What happens when you go into cold water? You pee.
How does this happen.
Vasoconstriction of vessels to preserve heat, pulls water into vasculature due to decreased hydrostatic pressure in vessels. Volume goes up, ADH goes down, ANP goes up due to increased volume.
Central Blood volume refers to the blood in the central or cardiopulmonary compartment. During cold temperature there is peripheral vasoconstriction to prevent heat dissipation from the extremities which means there is less blood in the peripheries and more in the central compartment โ> Central Blood volume increases Greater volume in the heart will cause stretching of the atrial wall and stimulate ANP release ๏ increased ANP High Central blood volume ๏ high volume state ๏ downregulates ADH secretion ๏ normal/decreased ADH
Central Blood volume refers to the blood in the central or cardiopulmonary compartment. During cold temperature there is peripheral vasoconstriction to prevent heat dissipation from the extremities which means there is less blood in the peripheries and more in the central compartment โ> Central Blood volume increases Greater volume in the heart will cause stretching of the atrial wall and stimulate ANP release ๏ increased ANP High Central blood volume ๏ high volume state ๏ downregulates ADH secretion ๏ normal/decreased ADH
This question is describing what is literally called "Head Out Water Immersion." The pressure that the water exerts on the body is greater than the pressure that air exerts on the body. This hydrostatic pressure pushes the water in the limbs up into the central cavity (the rib cage protects from this hydrostatic pressure). Because there's more blood in the central cavity, the heart experiences an increase in volume. This is why you often need to pee more often when standing in the pool.
In summation: water pushes blood into center cavity -> increased blood volume in central cavity -> blood stretches heart -> increase in ANP
Wouldn't constriction of peripheral vessels also trigger sphlancnic vasoconstriction, which simulates renal ischemia and causes increased RAAS activity?
I missed this as well because I completely overthought it since they had to add (vasopressin) instead of just saying ADH which made me think of its role in constriction of smooth muscle, but the point is that there will be pooling of the blood volume in the viscera and vital organs which will increase ANP release from the atria and since ANP is released with higher blood volume/atrial stretch, you can draw the conclusion that ADH will be low because ANP is signaling to the kidneys that there is an abundance of volume. Also, since the viscera is going to get more blood flow compared to the extremities since he is going to be hypothermic, you should also get increased flow to the kidneys or at least preservation (to a certain extent) and this would not promote the release of ADH which is only released when the body senses an increase in blood osm.
This question has nothing to do with temperature (the vignette doesn't address the temperature of the water - so don't assume)
This is how you get the answer:
1) Being in outer-space or in a swimming pool up to the neck will:
a. Increases Central blood volume (more blood returns to the right side of heart = increased preload)
b. Increases ANP = increased dilation of ventricles ~ compensatory mechanism to reduce volume overload
c. Decreased ADH & Renin-aldo-system = body is in state of volume overload & needs to reduce systemic volume
submitted by โkeycompany(351)
Answer: Increased Central Blood Volume (CBV), Decreased ADH, Increased ANP.
The physiological response to hypothermia is vasoconstriction of peripheral vessels (i.e. the ones in your extremities) in an effort to keep your core body temperature normal, and thus your organs functioning properly. Peripheral Vasoconstriction will increase CBV. Increased CBV will cause an increase in preload, and thus cause an increase in ANP/BNP. ANP/BNP has inhibitory effects on the Renin-Angiotensin-Aldosterone System, resulting in decreased ADH.