The Liver Flashcards
What is the liver responsible for?
-creating lipids that circulate through the body
- converting excess carbohydrates and proteins into lipids(fats) for energy storage
What does the hepatic vein carry?
deoxygenated, filtered blood
Where does the hepatic vein flow?
To the heart
What does the hepatic artery carry?
Oxygen-rich blood. It branches extensively to provide the liver with oxygen
From where does the hepatic artery flow from?
From the heart to the liver
When you look at a diagram of the liver, what is left and what is right?
The left lobe is seen on the right side and is seen as smaller and vise versa.
What is the liver connected to?
The pancreas, gall bladder and small intestine.
What are the different parts of the Gall bladder?
Hepatic duct, cystic duct, common bile duct.
Why is the portal vein so nutrient-rich?
It comes from the small intestine, brings the absorbed nutrients, but also carries toxins. The liver cleanses it before moving onto the heart and body.
What does the gall bladder look like before and after a meal?
Before the meal, it is as big as a small pear, after is as small as a deflated grape/
What are sinusoids?
Specialized blood vessels in the liver?
What is one of the structural features of a sinusoid?
It has fenestrations.
What is a hepatocyte?
A cell in the liver
Compare sinusoids to capillaries.
Capillaries have a narrower lumen
Capillaries can be fenestrated
Sinusoids are fenestrated
sinusoids have wieder lumen
sinusoids have phagocytes (white blood cells)
Explain the structure of a sinusoid
When cut through, it looks like a hexagon. In the center there is the “central vein”. At each point of the hexagon, the hepatic artery and portal vein bleed into the central vein. Along the channel, the bile duct runs. The channel of the sinusoid (including blood from the portal vein and hepatic artery) in embedded with phagocytic cells which snatch red blood cells once they are old.
How is glucose stored in the liver?
It is stored as glycogen when glucose levels are high.
When glucose levels are low, glycogen is broken down into glucose and released into the blood stream.
How does glucose get into the liver?
It is absorbed by epithelial cells via active transport
It enters the capillary via facilitated diffusion
Now in bloodstream
What is the mg/mL of glucose that is considered homeostasis
90 mg/ 100mL
Explain how the liver reacts to an increase in glucose in the bloodstream after eating.
Due to food intake, glucose levels rise. This stimulates the beta cells of the pancreas, the pancreas releases insulin. A condensation reaction occurs and glucose is turned into glycogen and is stored in the liver and muscles. The glucose level drops and homeostasis is achieved.
Explain how the liver reacts to a drop in Glucose after not eating.
Glucose levels drop in the bloodstream which stimulates the alpha cells in the liver, the pancreas releases glucagon (hormone) which triggers the hydrolysis reaction of glycogen to be broken down into glucose. Glucose is released into the bloodstream, levels rise and the body achieves homeostasis again.
What hormone is released when the alpha cells of the pancreas are stimulated?
The hormone glucagon
What hormone is released when the beta cells of the pancreas are stimulated?
Insulin
What is iron needed for?
It is needed for oxygen transportation.
What is iron a component of?
hemoglobin, it is bound to the heme group
What captures iron?
Phagocytes
Why is iron stored in haemoglobin?
Because when it is free-floating, it is toxic to cells. So when iron is needed, it will be transported within ferritin proteins.
How many iron ions can be stored in one ferritin protein?
Up to 4500
Where is iron stored when in excess?
In the liver
Where is vitamin A found?
in eye rod cells
What is vitamin A ?
A pigment found in eye rod cells
Where is vitamin A stored?
In lipids within the liver, this is where 80% of the total vitamin A is stored.
What is another term for red blood cells?
Erythrocytes
What is another term for Vitamin D?
Calciferol
Explain the production of Vitamin D within the body
An active precursor of vitamin D is synthesized in the skin from cholesterol through sun. The liver then converts this precursor into active Vitamin D.
What is vitamin D neded for?
Cells need it to absorb calcium
What does the liver convert proteins and amino acids into?
Carbohydrates and lipids
What does the liver turn nitrogenous waste into?
Non-toxic forms for excretion
What are Albumins?
water-soluble main plasma proteins
They are used to transport molecules within the blood
What produces albumins?
The rough ER in hepatocytes
Where are 90% of proteins produced?
The hepatocytes
What, in hepatocytes, allows them to synthesize so many proteins?
Having a lot of Rough ERs
What are fibrinogens and what are they needed for
They are large, soluble glycoproteins which are required to form blood clots
What does the liver do with amino acids?
It converts them into glucose.
What happens when the liver converts amino acids into glucose?
Ammonia (NH3) is a biproduct. This is toxic, however, the liver can convert ammonia to urea which is then excreted via urine.
How much phospholipids are produced by liver cells?
Very extensive amounts do to them having a lot of Rough ER
What steroid does the Liver synthesize?
Cholestrol
What does the liver do if you eat too many carbohydrates?
It converts them into triglycerides.
What can the liver do with fatty acids?
Hepatocytes can break them down into other lipid molecules
What 3 groups does a triglyceride consist of?
Methyl, carboxyl, hydroxyl.
What are lipoproteins?
They are like a torjan horse which store triglycerides in the center. They are like a ball formed from a phospholipid layer.
What are the different types of lipoproteins?
Chylomicros, VLDL, LDL, HDL
Where are chlomicrons made?
In the small intestine from lipid molecules absorbed from food.
What is the function of chlomicrons?
To transport triglycerides to cells for nergy use(muscle cells) and for storage in adipose cells.
Where is VLDL made?
In the liver from excess dietary carbohydrates.
What is the function of VLDL?
To transport tryglicerides.
What does VLDL become once it loses some triglycerides?
LDL
What is bad cholestrol?
LDL
What is good cholestrol?
HDL
Where is LDL made?
In the liver from VLDL
What is the role of LDL?
To deliver cholesterol to cells, deposits them
Where is HDL made?
In the liver and small intestine
What is the role of HDL?
To pick up excess cholestrol from cells and deliver it to the liver where excess is eliminated from the body via bile and then small intestine.
What do excess cholesterol deposits result in?
Restricted blood flow, heart attack and strokes
WHat is the average number of days that RBC’s circulate?
120 days
What is homopoesis?
Red blood cell making, comes from the hemopoietic bone marrow.
What is a Reticulocyte?
An immature red blood cell
What happens to old red blood cells in the sinusoid?
They are phagocyzed by kupffer cells in the sinusoid. Lysosomes with digestive enzymes break apart the red blood cells into cell stuff and hemoglobin. Hemoglobin is broken down into the heme( heme group and iron) and globin(protein). The protein is broken down via hydrolysis into amino acids. The heme becomes bilirubin(a part of bile) and is excreted via waste. Amino acids are brought back to bone marrow for recycling. Iron is recycled, transported by ferritin.
Where do amino acids from the globin of hemoglobin of red blood cells go?
They are brought back to bone marrow for recycling.
Where does iron from the globin of hemoglobin of red blood cells go?
It is recycles and transported via a ferritin protein.
Where does the heme from the hemoglobin of RBC’s go?
It becomes bilirubin(a part of bile) and is excreted via waste.
What is bile used for?
Breaking apart globs of fat in the small intestine
Where are bile and lipase secreted into?
The duodenum
What is bile made of?
Bile salts(made from cholesterol in hepatocytes)
water
bilirubin
fats
What are the two functions of bile?
Its a form of excretion for waste (eg. heme) and it assists with the digestion of fats
What is jaundice?
A yellowish discoloration of the skin, eye white, mucours membranes. It is not a disease, but it means something with the liver/ gall bladder is wrong.
What causes jaundice?
An overwhelmed RBC recycling mechanism(excessive RBC damage). Then there is build up of the heme(pigment)
Liver cancer(tumor blocking the bile canals, bilirubin builds up in liver)
Alcoholism( damaged hepatocytes)
premature babies can also be born with an underdeveloped liver
How can you treat jaundice?
By treating the disease causing jaundice) or UV treatment. UV turns bilirubin non-toxic(UV light blanket/ bed)
Explain the making of bilirubin
Red blood cells are broken down by phagocytic cells, the heme becomes bilirubin and is transported by albumin to liver cells where it is mixed with excell cholestrol (from LDL) creating bile
Explain how bile is released.
The presence of fatty acids trigger the release of CCk. CCK signals gall bladder to contract and release. This secretes bile into the small intestine.
What turns ethanol into acetyldehyde (toxin)?
An enzyme from the liver called ADH. This is the reason for hangover symptoms.
What 2 bloodvessels supply the sinusoid?
Hepatic artery
portal vein
Typical features of a sinusoid
1 cell thick
phagocytic cells
fenestrations
Nutrients stored in the liver
Glucose as Glycogen
Iron in ferritin proteins
Lipids
Which blood vessel leads from muscles to the liver?
hepatic artery
Compare contrast pathway for lactate in hepatocytes versus mitochondria-rich tissue.
both produce pyruvate from lactate
both produce CO2 + H20 via acetyl Coa
Hepatocytes produce glucose from lactate, Mitochondria tissue not
The function of hepatocytes?
Recycle red blood cells
regulate nutrient levels
store iron
produce lipoproteins
Explain the dual supply in the liver
Dual supply comes from the oxygen rich hepatic artery and nutrient rich but oxygen depleted portal vein.
The hepatic arteries oxygen supply allows for all the processes of the liver to occur, suppling it with oxygen.
The hepatic portal vein carries blood from the intestines, this allows the liver to take these nutrients and store them. The hepatic poral vein allows blood to be filtered.
Where does the emulsification and lipase digestion take place?
In the small intestine
Functions of fats in the body
Serve as temperature regulators, insulin,
Protect the myelin sheath
Long term energy storage (survival mechanism)
How does an increase in altitude increase erythrocytes and decrease plasma in blood?
As there is less partial pressure of oxygen, there is less oxygen for the body to function. Red blood cells multiply more to increase storage for oxygen. As RBCs increasing means that the number of hemoglobins increase aswell, these will have higher affinity.
