Exam 4 Part I Flashcards
The hepatic portal circulation receives from the
digestive organs and spleen and delivers it to the liver.
Some advantages of having direct access (portal access) from the digestive organs and spleen to the liver are that:
glucose goes first to the liver, which contributes to the glucose buffer function of the liver.
Alcohol, etc., can get detoxified immediately.
Bacteria get phagocytized
In the spleen, old RBCs are trapped & Hb is broken down, the product goes to the liver & is processed for excretion there
In the liver (and also in the spleen, red bone marrow and other sites of reticuloendothelial cells), heme of old RBCs is converted [into biliverdin which is converted] into
bilirubin
In the blood, bilirubin, which is insoluble, is bound to
albumin
The liver conjugates the bilirubin (with glucuronic acid), making it soluble. Then conjugated bilirubin is excreted into the
duodenum
In the colon, some bilirubin is converted by bacteria to
urobilinogen
Jaundice
Jaundice = increased bilirubin in blood
Prehepatic jaundice–
Prehepatic– hemolytic – excessive breakdown, more non-conjugated form
hepatic jaundice
The jaundice of someone with liver disease, for example, from acetaminophen or other drug toxicity, alcohol consumption,, hepatitis or other causes of liver failure. May be a problem before or after conjugation.
n posthepatic jaundice, one would expect
increased conjugated vs. non-conjugated. If bile duct obstruction is total, no bilirubin reaches the intestines to be converted to urobilinogen, and thus none is found in the urine.
amino acid metabolism
deamination of excess amino acids → gluconeogenesis: amino acids converted to glucose (can also be from fats). In liver failure → hypoglycemia because can’t convert to glucose when needed.
transamination
allows synthesis of all non-essential amino acids. Liver has the ability to synthesize all. (Essential amino acids must be taken in in diet.)
carbohydrate metabolism
conversion of galactose and fructose to glucose
fat metabolism
beta-oxidation of fatty acids
synthesis of cholesterol
conversion of large quantities of CHOs and proteins to fats
synthesis of lipoproteins for transport of fats in the blood
vitamin storage
A, D, B12, one source says also E, K
mineral storage
Fe, Cu
phagocytosis
By Kupffer cells (RE cells = reticuloendothelial cells). Old red blood cells, bacterial cells, especially from colon.
65% of macrophages are in the
liver
synthesis of heparin
Synthesis of heparin: Mast cells around caps., also in lung, very important in places with many caps. = slow-flowing blood.
Liver produces __, so important to have an anti-coagulant handy.
Liver produces clotting factors, so important to have an anti-coagulant handy.
albumins
prevents circulatory shock by keeping blood volume up osmotically.
Alcoholic or other edema from liver’s not being able to produce enough plasma proteins →
ascites, low blood flow to kidneys causes fluid retention.
clotting factors and pathology
“fulminant (very quick, very serious) acute liver failure. Coagulopathy always present: International normalized ratio (INR) ≥ 1.5. What is INR? Do you remember?
alpha and beta-globulins
carriers for fats etc.
The liver is able to convert a lot of potentially toxic substances into
The liver is able to convert a lot of potentially toxic substances into less toxic ones or less biologically active ones: In liver failure, toxic substances abound.
ammonia (from colon) →
ammonia (from colon) → urea → kidney.
Hepatic failure can lead to encephalopathy.
Hepatic failure can lead to encephalopathy. One element is that increased ammonia is toxic to neurons.
steroid hormones:
steroid hormones: liver stops their activity. Liver failure → ♂ feminization including gynecomastia.
Enterohepatic circulation:
Enterohepatic circulation: Recycles bile salts from the small intestine back to the liver 20X, important for efficiency of fat digestion/absorption.
Acute hepatic failure:
Acute hepatic failure: often affects young people, high mortality. “PT prolongation (elevated INR) or mental status changes (from encephalopathy) is grounds for hospital admission.”
Ascites not completely understood, one contributor:
Ascites not completely understood, one contributor: Decreased albumin production → fluid leaks into abdomen → drop in blood pressure at kidneys causes additional fluid retention. Also, scarring from cirrhosis causes blood flow obstruction → portal Htn. → ascites
A. Order of energy use:
CHO: glucose, glycogen
excess amino acids
fat
protein in tissues
“the protein-sparing effect of exercise.”
Fat’s being used first before protein in tissues is the order with exercise. This is called “the protein-sparing effect of exercise.” (In part most likely because growth hormone is protein anabolic) Without exercise, fat and protein are used at the same time.
Since nearly all energy used comes from reactions of oxygen with foods, an approximation of metabolic rate can be made from
Since nearly all energy used comes from reactions of oxygen with foods, an approximation of metabolic rate can be made from how much 02 is used. If a person is metabolizing different foods (CHO, fat or protein), a liter of 02 used will yield a different number of calories.
exercise
This is the factor that affects the metabolic rate the most.
Skeletal muscle at rest contributes _% of total from normal muscle tone.
25%
After a meal, the metabolic rate rises.
After a meal, the metabolic rate rises. This is often attributed to the processing of food (digestion, absorption and storage), but Guyton claims it has more to do with a protein meal, that certain amino acids stimulate cellular processes.
Consuming protein can make the metabolic rate
Consuming protein can make the metabolic rate increase 30% for 3-12 hours.
A child has __times the metabolic rate of an old person.
A child has two times the metabolic rate of an old person. The rapid metabolism of the child has partly to do with growth and partly with size.
thyroid hormones
Thyroid hormones have a lot to do with the normal regulation of metabolism. They increase the rates of almost all the chemical reactions in the body.
The NE & Epin. that is released during sympathetic stimulation can stimulate
The NE & Epin. that is released during sympathetic stimulation can stimulate glycogenolysis in muscle and liver.
Brown fat has a higher rate of metabolism and then can also be stimulated
Brown fat has a higher rate of metabolism and then can also be stimulated by NE and epin.
estrogen also inc. metabolic rate but not as much as
testosterone.
Also in both sexes adrenal cortical dehydroepiandrosterone (DHEA)
Protein anabolic and muscle, for example, demands more energy
Growth hormone and metabolism
Growth hormone: direct stimulation of cell metabolism, affects all cells, stimulates protein synthesis. 15-20% increase.
Fever and metabolism
Fever: all chemical reactions increased → rate inc 120%/10o C rise in T
climate and metabolism
Climate: higher in arctic climates than in tropical. Partly because cold is the major stimulus for thyroid hormones (“more hyperthyroidism in cold climates”)
sleep and metabolism
metabolism drops due to
decreased muscle tone generally
decreased sympathetic activity
Basal metabolic rate
Basal metabolic rate
The BMR is taken under certain well-specified conditions of rest, room T, not having eaten (for 12 hours). It is calculated/body surface area and is a method of comparing metabolic rate of different people under basal conditions. [An average value is 38Cal./sq. meter – hr.]
Most heat is lost through the skin. Subcutaneous fat
opposes this
Radiation
Radiation is the giving off into the air of waves of energy in the infared region (5 to 20 micron wavelength). 60% of the heat lost from the body is by radiation.
_% of the heat lost from the body is by radiation.
. 60% of the heat lost from the body is by radiation.
Changes in blood flow through the skin determine to a great extent how much
Changes in blood flow through the skin determine to a great extent how much heat will be lost. Vasodilation → ↑ heat loss
Heat is first conducted to the air immediately around the body, and then
Heat is first conducted to the air immediately around the body, and then convection (by air currents) moves the heat away and moves new air into its place.
Together conduction and convection to air comprise 15% of heat loss. A small amount of conduction to solid objects such as clothes and chairs occurs (3%). The rest of heat loss is evaporated at
22%
Most eccrine glands use
Most eccrine glands use ACh
The only way to get rid of heat in an environment hotter than the body is to
The only way to get rid of heat in an environment hotter than the body is to have a layer of water on the body surface which is transferred
lungs and water loss
Lungs: Small amount of heat is lost in respiratory surfaces, 300 ml/day of H2O is vaporized.
urine/feces and heat loss
Urine and feces: Excreted at body T, very small amt. of heat is lost.
skin and heat loss
The skin is not totally impermeable to H2O, 300-800 ml per day lost, small amount of heat lost.
conserving heat by external means
This is best accomplished by wearing loose clothing which allows for a layer of air that prevents conduction to the outside air and convection. Then if one coats the inside with a layer of gold (!) which reflects radiation back to the body, more heat is conserved.
