Another "phew" question. Took a while to break it down. I had a lot of help from this page which I have linked before Colorado State - digestion.
Protein content in stomach stimulates G-cells to secrete Gastrin. This stimulates pepsinogen and HCL release. Pepsin starts to denature the dietary proteins. The stomach also secretes Gastric Lipase which starts the degradation of fat. The acid food enters the duodenum which stimulates Secretin release. Secretin stimulates the pancreas to release its juice.
Fat and proteins in the duodenum stimulates the release of CCK which stimulates the contraction of the gall bladder and the bile enters the duodenum through papilla vateri.
A common form of carbohydrate is starch, which is broken down by amylase to a disaccharide and later on different enzymes like maltase, sucrase and lactase degrade it further.
Peptides and amino acids are absorbed in the small intestine in a symport with sodium (Na+). Fructose has its own transporter. On the basolateral border of the enterocyte there are GLUT-2s that transport the sugars into the blood.
Fats are broken down and bile emulsifies it to for us to be able to absorb it. In the intestinal cell it is rebuilt and repackaged and distributed via the lymphatic system.
Fat and proteins in the duodenum stimulates the release of CCK which stimulates the contraction of the gall bladder and the bile enters the duodenum through papilla vateri.
A common form of carbohydrate is starch, which is broken down by amylase to a disaccharide and later on different enzymes like maltase, sucrase and lactase degrade it further.
Peptides and amino acids are absorbed in the small intestine in a symport with sodium (Na+). Fructose has its own transporter. On the basolateral border of the enterocyte there are GLUT-2s that transport the sugars into the blood.
Fats are broken down and bile emulsifies it to for us to be able to absorb it. In the intestinal cell it is rebuilt and repackaged and distributed via the lymphatic system.
 |
| Digestion of Macronutrients |
There are four types of causes for diarrhea.
1. Osmotic diarrhea. This is where you add something that you can't absorb. For istance, lactose intolerant people lack the enzyme lactase. This leaves more particles in the intestine which osmotically draws out water into the lumen. The lactose is the degraded by colonic bacteria which produces gases.
2. Secretory diarrhea. Here the intestine releases more ions than it should into the lumen and then water follows. A common cause is Cholera. This bugs toxins mess with the cell and make it hyperactive which can give a lethal diarrhea and millions have died from dehydration.
3. Inflammatory and infectious diarrhea. The intestines epithelium is basically damaged by either an inflammatory disease such as Crohn's or Ulcerous Colitis or it is invaded by salmonella or shigella. This leads to destruction of the intestines absorptive capacity.
4. Decreased motility. Decreased transit time can be said to reduce the intestines possibility to absorb water, leading to diarrea.
Steatorrhea
Decreased absorbtion of fat leads to excessive amounts of fat in the faeces. This could be due to a biliary duct obstruction for instance. Or a defect with the excretion of pancreatic lipase.
Inga kommentarer:
Skicka en kommentar