different types of fluids

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The regulation of body fluids is complex. If you cut yourself and bleed, your blood pressure goes down. This is soon evident in the tone of major arteries near the heart: With blood pressure down, stretch receptors in these major vessels are not stretched enough, which signals to the central nervous system that something is amiss. This stimulates the brain to activate an emergency system that releases pressor agents (i.e., hormones) to cause blood pressure to rise. Vasopressin, one of the two main hormones released this way from the pituitary, has two functions: to keep blood pressure up by causing blood vessels to contract, and to shut down fluid secretion from the kidneys, in order to conserve fluids by reducing urine output. The other hormone released by the pituitary, oxytocin, is released when the body is dehydrated, and also plays a role in pregnancy and lactation, for example, by signalling to breast cells when they should contract to produce milk.
I. Types of body fluids: 42 L total
A. INTRACELLULAR: 28 L
1. High K+, HPO4-2; moderate SO4-2 , protein- ; low Na+, Cl-
2. Partitioned among trillions of cells, but can be considered as a unit
B. EXTRACELLULAR: 14 L
1. High Na+, Cl-; moderate HCO3-; low K+, Ca+2, HPO4-2
2. Several types
a. INTERSTITIAL FLUID: 10.5 L
b. BLOOD PLASMA: 3.5 L
c. Cerebrospinal, ocular, joint fluids
d. Digestive secretions
e. URINE
II. FLUID BALANCE
A. INTAKE 2400 mL/day average
1. Ingested liquids 1500 mL/day
2. "solid" foods 700 mL/day
3. Electron transport 200 mL/day
B. OUTPUT 2400 mL/day
1. Lungs 350 mL/day obligatory
2. Skin: diffusion 350 mL/day ("intangible" perspiration) obligatory
3. Skin: perspiration 100+ mL/day ("tangible" perspiration)
4. Feces 200 mL/day minimum average;
5. URINE 1400 mL/day average; 500 mL/day obligatory minimum
C. G.I. TURNOVER ~8200 mL/day secreted, ~ 8000 mL/day reabsorbed
Saliva 1500 mL/day
Gastric Secretions 2500 mL/day
Bile 500 mL/day
Pancreatic juice 700 mL/day
Intestinal secretions 3000 mL/day
CIRCULATORY TURNOVER
Transcapillary fluid exchange ~ 25,000 L/day
balance between hydrostatic pressure [varies with distance from heart]
and colloid osmotic pressure due to plasma proteins

*********KIDNEY FACTS*****************
Total renal plasma flow 650 mL/min [~20% of cardiacoutput]
filtration fraction = 0.19
Glomerular filtration rate 125 mL/min plasma "reworked" ~ 50X/day
Rate of urine formation ~ 1 mL/min
D. "Tonicity" of body fluids: isotonic, hypertonic, and hypotonic
1. Isotonic ≡
2. Abnormalities of fluid balance
E. REGULATION
1. Thirst mechanism
2. Antidiuretic hormone (vasopressin)
III. Transport of material by body fluids
A. OXYGEN AND CARBON DIOXIDE
B. Other substances
IV. ACID-BASE BALANCE
A. BUFFER CONTROL of blood pH
1. The Henderson-Hasselbalch equation
pH = pKa + log{[A-] / [HA]}
2. In blood plasma, the bicarbonate-carbonic acid system is the most important buffer
H2CO3 ⇄ H+ + HCO3- pKa = 6.1
7.4 = 6.1 + log ...