Does vasoconstriction decrease or increase blood pressure?
It increases peripheral resistance, so it would increase blood pressure given a constant flow. That is, if you increase the resistance to blood flow, it requires a higher pressure difference to maintain any particular flow rate of blood. You need to push harder against resistance for a given flow.
Why does the systolic blood pressure increase during exercise?
More blood is required during exercise so that you can get enough oxygen to your body. This is the contraction of the heart ( systole). During diastole( relaxation) the arteries relax and your blood pressure goes back to normal because less blood is required when not exercising and you get the normal intake of oxygen instead.
Why does resistance decrease when you increase voltage?
The formula for resistance is Resistance = Voltage/Amperage. In my science textbook, though, it says that electric companies up the voltage of the electricity they send to homes, in order to decrease resistance. This happens because when you up-transform the voltage, the amperage decreases proportionally (thus keeping the wattage the same). So, since there's less amperage, there's less electrons moving through the wire, which means less of them crash with nuclei of atoms, therefore decreasing resistance. Okay, I see how that works, but doesn't that go against the formula, R=V/A ? They're increasing the voltage and decreasing the amperage, so mathematically and by the formula, shouldn't resistance increase? Expalin it to me, please.
Why does the thermal conductivity of metals decrease with an increase in temperature?
Thermal conductivity of any material is dependent on two things:i. Motion of free electronsii. Molecular vibrationsFor metals, the thermal conductivity is mainly a function of the motion of free electrons. As the temperature increases, the molecular vibrations increase (in turn decreasing the mean free path of molecules). So, they obstruct the flow of free electrons, thus reducing the conductivity. In case of non metals, there are no free electrons. So, only the molecular vibrations are responsible for conduction of heat and hence for non metals the conductivity increases with increase in temperature.
Is bulk modulus constant for a given substance, or can it vary with pressure?
Sketchy textbook says: "Because the density of seawater is greater due to the presence of salt, the pressure of seawater will be greater, and therefore the bulk modulus [of a submerged substance] will be greater." For reals?
What is the electrical resistance of human body?
There are a lot of factors involved and every person does not have the same electrical resistance. For instance, men tend to have lower resistance than women. Just like for the resistors used in electronics, the resistance of a person's arm depends on the arm's length and diameter. Resistance goes up with length and down with diameter. Since men tend to have thicker arms and legs (more muscle), they usually have lower resistance. (An implication of this is that .) A rough value for the internal resistance of the human body is 300-1,000 Ohms. Naturally, the resistance also depends on the path that electricity takes through the body - if the electricity goes in the left hand and out the right foot, then the resistance will be much higher than if it goes in and out of adjacent fingers.Within the body, the tissues with the greatest resistance are bone and fat - nerves and muscle have the least resistance. That said, the majority of the body's resistance is in the skin - the dead, dry cells of the epidermis (the skin's outer layer) are very poor conductors. Depending on the person, the resistance of dry skin is usually between 1,000-100,000 Ohms. The skin's resistance is much lower if it is wet or burnt/blistered. This means that when a person is electrocuted in real life, the body's resistance drops as the skin is burned. To determine a person's total resistance, just add together the resistance of each part of the body - remember that the electricity must pass through the skin twice (on the way in and on the way out), so the total resistance is:Rtotal = Rskin(in) + Rinternal + Rskin(out)Source: EEE COMMUNITY: Typical Body Resistance & Current Flow & Q & A: The Human Bodys ResistancePlease read my other answers related to transformer core, diff. b/w power & distribution TX, EHV lines, Lightning & airplanes, transformer testing, AC vs DC, Buchholz relay, 3ph vs 1 ph, grounding, reason for power trip, MCB vs MCCB, DC motors, electrocution of birds by power lines etc on Vijay Belekar.
What does vasodilation and vasoconstriction mean?
Vasodilation and vasoconstriction occur in order to control blood pressure and body temperature. Vasoconstriction causes the vessel to reduce its diameter, resulting in raised pressure and increase in body temp caused by friction from the blood passing through the internal walls of the vessel. Vasodilation is the exact opposite - if blood pressure or temperature is high, the vessel will increase its diameter in order to lower pressure within and decrease friction. Hope this helps!