Digestion Flashcards
What is the function role of the Mouth?
Breaking up food into smaller pieces via mastication and mix with saliva to aid with digestion and swallowing
What is Mastication?
The act of chewing food, the first stage of digestion
What is Pretension?
Gathering
What is Deglutition
Swallowing
What is the main function of the Salivary Gland?
Lubricate and facilitate packaging a food bolus for its passage down the oesophagus
What are some other functions of the Salivary Gland/Saliva?
Thermoregulation, oral cavity cleaning, buffering of weak acids, reduction of oral bacteria growth + protection
How many layers are there in a tooth?
4
What are the four layers of the teeth?
Enamel, Dentin, Cementum and Pulp
What are the function of the teeth?
Aid in initial digestion stage by helping break up the food
What are the types of teeth in a Carnivore?
Incisors, Canines, Premolars, Molars and Carnissials
What are the types of teeth in a Herbivore?
Eleodontal Incisors, 2nd Incisors, Premolars and Molars
What is the function of the Molars?
Grinding
What is the Oesophagus?
Tubular, elongated organ of the digestive system which connects the pharynx to the stomach
What is the main function of the Oesophagus?
Transport food entering the mouth through the throat and into the stomach
How long does it usually take the food to travel from the mouth to the stomach?
4-8 Seconds
How does the food go down?
Peristalsis of the circular muscle contracts and relaxes to push food down.
What takes place in the Monogastric stomach?
Mechanical digestion
What is Mechanical digestion?
Churning of the stomach makes food break down in size giving it a larger surface area
What do the gastric juices produced by churning consist of?
- Pepsinogen
- Hydrochloric acid (HCL)
- Mucus
What is produced by stimulus of the stomach wall?
Gastrin
What is produced to slow churning and reduce pH?
enterogastrone
What is Mucus produced for?
Protection from excess stomach acid and most of all autolysis. It also acts as a lubricant, reducing friction
What are the three cells that the stomach wall also contains?
Oxyntic cells, goblet cells and peptic cells
What do Oxyntic cells do?
Secrete hydrochloric acid (HCL)
What do goblet cells do?
Mucus
What do peptic cells do?
Secrete Pepsin
What is the Duodenum?
The first 20cm of the small intestine
Where does the duodenum receive secretions from?
Liver and Pancreas
What happens in the Duodenum?
- Further digestion takes place.
- Input of pancreatic juices.
- Lipids are broken down into fatty acids.
- Protein is broken down into amino acids.
- The digestion of carbohydrates takes place inside cells.
Why is there a large surface area in the Duodenum?
Large number of villi
What does the liver do?
Produce bile
What is Bile made up of?
Bile salts and Mineral salts
What do Bile salts do?
Help with the digestion of fats by breaking them down from large globules to smaller globules, lowering surface tension and making a larger surface area
What do Mineral salts do?
Neutralise the stomach acid (HCl) to around 7/8 pH in the small intestine
What does the Pancreas do?
Produces pancreatic juices which contain pancreatic amylase, pancreatic lipase and trypsinogen (or trypsin in its active form)
What does Pancreatic amylase do?
Converts the remaining amylose (starch) into maltose
What does Pancreatic lipase do?
Converts lipids into fatty acids and glycerol
What does Trypsinogen do?
Trypsinogen, upon meeting with the enzyme enterokinase, is activated and is called trypsin. Trypsin then continues to break down proteins in digestion.
What does the Jejunum and Ileum do?
The longest part of the small intestine, secretes endopeptidases and exopeptidases.
Nutrients and water are absorbed here aided by villi.
What happens to Sucrose?
Sucrose is hydrolysed into fructose and glucose by sucrase
What happens to Maltose?
Maltose is also hydrolysed into two glucose by maltase
What happens with the walls of the intestines here?
Here the walls of the small intestine begin to thin and narrow, and the blood supply is reduced
What does the Mucosa do in the jejunum and ileum?
Secretes small amounts of digestive enzymes and lubricates mucus while absorbing nutrients
95% of what is absorbed by the small intestine?
Carbohydrates and Proteins
What else does the small intestine absorb?
About 90% of the water that it receives during digestion
What does the large intestine do?
Absorbs water (by osmosis), minerals and vitamins
What does Chyme, at the start of the large intestine, consist of?
Water, bile, mucus, dead cells, bacteria and undigested food
What is different in the large intestine than the small intestine?
- larger lumen
- smaller in length
- thinner wall
Where are faeces stored and excreted?
Faeces are stored in the rectum and then egested through the sphincter muscle called the anus
