Total Body Water (TBW) in Adults
60% of body weight since it slowly decreases with age.
Total Body Water in Infants
75-80% of body weight so they are susceptible to significant changes in this.
Total Body Water in Elderly
Further decline in percentage of TBW due to decreased free fat mass and decreased muscle mass. Kidneys less efficient and feeling of thirst may decline. Healthy ones can adequately maintain their hydration status
Intracellular fluid (ICF)
comprises all the fluid within the cells, 2/3 of TBW
Extracellular fluid (ECF)
all the fluid outside the cells, 1/3 of TBW.
Starling forces
Net filtration = (forces favoring filtration) - (Forces opposing filtration)
Capillary hydrostatic pressure
primary force for fluid movement out of the arteriolar end of the capillary and into the interstitial space
Interstitial hydrostatic pressure
promotes movement of fluid and proteins into the lymphatic space
Osmolality
the number of milliosmoles per kilogram of water
Osmolarity
the number of milliosmoles per liter of solution
Edema
excessive accumulation of fluid within the interstitial fluid
Cause: possibly obstruction of lymph circulation
Sx: weight gain, swelling, puffiness, tight-fitting clothes and shoes, limited movement of affected joints, slower wound healing.
Dx: based on s
Generalized edema
manifested by a more uniform distribution of fluid in interstitial spaces
Localized edema
limited to a site of trauma, like a sprained finger.
Pitting Edema
a depression left in the skin when pressure gets applied
Sodium
normal range of 135 to 145 mEq/L
90% of ECF cations (positively charged)
Has a lot to do with nerve/muscle functions, and acid base balance
Aldosterone
secretion of this influenced by blood volume/pressure and concentrations of sodium/potassium.
Causes increased reabsorption of sodium, water retention and excretion of potassium
Renin-angiotensin-aldosterone system
kidney releases an enzyme called renin when blood pressure or volume reduces, or decrease in sodium levels or increase in potassium levels> renin stimulates the formation of angiotensin I> angiotensin-converting enzyme (ACE) converts angiotensin I to II i
Natriuretic peptides
Hormones produced by the myocardial atria.
released during an increase in transmural atrial pressure (increased volume), which
may occur with congestive heart failure.
promotes urinary excretion of sodium
Chloride
primary ECF anion (negatively charged) that provides electroneutrality, proportional to sodium levels.
Anti-Diuretic hormone (ADH)
secreted when plasma osmolality goes up or circulating blood volume goes down and blood pressure drops. increases water reabsorption into the plasma from the distal tubules and collecting ducts of the kidney.
Isotonic Alteration
Normal concentration of sodium in the ECF and no change in shifts of fluid in or out of cell; ideal amount of fluid.
Hypernatremia
when sodium levels >145 mEq/L. Water moves from ICF to ECF.
Causes: Too much sodium in the blood or loss of water
Sx: intracellular dehydration, confulsions, pulmonary edema, hypotension, tachycardia, etc.
Water deficit
hypertonic dehydration, rare
Cause: lack of access to water, pure water losses, hyperventilation and increased elimination of water
Sx: Hypovolemia, tachycardia, weak impulses, and postural hypotension. Headache, thirst, dry skin, fever, weight loss, conc
Hypertonic Alteration
increased osmolality above normal (>294 mOsm). Increase sodium concentration in ECF (hypernatremia), making water go out of the cells.
Causes: increased salt intake or deficit of water in ECF.
Hypotonic Alteration
When osmolality of ECF is less normal (<280 mOsm). Decrease in ECF sodium (hyponatremia), making water go into cells making them swell and possibly burst.
Causes: sodium deficit in ECF or the water excess. ex unsweet tea
Hyponatremia
when sodium level decreases <135. water will then move into cells
Causes: loss of sodium, dilution of blood from too much water or lack of eating
Sx: hypoosmolality and swelling in the tissues, lethargy, confusion, decreased reflexes, seizures and comas
T
Syndrome of inappropriate ADH (SIADH)
when ADH does not produce. this can cause water excess.
Hypochloremia
To have low chloride, <97 mEq/L. result of hyponatremia or elevated bicarbonate concentrations.
Causes: mainly excessive vomiting. In some cases, cystic fibrosis and altered acid-base balance
Sx: lethargy, confusion, apprehension, depressed reflexes, seiz
Water Excess
water intoxication from compulsive water drinking or SIADH.
Sx: cerebral edema with confusion. Weakness, nausea, muscle twitching, headache, and weight gain.
Dx: Check for decreased sodium concentration in urine or a reduced hematocrit due to dilutional e
Potassium
ECF concentration range is 3.5 to 5.0.
important for transmissive nerve impulse or cardiac impulses.
Balance of this is regulated by kidney, by aldosterone/insulin secretion, and by changes in pH.
Potassium adaptation
ability of the body to accommodate to increased levels of potassium intake over time. Sudden increase = fatal.
Hypokalemia
potassium deficiency <3.5 mEq/L
Causes: reduced intake of potassium, increased entry of potassium from ECF to ICF, increased aldosterone secretion and increased loss of potassium
Sx: decrease in neuromuscular excitability, smooth muscle atony (lack of ton
Hyperkalemia
Excessive potassium >5.5 mEq/L
Causes: impaired kidneys, medications, increased potassium intake, shift of potassium from ICF to ECF.
Sx: if mild, increased neuromuscular irritability like tingling of lips + fingers, restlessness, intestinal cramping and
Calcium
an ion mostly located in the bone.
responsible for bone and teeth formation, blood coagulation, hormone secretion and cell receptor function, and transmission of nerve impulses.
Phosphate
normal concentration range 2.5-4.5 mg/dL
mostly located in bone, similar to calcium
acts as an anion buffer in acid-base regulation and provides energy for muscle contraction
Hypocalcemia
when calcium concentration goes below normal (<8.5 mg/dl)
Causes: due to not enough intake/decreased vitamin D levels, inadquate intestinal absorption, or deposition of calcium into blood.
Sx: tingling, muscle spasm, intestinal cramping, hyperactive bowel
Hypercalcemia
when calcium concentration goes above normal (>12 mg/dl)
Causes: too much intake/excess vitamin D, a number of diseases like hyperparathyroidism, bone metastases, sarcoidosis.
Sx: fatigue, weakness, lethargy. very similar to not having enough calcium
Acid-Base Balance
ph 0-14: 0 is acidic, 14 is alkaline.
normal ph range 7.35-7.45.
different body fluids have different pH values (ex. pH of stomach acid=1-2)
the principle regulators of this includes the renal and respiratory systems, and body's buffer systems, together.
Body acids
end products of protein, carbohydrate, and fat (basically all the food we eat) metabolism. balanced by basic substances in the body to maintain normal pH.
Two kinds: volatile and nonvolatile
General relationship between ions
Wherever calcium goes, phosphate follows. Wherever sodium is, chloride is right there. Wherever salt goes, water follows.
Volatile acids
weak acids that do not release their hydrogen easily. Can be eliminated as CO2 gas.
Nonvolatile acids
strong acids like sulfuric, phosphoric, and other organic acids. They readily release their hydrogen. they can be eliminated by the kidney.
Carbonic acid
a volatile acid of the body that does not release their hydrogen easily, but in the presence of the enzyme carbonic annhydrase, it readily dissociates into CO2 and water. the acid then gets eliminated by CO2 gas
Buffering pair
consists of a weak acid and its matching base. used to absorb excessive acid or base without a significant change in pH.
Carbonic acid-bicarbonate
a major extracellular buffer that operates in both the lung and the kidney
Acid-Base Balance by Respiratory System
based on pH levels, this system compensates by increasing or decreasing hyperventilation to blow off or retain CO2, respectively.
Effects of CO2 in the blood
more pCO2 means increased carbonic acid fomation. Increase in carbonic acid leads to higher ph in blood.
Acid-Base Balance by Renal System
based on the pH levels, this system compensates by producing more or less acidic or alkaline urine
Four categories of acid-base imbalances
-respiratory acidosis
-respiratory alkalosis
-metabolic acidosis
-metabolic alkalosis
Anion gap
consists of the sum of concentrations of measures anions that is subtracted from the sum of the ocncentrations of measured cations. this equation is used to provide clues to the cause of metabolic acidosis
ROME
Respiratory
Opposite (pH and CO2)
Metabolic
Equal (pH and bicarbonate)
Metabolic acidosis
caused by decrease of bicarbonate from ECF. pH then decreases.
Cause: Often from renal failure since hydrogen ions are not getting produced in the kidney. diarrhea = excretion of bicarbonic acids.
Sx: anorexia, nausea, vomiting, diarrhea, and abdominal di
Metabolic alkalosis
increase in plasma bicarbonate concentration. pH then increases.
Causes: loss of metabolic acids via VOMITING or taking a lot of antacids
Respiratory acidosis
decreased ventilation> lack of breathing> not breathing out CO2> CO2 concentration build up in the blood> pH then decreases
pneumonia COPD
"slidin' the pH Down
Respiratory alkalosis
occurs with alveolar hyperventilation and excessive reduction of CO2, or hypocapnia that makes pH then increases
ex:hyperventilation into paper bag to solve loss of CO2
"Kickin' the pH up