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The Digestive System
The Digestive System
provides nutrients for body survivalFUNCTION
provides nutrients for body survival
Digestion breaking down of food into simpler particles
(nutrients).
via
Absorption intake of nutrients
Nutrients
Nutrients
• Carbohydrates —> made of monosaccharides
Nutrients
• Carbohydrates —> made of monosaccharides
• Lipids —> made of fatty acids
Nutrients
• Carbohydrates —> made of monosaccharides
• Lipids —> made of fatty acids
• Proteins —> made of amino acids
Nutrients
• Carbohydrates —> made of monosaccharides
• Lipids —> made of fatty acids
• Proteins —> made of amino acids
• Vitamins
Nutrients
• Carbohydrates —> made of monosaccharides
• Lipids —> made of fatty acids
• Proteins —> made of amino acids
• Vitamins
• Minerals
Nutrients• Carbohydrates —> made of monosaccharides
• Lipids —> made of fatty acids
• Proteins —> made of amino acids
• Vitamins
• Minerals
• Water
Structure of the digestive system
long tube running from your mouth to your bottom
(anus).
MouthKEYWORDS:
- First tract - Chew (teeth) , wet (saliva)
Saliva contains two important enzymes:
- ptyalin that begins the breaking down of carbohydrates.
- lysozyme which has a defensive function of killing harmful bacteria.
The chewed and insalivated food is called food bolus.
Tongue
KEYWORDS:
- Voluntary muscle - Helps - Chemoceptors —> chemical receptors
Tongue
No tongue map exists! It’s a wrong translation coming from an article written in 1901 by Dr. Hänig
Pharynx
KEYWORDS: - Second tract - Epiglottis, fold - Respiratory tract - Involuntary
EsophagusKEYWORDS:
- Connects pharynx to stomach - Peristalsis, “toothpaste”
- Bolus—> chyme - Mucus vs. auto digestion
thickenings
StomachKEYWORDS:
- Bag - Gastric juice —> protein digestion (hydrochloric acid HCl + pepsinogen/pepsin) - Cleavage
proteolisis = activation
KEYWORDS: - 7.5 - 8.0 m long - Digestion and absorption
gut-intestine-bowel
SMALL INTESTINE: - 6.5 m long
- duodenum - jejunum - ileum
LARGE INTESTINE: - 1.5 m long
- cecum - colon - rectum
Duodenum
Mild activity
enzymes
STRONG activity
enzymes
Inside the duodenum chyme is definitely decomposed by enzymes: - amylases for carbohydrates, - proteases for proteins, and - lipases for lipids.
produced in the pancreas as inactive
(proenzymes)
become active here thanks to
proteolisis
accumulates bile (gall) that facilitates lipid digestion
Absorption
• once the chyme passes through duodenum it becomes the chyle.
• nutrients in the chyle are absorbed in the small intestine.
Absorption
AbsorptionKEYWORDS:
- villi = projections of the tube - increase in size to 250-300 m2
- blood vessels
Large intestine• absorbs water from what remains of chyle.
• forms the feces.
• recently its role has been revised. We now think that it represents a microenvironment essential for mutualistic microorganism proliferation.
Microbiota• community of microorganisms in the large
bowel.
Rectum• Rectum is the last part of the large intestine
and stores feces before they are expelled.
