Types Of Digestion
Physical
-if the food is large, structures like the teeth chop it into smaller pieces.
-the stomach churns food, breaking it up into smaller pieces.
-this helps to increase the surface are and and let it pass through the digestive system more easily.
Chemical
-breaks down large, insoluble molecules into smaller, soluble ones.
-hydrolysing enzymes aka hydrolases.
-hydrolysis is the splitting up of molecules by adding water to bonds e.g. glycocidic.
-carbohydrases break down carbohydrates into monosaccharides (sugars).
-lipases break down lipids (fats/oils) into glycerol and fatty acids.
-protease breaks down proteins into amino acids.
-these soluble molecules are absorbed into the blood and are delivered round the body in order to build up tissues or be used in other processes, this is called assimilation.
-if the food is large, structures like the teeth chop it into smaller pieces.
-the stomach churns food, breaking it up into smaller pieces.
-this helps to increase the surface are and and let it pass through the digestive system more easily.
Chemical
-breaks down large, insoluble molecules into smaller, soluble ones.
-hydrolysing enzymes aka hydrolases.
-hydrolysis is the splitting up of molecules by adding water to bonds e.g. glycocidic.
-carbohydrases break down carbohydrates into monosaccharides (sugars).
-lipases break down lipids (fats/oils) into glycerol and fatty acids.
-protease breaks down proteins into amino acids.
-these soluble molecules are absorbed into the blood and are delivered round the body in order to build up tissues or be used in other processes, this is called assimilation.
Organs in the Digestive System
Salivary Glands
- situated near the mouth.
-secrete saliva (containing amylase) via a duct to the mouth.
Oesophagus
-carries food from the mouth to the stomach.
-its purpose is transport rather than digestion/absorption.
-it has a thick muscular wall.
Stomach
-a small sac with lots of folds, so that it can expand.
-the entrance and exit are controlled my spinicter muscles.
the stomach walls produce gastric juice (containing pepsin, HCl & mucus) to help with breakdown of food
-peristalsis of stomach turns food into an acidic fluid called chyme.
Pancreas
-a large gland situated below the stomach.
-secretes pancreatic juice (containing protease).
Small Intestine
-long muscular tube.
-enzymes produced my epithelial lining digest molecules further, along with enzyme secretions from nearby glands.
-inner walls folded into villi, which gives a larger surface area, increased further by microvilli on the epithelial calls of each villi.
Large Intestine
-absorbs water, particularly that from the gland secretions.
-this makes food in lumen thicker and drier, forming faeces.
Rectum
-faeces is stored here before being removed via the anus by a process called egestion.
- situated near the mouth.
-secrete saliva (containing amylase) via a duct to the mouth.
Oesophagus
-carries food from the mouth to the stomach.
-its purpose is transport rather than digestion/absorption.
-it has a thick muscular wall.
Stomach
-a small sac with lots of folds, so that it can expand.
-the entrance and exit are controlled my spinicter muscles.
the stomach walls produce gastric juice (containing pepsin, HCl & mucus) to help with breakdown of food
-peristalsis of stomach turns food into an acidic fluid called chyme.
Pancreas
-a large gland situated below the stomach.
-secretes pancreatic juice (containing protease).
Small Intestine
-long muscular tube.
-enzymes produced my epithelial lining digest molecules further, along with enzyme secretions from nearby glands.
-inner walls folded into villi, which gives a larger surface area, increased further by microvilli on the epithelial calls of each villi.
Large Intestine
-absorbs water, particularly that from the gland secretions.
-this makes food in lumen thicker and drier, forming faeces.
Rectum
-faeces is stored here before being removed via the anus by a process called egestion.
Questions
1) State one way in which the stomach is adapted:
a) to churn food. (1 mark)
b) to prevent the enzymes it produces from digesting the surface of the stomach. (1 mark)
2) What is hydrolysis? (2 marks)
3) Which two organs produce amylase? (2 marks)
4) Suggest a reason why the stomach does not have villi or microvilli. (1 mark)
a) to churn food. (1 mark)
b) to prevent the enzymes it produces from digesting the surface of the stomach. (1 mark)
2) What is hydrolysis? (2 marks)
3) Which two organs produce amylase? (2 marks)
4) Suggest a reason why the stomach does not have villi or microvilli. (1 mark)