Digestion Flashcards
What is ingestion?
This is taking food into the mouth.
What is digestion?
This is the breakdown of large, complex, insoluble food into small, simple, soluble molecules.
What is absorption?
The diffusion of soluble food molecules into the blood stream.
What is assimilation?
The food molecules are taken from the blood and used by cells for respiration, growth, development.
What is egestion?
This is the removal of undigested food from the body.
What types of digestion happen in the mouth?
1) Mechanical digestion
This involves the breaking down of large pieces of food into smaller pieces which provides a larger surface area for chemical digestion and easier to swallow
2) Chemical digestion
Saliva mixes with the food . An enzyme called salivary amylase in the saliva breakdown carbohydrates in the food.
What is the name of the thing formed in the mouth and where is it pushed back to?
Bolus and is pushed to the pharynx.
What happens in the oesophagus?
Food enters here. The epiglottis prevents the food from going into the trachea. The muscles of the oesophagus contact and relax to push the food down which is know as peristalsis.
What happens in the stomach?
The stomach secretes gastric juices which contains mucus, dilute hydrochloric acid (HCL) and the enzyme pepsin. The HCL kills the pathogens in the food and stops the action of the salivary amylase by creating an acid environment. The pepsin breakdown proteins to polypeptides then to peptones. The food is now semi- fluid and is called chyme.
What is located at the base of the stomach and what it looks like and does?
Pyloric sphincter which is a circular muscles that open and close to allow the food to pass.
What is the first part of the small intestine and say what it does.
Duodenum (6m long). Here bile from the gallbladder in the liver is secreted. Bile contains sodium-bicarbonate which neutralizes the acid and makes the environment alkaline. Bile also emulsifies fats , that is, breakdown fats into small droplets so increasing the surface area for digestion. The pancreas release pancreatic juice which contains pancreatic amylase , lipase and trypsin.
Pancreatic amylase: starch—> maltose
Lipase: lipids—> glycerol and fatty acids
Trypsin: peptones —> peptides
What are the 3 parts of the small intestine?
Duodenum
Jejunum
Ileum
What are all 3 parts of the small intestine covered with. State what it does and what it makes.
The villi cover all 3 parts and it’s tiny finger like projections that increase the surface area for absorption. The cells covering the villi also make enzymes such as
Maltese: maltose—> glucose
Sucrase: sucrose—> glucose + fructose
Lactase: lactose—> glucose + galactose
Peptidase: peptides—> amino acids
