The Digestive System Flashcards
What is the gastrointestinal system?
It is a continuous tube that extends from the mouth to the anus. It contains food from the time it is eaten to the time it is digest and absorbed or eliminated from the body
What organs are in the gastrointestinal system?
The mouth, the pharynx, the oesophagus, the stomach, the small and large intestine
What are the accessory digestive organs?
The teeth, the tongue, the salivary glands, the liver, the gallbladder and the pancreas
What are the 6 basic digestion processes?
Ingestion
Secretion
Mixing and propulsion
Digestion
Absorption
Defecation
What are the organs of the digestive system?
- the mouth
- the 3 salivary gland
- The oesophagus
- the pharynx
- the liver
- the stomach
- the pancreas
- the gallbladder
- the cecum
- the appendix
- the transverse, ascending and descending colon
- the rectum
- the anus
What is the mouth made up from?
Cheeks, hard and soft palates, lip and a tongue
What type of muscle is the tongue?
Skeletal muscle
What is on the surface of the tongue?
Papillae these contain some tastebuds
What do the glands in the tongue do?
They secrete lipase which digests triglycerides once it is in the stomach with acid
What are the 3 pairs of salivary glands?
The parotid, the submandibular and the sublingual salivary glands
What happens during mastication?
Food mixes with saliva and shaped into bolus
What starts the digestion of starches in the mouth?
The salivary amylase
What is the oesophagus?
It is a muscular tube that connects the pharynx to the stomach
What does swallowing consist of?
It is moving a bolus from the mouth to the stomach by peristalsis. It is a voluntary stage from the mouth to the oropharynx and then the involuntary stage
What does the stomach connect?
The oesophagus to the duodenum.
What are the 4 main regions of the stomach?
The cardia, the fundus, the body and the pylorus
What is between the pylorus and the duodenum?
The pyloric sphincter
What are the 4 basic layers of the stomach wall?
The mucosa, the submucosa, the muscular is and the serosa
What is on the surface of the stomach?
It has glands that produces mucus, hydrochloride acid, a pepsin for protein, intrinsic factor and gastrin
What is mechanical digestion?
It consists of mixing waves that macerate food and mix it with gastric juice forming chyme
What does lingual lipase produced by the tongue do?
It digests triglycerides in the acid in the stomach
What does mucus secreted by mucous cells do?
Cost the mucosa forming a thick barrier between the cells in the stomach lining and gastric juices
What is the enzyme that starts protein digestion?
Pepsin
Where does the pancreas sit?
Behind the stomach
What is the pancreas made up from?
Small clusters of glandular epithelial cells called acini
What is the enzyme that digests starch?
Pancreatic amylase
What is the enzyme that digests proteins?
Carboxypeptidase trypsin and chymotrypsin
What is the enzyme that digests triglycerides?
Pancreatic lipase
What is the enzyme that digests nucleus acids?
RNA and DNA
How many lobes does the liver have?
2
Where is the gallbladder?
It is a sac that is located in a depression under the liver that stores bile
What 3 components does the liver have?
Hepatocytes, bile canaliculi and hepatic sinusoids
What does hepatocytes do?
Produce bile
What are the functions of the liver?
Secretion of bile and bile salts
Carbohydrate, protein and lipid metabolism
Processing drugs and hormones
Excretion of bilirubin
Stores vitamins and mineral
Activates vitamin D
What do the glands in the small intestine do?
They produce enzymes and mucus
What’s special about the walls of the small intestine?
It has microvilli, villi and circular folds to provide a large surface area for digestion and absorption
What percentage of absorption happens in the small intestine?
90% the other 10% happens in the large intestine and the stomach
What does mechanical digestion in the small intestine involve?
Segmentations and migration waves of peristalsis
What is absorption?
It is the passage of nutrients from digested food in the gastrointestinal tract into the blood or lymph
How does absorption take place?
By simple diffusion, facilitated diffusion, osmosis and active transport
What regions does the large intestine include?
The cecum, colon, rectum and the anal canal
What is the colon divided into?
The ascending colon
The transverse colon
The descending colon
The sigmoid portions
What does the mucosa contain?
Absorptive cells that absorb water
And goblet cells that secrete mucus
What is mass peristalsis?
It is a strong peristaltic wave that drives the contents through the colon into the rectum
What happens in the large intestine?
Substances are further broken down and some vitamins are synthesised through bacterial action
What does the large intestine absorb?
Water, ions including sodium and chloride and some dietary vitamins
What is the elimination of faeces called?
Defaecation
What actions does defaecation have?
A reflex actions aided by voluntary contractions of the diaphragm and abdominal muscles and relaxation of the external anal sphincter
What are the 3 overlapping phases in digestive activities called?
Cephalic phase, gastric phase and intestinal phase
What happens during the cephalic phase?
The smell, sight, sound or thought of good activates in the brain. Making the salivary glands secrete salvia and gastric glands secrete gastric juice in order to prepare the mouth and stomach for food
What happens during the gastric phase?
Presence of food causes gastric juice secretion and gastric motility. The pyloric sphincter relaxes which promotes the gastric to empty
When does the intestinal phase start?
And is coordinated by what?
When the food enters the small intestine
It is coordinated by the hormones gastric, secretin and cholecystokinin
