DIGESTIVE SYSTEM
1. Introduc on
The diges ve system is responsible for breaking down food into simpler nutrients
that can be absorbed and u lized by the body.
It consists of the alimentary canal and accessory organs.
2. Main Func ons
1. Inges on – intake of food.
2. Diges on – mechanical and chemical breakdown of food.
3. Absorp on – nutrients absorbed into blood/lymph.
4. Assimila on – nutrients used by body cells.
5. Eges on – removal of undigested waste.
3. Organs of the Diges ve System
A. Alimentary Canal (also called gastrointes nal tract – GI tract)
Length: ~9 meters
1. Mouth (Buccal Cavity)
Food intake occurs here.
Teeth – mechanical diges on (chewing)
Saliva (from salivary glands) contains salivary amylase (ptyalin) → breaks starch into
maltose.
Tongue – helps in mixing food and swallowing.
2. Pharynx
Common passage for food and air.
Leads food to esophagus.
3. Esophagus (Food Pipe)
Muscular tube that transports food from pharynx to stomach by peristalsis.
, No diges on occurs here.
4. Stomach
J-shaped muscular organ.
Func ons:
o Churns food (mechanical diges on)
o Releases gastric juice (contains:
HCl – kills bacteria, ac vates pepsin.
Pepsin – breaks proteins into peptones.
Mucus – protects stomach lining)
5. Small Intes ne
Main site of diges on and absorp on
Length: ~6 meters
Divided into:
o Duodenum – receives bile and pancrea c juice.
o Jejunum
o Ileum
Enzymes from intes nal glands, pancreas, and bile aid diges on.
Villi and microvilli increase surface area for absorp on.
6. Large Intes ne
Absorbs water and minerals.
No diges on occurs here.
Parts:
o Cecum
o Colon
o Rectum
Stores waste un l defeca on.
7. Anus
Opening for removal of undigested waste as feces.
1. Introduc on
The diges ve system is responsible for breaking down food into simpler nutrients
that can be absorbed and u lized by the body.
It consists of the alimentary canal and accessory organs.
2. Main Func ons
1. Inges on – intake of food.
2. Diges on – mechanical and chemical breakdown of food.
3. Absorp on – nutrients absorbed into blood/lymph.
4. Assimila on – nutrients used by body cells.
5. Eges on – removal of undigested waste.
3. Organs of the Diges ve System
A. Alimentary Canal (also called gastrointes nal tract – GI tract)
Length: ~9 meters
1. Mouth (Buccal Cavity)
Food intake occurs here.
Teeth – mechanical diges on (chewing)
Saliva (from salivary glands) contains salivary amylase (ptyalin) → breaks starch into
maltose.
Tongue – helps in mixing food and swallowing.
2. Pharynx
Common passage for food and air.
Leads food to esophagus.
3. Esophagus (Food Pipe)
Muscular tube that transports food from pharynx to stomach by peristalsis.
, No diges on occurs here.
4. Stomach
J-shaped muscular organ.
Func ons:
o Churns food (mechanical diges on)
o Releases gastric juice (contains:
HCl – kills bacteria, ac vates pepsin.
Pepsin – breaks proteins into peptones.
Mucus – protects stomach lining)
5. Small Intes ne
Main site of diges on and absorp on
Length: ~6 meters
Divided into:
o Duodenum – receives bile and pancrea c juice.
o Jejunum
o Ileum
Enzymes from intes nal glands, pancreas, and bile aid diges on.
Villi and microvilli increase surface area for absorp on.
6. Large Intes ne
Absorbs water and minerals.
No diges on occurs here.
Parts:
o Cecum
o Colon
o Rectum
Stores waste un l defeca on.
7. Anus
Opening for removal of undigested waste as feces.
