Glycogenic function. Glycogen derived through glucose and laevulose
from starch, glycerine, milk and cane sugars. Less from proteids.
Peptones as a source. Its use in cell growth and heat production, in
white blood cells, in contracting muscle, becoming lactic acid. Excess
dissolves red globules, setting free hæmoglobin. Ammonia carbonate and
asparagin increases it. Arsenic, phosphorus or antimony arrests
glycogenesis. Liver increases leucocytes, and reduces size of red
globules. Reduction of proteids. Fibrine formers reduced, urea formed;
liver inactivity means less of soluble urea, and more of less soluble
and more dangerous products. Urea increases with hepatic circulation.
Hepatic disorder and suppression of urine dangerous. Red globules
probably destroyed. Bile: Amount, uses, oil solvent, helps endosmosis,
deodorant, stimulates glycogenesis, excretory. Source of bile
pigments, tests. Bile acids, dissolve blood globules, antiseptic,
tests. Bile increased by; bile absorbed from bowel, olive oil, salol,
salicylates, benzoic acid and benzoates, turpentine, terpene,
terpinol, euonymus, alkalies, arsenic, ether. Agents lessening biliary
secretion, starvation, excess of fat, alkaline iodides, atropia,
strychnia, hepatic diseases, septic duodenal fermentation. Arrest in
liver of copper, iron, iodides, bromides, nicotine, quinine, morphia,
curare, toxic bile products, ptomaines, toxins. Reduces toxicity of
peptones, casein, ammonia salts, indol, phenol.
The liver is the goal to which most of the products of gastric and
intestinal digestion are carried by the portal vein. In the hepatic
cells large quantities of _glycogen_, 6 (C_{6}H_{10}O_{5}) + H_{2}O, are
stored up after each meal. This is believed to be derived largely from
the transformation of glucose, (C_{6}H_{12}O_{6}) and laevulose
(C_{6}H_{12}O_{6}) which have been produced from starch in the
alimentary canal and conveyed by the portal vein to the liver. By the
liberal use of starch, glycerine, or the sugars of milk, fruit or cane,
(but not mannite, or glycol, or inosite) the glycogen is very greatly
increased (to 12 per cent. in the fowl), but it is diminished on a
purely albuminous diet. Yet it can be produced from albuminous food, as
it is always increased in the dog after a meal of flesh, and is largely
present in the livers of carnivorous animals that have been fed for a
month on flesh only (Landois). The peptones are therefore decomposed in
the liver with the production of glycogen and such waste products as
leucin and tyrosin, which are finally resolved into urea. A purely fatty
diet diminishes it enormously and during prolonged abstinence it
practically disappears. It passes, not into the bile, but into the
hepatic veins, and the general circulation, where it serves in its
decomposition to generate heat, and probably to hasten cell growth. In
the vegetable and animal world, in the germinating seed, and in
cartilage, muscle and epidermis of the fœtus and in the amnios, glycogen
and glucose are found in abundance. The liver, too, the great center for
the production of glycogen, is relatively much larger in the young and
growing animal, and also in the adult animal which has great power of
assimilation.
Glycogen is always present in the white blood globules so long as they
maintain their vitality and amœboid movements, but when they die, it is
replaced by sugar (Hoppe-Seyler). The red blood globules give up a
ferment which rapidly transforms glycogen into sugar.
Glycogen and sugar are evidently of use in muscular contraction as they
are always diminished in the vessels of contracting muscles (Sanderson),
being converted into lactic acid (Bernard).
Forced muscular movements soon expel glycogen from the dog’s liver,
passing it into the blood, and there the excess of glycogen dissolves
the red blood globules. If glycogen is injected into the blood,
achrodextrin and hæmaglobin appear in the urine (Landois).
Ammonia carbonate and asparagin, or glycin, with a carbhydrate diet
produced in rabbits a considerable increase of glycogen (Rohmann).
Poisoning by arsenic, phosphorus or antimony destroys the glycogenic
function of the liver, which then fails to respond even to diabetic
puncture of the medulla.
There are important changes effected in the blood globules in passing
through the liver. The _leucocytes_ are increased, the hepatic veins
containing 5 or even 10 times as many as the portal vein (Bernard,
Lehmann, McDonald). Their ratio to the red globules is in the portal
vein 1:524 and in the hepatic veins 1:136 (Hirt). The _red globules_
undergo marked changes, having, in the hepatic veins, a smaller size,
sharper outlines, less flattening in the disc, a habit of massing
together irregularly in place of adhering in rouleaux, and they dissolve
less readily in water.