Major site of chemical digestion of all remaining food (carbohydrates, fats and proteins).
• Also, main site of absorption of nutrients occur here.
Small Intestines (Duodenum, jejunum and ileum)