Physics question about head pressure and heart pressure?
Neglecting the pressure drop due to resistance, calculate the blood pressure in mmHg in an artery in the brain 32 cm above the heart. The pressure at the heart is 120mmHg and the density of blood is 1.05g/cm3.
Physics Question?
If you are lying down and stand up quickly, you can get dizzy or feel faint. This is because the blood vessels don't have time to expand to compensate for the blood pressure drop. If your brain is 0.4 m higher than your heart when you are standing, how much lower is your blood pressure at your brain than it is at your heart? The density of blood plasma is about 1025 kg/m3 and suppose your maximum (systolic) pressure of the blood at the heart is 117 mm of Hg (Note that 120 mm of Hg = 16 kP = 1.6 x 104 N/m2). Since most doctors still use mm of Hg, give your result in those units. Pressure at brain = mm of Hg.
Minimum pressure gauge of heart? - Physics Help!?
A giraffe's brain is approximately 3.1 m above its heart. Estimate the minimum gauge pressure that its heart must produce to move the blood to his brain. Ignore any effects from the blood flow through arteries of different area, and assume that giraffe blood is identical to human blood. ____kPa
Pressure Question - Physics?
Blood pressure is usually reported in millimeters of mercury (mmHg) or the height of a column of mercury producing the same pressure value. Typical values for an adult human are 130/80; the first value is the systolic pressure, during the contraction of the ventricles of the heart, and the second is the diastolic pressure, during the contraction of the auricles of the heart. The head of an adult male giraffe is 5.6 m above the ground; the giraffe's heart is 1.4 m above the ground. What is the minimum systolic pressure (in mmHg) required at the heart to drive blood to the head (neglect the additional pressure required to overcome the effects of viscosity)? The density of giraffe blood is 1.00 g/cm3, and that of mercury is 13.6 g/cm3. mmHg?
Why do I feel pressure and my heartbeat pulsating in my head and ears when I lie or bend down?
Simple physics. Your cardiac output is dictated by mainly 3 variables:Preload: this is how much the heart is filled before contraction. This is directly related to how hydrated you are (increases preload) and your body position (so squatting or leg raising increases preload while standing up decreases it). Know that the higher the preload (aka the more the heart is filled before contraction), the stronger the contraction will be (this is a fact, called frank-Starling mechanism).Contractility: how efficiently your heart muscle contracts. This is dictated by multiple variables which none of them changes when lying down so I will skip.Afterload: this is the resistance in your arteries against which your heart is pumping. So a person that has hypertension has higher afterload (aka heart needs to pump harder in order to get the blood flowing).When you lie in bed, your contractility is unchanged. Your preload will increase because normally when standing/sitting, your legs (which have large veins which are the main pool for your blood) are BELOW your heart on the vertical axis. When you lie down, all this pooled blood in your legs can easily reach your heart (because legs and heart are at the same elevation on the vertical axis) which by definition is increased preload.Same principle for the afterload. When you lie down, your head is at the same vertical with your heart so blood flows more easily from heart to head (when standing or sitting, your head is ABOVE your heart so the blood jet would lose some energy by the time it reaches your head). Given that the main vessels going to your head (the carotids) pass near your auditory system, you would actually be able to “hear” blood gooshing into your head. You usually never notice it but when the flow increases as you lie down, you get to notice it again. Also because of that increase preload, your heart is pumping stronger so you get to “feel it pounding”.For the bend down part, same principles apply (I’ll let you figure the details): your head is lower than your heart on the vertical axis -> more blood -> wooshing sound.Simple physics, yet magically amazing, isn’t it?
Physics pressure problem?
You need to know the density of blood to answer this, then use the equation for hydrostatic pressure as a function of depth: p = p0 + rho*g*h where p is the pressure you're trying to find, p0 is the pressure at some known location, rho is the density of the fluid, g is the acceleration of gravity, and h is how far down (h is positive) or up (h is negative) you travel to reach the point in question. In this case, p0 = 1.6*10^4 Pa h = -0.45 m g = 9.81 m/s^2 rho = unknown
Physics help with pressure please?
When you suddenly stand up after lying down for a while, your body may not compensate quickly enough for the pressure changes and you might feel dizzy for a moment. (a) If the gauge pressure of the blood at your heart is 13.87 kPa and your body doesn't compensate, what would the pressure be at your head, 57.2 cm above your heart? (b) If the gauge pressure of the blood at your heart is 13.87 kPa and your body doesn't compensate, what would it be at your feet, 1.30 102 cm below your heart? Hint: The density of blood is 1060 kg/m3.
What is pressure head formula?
Pressure head is the equivalent height of fluid and has units of length.Pressure head = [math]\frac{P}{\rho g}[/math]Where [math]\rho[/math] = fluid density [math][\frac{kg}{m^3}][/math][math]P[/math] = fluid pressure [math][\frac{N}{m^2}][/math]
Will raising my arm above my heart make my blood pressure reading lower?
Instead of asking Quora you should get two automated BP cuffs and take the BP and test the proposition. Or one cuff and take a lot of seperate measurements.It would not change your real blood pressure, i.e. the real world situation that we think cooreletes with your future vascular health. But it will return a number that is wrong in relationship to that question.With your upper arm by your side and a cuff on the upper arm in both a sitting and lying position the cuff will conveniently be within a few centimeters of your heart and that is the standard position.If your arm is rasied over your head the cuff will be 20 to 30 cm higher. That means there will be that much more of a column of blood ~water reducing the measured BP. It should be less by ~25 cmH2O or 18 mmHg. Good luck getting that trick past St. Peter at the end of your life. Even if you spent all your hours with your arms up your heart will still be experiencing the pressure that should have been measured with your arm by your side.
What causes head pressure when bending over?
The veins below mid-chest have one-way valves, pointing up. The compression of moving muscles, added to venous pressure, keeps blood moving toward the heart (despite gravity). Above the chest, gravity and venous pressure both point toward the heart, which is the desired organ to receive venous blood.Veins above mid-chest have no valves. So if you bend over or turn upside down, gravity is in the opposite direction of the venous pressure, causing more blood to 'congest' the face and brain.