What percentage is the body water content of an infant? Adult males? Adult females?
73 or more
60
50
What type of tissue is the least hydrated?
Adipose, 20 percent water
What percentage of skeletal muscle is water?
75
T or F? Body water content declines to about 20 percent in old age.
False. Declines to about 45.
What is the total amount, in liters, of water in the body?
40 L
What are the 2 types of fluid compartments?
Intracellular fluid (ICF)
Extracellular fluid (ECF)
Which fluid compartment is two-thirds of total body water, 25 L?
ICF, in cells
The extracellular fluid compartment holds how many L of water?
15
The majority of ECF can be found in what 2 places?
Plasma (3 L)
Interstitial fluid (12 L)
Name six other places that ECF can be found.
Lymph
CSF
Humors of the eye
Synovial fluid
Serous fluid
Gastrointestinal secretions
These dissociate into ions in water.
Electrolytes
The electrolyte concentration of a solution is known as its what?
Osmolality
How is osmolality expressed? It is the number of electrical charges in 1 L of solution.
Milliequivalents per liter (mEq/L)
T or F? Inorganic salts, both inorganic and organic acids and bases, and some proteins are electrolytes.
True
T or F? Covalent bonds dissociate in water to form charged particles.
False. Non-electrolytes have bonds, usually covalent, and do not dissociate.
Name 4 organic molecules which are non-electrolytes.
Glucose
Lipids
Creatinine
Urea
T or F? Any change in solute concentration in any compartment leads to net water flow.
True
How do fluid exchanges between plasma and IF occur?
Across capillary membranes.
The small net leakage of fluid that remains behind in the interstitial space is removed by what system?
Lymphatic
Fluid movement between compartments depends on the complex permeability properties of what?
Membranes
T or F? Movements of nutrients, respiratory gases, and wastes are typically multidirectional.
False. Movements are typically unidirectional.
For proper hydration, water intake must equal what?
Water output
What is the average daily water intake in adults? (L)
2.5 L
In what way does most water enter the body?
Ingestion of liquids and solid foods
What is the body water that is produced by cellular metabolism?
Metabolic water or water of oxidation
In what 4 ways does water leave the body?
Feces, 100 mL
Sweat, 200 mL
Insensible losses via skin and lungs, 700 mL
Urine, 1500 mL
In what 3 ways does water enter the body?
Metabolism, 250 mL
Foods, 750 mL
Beverages, 1500 mL
Healthy people maintain the tonicity (sodium) of their body fluids within what range?
280-300 milliOsmoles per kg
What 2 things occur when there is a rise in plasma osmolality?
Thirst
Release of ADH
What effect does the release of ADH have on the kidneys?
Causes the kidneys to conserve water and excrete concentrated urine.
T or F? A decline in osmolality inhibits both thirst and ADH, the latter followed by the output of large volumes of dilute urine.
True
The essential water loss through urine (500 mL) is known as what?
Obligatory
The 30 minutes between the intake of water and the start of the kidneys eliminating water reflects the time required for what to happen?
Inhibit ADH release
Diuresis, the free excretion of urine, reaches a peak how long after drinking?
1 hour
What chemical is the body's water magnet?
Ionic sodium
This may lead to weight loss, fever, mental confusion, hypovolemic shock, and loss of electrolytes.
Dehydration
Dehydration is a negative fluid balance. Name 6 things that can cause ECF water loss.
Hemorrhage
Severe burns
Prolonged vomiting or diarrhea
Profuse sweating
Water deprivation
Diuretic abuse
What are three signs and symptoms of dehydration?
Thirst
Dry flushed skin
Oliguria
T or F? Dehydration causes cells to shrink due to the loss of water into ECF by osmosis.
True
This occurs as a result of renal insufficiency or rapid excess water ingestion.
Water intoxication or cellular over hydration
What are 5 severe metabolic disturbances associated with hypotonic hydration?
Nausea
Vomiting
Muscular cramping
Cerebral edema
Possible death
What is the atypical accumulation of interstitial fluid that is caused by anything that increases flow of fluid out of the blood or hinders its return?
Edema (tissue swelling)
T or F? Edema can lead to congestive heart failure true hypertension.
True.
T or F? A decrease in blood pressure or in capillary permeability can lead to edema.
False. An increase in either can cause edema. Also, incompetent venous valves or blood vessel blockage.
What is the decrease in plasma proteins caused by protein malnutrition, liver disease, or glomerulonephritis (kidney failure)? It can cause edema.
Hypoproteinemia or other colloid osmotic pressure imbalances
T or F? Blocked or surgically removed lymph vessels cause leaked proteins to accumulate in IF drawing fluid from the blood. It results in low blood pressure and severely impaired circulation.
True
T or F? Water reabsorption in collecting ducts is proportional to ADH release.
True
Besides the hypothalamic osmoreceptors that regulate ADH release, what else can cause a release of ADH?
Change in blood volume or pressure (due to fever, sweating, vomiting, diarrhea, blood loss, traumatic burns)
Electrolyte balance usually refers to the salt, acid, or base balance?
Salt
Salts are ingested and lost via these 3 ways.
Sweat
Feces
Urine
Name 4 functions that salts play a major role in.
Controlling fluid movement
Excitability
Secretory activity
Membrane permeability
T or F? Sodium is the most abundant anion in ECF.
False. It is the most abundant cation (positively charged).
T or F? Sodium leaks into cells and is pumped out against its concentration by active transport.
True
T or F? Renal acid based control mechanisms are coupled to sodium ion transport.
True
What 2 major hormones regulate sodium balance?
Aldosterone
Atrial natriuretic peptide (ANP)
The release of this hormone triggers the active reabsorption of the remaining 10 percent of the sodium that was not reabsorbed in the proximal tubules (65) or in the loops of Henle (25). It also influences potassium secretion into filtrate.
Aldosterone
Water will follow sodium that is being reabsorbed if what hormone is present?
ADH
Granular cells of the JGA secrete renin in response to what 3 things?
Sympathetic nervous system stimulation
Decrease filtrate osmolality
Decrease stretch (due to low blood pressure)
ANP is released by these cells in response to stretch, an increase in blood volume.
Atrial cells
T or F? The release of ANP increases ADH, renin, angiotensin II, and aldosterone production.
False. ANP decreases production and increases excretion of sodium and water.
Name 3 hormones that also influence sodium balance of body fluids.
Estrogens, increase sodium reabsorption
Progesterone, decrease reabsorption
Glucocorticoids, from adrenal glands, increase reabsorption and promote edema
T or F? Potassium is part of the body's buffer system and is required for neuromuscular functioning and metabolic activities.
True
What is the term for increased potassium in blood? For decreased potassium? May result in a disruption of electrical conduction in the heart, leading to sudden death.
Hyperkalemia
Hypokalemia
99 percent of the body's calcium is found as calcium phosphate salts in what part of the body?
Bones
Calcium is important for these 4 functions.
Neuromuscular excitability
Blood clotting
Cell membrane permeability
Secretory activities
This increases muscle excitability and causes tetany.
Hypocalcemia
This inhibits neurons and muscle cells and may cause life threatening cardiac arrhythmias.
Hypercalcemia
What hormone is secreted by the glands located on the posterior aspect of the thyroid gland in the pharynx.
Parathyroid hormone (PTH)
Declining plasma levels of calcium stimulate the release of PTH which targets what 3 organs?
Bones
Small intestine
Kidneys
What does PTH activate in the bones that break down bone matrix?
Osteoclasts
What indirect affect does PTH have on the small intestine?
By stimulating the kidneys to transform vitamin D to its active form which is necessary for calcium absorption by the small intestine.
The effect of PTH on this organ increases calcium reabsorption while decreasing phosphate ion reabsorption (calcium conservation and phosphate excretion go hand in hand).
Kidneys
What is the major anion that accompanies sodium in ECF that helps maintain the osmotic pressure of blood?
Chloride
After reabsorption, how is excess chloride excreted?
Via urine
What percent of chloride is absorbed by the proximal convoluted tubule?
99
T or F? Chloride is part of the buffer system that regulates homeostasis.
True
What is the normal pH of arterial blood? Of ICF?
7.35 to 7.45
7.0
T or F? Alkalosis is a drop in arterial pH to below 7.35.
False. Alkalosis (alkalemia) is a blood pH of 7.45 and above, acidosis (academia) is a low pH.
What are the 3 steps of hydrogen concentration regulated?
Chemical buffers
Brain stem respiratory centers
Renal mechanisms
T or F? A high value in the measurement of partial pressure of carbon dioxide indicates respiratory acidosis (higher than the 35 to 45 mm Hg range).
True
This occurs when a person breathes shallowly. Carbon dioxide accumulates in the blood increasing Pco2.
Respiratory acidosis
This results when CO2 is eliminated from the body to quickly causing blood pH to increase and results in hyperventilation.
Respiratory alkalosis
When CO2 and H2O is released following cellular metabolism, it is broken down by the enzyme carbonic anhydrase into what?
Bicarbonate
What is the normal range of bicarbonate ion levels? Out of this range indicates a metabolic acid base imbalance.
22 to 26 mEq/L
T or F? Metabolic acidosis and alkalosis occurs at a cellular level.
True
This occurs when there is low blood pH and HCO3 levels. Can be caused by ingestion of too much alcohol, accumulation of lactic acid (from exercise or shock), diabetic crisis, starvation, or persistent diarrhea.
Metabolic acidosis
This is indicated by rising blood pH and HCO and is less common. Caused by vomiting. Compensation involves slow shallow breathing allowing CO2 to accumulate in the blood.
Metabolic alkalosis
T or F? Renal compensations occur during acidosis retaining bicarbonate to offset.
True
T or F? A weak acid dissociates completely into its ions.
False. A strong acid will dissociate completely.
What is a system of one or more compounds that act to resist pH changes when strong acid or base is added?
Chemical buffer system
What are 3 chemical buffer systems?
Bicarbonate
Phosphate
Protein
Do acids carry a positive or negative charge?
Positive
What charge do buffers carry?
Negative
HCl (hydrochloric acid, strong acid) and NaHCO3 (bicarbonate, a weak base) neutralize each other and form a weak acid and what?
NaCl (sodium chloride, salt)
NaOH (sodium hydroxide, strong base) and a weak acid neutralize each other and form bicarbonate (weak base) and what?
H2O
T or F? Chemical buffers can eliminate excess acids or bases from the body.
False
What major organ eliminates volatile carbonic acid?
Lungs (CO2)
What major organ prevents metabolic acidosis and eliminates fixed metabolic acids (phosphoric, uric, lactic and ketones)?
Kidneys
What are the two major renal mechanisms of acid base balance?
Conserving or generating HCO3
Excreting HCO3
The difference in body content between sexes arises as males develop greater what?
Muscle mass
T or F? Homeostatic mechanisms slow down with age.
