Chapter 26 (Lecture) Flashcards
if the cause of the imbalance is respiratory, often what will try to compensate
kidneys
if the cause of imbalance is metabolic, what will try to compensate
respiratory system
- breathing is imparied so PCO2 levels are high and blood pH is low
- if the kidneys are trying to compensate, HCO3- levels will also elevate
respiratory alkalosis
- breathing rate is increased - PCO2 levels will be lower and pH will be higher
- if the kidneys are trying to compensate HCO3- levels will begin to fall
respiratory alkalosis
- the is a renal problem-blood pH is lower and blood HCO3- levels are lowered
- respiratory systems compensates by increasing the increasing the rate and depth of breathing–so PCO2 levels go down below normal
metabolic acidosis
- there is a renal problem–blood pH is higher and blood HCO3- levels are elevated
- respiratory systems compensates by decreasing the rate and depth of breathing–so PCO2 levels go up and pH levels go down
metabolic alkalosis
- caused by any condition that impairs gas exchange, also shallow breathing can cause it
- most common cause of acidosis
- PCO2 increases and pH decreases
respiratory acidosis
- hyperventilation, tumor affecting respiratory center
- CO2 is washed out of the body too quickly
- PCO2 decreases and pH increases
respiratory alkalosis
- severe diarrhea, renal failure, starvation, excessive alcohol intake
- low blood pH and low blood HCO3- levels
- not caused by CO2 fluctuations
metabolic acidosis
- vomiting or suctioning of acidic gastric contents, excessive bicarbonate intake
- increasing blood pH and increasing HCO3- levels
metabolic alkalosis
normal pH range of plasma
7.35-7.45
normal range of PCO2 in plasma
35-45 mmHg
normal range of HCO3- in plasma
22-26 mEq/L
- the ultimate acid-base regulatory system
- slowest action, but it is the only system that can get rid of acids generated by metabolism (phosphoric, lactic, ketoic acids)
- kidneys can also conserve and generate new bicarbonate ions as needed
renal regulation
increased H+ leads to increased CO2 levels and to
increased respiration
buffer types
- physiological (respiratory and renal)
- chemical
- 1-2 times stronger than chemical buffers
- acts more slowly than chemical buffers
- works with CO2 levels
- increased H+ leads to increased CO2 levels and to increased respiration
respiratory regulation
- intracellular proteins are the most powerful ICF buffers in the body
- can bind or release H+ when necessary
protein buffer system
- does the same as a bicarbonate buffer, but works more in the nephron than in the plasma
- has a more powerful effect on the ICF and nephron
phosphate buffer system
NaH2PO4
- converts strong acids and bases into weak acids and bases
- primary buffer in the ECF
bicarbonate buffer system
H2CO3
- one or two molecule systems that resist changes in pH
- bind H+ if pH drops
- release H+ is pH rises
chemical buffers
types of chemical buffers
- bicarbonate
- phosphate
- protein
dissociate completely in solution and greatly affect pH
strong acids
ex: HCl
partially dissociate and act as buffers
weak acids
ex: H2CO3
whenever pH drops below 7.35
acidosis
fluid inside of cells, makes up about 40% or 25L of body weight
intracellular compartment
whenever pH rises above 7.45
alkalosis
decreased calcium ions in plasma
hypocalcemia
causes of hypocalcemia
nutritional, vitamin D deficiencies, burns
symptoms of hypocalcemia
- neuromuscular excitability
- tetany
- depressed excitability of the heart
increased calcium ions in the plasma
hypercalcemia
causes of hypercalcemia
hyperparathyroidism, too much vitamin D
symptoms of hypercalcemia
- bone wasting
- fractures
- kidney stones
- cardiac arrhythmias
- depressed respiration
total body water =
40L or roughly 60% of total body weight
all fluid outside of cells, makes about 20% or 15L of body
extracellular compartment
subcompartments within the extracellular fluid
- interstitial fluid
- plasma
- lymph
- CSF
- synovial fluid
- different than extracellular composition due to the presence of selectively permeable cell membrane
- most proteins, larger molecules remain in the intracellular fluid
- water moves in and out via osmosis
intracellular compartment composition
- fluid and electrolyte intake must equal output by kidneys, liver, and lungs
- substances such as RBC, albumins stay in the blood vessels
extracellular compartment composition
water intake should = ……. each day
water ouput
average daily water intake/output should equal
2500ml/day
water is obtained through
- 60% drinking
- 30% moist food
- 10% internal metabolic pathways
water is lost through
- urine = 60%
- feces = 4%
- sweat = 8%
- skin diffusion and lung evaporation (heat) = 28%
calcium levels are regulated by which hormone majorly
parathyroid hormone
smaller extent calcitonin
decreased blood calcium =
increased PTH secretion; raises blood calcium
PTH targets
bone, kidneys, GI tract
increased blood calcium =
decreased calcitonin; lowers blood Ca
increased K+ ions in plasma
hyperkalemia
causes of hyperkalemia
decreased aldosterone, cell rupture due to burns or other trauma
symptoms of hyperkalemia
- restlessness
- neuromuscular irritability followed by fatigue due to overexcitement, which leads to muscular weakness and flaccid paralysis
decreased K+ ions in plasma
hypokalemia
causes of hypokalemia
too much aldosterone, reduced intake, GI tract problems
weak acids that can accept H+ ions if the pH is too acidic, or can release H+ ions if the pH is too alkaline
buffers
symptoms of hypokalemia
causes hyperpolarization, leads to muscle weakness and mental confusion
decreased ECF K+ =
hyperpolarization of cell membranes
increased ECF K+ =
depolarization of cell membranes
major ICF cation
K+
what does the ICF-ECF concentration of K+ affect
membrane permeability
what are exchanged between the compartments
water, nutrients, gas
mEq/L
measures of electrical charges per liter
Fluid in both the ICF and ECF have a concentration of about
290-300 mOsm
.9%
concentration (osmolality) is due to which factors
- amount of solutes present
- amount of water present
increasing the number of solutes will do what to the concentration
increase
increasing the amount of water will do what to the concentration
lower it
pushes fluid into ICF from ECF
hydrostatic pressure
draws fluid from ICF into ECF
osmotic (oncotic) pressure
the more solutes a solution has, the ______ its osmotic pressure
greater
how can you raise osmolality of ECF
- losing water
- ingesting excess electrolytes
- excessive water loss of H2O from ECF
- ECF osmotic pressure rises
- cells lose H2O to ECF by osmosis; cells shrink
dehydration
- excessive H2O enters the ECF
- ECF osmotic pressure falls
- H2O moves into cells by osmosis; cells swell
hypotonic hydration
disorders of water imbalance
- dehydration
- hypotonic hydration
results from fluid in the interstitial space
edema
major ECF electrolyte
Na+
maintained mainly by aldosterone
Na+ homeostasis
too much Na+ in the plasma =
dehydration
too little Na+ in the plasma =
edema
causes of hypernatremia
- too much aldosterone
- hypertonic saline solutions
- dehydration
symptoms of hypernatremia
- CNS dehydration leads to confusion and lethargy
- neuromuscular irritability with twitching and convulsions
causes of hyponatremia
- vomiting
- diarrha
- burns
- dilution
- increased diuresis
- aldosterone deficiency
volume = 40 L, 60% body weight
total body water
volume = 25 L, 40% body weight
intracelluular fluid (ICF)
volume = 12 L, 80% of ECF
interstitial fluid (IF)
volume = 3L, 20% of ECF
plasma
what triggers the thirst mechanism
increased osmolality, decreased plasma volume
in the hypothalamus near the third ventricle
thirst center
causes the sensation of thirst, causes dry mouth
osmoreceptor over activity
quenches thirst
drinking
inhibits osmoreceptors
drinking, activation of stretch receptors in SI and stomach
typical sodium ion value
142 mEq/L
typical potassium value
3.7 mEq/L
typical calcium value
5 mEq/L
causes of edema
- incompetent venous valves
- hypoproteinemia
- liver disease
what would occur if there was an increase in plasma osmolality
- thirst
- release of ADH
- concentrated urine
what type of tissue is least hydrated
adipose tissue
water lost through expired air
insensible water loss
promotes net osmosis into tissue cells, causing them to swell as they become abnormally hydrated
hyponatremia
diuresis peaks how long after drinking water
one hour
what type of individual would have the most body water
infant
acts on the kidneys to decrease water excretion
ADH
when water output exceeds intake over a period of time
dehydration
most water is excreted via
kidneys
associated with the swelling of cells
hypotonic hydration
least abundant positive electrolyte in ECF
magnesium
common stimuli of ADH
- increased ECF osmolality
- decreased BP
- reduced blood volume
- stimulation of baroreceptors
what hormone increases sodium excretion
progesterone
aldosterone targets what area of the kidney
kidney tubules
most important factor that incluences K+ secretion
K+ concentration in ECF
what process is most affected by calcium levels
neuromuscular excitability
a condition that results from solute loss, water retention, or both
hyponatremia
enhances release of calcium from bone
parathyroid hormone
what happens when the concentration of Na+ decreases in the ascending limb of the nephron
aldosterone levels increase
electrolyte balance in the body usually refers to the balance of
salts
most abundant negative electrolyte in ECF
chloride
in addison’s disease, the adrenal cortex produces too little aldosterone, and so Na+ is lost. people with this disorder often crave
salty foods
most important force causing net outward water flow across capillary walls
hydrostatic pressure of capillary blood
