Human digestive system Flashcards
Why do we need digestion?
The cell surface membrane in our body cells are partially permeable and thus only small molecules such as glucose are able to pass through. Thus, we need to digest the large molecules such as starch into small molecules through digestion
Comparison between physical digestion and chemical digestion
Physical digestion where food is broken down into smaller pieces which increases the surface area to volume ratio for enzymes to digest the food faster
Chemical digestion is where food is broken down from large food molecules into smaller food molecules via enzymes)
Function of teeth
Mouth contains teeth which helps to grind and chew food into smaller pieces so as to increase surface area to volume ratio so that food gets digested by the enzymes faster.
Function of salivary glands
Produces saliva containing salivary amylase. The tongue helps to roll food into small balls for swallowing
What is peristalsis and its function?
Peristalsis is a wave like rhythmic structure where muscles behind the food contracts to push the food forward and muscles in front of the food relaxes for food to go through. Peristalsis ensures the flow of food and helps digestive juices to mix with the food.
What do the walls of the stomach secrete?
The walls of the stomach secrete gastric juice containing hydrochloric acid which activates pepsin and kills bacteria in the food and also pepsin which digests proteins into polypeptides
How does bile emulsify fats?
Bile emulsifies fats by increasing the surface area to volume ratio of fats for it to be digested by the lipase faster. It is a form of physical digestion.
Function of rectum
The rectum helps to absorb the remaining water and mineral salts from the food before turning them into faeces. Rectum temporarily stores faeces and the anus expels the faeces via egestion
Action of digestive enzymes in pancreatic juice from
Starch
Protein
Fats
Starch to maltose by pancreatic amylase,
Protein to Polypeptides by Pepsin,
Fats to fatty acids and glycerol by lipase
Action of digestive enzymes at intestinal juice
Maltose to glucose by maltase
Polypeptides to amino acids by lipase
What digestion is used and what enzymes are digested in the teeth?
(Both physical and chemical digestion)
Salivary amylase digests starch into maltose.
How does digestion occur in the stomach?
Enzyme pepsin digests proteins into polypeptides
What are the three enzymes produced by the pancreas?
Pancreatic amylase(Starch-Maltose)
Protease(Protein-Polypeptides)
Lipase(Fats-Fatty acids and glycerol)
What happens to the small and soluble food molecules after being digested?
They are absorbed into the small intestine into the bloodstream by diffusion. Most of the water and mineral salts are also absorbed in the small intestine.,Undirected food then moves down into the large intestine and forms the faeces.
