Thunder's Place

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# Girth theory: Pumping vs. clamping

A hole in the can would equalize the pressure immediately, wouldn’t it?

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Yes, so would a rupture in the tunica.

Originally Posted by pudendum
Yes, so would a rupture in the tunica.

LOL

06/21/07 NBP = 7.75(tape) FSL = 7.875 EG = 5.00 Volume= 15.42

09/13/07 NBP = 8.375 FSL = 8.75 EG = 5.38 Volume = 19.29 (+25%)

12/26/07 NBP = 8.625 FSL = 8.75 EG = 5.50 Volume = 20.82 (+35%)

Originally Posted by pudendum

I agree this is definitely an effect with air. Gases are very compressible. If instead the can is filled with water, the effects would be different, because fluids are far less compressible.

If you remove water from a can, air rushes into the can to fill the space taken by the water. If you pump water out of the can without letting air in to replace it, the can will collapse. In essence, you are pulling a vacuum on the can by removing the water.

Real life example:

I worked in a Chemical plant where we unloaded tankers trucks or rail cars full of liquids. These tankers have a little 1” vent line on the top of the tank which you must open before you start pumping the liquid out.

I saw first hand, a 20,000 gallon tank collapse like a beer can because the operator started pumping liquid out and forgot to open the vent. Good way to lose your job.

A hole in the can would equalize the pressure immediately, wouldn’t it?

Exactly.

Horny Bastard

Originally Posted by mravg
If you remove water from a can, air rushes into the can to fill the space taken by the water. If you pump water out of the can without letting air in to replace it, the can will collapse. In essence, you are pulling a vacuum on the can by removing the water.

That is an open system though, and in your example an active pressure differential is being created by pulling a vacuum.

With a penis pump, the system isn’t quite the same as there is no “open” part of the equation. You are pulling a vacuum, but there internal tissues are not being replaced with air.

06/21/07 NBP = 7.75(tape) FSL = 7.875 EG = 5.00 Volume= 15.42

09/13/07 NBP = 8.375 FSL = 8.75 EG = 5.38 Volume = 19.29 (+25%)

12/26/07 NBP = 8.625 FSL = 8.75 EG = 5.50 Volume = 20.82 (+35%)

Originally Posted by pudendum
Yes, so would a rupture in the tunica.

Smart ass.

This place runs on donations, help out if you can. Thanks.

Originally Posted by mravg
Thanks man!
I was going to get to your comment below next:

You are right. It is just the differential. Like if you turn on your water hose but the end is blocked off, the hose gets full and rigid. If you poke a nail through the hose, water is leaking out but the hose stays rigid because the pressure coming in is maintained. I was going to look up “high flow priapism” which I don’t understand very well, but it is an example of what you are talking about.

You propose that there is a normal venous link in the penis at peak erection. This is true in the spongiosum, as this is critical to allow it to stay soft enough to allow ejaculation. Venous leak is something we all hope we don’t have. At peak erection, venous outflow and arterial in flow are near zero.

Here are 2 quotes regarding erection and blood flow.

Quote
“Activation of the autonomic nerve produces a full erection, that is, filling and trapping of blood in the cavernous bodies. After full erection is achieved, contraction of the ischiocavernosus muscle (from activation of the somatic nerves) compresses the proximal corpora and raises the pressure in the entire corpora well above the systolic blood pressure, resulting in rigid erection. This rigid phase occurs naturally during masturbation or sexual intercourse but can also occur from slight bending of the penis, without muscular action.”

“When the smooth muscles relax owing to release of neurotransmitters [from nerves], the resistance to incoming flow drops to a minimum. This allows arterial and arteriolar vasodilatation and expansion of the sinusoids [of the cavernosa] to receive a large increase of flow. Trapping of blood causes the penis to lengthen and widen rapidly until the capacity of the tunica albuginea is reached. Meanwhile, expansion of the sinusoidal walls against one another and against the tunica albuginea results in compression of the subtunical venular plexus [network of veins in the cavernsoa]. Meanwhile, uneven stretching of the layers of the tunica albuginea also compresses the emissary veins and effectively reduces the venous flow to a minimum.”

Tom F. Lue, MD Male Sexual Dysfunction. Chapter 37. Physiology of Penile Erection. Lange Urology. McGraw-Hill Companies.

I have a great graph from a monkey where nerves were stimulated to cause erection. It shows the pressure in the cavernosa and the blood flow into the penis in the different stages of erection. I hope that you will allow me to show this picture.

Smart ass.

Thank you, I resemble that. :)

Originally Posted by newguy01

That is an open system though, and in your example an active pressure differential is being created by pulling a vacuum.

With a penis pump, the system isn’t quite the same as there is no “open” part of the equation. You are pulling a vacuum, but there internal tissues are not being replaced with air.

The pressure inside the penis is being maintained by the circulatory system controls outside the penis, (blood pressure generated by the heart, vasoconstriction etc) so I would say it is an open system.

You are right that gas or liquid inside a closed balloon behave differently. If you pull a vacuum on a gas filled sealed balloon, the balloon will grow as external pressure becomes smaller relative to internal pressure. The gas expands along with the balloon, and the pressure inside the balloon will drop as the gas expands. (Paradoxically the balloon is bigger but the pressure inside it is less).

With a liquid filled balloon, if you pull a vacuum around the balloon it will not expand because the liquid won’t expand.

But the penis is different. Pulling a vacuum around the penis causes the penis to expand due to the pressure differential, because you have a pump (your heart) providing the a constant pressure and sufficient liquid to accommodate the expansion.

Horny Bastard

Originally Posted by pudendum

I have a great graph from a monkey where nerves were stimulated to cause erection. It shows the pressure in the cavernosa and the blood flow into the penis in the different stages of erection. I hope that you will allow me to show this picture.

Interesting.

The flow, for most of the graph is very low, but not zero. That is basically the example I gave of the garden hose with the pin prick in it. Also remember it is just one artery.

I have not researched the hemodynamics of normal erections, but I figure there is probably some low flow of blood through the penis during erection in order to prevent ischemic damage. Figure some guys on this forum say they have continuous sex for 1,2, 3 or more hours. With zero replacement of erectile blood, I imagine that oxygen deprivation in the penis would make this kind of marathon sex very damaging.

Horny Bastard

Originally Posted by Mr. Happy
I’d agree to that.

I think that there is a general idea that higher pressure = greater efficacy and I, for one, am not convinced that this is true. But I also think it has to do with what we mean by effective. Does it mean gaining quickly?

I’m not sure that is unilaterally true.

I would look at safety, and how a practice contributes to the overall health of the organ as well, not simply gains.

Agree.

I spent the first years of bodybuilding over training. I know there is a minimum to maintain and a minimum for growth. I, for a long time, came close to maximum and it did not provide any growth. It is much more interesting to know minimums for maintenance and growth rather than the limits - at least now that I am older.

Mravg and Pudendum,

I think the other thing that is not taken in to account is the pliability changes in the tunica. Under stress and time, it does change and allows for greater expansion. This may also explain why low level pumping works.

Originally Posted by mravg
If you remove water from a can, air rushes into the can to fill the space taken by the water. If you pump water out of the can without letting air in to replace it, the can will collapse. In essence, you are pulling a vacuum on the can by removing the water.

Real life example:
I worked in a Chemical plant where we unloaded tankers trucks or rail cars full of liquids. These tankers have a little 1” vent line on the top of the tank which you must open before you start pumping the liquid out.
I saw first hand, a 20,000 gallon tank collapse like a beer can because the operator started pumping liquid out and forgot to open the vent. Good way to lose your job.

That is true in an open system where air is necessary to replace fluid volume and I agree. I’ve seen similar collapses and I agree with you on this one.

I just have a question. What’s this got to do with the erection chambers?

The erection chambers fill due to changes in arterial pressure in, smooth muscle relaxation in the walls of the blood spaces in the erectile chambers (venous sinusoids) and closing down the blood flow out in the veins draining the penis. To empty the veins open up and the smooth muscle in the cavernosa contract forcing blood out. There is no open system here. Air does not replace fluid.

When I was commenting on you aluminum cam system (sealed completely), I was suggesting replacing the air in the can with fluid at 200 mm Hg, not emptying or filling the can. I was talking about exposing it to the pressures you use when you pump.

I think we’re talking about entirely different things.

Originally Posted by mravg
The pressure inside the penis is being maintained by the circulatory system controls outside the penis, (blood pressure generated by the heart, vasoconstriction etc) so I would say it is an open system.
You are right that gas or liquid inside a closed balloon behave differently. If you pull a vacuum on a gas filled sealed balloon, the balloon will grow as external pressure becomes smaller relative to internal pressure. The gas expands along with the balloon, and the pressure inside the balloon will drop as the gas expands. (Paradoxically the balloon is bigger but the pressure inside it is less).

With a liquid filled balloon, if you pull a vacuum around the balloon it will not expand because the liquid won’t expand.
But the penis is different. Pulling a vacuum around the penis causes the penis to expand due to the pressure differential, because you have a pump (your heart) providing the a constant pressure and sufficient liquid to accommodate the expansion.

Open system is a relative term. The penis is complex. You will agree that it does not exchange for air or any other gas. It also has very specialized physiologic mechanisms to empty and fill. I think we agree. In the sense of the open systems you described, the penis is not an open system.

This is particularly true at peak erection where blood flow in and out of the penis falls to near zero (see graph attachment in my prior post).

I am not sure how you can say there is a difference between a filled balloon and the penis as far as response to negative pressure at peak erection (I will grant you that up to this point, blood is drawn into the penis by the negative pressure; this is what made it good for guys with ED). You don’t think there is a distending pressure of the fluid in the balloon. For our balloon example lets make the balloon a thicker latex (like old condoms), this makes it more resistant to rupture. The effect of the negative pressure will depend on the factors of wall flexibility or distensibility.

Again at peak erection, the penis is exactly like the balloon, an isolated system, Therefore the effects depend on compliance, not inflow or outflow. Remember, I’m talking about peak erection.

Originally Posted by mravg
Interesting.
The flow, for most of the graph is very low, but not zero. That is basically the example I gave of the garden hose with the pin prick in it. Also remember it is just one artery.

I have not researched the hemodynamics of normal erections, but I figure there is probably some low flow of blood through the penis during erection in order to prevent ischemic damage. Figure some guys on this forum say they have continuous sex for 1,2, 3 or more hours. With zero replacement of erectile blood, I imagine that oxygen deprivation in the penis would make this kind of marathon sex very damaging.

How much blood do you think it takes to fill the penis? Second, this is a monkey penis that is smaller in volume that a human penis. There is no reason not to believe that blood flow will be relatively higher in the arteries filling the erectile chambers in us, a larger higher order primates.

Blood flow at peak erection is essentially zero:

Quote
“…the penis becomes even harder, with an intracavernous pressure reaching several hundred millimeters of mercury (the phase of rigid erection). During this phase, the inflow and outflow of blood temporarily cease.”

Lue T. Erectile dysfunction. New England Journal of Medicine 342 (2000) 1802-13.

.
and
Quote
Skeletal or Rigid Erection Phase (5): As a result of contraction of the ischiocavernous muscle, the intracavernous pressure rises well above the systolic pressure, resulting in rigid erection. During this phase, almost no blood flows through the cavernous artery; however, the short duration prevents the development of ischemia [oxygen too low in the tissues] or tissue damage.” (Figure 37-1)

Tom F. Lue, MD Male Sexual Dysfunction. Chapter 37. Physiology of Penile Erection. Lange Urology. McGraw-Hill Companies.

The tissues of the penis can withstand a low oxygen environment for some time. It is only after extended periods of sustained peak erections that low oxygen in the tissues (ischemia) is a problem; one of the problems in priapism.

By the way, it’s interesting that this reference uses the term Skeletal Erection Phase. Is this why we call it a boner?

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