Digestive System Flashcards
Order of digestive system
Mouth - epiglottis - oesophagus - stomach - liver - bile duct - gall bladder - small intestine - large intestine - appendix - rectum - anus
Function of mouth
Food is mechanically broken down by the teeth and therefore increasing the surface area. Food is shaped into a bolus.
Function of epiglottis
A flap made of elastic cartilage covered with a mucus membrane and is attached to the larynx. During swallowing, it closes to prevent aspiration.
Function of oesophagus
This connects the pharynx to the stomach acid and is also called the gullet. Its function is to move the bolus of food by peristalsis. Mucus is also produced which acts as a lubricant and help protect against escaped stomach acid.
Function of stomach
Muscular bad that secretes acid. There are 2 openings surrounded by a sphincter. One opening is connected to the oesophagus and the other is connected to the duodenum (small intestine). Gastric juice is produced by the wall and helps to break the food down. Strong contractions help to mix food with gastric juice and turn it into chyme. Gastric juices includes water, hydrochloric acid, mucus and protease.
Function of the liver
This acts as a chemical factory. In terms of digestion, it produces bile which is secreted into the small intestine to help digest fat. But, it also helps to maintain blood-glucose levels, heat levels, hormone levels, stores minerals and helps detoxify chemicals like alcohol.
Function of the bile duct
A tube-like structure that carries bile to the duodenum
Function of the gall bladder
Stores and concentrates bile and then releases it into the duodenum. It also neutralises the stomach acid so the enzymes can work efficiently.
Function of the small intestine
Most food is digested here. It’s 7m long. Food is broken down using enzymes produced by the pancreas and bile from the liver and gall bladder. Most nutrient absorption occurs here with the aid of villi.
Function of the pancreas
Produces many digestive enzymes which help break down fats, proteins, and carbohydrates.
Function of the large intestine
Also known as the colon. It connects the small intestine to the rectum. It absorbs the remaining water and turns undigested food into faeces.
Function of the rectum
Connects the colon to the anus. It recieves faeces and stores it until it is removed from the body.
Function of the anus
Last part of the digestive tract. It is a ring of muscles and 2 sphincters which allow the faeces out.
Function of the salivary glands
Produce saliva which contains amylase.
Function of the pancreatic duct
Joins the pancreas to the bile duct before joining the duodenum.
Function of the villi
Finger-like projections that increase the surface area of the small intestine, has a good blood supply and thin walls which allow for diffusion. Lacteals absorb fatty acids and glycerol.
Function of amylase
Converts starch into simple sugars
Where amylase works
Salivary glands
Pancreas
Small intestine
Function of protease
Converts proteins into amino acids
Where protease works
Stomach (where its called pepsin)
Small intestine
Pancreas
Function of lipase
Converts fats into glycerol and fatty acids
Where lipase works
Pancreas
Small intestine
Function of bile
Emulsifies fats and neutralises stomach acid
Use of carbohydrates in the body
Fuel the body, especially the CNS and the brain, and protects against disease
Food sources of carbohydrates
Bread, pasta, whole grains, bread
Where carbohydrates get broken down
Teeth mechanically make down the carbs, amylase is produced by the salivary glands. In the stomach it is turned into chyme. In the duodenum, where anylase produced from the pancreas and small intestine break it down even further. Simple sugars are absorbed into the blood through the villi
Use of fats and lipids in the body
Fats help with vitamin absorption, blood clotting and muscle moevement. They also give us energy and keep us warm.
Food sources of fats and lipids
Healthy fats - nuts, seeds, fish, avocados, cheese, butter
Where fats and lipids are broken down
Teeth mechanically break down food. The food is moved by the stomach where it’s turned into chyme. It then moves to the duodenum where bile emulsifies fats into smaller pieces so lipase and the small intestine can break it down more. Fatty acids and glycerol are absorbed into the lacteals and enter the lymphatic system
Use of proteins in the body
Building blocks of the body. Key component in muscles, skin and hair.
Food sources of proteins
Meat, fish, eggs, soy, nuts
Where proteins are absorbed
Teeth mechanically break down food. The food is then swallowed and moved down the oseophagus by peristalsis until it enters the stomach where it is turned into chyme. The enzyme pepsin is secreted here, which breaks down the protein. It is released from the stomach into the duodenum, the enzyme protease from the pancreas and small intestine break it down. Amino acids are absorbed into the blood stream through the blood stream.
Mechanical digestion definition
Physically breaking food down into smaller pieces eg the action of chewing, the stomach breaking food down by peristalsis
Chemical digestion definition
Enzymes acting as a catalyst
Function of lacteals
Fats can’t be absorbed directly into the capillaries, as they’re too big. They go into the lacteals in the villi, and then into the lymphatic system
Definition of assimilation
Movement of digested food molecules into the cells of the body
Liver’s role in assimilation
Nutrients from the small intestine are taken by the hepatic portal vein to the liver (apart from fatty acids and glycerol).
The liver converts excess glucose into glucagon and stores it until muscle cells need it for energy.
Some amino acids are removed and used to make plasma proteins. Excess amino acids can’t be stored and are assimilated by liver cells. Some become glucose, others urea.
Biological explanation of gall stones
Gall stones can form if there are unusually high levels of cholesterol inside the gallbladder, or high levels of a waste product called bilirubin.
How gallstones are diagnosed
GP will ask about symptoms
Murphy’s sign test to see if the gallbladder is inflammed
Blood tests to check for infections. If gallstones have moved into the bile duct, the liver can’t function properly.
Ultrasound scan
MRI and endoscope
Lithiotripsy (soundwaves) positives and negatives
+ non-surgical, non-invasive, no general anaesthetic
- less effective, stones could reoccur
Keyhole surgery positives and negatives
+ less risk of infection, stones won’t come back
- can’t be performed on over-weight patients
Open surgery positives and negatives
+ stones won’t come back
- larger scar, longer healing time, greater risk of infection
Open surgery positives and negatives
+ stones won’t come back
- larger scar, longer healing time, greater risk of infection
