Biology: Human Physiology: Digestive System

Flussdiagrammknoten

• Alimentary Canal

• E S O P H A G U S ​​​

• STOMACH

• SMALL INTESTINE

• LARGE INTESTINE

• R E C T U M

• ANUS

• - Secretes gastric juice    - Digestive fluid mixes with the food - HCL breaks down food and exposes peptide bonds + kills most bacteria - Pepsin breaks peptide bonds  

• Chemical digestion: pepsin + HCL Mechanical digestion: peristalsis

• - Smooth muscles control - Controlled by autonomic nervous system - Two layers of muscle    - circular    - longitudinal - Movement of food = peristalsis

• - Digestion is completed here - Products are absorbed into the blood stream - Content enters the first part, where bile (from the gallbladder and liver) enters - The small intestine has villi which increases surface area

• - Main function is to reabsorb water - Long and folded to maximise absorption - Mucus is secreted for lubrication and aids the movement of feces

• - Villi increase surface area for absorption - Villi have microvilli which have protein pumps          - Absorb food by active transport and facilitated diffusion       - Villi have one layer of epithelial cells which lead to easier absorption - Blood capillaries are near the surface which minimizes the distance the molecules have to travel - Lymph vessels (lacteal) near the surface which allows for easy absorption of lipids

• Pancreas and Digestine

• Pancreas produces enzymes that aid digestion       - Lipase - hydrolizes lipids to glycerol and fatty acids       - Amylase - hydrolizes starch to maltose       - Trypsin - hydrolizes large polypeptides to small polypeptides