F&E help

I know there are a lot of threads about this topic, but some of them are pretty old, so helpful links are gone. Here is my problem: I understand simple concepts like Na+/water relationship and fluid volume problems, hypo/hyperkalemia.

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Acid-Base Tutorial - Physiology

Pathophysiology of fluid imbalance

Fluid imbalance can arise due to hypovolemia, normovolemia with maldistribution of fluid, and hypervolemia. Trauma is among the most frequent causes of hypovolemia, with its often profuse attendant blood loss. Another common cause is dehydration, which primarily entails loss of plasma rather than whole blood. The consequences of hypovolemia include reduction in circulating blood volume, lower venous return and, in profound cases, arterial hypotension. Myocardial failure may result from increased myocardial oxygen demand in conjunction with reduced tissue perfusion.

Critical Care | Full text | Pathophysiology of fluid imbalance

Third space edema........a great article about fluid and fluid shifts

Suppose your patient has edema-indicating that there's enough fluid in his body-but his vital signs and urine output suggest that he's hypovolemic. What's going on? He's experiencing third-spacing, a shifting of fluid into interstitial spaces. Find out what needs to be done to get that fluid back where it belongs.

Third-spacing: Where has all the fluid gone?

Human beings are, essentially, big bags of water, the volume of which must be kept under tight control to prevent us from either drying out or drowning. The kidney is a sophisticated organ, which maintains circulating volume and excretes waste products in response to materials presented to it. Overall control of body fluid is via a complex set of reflexes in the vascular system and the brain. This is the extrinsic system of volume control. The kidney is partially independent of the circulation in that it is able to control it's own blood flow and protect itself in the face of hypoxemia. This is the intrinsic system of control.

http://www.ccmtutorials.com/renal/pathphys/page_04.htm

The human body consists of 60 - 70% fluid - an isotonic salt solution containing a variety of dissolved chemicals and cellular material. The distribution of body water between the intracellular, interstitial and intravascular compartments is tightly controlled along electrical and physicochemical lines. This control of fluid and electrolyte balance is essential to prevent the human from either drying out or drowning. The principle organ involved in this balance is the kidney. The kidney acts in tandem with a variety of neuroendocrine modulatory influences.

Critical Care Medicine Tutorials

The main fluid in the body is water. Total body water is 60% of body weight. The water is distributed in three main compartments separated from each other by cell membranes. The intracellular compartment is the area within the cell. The extracellular compartment consists of the interstitial area (between and around cells) and the inside of the blood vessels (plasma).

http://www.elmhurst.edu/~chm/vchembook/250fluidbal.html

https://allnurses.com/general-nursing-student/fluid-and-electrolytes-200537.html

http://www.acid-base.com/