Blood Pressure

[lohita]

Why is Blood pressure high when we stand where as when we sit is low

[MrMistery]

Hmmm... good question. You won't find the answer in any book but you can deduct it logically: when he stand there are some muscles that keep you from crashing on the floor because of gravity, when we sit some of those muscles are inactive. Therefore, fewer oxygen is needed. Therefore blood presure is a bit lower

[lohita]

well ... thanks for ur answere. Then how come some people suffer from high and low blood pressure?

[lohita]

And which way is accurate blood pressure standing or sitting?

[mith]

I always thought it was because since you're taller when you stand, more pressure is needed.

[Einstein2]

[color=blue][/color

BLOOD FLOW AND PRESSURE REGULATION
Short-term cardiovascular regulatory mechanisms are intended to buffer transient changes in blood flow to vital organs occurring as a consequence of posture change,
exercise, hemorrhage, or other acute stresses. The buffering is accomplished by two mechanisms: (a) Autoregulatory adaption of blood vessels to altered or redistributed
volumes and pressure; (b) Rapid autonomic sympathetic and parasympathetic neural responses affecting the heart rate, cardiac contractility, and vascular resistance.

For more details refer to this article.

METTE OLUFSEN etal., Modeling Cerebral Blood Flow Control During Posture Change From Sitting to Standing. Cardiovascular Engineering: An International Journal, Vol. 4, No. 1, March 2004 ( C ° 2004).

[MrMistery]

Yeah... whateva...

Then how come some people suffer from high and low blood pressure?

Blood pressure is regulated by a tone of factors... anyone of those goes wrong and you're in trouble
@mithrill
it is a factor... there are many... however it influences it in a small amount

[ste2005]

the bp can sometime be high due to the person being excited or nervous no matter what happens it is normal

[victor]

I think the hormone factor is taking part also. This hormone is Adrenaline. The works of Adrenaline is increases the blood pressure by narrowing the arthery or vein. For the high blood pressure is because of unexpected suddenly arthery narrowing...(I'm sorry, my english is so bad...) then, because of this sudden arthery narrowing (Artheriosclerocys), the blood pressure will go up.

[MrMistery]

Not only adrenaline, but also noradrenaline and acetilcholine influence blood pressure. As i said, there are a ton of factors that influence blood presure... Even your diet(ESCPECIALLY YOUR DIET!!!)

[D_Juggz]

look guys, as far as blood pressure goes there are MANY factors causing it to go up and or down. As far as the sitting and standing question goes. it mainly has to do with when you standing your using muscles which pump your venous blood back to your heart quicker, causing right atrial strech, increasing heart rate, thus, increasing BP.

There is no 'normal' blood pressure, it depends on the individual. People can suffer from hypertension (high BP) or hypotension (low BP) due to pysiological or pathiological reasons. There are many diseases/conditions that could cause this. Some majour risk factors for having high BP is old age, being male, being obese,being unfit.

short-term blood pressure regulatory mechanisms include: vasoconstirction/dilation due to hormones (adreniline, seritonin, noradreniline...there are heaps of them)

long-term BP reg mech include the renin angiotensin complexes (i don't know much about these right now, im studying them at the moment) - google it.

Hope this helps.
D_J

[biostudent84]

And which way is accurate blood pressure standing or sitting?

The quick answer is that they are both accurate. When blood pressure is measured with equpment, the idea is to detect changes in average blood pressure. To standardize this, when you go to the doctor, your blood pressure is always measured at your left upper arm while you are sitting.

If your doctor is good, to increaes the accuracy of this, blood pressure is taken once. The first is by the nurse that initially checks you out. The second is by the doctor after you've had time to relax, as the stress of going the the doctor can cause an increase of blood pressure.

Checking your pressure often also keeps the accuracy high. At least once a month is reccomended, once a week is best.