Embedded Files
In this section (IB Topic 6.1)
In this section (IB Topic 6.1)
- Structure of the digestive system (alimentary canal and accessory organs)
- Structure of the digestive system (alimentary canal and accessory organs)
- Peristalsis
- Peristalsis
- Digestion
- Digestion
- Absorption and assimilation
- Absorption and assimilation
- LAB: modeling absorption with visking tubing membranes (see here)
- LAB: modeling absorption with visking tubing membranes (see here)
6.1 Vocabulary
6.1 Vocabulary
6.1_Vocabulary.pdfDigestion_Lipids.pdfAnswers here.
Structure of the digestive system
Structure of the digestive system
A lacteal is a lymphatic capillary that absorbs and transports dietary fats in the villi of the small intestine.
Drawing the digestive system in IB biology
BioDigital is a free online resource that allow students to study human physiology by directly observing virtual animation of human bodies. It is ver well done and we'll use it throughout the physiology unit. Give it a go at https://www.biodigital.com/
structures_intestines_villi.pdfAnswers here.
Watch here.
Digestion
Digestion
Chemical digestion is achieved by hydrochloric acid in the stomach and by hydrolytic enzymes (which catalyze hydrolysis reactions). A few enzymes are released by the salivary glands, but most enzymes are synthesized by the pancreatic juice and function in the lumen of the small intestine:
Chemical digestion is achieved by hydrochloric acid in the stomach and by hydrolytic enzymes (which catalyze hydrolysis reactions). A few enzymes are released by the salivary glands, but most enzymes are synthesized by the pancreatic juice and function in the lumen of the small intestine:
- Starch is digested to maltose by amylase
- Triglycerides are digested to fatty acids acids and glycerol by lipase
- Phospholipids are digested to fatty acids, glycerol and phosphate by phospholipase
- Polypeptides are digested to shorter peptides by protease
The wall of the intestine produces a variety of enzymes, many of which, remain immobilized in the plasma membrane of the epithelium cells, in the intestine lining .
- DNA and RNA are digested to nucleotides by nucleases (immobilized)
- Maltose is digested into glucose by maltase (immobilized)
- Lactose is digested into glucose and galactose (immobilized)
- Sucrose is digested into glucose and fructose by sucrase (immobilized)
- Peptides are shortened from their ends by exopeptidase (immobilized)
- Dipeptides are digested into amino acids by dipeptidases (immobilized).
Methods of absorption:
Methods of absorption:
- Simple diffusion: fatty acids and monoglycerides move through the phospholipid bilayer of epithelial cells. Synthesis of triglycerides occurs in the epithelial cells (triglycerides can't diffuse back to the lumen) FACT: Most substances are absorbed in the intestine, but alcohol and other small molecules diffuse through the wall of the stomach, before reaching the intestine.
- Facilitated diffusion: epithelial cells have transmembrane fatty acid transporters to increase the absorption of fatty acids. Glucose is also absorbed by facilitated diffusion through glucose channels in the epithelial cells.
- Active transport: epithelial cells have sodium potassium pumps that lower the concentration of sodium ions inside the epithelial cells. The sodium concentration gradient is then used by sodium-glucose co-transporter proteins (facilitated diffusion). Active transport of ions (sodium and potassium) is coupled with facilitated diffusion of glucose, through a co-transporter membrane protein.
- Exocytosis: lipoproteins particles are made of triglycerides, cholesterol, phospholipids and proteins. Lipoproteins are released by exocytosis through the plasma membrane on the inner side of the epithelial cells and enter the lacteal, to be transported in the lymph (chyle).
Absorption of calcium: duodenum and upper jejunum.
Absorption of calcium: duodenum and upper jejunum.
Report abuse