Upon digestion amino acids and monosaccharides are brought to the liver by the [blank_start]mesenteric vein[blank_end], which will merge into the [blank_start]hepatic portal[blank_end] vein. Chylomicrons are secreted into the [blank_start]lacteals[blank_end], which are a part of the lymphatic system. Lymph vessels (and their chylomicron rich content) will be emptied into the subclavian veins.
Volatile fatty acids are short chained carbons typically produced by bacterial fermentation. The 3 main VFAs are:
1. [blank_start]acetic acid[blank_end]
2. [blank_start]butyric acid[blank_end]
3. [blank_start]propionic acid[blank_end]
There are [blank_start]20[blank_end] amino acids that make the proteins of the body. An amino acid that is [blank_start]essential[blank_end] must be [blank_start]consumed[blank_end] in the diet. Conditionally or [blank_start]pseudoessential[blank_end] amino acids are only essential in certain conditions (age, health status) or can only be made out of essential amino acids. An example of a conditional EAA is [blank_start]arginine[blank_end] in human infants and chicks.
[blank_start]Scurvy[blank_end] is the disease that you will develop if you don't consume enough [blank_start]Vitamin C (ascorbic acid)[blank_end] - another essential nutrient for humans.
Vitamin C (ascorbic acid)
[blank_start]ATP (adenosine triphosphate)[blank_end] is the universal energy carrier and it is generated by the degradation of metabolic fuels:
1. [blank_start]glucose[blank_end] is the preferred method and the only method available in all tissues.
2. [blank_start]fatty acids[blank_end] through beta oxidation of [blank_start]fatty acids[blank_end]; used in some tissues (e.g. muscles at rest) but can't be used in the brain
3. [blank_start]ketone bodies[blank_end] - they are made out of FAs by the liver and distributed through the body via the blood supply. This is not ideal as too much of it creates acidosis and the brain does not like to use it
4. [blank_start]amino acids[blank_end] - pathological (starvation or diabetes)
ATP (adenosine triphosphate)
[blank_start]Eukaryotic[blank_end] produces lactate. This is what we do when we are in anaerobic conditions and need energy at a rapid pace. This is also called anaerobic glycolysis.
[blank_start]Prokaryotic[blank_end] produces ethanol and CO2. This is what occurs in the rumen of the ruminants.
[blank_start]Hormonal responses[blank_end] and the [blank_start]autonomic nervous system[blank_end] are responsible for the coordination of all organs involved for digestion.
autonomic nervous system
[blank_start]Endopeptidase[blank_end] digests proteins by cutting the link between amino acids anywhere in the chain.
[blank_start]Exopeptidase[blank_end] removes terminal amino acids, cutting off a single amino acid at a time. The results of the digestion by these enzymes are either [blank_start]oligopeptides[blank_end] which are short peptide chains or even single amino acids.
Protein digestion starts in the [blank_start]stomach[blank_end] thanks to [blank_start]pepsin[blank_end] but happens mainly in the [blank_start]duodenum and jejunum[blank_end] thanks to the enzymes secreted by the [blank_start]pancreas[blank_end] and the ones found on the cytoplasmic membrane of [blank_start]enterocytes[blank_end].
duodenum and jejunum
Carbohydrate digestion starts in the [blank_start]mouth[blank_end] thanks to [blank_start]amylase[blank_end] secreted by the [blank_start]salivary glands[blank_end]. However, it happens mainly in the [blank_start]duodenum and jejunum[blank_end] where, thanks to the pancreatic [blank_start]amylase[blank_end], starches are glycogen are digested. Cellulose on the other hand, is digested by microorganisms through a process called [blank_start]fermentation[blank_end], which happens in a special compartment that can change depending on the species. For example, in ruminants, this process occurs mainly in the [blank_start]rumen[blank_end] and in horses, it occurs in the [blank_start]cecum[blank_end] and the [blank_start]colon[blank_end].