GI tract

Question 1

What is the function of the oral cavity?

Answer 1

Chewing reduces food into smaller particles. The saliva contains amylas that degrades starch through hydrolysis and the saliva also lubricates the bolus making it easier to swallow.

Question 2

What is the function of the esophagus?

Answer 2

To swallow food and make sure it goes down and not in your lungs and not upwards through it’s 2 sphincters. The upper sphincter that is skeletal muscle and the lower that is a sheet of smooth muscle and then the diaphragm that is skeletal muscles responsible for our breathing will contract around the esophagus and act as a sphincter.

Question 3

What is the function of the fundus?

Answer 3

To churn food and hydrolyse them to make chyme and to store the chyme.

Question 4

How can the small intestines be divided?

Answer 4

Dodeunum, jejenum, illeum.

Question 5

What are the general function of the large intestine?

Answer 5

Absorbtion of water, ions, vitamin K,

Question 6

What is the general function of the rectum?

Answer 6

Storage

Question 7

What is the general function of the anus?

Answer 7

Expulsion

Question 8

How can the stomach store so much food and then go back to such a small size?

Answer 8

It has folding of the gastric wall which enabled it to stretch out to become smooth and give a larger surface area to secrete enzymes.

Question 9

What is the brush boarder?

Answer 9

The surface of the small intestines that are covered in small vili that is covered in small microvili that gives a larger surface area for secretion of enzymes and absorbtion. The brush boarder in the doedeunum has a coat of many important enzymes that digest food or active other enzymes.

Question 10

What is the anatomy of the Hepa?

Answer 10

The hepa is made out of multiple lobes called hepatic lobule. In these lobules there are lots of hepatocytes and surrounded in a 6 edged ring fashion there are the portal triad. The portal triad is the common hepatic duct, the proper hepatic artery and the portal vein. The common hepatic duct is where bile leaves the hepa, the proper hepatic artery supplies the hepatocytes with oxygen. The portal vein supplies the hepatocytes with nutrient rich food from the intestinal tract. Then all the blood from the hepa will leave through the central vein.

Question 11

What is the billary tree and how does it work?

Answer 11

Bile are made out of bile pigments and bile salts. The bile salts emulsiftise fat. The bile from the hepa goes through the common hepatic duct and goes through the cystic duct and goes into the gallbladder to be stored. CCK is a hormone that will cause the gallbladder to contract to release bile to go back through the cystic duct and through the common bile duct it enters the duodenum then it travels along to the illeum where it is absorbed and travels back to the hepa to be reused.

Question 12

What is the anatomy of the pancreas?

Answer 12

It sits in the retroperoteneum which means it sits back in the abdomen. It can be divided into the exocrine pancrease that releases salts and enzymes into the dodeunum and the endocrinic pancreases that releases hormones into the blood stream.

Question 13

What is the anatomy and function of the colon, rectum and anus?

Answer 13

The colon can be divided into many smaller parts and it’s function is to absorb water and inorganic ions such as sodium and potassium. It also has lots of microorganisms that are important for the digestion of nutrients especially carbohydrates.

The rectum is responsible for storage and the anus has the internal and external anal sphincter. The internal are smooth muscle and the external are skeletal muscles.

Question 14

How will chyme regulate the GI system?

Answer 14

Chyme gets delivered to the dodeunum which triggers a release of secretin that goes to the pancreas and that release bicorbanate rich solutions that will neutralise the acid from the stomach. The secretin also goes back to the fundus that will inhibit stomach motility and acid release. Chyme will also trigger the release of CCK, that goes to the pancreas that trigger release of pancreatic enzymes that helps the digestive process, such as lipase, and CCK also goes to the gallbladder and cause the gallbladder to contract so it releases bile. CCK also goes to the fundus and decrease stomach motility so the body has time to digest the food. The nutrient from the chyme that triggers CCK to be released is fat. And the secretin is triggered by a low pH.

Question 15

What are some important parts of the GI system that isn’t organs?

Answer 15

Immune system, nervous system, hormones, microbes.

Question 16

What is the peristaltic reflex?

Answer 16

The contraction and relaxation in a syncronised matter either in propulsion to move food forward or for segmentation.

Question 17

What is the anatomy of the stomach?

Answer 17

Cardia, fundus, corpus, pyloris.

Question 18

What are the three phases of digestion?

Answer 18

Brush boarder, mucusphase where the food is absorbed through the brush boarder and transport phase where the nutrient is transported.

Question 19

What is the function of dodeunum?

Answer 19

To digest food with enzymes from the pancreas, liver and the gallbladder and the brush boarder as well as neutralise the low pH from the stomach.

Question 20

What is the function or the jejenum?

Answer 20

To absorb nutrients.

Question 21

What is the function of the illeum?

Answer 21

The illeum absorbs certain vitamins.

Question 22

How does the stomach hydrolyse bolus into chyme?

Answer 22

There are specialised cells in the stomach that secrete different enzymes.

Proietol cells release HCl, Chief cells release pepsinagen that with HCl turns into pepsin. Pepsin breaks down protein. Then there are mucus cells that release mucuin that coats the stomach wall and protects it from pepsin and HCl.

Question 23

Which nutrients are digested in the stomach?

Answer 23

Only protein.

Question 24

How is the bolus mechanically degraded?

Answer 24

The stomach wall have a thick layer of smooth muscles and they a peace maker cells that will lead to a synchronized churning of the food.

Question 25

Why is the inactive form pepsinogen released instead of pepsin straight away?

Answer 25

To not break down the stomach walls.

Question 26

How are carbohydrates digested?

Answer 26

First in the mouth through amylase and mechanical digestion, then in the stomach through mechanical digestion and then in the duodenum through hydrolysis. The pancreas release amylase, the brush border releases lactase and other enzymes that breaks down carbohydrates into simple monosackarides.

Question 27

How are fat digested?

Answer 27

First mechanically in the mouth and stomach then in the duodenum bile breaks organizes the fat and the pancreases release lipas that breaks down the fat into fatty acid chains and glyceride.

Question 28

How are proteins digested?

Answer 28

First mechanically in the mouth, mechanically and chemically in the stomach through the churning and the enzyme pepsin then in the duodenum the brush border breaks down proteins with peptidase, the pancreas release trypsinagen and chymontrypsingen which are inactive forms of the enzymes that the brush boarder activates with enteropeptidase into trypsin and chymotrypsin. This breaks down the proteins into singular amino acids.

Question 29

How are carbohydrates absorbed?

Answer 29

When carbohydrates are digested into monosacharides they are absorbed through secondary active transport so an ion is released towards the concentration gradient and the energy release enables absorbtion of monosacharides and they enter the blood capillary in the jejunum.

Question 30

How are nucleotide digested?

Answer 30

The nucleotides are breaken down with nucleosides that come from the brush border in the dodeunum that breaks the nucleotides into phostphates and bases.

Question 31

How are proteins absorbed?

Answer 31

In the jejenum the amino acids are then absorbed through primary active transport, so it takes ATP, and goes into the blood capillary.

Question 32

How are nucleotides absorbed?

Answer 32

In the jejenum Tthe bases and phostphate groups are through primary active transport are absorbed into blood capillary.

Question 33

How are fat absorbed?

Answer 33

The fatty acids are diffused through the membrane and divided into chylomicrons which are too big to go through the capillary and are instead diffused through the lymphatic capillary system where they are further broken down and then absorbed through the vein, travels through the heart and then the arteries distribute them throughout the body. The absorption occurs mostly in the jejunum.

Question 34

What is the function of hepa?

Answer 34

The hepa are responsible for catabolism and anabolism, storage of carbohydrates and fats. Carbs and fats can be stored as glycogen, they can be stored as lipoproteins, triglycerides. It distributes proteins to the blood stream and reabsorb and break down the proteins. It is also responsible for detoxification through enzymes such as cytochrome P450 can react to lots of different substrates which will decrease the effect of drugs and they produce bile.It also makes bile.

Question 35

What cell types are there of the endocrinic pancreas and what are their function?

Answer 35

There are many islet cells that sit in islands. There are alpha islet cells that release glucagon that take glycogen and breaks them down into glucose. Glucogon also breaks down many othr macromolecules. The b-islet cells release insulin, that cause glucose to be stored as glycogen but also build up and store many other molecules. delta islet cells release somato statin that causes the effect of the other hormones to stop.

Question 36

Which enzymes and salts does the exocrinic pancreas release?

Answer 36

Bicorbanate that neutralices the acid to riase the pH so the intestines don’t take damage. It also release amylase and lipase and proteolytic that can be divided into trypsinogen and chymotrypsinogen which are later activated in the dodeunum by the enzyme enteropeptidodase.

Question 37

Except chyme what are other ways the GI tract is regulated by?

Answer 37

The GI tract has it’s own nervous system called the enteric nervous system. First the gastrocolic reflex signals the colon to move the food along to make room for the new food in the fundus.

There are also hormonal control that regulate the GI tract. Gastrin is released from mucusic cells when food is in the stomach. It goes to the blood stream to the fundus to stimulate gastric secretion. It leads to secretion of HCl, pepsinogen, and increase stomach motility. The pH will lower which will trigger a decrease of the gastrin release.