Lipid Metab / Panc Flashcards
What are the three ketone bodies formed by acetyl CoA?
Acetone
Acetylacetate
D,B - hydroxybutyrate
What ketone body cannot be converted directly back into acetyl CoA?
Acetone
Fatty acids undergo what to become acetyl-CoA?
beta oxidation
What is the payout per beta oxidation step?
1 acetyl coa, 1 NADH, 1 FADH2
What fates does an acety Coa molecule have/
Can enter citric acid cycle, can create ketone bodies, can make fatty acids
Hormone sensitive lipase does what?
converts diglycerides into monoglycerides
What enzyme converts monoglycerides into FFA?
monoglyceride lipase, by removing a glycerol
Adipose triglyceride lipase does what?
breaks down triglycerides
When a glucagon signalling molecule binds with a receptor, what is the mechanism for triglyceride mobilization?
A g-protein pathway creates a cAMP second messenger which activates protein kinase A, causing it to phosphorylate Hormone sensitive lipase and perilipin. HSL moves into the fatty droplet and converts diglycerides into monoglycerides. Perilipin and comparitive gene indicator dissociate, and CGI phosphorylates Adipose triglyceride lipase, causing the breakdown of triglycerides. Monoglycerides interact with monoglyceride lipase to have a glycerol removed creating a FFA which can then be sent out of the cell into the blood to be sent to the tissue in need.
FFAs are carried in the blood how?
serum albumin or lipoproteins/chylomicrons
What are the 4 classes of lipoproteins?
Chylomicrons
Very Low Density Lipoproteins
Low Density Lipopro
High Density Lipopro
What are the three sources of lipids?
Dietary lipids,
Adipose storage
Synthesis in tissue
What are the fates of lipids in the body? give an example of each
Energy substrates - triglycerides
Precursor molecules - sterols to make hormones
Structural elements - phospholipids
Signalling molecule - steroids, thromboxanes, etc.
Do lipids change the osmolarity of a cell?
No
If a genetic mutation occured to the ApoC-II protein, what would be the consequence?
dietary fats could not be taken into the blood because the structural elements of the chylomicron would be compromised.
Lipoprotein lipases in the capillaries are activated by what?>
ApoC-II portion of the chylomicrons
Lipoprotein lipases do what>
Convert triglycerides into FFA and glycerol
What is the rate limiting step of lipid synthesis?
Formation of Malonyl Coa via Acetyl Coa Carboylase (ACC)
What vitamin/coenzyme is critical for Acetyl CoA Carboxylase?
Biotin, B7
What is needed for the initiation of acyl chain elogation?
Malonyl CoA
During fatty acid synthesis, what is used to reduce unsaturated acyl groups to saturated?
NADPH
low levels of what lead to foam cells not being fully emptied of cholesterol, leading to apoptosis and cholesterol plaque accumulation?
HDL and LDL
What transports cholesterol?
HDL and LDL
What transports fatty acids?
VLDL and chylomicrons
What are three essential fatty acids?
Linoleate, a-linolenate, Arachidonate
When ACC is phosphorylated, what is happening?
When ACC is phosphorylated, it is not active. Lipid synthesis is NOT occurring
What dephosphorylates ACC to drive lipid synthesis?
Phosphatase, activated by insulin, drives fatty acid synthesis by converting acetyl coa to malonyl coa
What are the two types of fatty acid synthase?
Which one do humans use?
FAS I and FAS II
FAS I in humans
What is a limiting factor of FAS I
Only creates 16 carbon length chains
Where does B-oxidation occur?
In mitochondria
Where does ketone body formaiton occur?
Mitochondria
Where does fatty acid synthesis occur?
Cytosol
Since acetyl coa is produced in mitochondria and is needed in cytoplasm for fatty acid synthesis, how does it get to the cytoplasm?
Via the citrate shuttle. Acetyl coa is made into citrate via citrate synthase, then shuttle thru a citrate transporter to the cytosol. Here in the cytosol Acetyl CoA is reformed via citrate lyase while consuming an ATP to do so
Acyl carrier protein is dependent on what coenzyme/vitamin?
Pantothenic acid B5
Malonyl groups are esterified to what part of the pantothenic acid on the acyl carrier protein?
To the SH group
How is fatty acyl coa transported into the mitochondria for beta oxidation?
Carnitine shuttle… the Coa group is removed from the fatty acyl and the fatty acid portion is then binded to a carnitine via carnitine acyltransferase 1 along the outer membrane of the mito. The fatty carnitine then travels thru a transporter to the matrix of the mitochondria where a coa group is added back to the fatty portion, removing carnitine via carnitine acyltransferase II.
Glucagon activated PKA how?
Initiating a signal tranduction that leads to second messenger cAMP to turn on PKA, phosphorylating ACC, halting lipid synthesis and increasing fatty acid mobilization.
Triglyceride mobilization has what end product?
Free fatty acids being released from adipose tissue into the blood to be transported to respiring tissues.
Phospholipids are synthesized in what compartment of the cell?
Endoplasmic reticulum
How is palmitate created?
via fatty acid synthase adding malonyl coa carbons together
In fatty acid oxidation, which carbon gets oxidized? Which enzyme is important to know?
The beta carbon is oxidized, shortening the fatty acid chain by two carbons each time. Acyl coa dehydrogenase is a part of the ETC and will feed products directly into it.
Define exocrine
exocrine secretions are secreted onto a surface, consist of epithelial cells, and secrete a variety f substances including micelles, cells, lipids and polypeptides
Define endocrine
Secreted into the vasculature, contain epithelial and nonepithelial cells, and secrete via exocytosis largely proteins and hormones
What are three types of exocrine secretions
Merocrine,
Holocrine,
Apocrine
What is merocrine and give an example
most common exocrine secretion type, happens by exocytosis on apical end of epi cell, an example is salivary glands and the pancreas
What is holocrine and give and example
An exocrine type where secretory cells disintegrate to form the secretion. Sebacious glands on the skin that form sebum are an example
What is apocrine and what is an example
Secretions that are enclosed by a membrane with a cytoplasmm of proteins and lipids, and example is mammary glands
What cells are involved in the endocrine function of the pancreas
islets of langerhans
What cells are involved in the exocrine function of the pancres
Acinar cells
What is the majority of cells in the pancreas
Acinar cells
Acinar cells secrete _____ into the _____
Zymogen granules, intercalated ducts
What cells produce and secrete HCO3- that flushes secretions into the duodenum? Why is this important?
Controacinar cells, because the secretions (zymogen granules) are activated upon presence of low pH
Name two molecules that activate acinar and controacinar activity
CCK and secretin
What are the 4 cell types found in the islet of langerhans
? What do they do?
alpha cells - secrete glucagon
Beta cells - secrete insulin
delta cells - secrete somatostatin
PP cells - pancreatic peptide
what cell is the most abundant in the islet of langerhans?
beta cells consist of about 65% of the cells
alpha cells about 30%
(delta cells about 4%)
(PP cells less than 1%)
About how much blood is in the liver at any given time?
20%
Functions of the liver?
Bile secretion
Blood detox
Metabolism regulator
Blood resevoir
How much does the liver receive of normal cardiac output?
30%
What cell types are found in the liver
Hepatocytes
Kupffer cells
Sinusoidal epithelial cells
Hepatocytes are responsible for what?
Metabolism, bile production, detox of endogenous and xenobiotics, protection from infection
Kupffer cells are responsible for what?
Macrophages for the liver. The remove pathogens and debris from the blood
What is unique about sinusoidal epithelial cells?
They have no basement membrane
What two vessels does the liver receive blood from and how much from each?
Hepatic portal vein - about 70%
Proper hepatic artery - about 30%
What portion of the liver has an endocrine focus?
The classic hepatic lobule
Which portion of the liver has an exocrine focus?
The portal lobule
Bile from heptocytes is directed to bile ducts
Which portion of the liver contains microvascular units and is divided by a gradient of hepatocyte oxygenation?
Hepatic Acinus
Which zone of the liver is most oxygen and nutrient rich?
Zone I of the hepatic acinus
Where is glutaminase found only?
In zone III of the hepatic acinus
Where does the majority of blood sugar regulation occur in the liver?
Zone I of the hepatic acinus
What zone will of the hepatic acinus will have a high concentration of detoxifying enzymes?
Zone III
What phase of drug detoxification are drugs/molecules conjugated to hydrophillic molecules by transferases?
Phase II
What phase of drug detox are drugs transported directly into bile?
Phase III
What phase of liver detox are drugs converted into polar compounds via oxidation by cytochrome P450 and microsomal oxidases?
Phase I
Bile salts are products of what?
Cholesterol metabolism
Bile has the main function of what?
emulsifying fats by acting as a detergent to solubilize them, and alkalinize the intestinal contents.
T/F Bile is recycled
True
What stimulates bile release?
CCK cause contraciton of the gallbladder smooth muscle and relaxation of hepatopancreatic sphincter
Secretin does what in relation to bile
Stimulates HCO3- secretion into bile
