chapter 27- water, electrolyte and balance (A&P)
Which statement is correct?
Sodium is more abundant in the extracellular fluid, and potassium is more abundant in the intracellular fluid.
strong acids
completely dissociate in solution -hydrochloric acid
When carbon dioxide is produced by cellular respiration, it reacts with Blank______ to form carbonic acid.
water
Sensible perpiration
water excreted by sweat glands
what happens if blood osmolarity becomes greater than interstitial fluid
water will move out into the plasma by osmosis
When carbon dioxide increases, the pH Blank______.
decreases
Electrolyte
A substance that dissolves in water to give a solution that conducts electric current -ions derived from salts, acids, bases, and proteins
Hyperhydration
A temporary excess of water; beyond the normal state of hydration. -dangerous
major extracellular ions
Na, cl, ca2+, mg2, po43(phosphate)
what happens if na+ increases in extracellular fluid
-osmolality increases -this promotes adh secretion
mechanisms that decrease thrist
-osmoreceptors detect normal solute levels -baroreceptors detect increased stretch -mouth isnt dry -stomach is distended
aldosterone
"salt-retaining hormone" which promotes the retention of Na+ by the kidneys. na+ retention promotes water retention, which promotes a higher blood volume and pressure -increases na+ reabsorption from the distal convoluted tube and collecting duct
chloride ions
-predominant anions in extracellular fluid -tied to regulation/movement of sodium -has an inhibitory effect on electrically excitable cells such as neurons and skeletal muscle fibers
Effect of alkalosis
- increases neuronal excitability. - pH change from 7.4 to 8.0 usually will induce seizures.
extracellular solutes
- sodium - chloride - proteins - glucose - exogenous substances
phosphate in the body
-85% of phosphate is in the form of calcium phosphate salts in the bones and teeth. -many are covalently bound to organic molecules -important components of dna,rna and atp -regulates enzyme activity -acts as buffers
Describe the process by which nephron cells move H+ into the kidney tubule lumen and HCO3- into the extracellular fluid.
-by increasing or decreasing the rate of H+ secretion and the rate of HCO3- reabsorption
potassium ions
-critical factor for determining the resting membrane potential for electrically excitable cells (decreased k+= cell hyperpolarizes)
Secretion of H+ in the nephron can
-decrease filtrate ph to 4.5, low ph inhibits the secretion of additonal h+
osmolality of a solution
-determined by number of solutes in a volume of a solution
sodium ions
-dominant extracellular cations -exert osmotic pressure -osmotic pressure causes water to move toward an area with a higher solute concertation -too much= water moves outside the cell -too little= water moves inside the cell
carbonic acid bicarbonate buffer system
-hco3- acts as weak base =h2co3 acts as a weak acid -cannot protect ph changes due to respiratory problems
stomach distension and thirst
-influential in decreasing thrist
regulation of phosphate in the body
-kidneys reabsorb some -pth increases phosphate levels by promoting bone reabsorption
Arterial Juxtaglomerular apparatus baroreceptors
-low blood pressure causes arterial baroreceptors to send ap to the hypothalamus -in the kidney juxtaglomerular apparatus baroreceptors stimulate juxtaglomerular cells to secrete renin when blood pressure drops
during respiratory acidosis what happens?
-low ph (high CO2) -buffers help to resist the decrease in ph -kidneys increase rate of H+ secretion and reabsorb HCO3- (kidneys not very effective if it happens quickly)
Na+ in kidneys
-major route in which Na+ is excreted -concentration of Na+ in the urine is determined by the amount of na+ and water reabsorbed from the filtrate -high reabsorption = low quantities in urine and vice versa
hypothalamic osmoreceptors
-neurons in the supraoptic nucleus of the hypothalamus function as osmoreceptors by detexting increases in the concetration of extracellular fluid -when these receptors shrink they send ap
what causes edema
-results from an increase in permeability of capillary walls or change in hydrostatic pressure -this allows proteins to go through into the interstitial fluid -reduced concentration of plasma proteins -increased venous pressure -blockage of lymph vessels
respiratory alkalosis
-results from hyperventilation -increased ph -kidneys decrease H+ secretion
calcitonin
-secreted by parafollicular cells of the thyroid gland -lowers extracellular calcium levels by preventing calcium levels from rising (inhibits osteoclasts)
parathyroid hormone regulation of ca2+
-secreted when levels are too low -pth increases blood ca2+ through 1.esteoclasts- reabsorbing of bone 2.renal tubules-reabsorption from kidney tubules 3.vitamin d3-increases rate of active vd3 formation which increases ca2+ levels
regulation of k+
-secretion of aldosterone -elevated levels of k+ stimulate aldosterone secretion which increases na+ reabsorption and K+ secretion by na+/K+ pump -aldosterone increases the rate of k+ secretion in the kidney which lowers k+ levels in the blood
Na+ excreted in sweat
-small amount -heavy exercise and warm environments can increase amount excreted
what happens if you sweat too much and dont drink enough fluids?
-sweating decreases the volume of fluid in the body but increases concentration of body fluid -
protein buffer sytsem
-the most abundant in intracellular fluods and in plasma -hemoglobin buffer in rbc -albumin is plasma buffer -
Na+ transport mechanisms of the distal convoluted tube and collecting
-under hormonal control
carbonic acid-bicarbonate buffer system responds to
1. addition of substances such as co2 or lactate during exercise 2.increased fatty acid and ketone body production 3. addition of basic substances (NaHCO3)
Rank men, women and infants from greatest to least amount of body water.
1. infants 2.men 3.women
Put the following statements in order to explain the process of acid-base regulation by the kidney, starting with the decrease in blood pH.
1.blood ph decreases 2. co2 diffuses into the kidney tubule cells 3.the carbonic aicd-bicarbonate equation is driven to the right (forming H+ and HCO3-) 4.H+ is secreted into filtrate in exchange for na+ 5.na+ and bicarbonate are symported into the interstitial fluid and diffuse into the blood 6.in the blood bicarbonate ions are combined with h+ to increase the blood ph
Put the following mechanisms in order of their buffering capacity on acid-base balance (least to greatest).
1.buffer system 2.respiratory system 3.renal system
regulation of H+ concentration
1.buffers-resists changes in ph -carbonic acid -protein -phosphate 2.respiraotry system 3. kidneys
regulation of fluid balance
1.hypothalamic osmoreceptors 2.arterial and juxtaglomerular apparatus baroreceptors 3.dryness of mouth 4. distension of stomach
ca2+ regulation
1.kidneys-long term regulation 2.digestive tract-long term regulation 3.bones- short term regulation -pth, vitamin d3, and calcitonin also regulate
An individual takes in 2,000 ml of water during the day. Ideally they should lose Blank______ ml of water during the day.
2000
water loss from evaporation
35%
water loss in feces
4%
How much of body weight is water?
50% or more
water loss in urine
60%
Infant body weight (Water)
75%
What hormone is released in response to changes in blood osmolality and results in changes in extracellular sodium concentration?
ADH
Which of these mechanisms is the most important for regulating blood osmolality?
ADH
When blood pressure is increased, Blank______ is released and the reabsorption of Blank______ is decreased.
ANH, sodium
Na+/K+ pump
Active transporter that moves three Na+ out of a cell and two K+ into the cell against their respective concentration gradients.
What is the principle hormone that regulates potassium ion concentrations in body fluids?
Aldosterone -Aldosterone causes sodium to be absorbed and potassium to be excreted into the lumen by principal cells
intracellular fluid compartment
All fluids inside cells of body About 40% of total body weight
Bicarbonate acts as a weak Blank______ by binding H+, removing the ions from solution, and raising pH
Base
Name the most important buffering system in the blood.
Bicarbonate/carbonic acid system
The primary mechanisms that regulate Na+ levels in the ECF directly monitor what two variables? Select all that apply.
Blood pressure Blood osmolality
Which of the following is correct?
Chloride is the most abundant anion in extracellular fluid, and proteins are the major anions in intracellular fluid.
plasma anion
Cl
regulation of cl-
Coupled to Na+ reabsorption Filtered and Reabsorbed
Which is under hormonal control?
Distal convoluted tubule
Which of the following structures are involved in the renin-angiotensin-aldosterone mechanism?
Distal convoluted tubules Cells of the juxtaglomerular apparatus
What causes osmotic pressure and movement of water between the fluid compartments?
Electrolytes
extracellular fluid compartment
Fluid outside cells; (interstitial fluid, plasma, lymph, csf, synovial fluid) 20% of body weight
What pressure drives filtration
Glomerular Blood Hydrostatic pressure (GBHP)
The kidneys directly regulate acid-base balance by Blank______. Select all that apply.
H+ secretion bicarbonate reabsorption
interstitial fluid cation
Na+
plasma cation
Na+
osmotic pressure of the extracellular fluid is caused mostly by
NA+
What is the purpose of buffers in the urine? Describe how the ammonia buffer system operates.
NH3 is produced in the cells of the nephron when amino acids, such as glutamine, are deaminated. Subsequently, NH3 diffuses from the nephron cells into the filtrate and combines with H+ in the filtrate to form ammonium ions
intracellular anion
Phosphate
What chemical buffer system is important for regulating intracellular pH?
Phosphate system
intracellular cation
Potassium (K+)
Name the factors that cause an increase and a decrease in H+ secretion.
The rate of H+ secretion and HCO3− reabsorption increases when the pH of the body fluids decreases, and this process slows when the pH of the body fluids increases
When blood pH decreases, which of the following occurs to correct the imbalance?
The respiratory center increases the breathing rate.
If blood pH increases, which of the following occurs to correct the imbalance?
The respiratory rate is decreased.
Which of the following is an important function of electrolytes in the extracellular fluid?
They control the movement of water between fluid compartments.
Indicate which of the following explain why electrolytes are physiologically important.
They strongly affect the osmolarity of the body fluids and the body's water content and distribution. They determine the electrical potential (charge difference) across cell membranes.
High levels of ammonium ions in the urine indicate:
a high level of H+ secretion into the urine
The carbonic acid/bicarbonate buffer system has Blank______ capacity to resist changes in blood pH.
a limited
High levels of bicarbonate ions in the urine indicate:
a low level of H+ secretion into the urine
In the bicarbonate buffer system, carbonic acid acts as a weak Blank______ by releasing H+ and lowering pH.
acid
A blood pH of 7.20 indicates Blank______.
acidosis
protein buffer system
acts inside & outside the cell; binds with acids & bases to neutralize them -proteins provide 3/4 of body's buffer capacity -hemoglobin is an important buffer -histone proteins
Hyperchloremia
an excess of chloride in the blood plasma -indication of dehydration -Cushing syndrome
ADH
antidiuretic hormone -stimulates water reabsorption in the kidneys and thrist
In what part of the renal tubule is most Mg2+ reabsorbed?
ascending limb (loop of henle)
Hypophosphatemia
below-normal serum concentration of inorganic phosphorus
Most phosphate in the body is found in Blank______.
bone and teeth
The level of extracellular Blank______ ions is regulated by the kidneys, bones, and digestive tract.
calcium
intercalated cells
cells in the collecting ducts of the kidneys that can absorb potassium if necessary -Regulate the amount of HCO3- and H+ in the urine in order to maintain the body's acid-base balance
carbonic acid-bicarbonate buffer system
chemical system that helps maintain pH homeostasis of the blood -regulating extarcellular ph -H+ added due to increase in acidic substances , binds to HCO3- this resists a decrease in ph (acts as a base) -H+ removed= H2CO3 forms HCO3- and H+ to resist change from basic substances (acts as an acid)
The most abundant anion in extracellular fluid is
chloride
interstitial fluid
cl-
Magnesium ions serve as Blank______.
cofactors for important enzymes
Aldosterone Blank______ urine output.
decreases
Which of these results in an increased blood Na+ concentration?
decrease in ADH secretion
Which of these conditions decrease extracellular fluid volume?
decreased aldosterone secretion
metabolic acidosis
decreased pH in blood and body tissues as a result of an upset in metabolism -hyperventilation
Hypochloremia
deficiency of chloride in the blood plasma -heart failure or addison disease
Hypocalcemia
deficient calcium in the blood
Hypokalemia
deficient potassium in the blood -due to elevated aldosterone levels -insulin administration
Hyponatremia
deficient sodium in the blood
blood osmolarity increases when
dehydrated
nonelectrolyte
do not dissociate into ions in water -lipids, urea, and glucose
when does permeability to capillary wall increase
during inflammatory response
Hyperphosphatemia
excessive phosphate in the blood
Hyperkalemia
excessive potassium in the blood
The carbonic acid/bicarbonate buffer system is important for regulating the pH of fluid in the ____ compartment.
extracellular
True or false: Both the adrenal medulla and the juxtaglomerular cells of the kidney play an important role in regulating blood volume.
false
True or false: Water loss is constant per kilogram of body weight.
false
Intracellular and extracellular are two major Blank______ of the body.
fluid compartments
fluid input
food/beverages- 90% cellular respiration- 10%
Solutions with a higher sodium ion concentration have a Blank______ osmotic pressure than solutions with a lower sodium ion concentration.
greater
Water loss varies Blank______ depending on physical activity level and environmental conditions.
greatly
Too much sodium can cause?
high blood pressure
metabolic alkalosis
high pH, high HCO3
Hypernatremia
high sodium
Osmosis is the diffusion of water toward a solution with a Blank______ solute concentration.
higher
renin-angiotensin system
hormone pathway that *increases thirst and raises blood pressure* if blood volume falls (often due to *dehydration*), detected as decreased blood flow to the kidneys; aka *RAS* or renin-angiotensin-aldosterone system (*RAAS*)
Slight deviations from the normal concentration of Blank______ ions can shut down metabolic pathways as well as alter the structure and function of other macromolecules.
hydrogen
The structure that promotes the thirst sensation is the Blank______.
hypothalamus
When blood pressure is decreased, the release of renin is Blank______ and the reabsorption of sodium is Blank______.
increased, increased
What would the effect of constricting the efferent arteriole be on glomerular filtration rate?
increases
decreased osmolality
inhibits thirst and ADH secretion
Water input and output
input: - ingested fluids - ingested foods - metabolism total: 2400-3200 mL output: - urine - feces - swear - exhaled air total: 2400-3200 mL - urine output is typically 1.5 L a day - can be as great as 20 L per day or as little as 0.5 L per day - kidneys alter urine output to compensate for variations in water intake/loss
insensible perspiration
interstitial fluid lost by evaporation through the stratum corneum
Which organ is primarily responsible for removing excess electrolytes from the body?`
kidney
The sodium ion reabsorption from the renal tubule decreases, Blank______ are excreted in the urine.
large amounts of sodium ions
Proteins are Blank______ abundant than bicarbonate ions in extracellular fluids.
less
When carbon dioxide decreases, the carbonic acid/bicarbonate equation is driven to produce Blank______ H+ ions.
less
Of the magnesium that is reabsorbed, most is reabsorbed through the Blank______.
loop of Henle (nephron loop)
Acidosis:
may lead to coma
Dehydration
occurs when body fluid drops below its set point -increasing osmolaity -the concentration of solutes in ef increases which allows water to move out of the cell by osmosis -
body fluid osmolality
osmolality maintained at 280-300
Parathyroid hormone increases the activity of Blank______ cells in bone and increases the rate of calcium Blank______ in the kidney tubules.
osteoclast; reabsorption
HPO42- and H2PO4- are components of the Blank______ buffering system.
phosphate
What electrolyte is important for bone composition, as a component of nucleic acids and ATP, and as an intracellular buffer?
phosphate
The renal system is an example of a Blank______ buffer.
physiological
An imbalance in this ion is very dangerous because this ion influences the resting potential of excitable cells.
potassium
Imbalances in , ___ ionsthe most dangerous of all electrolyte imbalances because this ion influences the resting membrane potential of excitable cells.
potassium
The most abundant cation in intracellular fluids is Blank______.
potassium
osmotic pressure
pressure that must be applied to prevent osmotic movement across a selectively permeable membrane
Which cells found in the collecting duct of the nephron, adjust urine in order to maintain the body's water, Na+, and K+ balance?
principal cells
Which buffer system is the most abundant in the body?
protein
The three major chemical buffer systems of the body are the Blank______ buffer systems.
protein phosphate carbonic acid/bicarbonate
intracellular solutes
proteins/potassium/magnesium/sulfate/monohydrogen phosphate ions
phosphate buffer system
reacts with acids & bases to form compounds that alter pH; especially effective in renal tubules
phosphate buffer system
reacts with acids & bases to form compounds that alter pH; especially effective in renal tubules -intracellular -when ph decreases ions bind to H+ and vice versa
Long-term suppression of thirst is regulated by Blank______ of blood osmolarity.
reduction
acids
release H+
weak acids
release h+ into solution but nit completely dissociated -carbonic acid
bases
remove H+ from solution
The addition of CO2 to the body fluids raises H+ concentration and lowers pH, while the removal of CO2 has the opposite effect. This is the basis for the strong buffering capacity of the Blank______ system.
respiratory
Hypoventilation can lead to Blank______.
respiratory acidosis
Insensible perspiration:
results in heat loss from the body
A decrease in extracellular K+:
results when aldosterone levels increase -aldosterone causes the release potassium
The kidneys directly regulate acid-base balance by increasing or decreasing the rate of H+ Blank______ and the rate of bicarbonate Blank______.
secretion, reabsorption
The most significant solute in determining total body water and the osmotic pressure of the ECF is Blank______.
sodium
Which two ions are most affected by aldosterone?
sodium and potassium
Examples of electrolytes
sodium, chloride, potassium
increased osmolality
triggers thirst and ADH secretion
the sensation of thirst increases when
the levels of angiotensin II increase
hydrostatic pressure
the pressure within a blood vessel that tends to push water out of the vessel
males body weight due to water is more than a female bc
they have low % of adipose tissue (adipose tissue has low water content)
low blood pressure increases
thrist
True or false: Although Na+ levels affect blood pressure and blood osmolality, Na+ itself is not directly monitored for the primary mechanisms regulating its concentration.
true -it monitors blood osmolarity and blood pressure
calcium absorption from the digestive track is dependent on
vitamin d 3
Calcium ion concentration in the blood decreases when
vitamin D levels are lower than normal
mechanisms that increase thirst
•Osmoreceptors detect increased solute concentrations. •Baroreceptors detect less stretch in vessels. •Decrease in saliva production.
