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Topic: Blood flow


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  What is blood viscoelasticity
Blood is a complex fluid whose flow properties are significantly affected by the arrangement, orientation and deformability of red blood cells.
Blood is a viscoelastic fluid and its rheological properties, viscosity and elasticity, depend on the rate of flow or shear rate.
In this region the viscoelasticity of the blood is dominated by the deformability of the red blood cells.
www.vilastic.com /FAQ_Blood.htm   (1170 words)

  
  Blood flow - Wikipedia, the free encyclopedia   (Site not responding. Last check: 2007-11-05)
Blood flow is the flow of blood in the cardiovascular system.
In the last equation it is important to note that blood flow changes with the fourth power with change of radius.
This is important in angioplasty, as it enables the increase of blood flow with balloon catheter to the deprived organ significantly with only a small increase in radius of a vessel.
en.wikipedia.org /wiki/Blood_flow   (159 words)

  
 Blood flow studies
Blood flow studies measure blood flow and pressure.
Blood pressure is first taken in both arms.
The blood pressure cuff may be moved to other positions on the same or other extremities during the test.
www.mercydesmoines.org /adam/encyclopedia/ency/003442.asp   (415 words)

  
 Learn about low blood pressure, symptoms, causes and treatment by MedicineNet.com
Blood pressure is determined by two factors: 1) The amount of blood pumped by the left ventricle of the heart into the arteries, and 2) the resistance to the flow of blood caused by the walls of the arterioles (smaller arteries).
Blood pressure tends to be lower if less blood is being pumped into the arteries or if the arterioles are wider and more flexible and resisting the flow of blood less.
Blood flow to the kidneys decrease to reduce the formation of urine, and increase the volume of blood in the arteries and veins.
www.medicinenet.com /low_blood_pressure/page2.htm   (904 words)

  
 Bloodpressure
Blood pressure is the force created by the heart as it pushes blood into the arteries and the circulatory system.
As the blood goes through the arterioles, the arterioles either contract or expand altering both the amount of blood flow and the resistance to blood flow.
It controls the expansion and contraction of blood vessels, and thus blood pressure, by regulating the amount of nitric oxide to which the vessels are exposed.
www.mamashealth.com /bloodpressure.asp   (1099 words)

  
 Blood Flow Through Your Heart and Lungs
Blood returns to your heart from your body and lungs.
Blood flows from the upper to the lower chambers.
Blood flows through each chamber one time on its way through your heart — first through the right side of your heart and then through the left.
www.guidant.com /condition/heart/heart_bloodflow.shtml   (484 words)

  
 High Blood Pressure (Hypertension) - Texas Heart Institute Heart Information Center
Hypertension, the medical term for high blood pressure, is known as "the silent killer." At least 65 million Americans have high blood pressure, and as many as 21 million of them do not even know they have the condition.
The moving blood pushes against the arterial walls, and this force is measured as blood pressure.
Those with a blood pressure reading anywhere from 120/80 up to 139/89 (once thought to be normal) are now classified within a category called "prehypertension." The NHLBI says that about 45 million Americans fall within the prehypertension category, which puts them at twice the risk of developing high blood pressure later in life.
texasheart.org /HIC/Topics/Cond/hbp.cfm   (1610 words)

  
 MedlinePlus Medical Encyclopedia: Blood flow studies   (Site not responding. Last check: 2007-11-05)
Blood flow studies measure blood flow and pressure.
Blood pressure is first taken in both arms.
The blood pressure cuff may be moved to other positions on the same or other extremities during the test.
www.nlm.nih.gov /medlineplus/ency/article/003442.htm   (623 words)

  
 High blood pressure (hypertension) - causes, treatments and medications
This means that the hypertension in these individuals is secondary to (caused by) a specific disorder of a particular organ or blood vessel, such as the kidney, adrenal gland, or aortic artery.
One important cause of renal hypertension is narrowing (stenosis) of the artery that supplies blood to the kidneys (renal artery).
The purpose of these tests is to try to determine whether there is a restricted blood flow to the kidney and whether angioplasty (removal of the restriction in the renal arteries) is likely to be beneficial.
www.medicinenet.com /high_blood_pressure/page4.htm   (1289 words)

  
 BioMed Central | Full text | Heterogeneity of human adipose blood flow
The standard reference human adipose blood flow value of about 28 ml/kg/min [1] is based on Xenon washout measurements [2] of the local flow to a roughly 0.1 ml tissue region.
The flow limited assumption is directly tested in this paper by determining whether the PBPK model could accurately describe the long time experimental human pharmacokinetics of cannabinol [20] and cannabidiol [21] using the adipose perfusion rates determined from modeling the volatile anesthetics.
As discussed in the Methods, heterogeneity of the adipose blood flow was characterized by dividing it into N equal weight compartments and determining the flow in each compartment that optimized the fit to the experimental data.
www.biomedcentral.com /1472-6904/7/1   (7425 words)

  
 Blood Flow
Blood volume affects flow, blood is unequally distributed in the body.
Blood flow is result of differences in pressure and is directly proportional to pressure gradient and inversely proportional to resistance (R), which opposes flow.
Resistance is greater and flow is reduced in vessels of smaller radius (r).
www.mtsu.edu /~jshardo/bly2020/cardiovascular/blood_pressure.html   (819 words)

  
 ScienceDaily: Caffeine Limits Blood Flow To Heart Muscle During Exercise
In one part of the study, PET scans that showed blood flow in the hearts of 10 participants were performed before and immediately after they rode a stationary exercise bicycle.
Blood flow normally increases in response to exercise, and the results indicate that caffeine reduces the body's ability to boost blood flow to the muscle of the heart on demand.
The ratio of exercise blood flow to resting blood flow, called the myocardial flow reserve, was 22 percent lower in the group at normal air pressure after ingesting caffeine and 39 percent lower in the group in the high-altitude chamber.
www.sciencedaily.com /releases/2006/01/060114232653.htm   (1113 words)

  
 Stroke Busters in Turbulent Blood [PSC]
When there's low flow velocity and recirculation, the vessel wall feels "low shear stress." Like the force you exert on a desktop as you slide your hand across it, shear stress is force in the direction of flow.
In the spacious region, flow along the outer wall is often slow with recirculation, prime territory for trouble.
Turbulent flow is much more complex and greatly complicates the numerical problem, multiplying the demand on computing at least 100 times, well beyond the ability of most hemodynamics software and workstation computers.
www.psc.edu /science/2002/tufo/stroke_busters_in_turbulent_blood.html   (1890 words)

  
 Red Gold . Blood Journey . Phase 2 | PBS
Pulmonary circulation, in which blood goes from the heart to the lungs and back to the heart, is when the blood exchanges carbon dioxide, a waste product it has picked up from the rest of the body, for oxygen, which it will carry to the rest of the body.
The de-oxygenated, carbon-dioxide-laden blood returning to the heart from the body enters the right side of the heart through two veins (one for blood coming from the lower half of the body, the other for blood from the upper half).
The flow of the blood from the heart to the rest of the body and back to the heart is systemic circulation.
www.pbs.org /wnet/redgold/journey/phase2_a1.html   (465 words)

  
 Non-Invasive Technologies to Measure Ocular Blood Flow - Ophthalmology Technology Spotlight - Medcompare
Flow towards the CDI probe is displayed in red and represents arterial flow, whereas that away from the probe is blue and represents venous flow.
The frequencies of DSPS represent the mean speed of red blood cells moving in the sampled volume, whereas the signal intensity of each frequency represents the number of moving red blood cells.
This is because the main source of blood supply of the optic nerve head is via a portion of the posterior communicating artery (PCA) circulation, which is difficult to isolate in measurements.
www.medcompare.com /spotlight.asp?spotlightid=61   (867 words)

  
 Circulatory System   (Site not responding. Last check: 2007-11-05)
The blood is the transport system by which oxygen and nutrients reach the body's cells, and waste materials are carried away.
The blood flows through a one-way valve, which makes sure it always moves in the correct direction, into the larger, lower chamber called the ventricle.
Blood leaves the left side of the heart and travels through arteries which gradually divide into capillaries.
users.tpg.com.au /users/amcgann/body/circulatory.html   (263 words)

  
 RENAL BLOOD FLOW-GLOMERULAR FILTRATION RATE
In spite of the high rate of oxygen utilization, the very great renal blood flow relative to the oxygen consumption indicates that factors other than the oxygen requirements are responsible for the control of renal blood flow.
Total renal blood flow can be measured by estimating the clearance of a substance that is completely removed from the blood in a single pass through the kidney.
Blood flowing through the renal artery is distributed via a series of divisions (see fig 2) and ends by feeding the glomeruli through the afferent arterioles.
www.uhmc.sunysb.edu /internalmed/nephro/webpages/Part_A.htm   (4603 words)

  
 Blood Flow to Brain Linked to Dementia
In the study, researchers used brain imaging to measure blood flow into the brain as well as brain damage in three groups: 17 older adults with dementia; 16 older adults with normal brain function; and 15 young, healthy adults.
The average blood flow into the brain among the dementia group was 443 milliliters per minute, which was 108 milliliters per minute lower than older adults of the same age with good brain function.
In comparison, average blood flow in the brain was 742 milliliters per minute among the healthy, young adults.
www.webmd.com /heart-disease/news/20050830/blood-flow-to-brain-linked-to-dementia   (489 words)

  
 ► Blood flow studies
A duplex study is a test which uses Doppler ultrasound to assess and/or monitor blood flow through arteries or veins.
A blood pressure cuff is applied to the extremity being tested and inflated until the pulsatile flow is no longer heard.
The blood pressure when flow returns is recorded and the information is transmitted to a computer which records and interprets the information.
www.umm.edu /ency/article/003442.htm   (510 words)

  
 Blood Flow in Wings   (Site not responding. Last check: 2007-11-05)
The wing veins of insects generally are pathways for the flow of haemolymph (blood), for the passage of tracheae (which provide air exchange), and for the routing of nerves.
In general, blood from the lateral intermuscular spaces of the thorax enters the wing at the humeral angle, flows distally to the wing apex through the large anterior veins and moves en route through cross veins toward the posterior margin.
There are some unique aspects to the flow pattern in the Odonata, tied to the peculiar features of the Odonata veins: the arculus, nodus, and pterostigma.
www.windsofkansas.com /bloodflow.html   (321 words)

  
 Vascular Ultrasound Imaging
Ultrasound images are captured in real-time, so they can help radiologists monitor the blood flow to organs and tissues throughout the body, as well as evaluate the placement and success of repair, such as after arterial bypass surgery.
With knowledge about the arterial blood flow gained from an ultrasound image, the radiologist can often determine whether a patient is a good candidate for a procedure like angioplasty.
Blood flow changes the pitch of the sound beam; this Doppler effect can be heard or detected on the image as color or displayed graphically.
www.radiologyinfo.org /content/ultrasound-vascular.htm   (1154 words)

  
 How blood flow dictates gene expression
The researchers surmise that the mechanical stimulus of blood flowing in a vessel leads to the upregulation of Klf2, which either activates or represses genes that control smooth muscle tone, that is the caliber of the vessel.
However, when Klf2 is genetically deleted, or "knocked out," from the blood vessels of mouse embryos, they had an abnormally high cardiac output, as measured by ultrasound, while the overall structure of their blood vessels was normal.
Now that Klf2 has been established as an important regulator of blood flow in live animals and is required for the development of a healthy cardiovascular system, the next step is to elucidate the role of Klf2 in normal adult blood vessels and in the pathogenesis of vascular diseases, such as atherosclerosis.
www.eurekalert.org /pub_releases/2006-12/uops-hbf122006.php   (694 words)

  
 Potential Key to Brain Blood-Flow Disorders | Huliq: Breaking News
Though this cellular activity can be visualized in modern-day functional brain scans, the mechanisms by which these neurons signal blood vessels to dilate and increasing blood flow remain largely unknown, and are central to understanding brain function.
The diameter of blood vessels in the brain can be modulated by extracellular potassium, a common element present inside and outside all cells of the body.
The authors showed that removing the BK channels, either by drugs or genetically, significantly reduced the dilation of the blood vessel in response to brain activity; hence the astrocytic BK channel is an important participant in the signaling mechanism.
www.huliq.com /4744/potential-key-to-brain-blood-flow-disorders   (1048 words)

  
 Resources : Learn More About : Heart & Blood Flow : St. Jude Medical   (Site not responding. Last check: 2007-11-05)
The right side receives blood that is low in oxygen from all the veins in the body, and then it pumps that blood through the pulmonary artery to the lungs, where it will become re-oxygenated.
As blood circulates through the heart to go to the lungs or body, some of the blood flows into a set of much smaller blood vessels that provide blood flow directly to the muscle of the heart.
These leaflets open to allow blood to flow through the valve, and they close to prevent blood from flowing back into the chamber from which it just came.
www.sjm.com /resources/learnmoreabout.aspx?section=HeartAndBloodFlow   (801 words)

  
 Blood Flow
Blood flow is the quantity of blood that passes through the arterial or venous circulation within a period of time and is often expressed in milliliters or liters per minute.
The direction and rate of blood flow in the capillaries cause a Doppler shift in the returned light, and it is this shift that constitutes the signal and used to determine blood flow.
For periodic determination of flow rates, the thermodilution method uses a small temperature probe to monitor the change in blood temperature when a bolus of cool fluid (of known volume and temperature) is injected into the circulatory system.
www.adinstruments.com /applications/research/Blood-Flow/?source=google   (886 words)

  
 Blood flow
The flow through the channel was varied in a controlled manner with a liquid pump in the velocity range from 0 to 3mm/sec.
Flux response of the imager is not at zero for the zero velocity of flow due to the Brownian motion of the scattering particles in Intralipid™.
An inflatable cuff, used for blood pressure measurements, is pumped to stop the blood flow.
lob.epfl.ch /page46466.html   (2030 words)

  
 All About the Heart
The atria are the chambers that fill with the blood returning to the heart from the body and lungs.
The movement of the blood through the heart and around the body is called circulation (say: sur-kyoo-lay-shun), and your heart is really good at it.
Each time the blood circulates from the heart out to the body, about 20% (one fifth) of it goes through the kidneys.
www.kidshealth.org /kid/body/heart_noSW.html   (1354 words)

  
 Brain Blood Flow Biofeedback
Blood flow biofeedback is a technique of a conscious control of blood flow.
The brain blood flow technique is based on non-invasive method of measuring bioimpedance.
Changes in bioimpedance are generated by blood volume and blood flow and registered by a device.
webideas.com /regbiofeedback/whatisbbfb.html   (268 words)

  
 USATODAY.com - Acupuncture's secret: Blood flow to brain   (Site not responding. Last check: 2007-11-05)
Acupuncture on pain-relief points cuts blood flow to key areas of the brain within seconds, providing the clearest explanation to date for how the ancient technique might relieve pain and treat addictions, a Harvard scientist reports today.
Blood flow decreased in certain areas of the brain within seconds of volunteers reporting a heaviness in their hands, a sign the acupuncture is working correctly, Rosen says.
The reduced blood flow could lead to dopamine changes that trigger a "cascade" effect, releasing endorphins, the brain's natural pain-relieving and comforting chemicals, Rosen says.
www.usatoday.com /news/health/2004-03-03-acupuncture-blood-usat_x.htm   (531 words)

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