Adaptations for nutrition (The human digestive system (The Functions of…
Adaptations for nutrition
Modes of nutrition
The human digestive system
The Functions of the gut
Structure of the gut wall
Outer layer is the serosa. Tough connective tissue, protecting the gut wall.
The muscle comprises2 layers in different directions. The inner circle muscles contract and the longitudinal muscles relax, pushing the food along.
Submucosa is connective tissue containing blood and lymph vessels., which remove absorbed products of digestion, and nerves that co-ordinate peristalsis.
The mucosa is the innermost layer and lines the gut wall. Its epithelium secretes mucus, lubricating and protecting the mucosa. It secretes digestive juices and also can absorb digested food.
Specialisation in the mammalian gut
The buccal cavity
The small intestine
Bile is made in the liver, stored in the gall bladder then passes through the bile duct into the duodenum. It doesn't contain enzymes. Bile contains salts which are amphipathic (their molecules have hydrophobic and hydrophilic parts). They emulsify lipids in the food by lowering their surface tension and breaking up large globules into smaller.
Pancreatic juice is secreted by islet cells, which are exocrine glands I the pancreas. It enters the duodenum through the pancreatic duct.
Adaptations to different diets
The pork tapeworm
Live on or in an organism of another species, the host, and obtain nourishment at the hosts expense, causing some degree of harm or death.