Digestive System Flashcards
What does a mouth do in the digestive system
Ingestion: the consumption of a substance.
• Mechanical and chemical digestion takes place.
• Your teeth chew the food and break it down into smaller
pieces mechanically. Why is this important?
• Amylase contained within the saliva starts to break down
starch into maltose.
• With the help of the tongue food is rolled into balls of food
called bolus and swallowed.
What does the oesophagus do in the digestive system
The food pipe connecting the mouth to the stomach
• Food is moved down here with the aid of muscular
contractions known as peristalsis. (Note: peristalsis also occurs in the intestines
What does the stomach do in a digestive system
Large muscular bag – contracts and relaxes to churn the food. - Food can be held here for 2-4 hours.
- The food is mixed with gastric juice, produced by millions of gastric glands located in the stomach walls.
Gastric juice consists of:
•Pepsin – a protease enzyme released in an inactive form,
activated by HCl.
•HCl – kills bacteria and provides acidic (pH 2) conditions which are
optimal for pepsin.
•Goblet cells produce mucus – lines the stomach to prevent damage from the hydrochloric acid.
What does the Small Intestines do in a digetive system
This is the first section of the small intestine
•It is where digestion is completed.
•Digestive juices are secreted from the pancreas (pancreatic juice)
and the intestine walls. These include carbohydrases (including
maltase and pancreatic amylase), proteases and lipases. •Bile is also released here from the liver
What does bile do in the digetive system
Made in the liver.
•Stored in the gall bladder.
•Emulsifies fats providing a larger surface area on which lipase
can act.
•Also neutralizes the stomach content (bile is alkaline)
What does Absorption in the small intestine do in the digestive system
The ileum is the part of the small intestine where most of the absorption of foods takes place.
Absorption: digested food molecules are absorbed.
• The inner surface is folded, producing finger-like projections
called villi.
• Absorption may take place passively or via active transport.
What does the villi do in the digestive system
• Microvilli increase surface area and therefore increases the rate of diffusion.
• Villi have very thin walls (one cell thick) to decrease diffusion distance, which increases rate of diffusion
• Each villus has a network of capillaries which maintains a concentration gradient for the diffusion of amino acids and glucose into the bloodstream
• Fatty acids and glycerol are transported into the lacteal and travel in the lymphatic system.
What does colon do in the digestive system do
Most useful substances have been removed by the time food
enters the large intestines, what’s left is;
•Undigested food •Mucus
•Dead cells •Bacteria
The main role is the reabsorption of water and mineral ions such as sodium and chloride. Water found in the large intestines is not only from our dietary intake but also additional quantities added by the body within digestive juices.
What does the rectum do in the digestive system
What remains after this point is known as faeces and is stored
in the rectum until it is egested from the body via the anus.
Egestion: discharge of undigested material from the digestive tract.
