circulation 1,2 and 3 Flashcards
understand the virchow`s triad and its application
layers of the arteriole
innermost - the endothelium (tunica intima )
middle layer - the thick and elastic muscular layer .(tunica media)
outermost collagen (tunica externa)
how are the endothelial cells connected to the tunica media
connected through the basal lamina where they sit on
arrangement of molecules and cells in a normal artery
red blood cells next to the lumen
neutrophils and other immune cells towards the middle
contents of the lumen
red blood cells and platelets
constituents of a thrombus
platelets
fibrin
white blood cells
appearance of the platelets , fibrin and white blood cells in the microscope
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where are platelets contained
contained in the lumen and do not get in contact with the interstitial collagen unless there is an injury
is plasma contained in the lumen
yes together with plasma proteins that are present
are clotting factors contained in plasma
yes , only red blood cells,plasma proteins ,platelets and white blood cells are not contained in plasma
Haemostasis
process by which blood is stopped from leaking and oozing
phases of haemostasis
1.vasoconstriction -Any defect of the blood vessel that causes vasodilation for example in acute inflammation will result in vasoconstriction which reduces the flow of blood and limits blood loss.
2.primary haemostasis -there is platelet plug formation platelet plug is formed under the signal Von Willibrand Factor .
3.secondary haemostasis - the coagulation cascade takes place and there is formation of a fibrin meshwork to cover for the damage.
what are platelets
platelets are cells that are produced by the bone marrow .
they are cells that are formed form a progenitor un commited cell known as a megakaryocyte.
A megakaryocyte is a large cell with many nuclei.
The megakaryocyte undergoes nuclear division but not cell division hence a big cell with many nuclei
Formation of a platelet
The formation of a megakaryocytes takes place in the bone marrow.
Platelets are formed from megakaryocytes
the megakaryocytes undergo nuclear division but not cell division .
The platelets will bud off as fragments from the cytoplasmic extension to form the present platelets that are smaller compared to megakaryocytes.
Functional rationale of platelets
Trauma that is inflicted on the blood vessel cause the exposure of the platelets with the collagen in the tunica externa.
When the platelets are exposed they release adhesion factors that make them sticky , clump together and they adhere on the blood vessels in an attempt to close the gap between the damaged vessel.
what are clotting factors
these are proteins in the blood that aid in blood clotting and are named with a roman numeral
functionale rationale of clotting factors
they are an amplification system that will result in thrombin formation
What is the function of thrombin
thrombin converts soluble fibrinogen to insoluble fibrin which forms a mesh of strands that prevent the loss of blood.
what is the clotting cascade
clotting cascade is an amplification system that results in thrombin being activated being activated .
what is initial damage
damage that leads to the exposure of interstitial collagen ( that is collagen in the connective tissue ) there is also exposure of the tissue factor that is a protein that is used up as a clotting factor.
consequences of a defect in a vessel example in trauma
blood vessel has a defect ,plasma with protein clotting factors and the red blood cells form the inner lumen leak out and are exposed to the collagen factors,tissue factor that is present in the muscles of the vessels are exposed and released, tissue factor binds with another clotting protein to initiate blood clotting cascade,
how are the clotting factor activated ?
clotting cascade is initiated when the tissue factor binds on the clotting factors , many clotting factors are serine proteases ( protein enzymes ) they have a serine amino-acid in them and they cleave clotting factors together in order to form the active molecule, the activated clotting factor will have a site for binding for the next clotting factor to cleave onto it .
end product of the clotting cascade
thrombin
function of thrombin
activation of fibrinogen to fibrin
what is the endpoint of the protein cascade
Endpoint of clotting cascade is production of insoluble fibrin strands that form a meshwork