Digestive system and nutrition
Digestion – Mechanical and Chemical breakdown of foods and absorption of nutrients
- Mechanical: large pieces of food into smaller piece
- Chemical: breaking chemical bonds
Alimentary canal:
Muscular tube that passes through thoracic and abdominopelvic
cavities
Food passageway between mouth and anus
~8 meters long
Structure:
Mucosa
- The inner later of the wall
- Consists of epithelium, underlying connective tissue and a little of smooth muscle
- Carries on secretion and absorption of dietary nutrients
- In some regions, the mucosa is modified into folds or projections which increase SA
Submucosa
- Lies under mucosa
- Consists of loose connective tissue, housing blood and lymphatic vessels, nerve and
glands
- Nourishes the surrounding layers of the canal
- Vessel’s transport absorbed nutrients away from digestive organs
Muscularis
- Consists of 2 layers of smooth muscle
o Inner circular layer and outer longitudinal layer
- Propels food through the canal
Serosa
- Outer serous layer or visceral peritoneum
- Protects underlying tissues and secretes serous fluid to reduce friction between
organs
Movement of the tubes
- Mixing movement
o Occur when smooth muscles contract rhythmically in a small section of the
tube
o Segmentation in the small intestine aids mixing by alternately contracting
and relaxing the smooth muscle in each area
- Propelling movement
o Include a wavelike motion call peristalsis
o A portion of the tube will be contracted while relaxation occurs ahead of
the ring
Digestion – Mechanical and Chemical breakdown of foods and absorption of nutrients
- Mechanical: large pieces of food into smaller piece
- Chemical: breaking chemical bonds
Alimentary canal:
Muscular tube that passes through thoracic and abdominopelvic
cavities
Food passageway between mouth and anus
~8 meters long
Structure:
Mucosa
- The inner later of the wall
- Consists of epithelium, underlying connective tissue and a little of smooth muscle
- Carries on secretion and absorption of dietary nutrients
- In some regions, the mucosa is modified into folds or projections which increase SA
Submucosa
- Lies under mucosa
- Consists of loose connective tissue, housing blood and lymphatic vessels, nerve and
glands
- Nourishes the surrounding layers of the canal
- Vessel’s transport absorbed nutrients away from digestive organs
Muscularis
- Consists of 2 layers of smooth muscle
o Inner circular layer and outer longitudinal layer
- Propels food through the canal
Serosa
- Outer serous layer or visceral peritoneum
- Protects underlying tissues and secretes serous fluid to reduce friction between
organs
Movement of the tubes
- Mixing movement
o Occur when smooth muscles contract rhythmically in a small section of the
tube
o Segmentation in the small intestine aids mixing by alternately contracting
and relaxing the smooth muscle in each area
- Propelling movement
o Include a wavelike motion call peristalsis
o A portion of the tube will be contracted while relaxation occurs ahead of
the ring
