Rucete ✏ Biology In a Nutshell
1. Breakdown by Enzymes
- Starches → glucose
- Proteins → amino acids
- Fats/Lipids → glycerol and fatty acids
- Nucleic acids → nucleotides
2. Digestion Pathway
a) Mouth
- Salivary glands secrete amylase, which begins starch digestion.
b) Pharynx
- Connects mouth to esophagus.
c) Esophagus
- Moves food to stomach via peristalsis (muscle contractions).
d) Stomach
- Produces gastric juice (including HCl and pepsin)
- Functions: storage, mixing, mechanical and chemical digestion, and controlled release of contents
e) Small Intestine
- Site of digestion and absorption
- Sections: duodenum, jejunum, ileum
- Enzymes: proteases, aminopeptidase, maltase, lactase
- Structures: villi and microvilli absorb nutrients
- Receives digestive enzymes from:
- Pancreas: trypsin, chymotrypsin, lipase, pancreatic amylase
- Liver: produces bile (emulsifies fat, not an enzyme)
f) Large Intestine
- Parts: cecum, colon, rectum
- Functions:
- Reabsorption of water
- Formation of solid feces
- Houses beneficial bacteria
3. Digestive Hormones
- Gastrin: Stimulates gastric juice secretion
- Secretin: Stimulates pancreas to produce bicarbonate; liver to produce bile
- Cholecystokinin (CCK): Stimulates gallbladder to release bile; pancreas to release enzymes
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Biology in a nutshell