Ch. 18 (TEST #3) Flashcards
What are the three layers of the artery?
Tunica intima - endothelial layer (smooth surface decreases resistance and friction)
Tunica media- smooth muscle layer (constricts and dilates)
tunica externa - collagen and elastic fibers (protects and anchors, also is infiltrated with nerves to communicate with media)
What are some functions of the vascular endothelium?
Its a semi-permeable membrane - food and O2 to the tissues and waste and CO2 into vessel (on the capillary level)
Creates compounds that cause vasodilation or vasoconstriction
Creates growth factors that stimulate smooth muscle growth (important in vessel healing) IF STIMULATED AT WRONG TIMES MUSCLE CAN OVERGROW AND LEAD TO TURBULENT FLOW
Forms a smooth lining that resists clot formation
creates compounds to promote clot formation in injured areas
metabolizes hormones
regulates immune and inflammatory reactions
THINK ABOUT THESE WHEN ASKED ABOUT SOME ENDOTHELIAL DYSFUNCTIONS
What are some functions of the vascular smooth muscle cells?
Vasoconstriction and vasodilation
Synthesizes components of extracellular matrix (collagen and elastin)
Regulated by angiotensin II, catecholamines, and growth promoters
Which vessel layer can expand to accomodate pressure changes (mainly arterial)?
Tunica media (smooth muscle layer)
What are some disorders of the arterial circulation?
Hyperlipidemia => atherosclerosis
- is a progressive disorder
- affects any artery in the body
Vasculitis
- caused by direct injury, infection, immune reaction
- affects not only arteries, but veins and capillaries
aneurysms
- caused by a weakness in the arterial wall
- affects arteries only
What do we have to look out for with arterial circulation disorders (think abou arteries role)?
Hypoxia (disorders in flow could prevent cells from getting nutrients)
cells dont get nutrients and O2 => hypoxia => eventually leads to cell injury => can lead to necrotic cell death => spilling of cellular components => further increase inflammatory processes
What is hyperlipidemia?
High amount of lipids in the blood
What happens to the high amount of lipids with hyperlipidemia?
They will accumulate in the vascular endothelium => plaque formation => blocks flow through artery or causes turbulent flow
What are lipoproteins and how are they related to density?
These are proteins that carry lipids
more protein = higher density
less protein = lower density
Are lipids soluble in plasma?
NO, thats why they have to be transported by proteins
Are lipids good or bad?
They are good (we need them to repair lipid bi-layer or make new bi-layer during cell reproduction also schwann cells for myelin sheath in nerves) in a certain quantity
What are the different densities of lipoproteins from most dense to least dense?
HDL
LDL
VLDL
Chylomicrons
What makes HDLs heart healthy
They mainly help carry lipids out of the body (take them from peripheral tissues back to the liver for excretion)
Why are LDL considered bad?
These are the bodies main carriers of lipids.
What are triglycerides?
these are what we get from our diet directly (fats broken down into them), basically are a precursor to cholesterol (these are 80%-90% of what chylomicrons are)
So if someone hasnt fasted for a cholesterol test, what will be falsely elevated?
triglycerides (not cholesterols though it may a little, it takes a little more to make cholesterol)
What are the two ways we get lipids?
Through our diet (small intestine)
Through our liver making them (
SO EVEN WITH A LOW FAT DIET OUR LIVER CAN STILL MAKE CHOLESTEROL
What does our small intestine do with the fats we get in our diet (exogenous pathway)?
gets packaged into chylomicrons and absorbed into our blood vessels and carried by proteins
Then it can be deposited into our adipose and skeletal muscle tissues OR taken straight to the liver
Whatever is left is packaged as IDLs and eventually LDLs and are sent to the liver.
What is the livers role in lipid transportation (endogenous pathway)?
The liver takes in the LDLs that are left over from the exogenous pathway as well as left overs from the liver endogenous secretions of VLDL that werent absorbed by tissue (which are now LDLs) through its LDL receptors.
Once taken in by the LDL receptors the receptor pathway can break it down into Bile acid and cholesterol and excrete it by the GI system, or it can be converted into HDL and reversely transported back through the body picking up cholesterol form peripheral tissues (also can inhibit cellular absorption of LDL) and sent back to the liver to be excreted as bile acid and cholesterol by the GI system.
The liver can also make VLDLs that are sent back into the bloodstream to distribute more energy (adipose or skeletal muscle) which will then be processed again by the receptor pathway of the liver once they are converted to LDLs.
What happens when we have an issue with our liver or its receptors, what is an alternative pathway we can take?
An alternative, not so good pathway is known as the scavenger pathway, if we have to use this pathway we usually will already be having deposits in our vessels
So dietary lipids are absorbed as what?
chylomicrons
What takes up triglycerides from chylomicrons?
Fat (adipose) and muscle tissue
What happens with the left over chylomicrons after absorbtion?
The reminants are IDLs which convert to LDLs and are sent to the liver (where they will then be released from the liver as either HDLs or VLDLs
Why would we send the chylomicrons to the fat and muscle tissue to be absorbed?
THEY ARE A GREAT SOURCE OF ENERGY
they either get used by the muscle cells for energy or get stored in the fat tissue for use later
So if we eat a lot of fat but dont use our muscles very often then a lot of it will be stored in the fat tissue
What are endogenous triglycerides?
triglycerides that are made by the liver
So after our liver releases VLDLs into the blood stream and the triglycerides are distrubuted for energy, what form are they sent back to the liver in?
LDLs
What are our main carriers of cholesterol?
LDLs
So cholesterol can be affected by how many LDL receptors our liver has, or how well they function?
YES YES YES
we need our receptors to take in the LDLs for removal
What percentage of all LDLs are removed by the receptor pathway?
60%
How does the nonreceptor dependent pathway work?
This is where the LDLs are taken up by phagocytic monocytes (macrophages) and other scavenger cells (this is how foam cells are made)
Why would the nonreceptor pathway be activated?
If the receptor pathway is broken or there is too much LDL for the receptor pathway to handle itself.
Where are HDLs made mostly?
In the liver