Research - By: (Me) Nicholas Ellis @ http://www.youtube.com/sn1pe352
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A. Iida, et al., "Metalloprotease-Dependent Onset of Blood Circulation in Zebrafish," Current Biology, 20:1-7, 2010, DOI 10.1016/j.cub.2010.04.052
Scientists capture the moment when blood cells begin coursing through vessels in the developing embryo of a zebrafish.
The humble zebrafish is being used by scientists for a not-so-humble purpose: to help cure cancer and other diseases.
The tiny zebrafish are popular with researchers because they're transparent and develop rapidly.
For instance, scientists say they can view a complete cardiovascular system in embryos in less than two days.
What does it take for blood to start flowing for the first time in an embryo?
That's the question that Atsuko Sehara-Fujisawa at Kyoto University and colleagues set out to answer by catching zebrafish blood vessels on film as they matured.
The researchers saw that the blood cell precursors entered blood vessels and stayed there immobile, possibly tethered to the inner wall by adhesion molecules called PSGL1.
It's not until an enzyme called ADAM8, a metalloprotease, is expressed by the blood cells -- cutting loose or weakening the tethering proteins -- that the blood begins to flow.
See the blood cells (labeled with a red dye) as they start to flow within the blood vessel (green dye).
A REFUTATION OF THE PRESSURE PROPULSION PREMISE OF HEART FUNCTION
1. Rudolf Steiner Research Center, Royal Oak, MI
2. Dept. of Anesthesiology, Albany Medical College, Albany, NY
3. Dept. of Anesthesiology and Physiology, Albany Medical College, NY
4. Cardiovascular Consultants Ltd., Minneapolis, MN. Department of Medicine, University of Minnesota, MN
Physiological Conclusions
The autonomic vortex movement of the blood discussed herein is inherent to the blood motion.
It is not an accidental local disturbance often explained as turbulence or eddy currents, nor a localized phenomena with a single functional purpose as in heart valve dynamics.
From a broader view it is to be expected that blood should so move, considering that fluids in nature tend to move curvilinearly, which is their path of least energy.
The extreme expression of this tendency in nature, in terms of order, stability and minimal expenditure of energy are tornados and "jet" streams.
Embryological Observations
Steiner 6 indicated that embryology provides the clues for solving the problem of the circulation. In relation to this,
Bremer 9 performed a remarkable series of observations of blood circulation in the very early chick embryo before the formation of the heart valves.
He described the two streams of spiraling blood with different forward velocities in the single tube stage heart.
Nevertheless, the blood is noted to have a definite direction of flow within the conduits and moves without an apparent propelling mechanism.
These streams spiral around their own longitudinal axes and around each other.
The streams appear to be a considerable distance apart, do not fill their vessels, and appear to be in discontinuous segments.
In a movie made by Bremer of the beating embryonic heart, one observes that the spiraling blood is boosted by the pulsating heart without creating turbulence in the blood.
This suggests that the momentum transfer occurring between the heart and blood is in phase; the heart must somehow sense the motion of the blood and respond to it in turn with a spiraling impulses at the same velocities as the blood, thereby combining blood and heart momenta.
It is assumed that heart muscle layers have the same velocity distribution pattern as the concentric streams of a free vortex to enable heart and blood motions to couple in multi-velocity phase.
It was significant to observe that the movement of the heart occurred with minimal inward motion of the heart wall.
That the streaming of the blood can be observed before the functioning of the heart is supported by observations that the circulation in the early chick embryo is maintained for around 10 minutes after the heart had been excised 10.
Moreover, the inherent mobility of the blood was highlighted by Pomerance and Davies 11, who found an embryo that lived to term without a heart but was born dead and grossly disfigured.
Thus, the composite view of the embryonic cardiovascular system tells us that the blood is not propelled by pressure, but rather moves with its own biological momentum and with its own intrinsic flow pattern.
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Blood flow in rat brain capillaries: Two-photon microscopyby lovethecanasian4,547 views
The researchers saw that the blood cell precursors entered blood vessels and stayed there immobile, possibly tethered to the inner wall by adhesion molecules called PSGL1.
It's not until an enzyme called ADAM8, a metalloprotease, is expressed by the blood cells -- cutting loose or weakening the tethering proteins -- that the blood begins to flow.
See the blood cells (labeled with a red dye) as they start to flow within the blood vessel (green dye).
sn1pe352 2 months ago in playlist Bjorn Nordenstrom : Biologically Closed Electric Circuits
Fluid particles downstream of the branching orifice returned these particles upstream to exit via the branching tube.
In a region very close to the tube wall, streamlines were also observed moving upstream to be captured by the branching vessel.
The interaction of this local upstream flow with the general downstream flow produced a pair of stagnation points located downstream and lateral to the branching orifice.
stagnation regions are discussed in relation to atheroma and thrombus formation.
sn1pe352 2 months ago