Ch 24 HW assignment
Which hormone plays a major role in calcium homeostasis?
Parathyroid hormone
Why are electrolytes physiologically important?
-they affect the osmolarity of the body fluids -they are chemically reactive and participate in metabolism -they determine the electrical potential across cell membranes
The typical American diet contains 3 to 7 g of sodium per day. How much sodium per day does a typical adult need?
0.5 g
Reduced blood osmolarity stops the osmoreceptor response and produces long-term thirst satiation. Approximately how long after drinking will these long-term changes take effect?
30 minutes
If the pH of the tubular fluid drops too low, H+ concentration in the fluid is so high that tubular secretion ceases. What is the limiting pH for tubular secretion?
4.5
The total body water content of a 70kg (150 lb) young male is about ______.
40 L
Which blood pH values are considered lethal?
6.9 7.8
What is the normal pH range of tissue fluid?
7.35 - 7.45
Which would be considered a normal pH value for arterial blood?
7.4
True or false: The only way to control water output significantly is through variations in urine volume.
True
Which is the best definition of a weak base?
A base that binds only some of the available H+ and has relatively small effect on pH
The bicarbonate system works quite well because the lungs and kidneys constantly remove which of the following? This prevents equilibrium from being reached.
CO2
The atrial and brain natriuretic peptides inhibit the secretion of which of the following?
ADH Renin
Most magnesium is found in intracellular fluid complexed with ______.
ATP
An increase in the amount of ammonium chloride in the urine most likely indicates which of the following?
Acidosis
Estrogen causes women to retain salt and water during pregnancy by mimicking the effects of which other steroid hormone?
Aldosterone
Which is referred to as the "salt-retaining hormone" because it plays the primary role in adjusting sodium excretion?
Aldosterone
Which term refers to a tissue fluid pH above 7.45?
Alkalosis
What is the complete chemical equation for the bicarbonate buffer system?
CO2 + H2O <-> H2CO3 <-> HCO3- + H+
How does blood plasma differ from the intracellular fluid?
Ca2+ concentration is higher in plasma. Na+ concentration is higher in plasma. K+ concentration is lower in plasma.
Since HCl is a strong acid and would lower the pH of the tubular fluid below the limiting pH, H+ is instead excreted as which of the following?
Ammonium chloride
Which is likely to be increased in the urine of a person with diabetic acidosis?
Ammonium chloride
Chloride (Cl-), bicarbonate (HCO3-), and phosphates (Pi) are examples of what?
Anions
Increased blood osmolarity stimulates hypothalamic osmoreceptors. This triggers the posterior pituitary to release which of the following?
Antidiuretic hormone
Which regulate sodium homeostasis?
Antidiuretic hormone Natriuretic peptides Aldosterone
In response to ADH release, collecting duct cells in the kidneys increase their expression of which of the following?
Aquaporins
Since there is so much chloride in the tubular fluid, why is H+ excreted as ammonium chloride (NH4Cl) and not simply excreted as hydrochloric acid (HCl)?
Because HCl is too strong of an acid and would drop the pH of the tubular fluid below the limiting pH
After several days of severe vomiting, a pregnant woman suffers from alkalosis. Her urine will contain an elevated concentration of which of the following?
Bicarbonate
Name the three important chemical buffer systems in the body.
Bicarbonate, phosphate, and protein
Which inhibit ADH release?
Blood osmolarity is too low. Blood volume and pressure are too high.
About 54% of the body's magnesium is found in which type of tissue?
Bone
Which hormone regulates phosphate homeostasis as part of the mechanism for increasing extracellular free calcium concentrations?
Parathyroid hormone
Tetany occurs when the plasma concentration of which ion drops to 6 mg/dL?
Calcium
Which is a cation that lends strength to the skeleton, activates muscle contraction, serves as a second messenger for some hormones and neurotransmitters, and is an essential factor in blood clotting?
Calcium
Which of these ions are major cation electrolytes?
Calcium Sodium
Why do cells maintain a very low intracellular calcium concentration?
Calcium phosphate crystals would precipitate in the cytoplasm if levels were high.
The renal tubules are incapable of reabsorbing HCO3- directly. Instead, an enzyme breaks down the H2CO3 in the tubular fluid to form CO2, which can be reabsorbed. What is the name of the enzyme?
Carbonic anhydrase
The buffering ability of proteins is primarily due to which of the following?
Carboxyl side groups release H+ when pH begins to rise Amino side groups bind H+ when pH falls
Potassium imbalances are the most dangerous of all electrolyte imbalances. What is the most serious consequence of potassium imbalance?
Cardiac abnormalities
Which can occur during rapid-onset hyperkalemia?
Cardiac arrest
Sodium, potassium, calcium and hydrogen ions are examples of which of the following?
Cations
Which statements are true regarding fluid sequestration? Select all that apply
Causes of fluid sequestration include edema and hemorrhage. It is a condition in which excess fluid accumulates in a particular location.
Cells maintain a very low intracellular calcium concentration to avoid crystallization of calcium phosphate. Which mechanisms maintain intracellular calcium concentrations low?
Cells often have a protein called calsequestrin, which binds the stored Ca2+ and keeps it chemically unreactive. Cells sequester Ca2+ in the smooth ER and release it only when needed. Cells actively pump out Ca2+.
Choose the types of transcellular fluids.
Cerebrospinal, synovial, peritoneal, pleural, and pericardial fluids Vitreous and aqueous humors of the eye Bile and fluid in the digestive, urinary, and respiratory tracts
Respiratory compensation involves correcting a pH imbalance by which of the following mechanisms?
Changing pulmonary ventilation rate
Which type of buffer is defined as a substance that binds H+ and removes it from solution as its concentration begins to rise, or releases H+ into solution as its concentration falls?
Chemical
Which term refers to a compound that helps maintain a stable pH by binding protons if H+ concentration begins to rise, and releasing them into solution if H+ concentration falls?
Chemical buffer
What is the most abundant anion in the extracellular fluid?
Chloride
Which ion tends not to be independently regulated, but instead passively follows sodium as it is retained or excreted?
Chloride
Which ions are the most abundant anions of the ECF and thus make a major contribution to its osmolarity?
Chloride
Which ions are the most abundant anions of the ECF? They are required for the formation of stomach acid and play a major role in the regulation of body pH.
Chloride
Which are possible effects of fluid deficiency?
Circulatory shock Neurological dysfunction
The intestinal absorption of magnesium is mainly regulated by vitamin
D
When is a person in a state of fluid balance?
Daily fluid gains equal losses.
What are the primary effects of aldosterone on urine composition?
Decreases NaCl, increases K+, and decreases pH
Which are types of fluid deficiency? Choose two of the options from the list below.
Dehydration Volume depletion
Which statement about dehydration is true?
Dehydration raises blood osmolarity.
Which factors can lead to volume depletion (hypovolemia), in which proportionate amounts of water and sodium are lost?
Diarrhea Chronic vomiting Hemorrhage
Acidosis depresses the central nervous system and alkalosis makes the nervous system hyperexcitable. Based on this, which of the following are possible symptoms of acidosis?
Disorientation Confusion Coma
Which are fast-acting stimuli that cause a temporary, short-term inhibition of thirst?
Distension of the stomach Cooling the mouth Moistening the mouth
What is the primary effect of chloride imbalances?
Disturbances in acid-base balance
Water balance is most directly tied to which of the following?
Electrolyte balance
Which statements are true regarding acid-base imbalances?
Electrolyte imbalances can cause pH imbalances. pH imbalances can cause electrolyte imbalances. Fluid imbalances can cause pH imbalances.
Which term is used to refer to the ions that participate in important metabolic and physiological processes?
Electrolytes
Match the steroid hormones below with their effects on Na+ homeostasis.
Estrogen -> Mimics the effect of aldosterone and causes women to retain water during pregnancy and part of the menstrual cycle Progesterone -> Reduces sodium reabsorption and has a diuretic effect Glucocorticoid -> Choice, Promotes sodium reabsorption and edema Promotes sodium reabsorption and edema
Which are possible causes of hypokalemia?
Excessive use of laxatives Heavy sweating, chronic vomiting or diarrhea Alkalosis Aldosterone hypersecretion
True or false: Dehydration affects the extracellular fluid exclusively.
False
True or false: During dehydration, the kidneys restore blood volume by the formation of metabolic water.
False
True or false: We salivate more when we are thirsty because of sympathetic output from the hypothalamus.
False
True or false: Respiratory loss decreases in cold weather.
False: Respiratory loss increases in cold weather because cold air is drier and absorbs more body water.
Most of the body's magnesium is lost in which of the following?
Feces
The blood, lymph, tissue fluid, and transcellular fluid are all examples of which of the following?
Fluid compartments
Edema is the most common form of which of the following?
Fluid sequestration
Which are important functions of phosphate ions?
Helping to stabilize the pH of body fluids Regulating metabolic pathways by activating and deactivating enzymes
What can lead to a sudden increase in extracellular potassium?
Hemolytic anemia A transfusion with outdated blood in which K+ has leaked out during storage A crush injury
Which reduces the sodium permeability of plasma membranes and inhibits the depolarization of nerve and muscle cells, as well as causing muscular weakness, depressed reflexes, and cardiac arrhythmia?
Hypercalcemia
Which may be caused by alkalosis?
Hypercalcemia Hypokalemia Hyperchloremia
Hypovolemia and dehydration are both examples of fluid deficiency. How do they differ?
In dehydration water is lost, and in hypovolemia both water and electrolytes are lost.
The following electrolyte imbalances may all be caused by acidosis. Match each type of imbalance to the explanation of how it may be caused by acidosis.
Hyperkalemia -> H+ diffuses into cells and displaces K+ (As K+ leaves the ICF, K+ concentration in the ECF rises). Hypochloremia ->More Cl- is excreted as NH4Cl to buffer the excess acid in the renal tubules, leaving less Cl- in the ECF. Hypocalcemia -> Acidosis causes more Ca2+ to bind to plasma protein and citrate ions, lowering the concentration of free, ionized Ca2+.
Which term refers to a plasma magnesium concentration above 2.0 mEq/L?
Hypermagnesemia
Which causes an increase in the sodium permeability of plasma membranes, making the nervous and muscular systems to be overly excitable?
Hypocalcemia
Which term refers to plasma concentrations of calcium less than 4.5 mEq/L?
Hypocalcemia
Which may be caused by acidosis?
Hypochloremia Hyperkalemia Hypocalcemia
Which term refers to a plasma potassium concentration of less than 3.5 mEq/L?
Hypokalemia
The following electrolyte imbalances may all be caused by alkalosis. Match each type of imbalance to the explanation of how it may be caused by alkalosis.
Hypokalemia -> H+ diffuses from ICF to ECF. More K+ remains in the ICF to compensate for the H+ loss, causing a drop in ECF K+ concentration. Hyperchloremia -More Cl- is reabsorbed from the renal tubules, so ingested Cl- accumulates in the ECF rather than being excreted. Hypercalcemia -> Alkalosis causes more Ca2+ to dissociate from plasma protein and citrate ions, raising the concentration of free Ca2+.
Hyperactivity of the nervous and muscular system is a symptom of which of the following?
Hypomagnesemia
Which term refers to a plasma sodium concentration less than 130 mEq/L?
Hyponatremia
Which statements are true regarding how water intake is regulated?
Hypothalamic neurons produce antidiuretic hormone (ADH), thus promoting water conservation. Osmoreceptors respond to angiotensin II and to rising osmolarity of the ECF. Cerebral cortex produces a conscious sense of thirst.
Which best defines osmoreceptors?
Hypothalamic neurons that respond to increased solute concentration in the extracellular fluid
What might happen if you lost large volumes of water and salt and then drank large quantities of plain water?
Hypotonic hydration
Which term (also called water intoxication or positive water balance), refers to a condition in which more water than sodium is retained or ingested?
Hypotonic hydration
Which are types of fluid excess?
Hypotonic hydration Volume excess
In which form of fluid imbalance is total body water reduced and osmolarity elevated?
Hypotonic hydration (positive water balance, water intoxication)
Which may occur when proportionate amounts of water and sodium are lost without replacement, for example due to hemorrhage, chronic vomiting, or diarrhea?
Hypovolemia
Which term is another name for volume depletion? This occurs when proportionate amounts of both water and sodium are lost without replacement.
Hypovolemia
In which form of fluid imbalance is total body water reduced while osmolarity remains normal?
Hypovolemia (volume depletion)
Match each form of fluid imbalance to its description.
Hypovolemia -> Total body water is reduced; ECF remains isotonic. Dehydration -> Total body water is reduced; ECF becomes hypertonic. Volume excess-> Total body water is elevated; ECF remains isotonic. Hypotonic hydration ->Total body water is elevated; ECF becomes hypotonic.
Dehydration that occurs in cases such as in profuse sweating affects which of the following fluid compartments?
ICF, blood, and tissue fluid
Which are effects of dehydration?
Increased blood osmolarity Reduced blood pressure Reduced salivation
Parathyroid hormone (PTH) increases excretion of phosphate in order to do which of the following?
Increasing the concentration of free calcium ions in the ECF
Which represents the largest fluid compartment in the body?
Intracellular fluid
Which are true regarding renal compensation?
It adjusts for pH imbalances by changing the rate of H+ secretion by the kidneys. It is slower than respiratory compensation, but better at restoring a fully normal pH.
Which best describes how aldosterone acts as the "salt retaining hormone"?
It increases the number of Na+-K+ pumps in the nephron.
What happens to ECF osmolarity during dehydration?
It increases.
Which are true regarding phosphate?
It is a component of nucleic acids, phospholipids, ATP, GTP, and cAMP. It can be generated by the hydrolysis of ATP. It exist in fluids as an equilibrium mixture of phosphate, monohydrogen phosphate and dihydrogen phosphate.
Which are important functions of sodium?
It is involved in generating body heat via the Na-K pump. It participates in muscle and nerve depolarization. It participates in cotransport of glucose, K+ and Ca+.
Which statements are true regarding fluid replacement therapy (i.e. intravenous fluids)?
It is usually used for persons who are seriously ill. Patients need to be carefully monitored when they receive intravenous fluids. The type of fluid replacement needs to be carefully selected.
Which statements are true regarding the phosphate buffer system? Select all that apply.
It plays an important role in the renal tubules. It plays an important role in the ICF where there is constant production of metabolic acids. Its optimal pH is 6.8.
Which organ can neutralize more acid or base than either the respiratory system or the chemical buffers?
Kidney
Fluid deficiency can cause serious effects. For example, circulatory shock may be caused by which of the following?
Loss of blood volume
Why do people salivate less when they are thirsty?
Lower capillary blood pressure and higher osmolarity of the blood leads to a decrease in saliva production. Sympathetic output from the hypothalamus inhibits the salivary glands.
Long-term satiation of thirst depends on which of the following?
Lowering of blood osmolarity
______ acidosis can result from increased production of organic acids, such as lactic acid in anaerobic fermentation and ketone bodies in alcoholism and diabetes mellitus.
Metabolic
Increased production of organic acids, such as lactic acid in anaerobic fermentation and ketone bodies in alcoholism and diabetes mellitus can cause which of the following?
Metabolic acidosis
______ may be caused by diabetes mellitus, hyperkalemia; chronic diarrhea and excessive alcohol consumption, whereas ______ is rare and may be caused by chronic vomiting; overuse of antacids and aldosterone hypersecretion.
Metabolic acidosis, metabolic alkalosis
Which is produced as a by-product of dehydration synthesis reactions and aerobic respiration?
Metabolic water
Which term refers to water formed by dehydration synthesis and aerobic respiration?
Metabolic water
Which term refers to water that is produced as a by-product of dehydration synthesis reactions and aerobic respiration?
Metabolic water
Acidosis depresses the central nervous system and alkalosis makes the nervous system hyperexcitable. Based on this, which of the following are possible symptoms of alkalosis?
Muscle spasms Convulsions
Hypercalcemia causes which of the following?
Muscular weakness, depressed reflexes, and cardiac arrhythmia Inhibition of depolarization of nerve and muscle cells Reduced sodium permeability of plasma membranes
Which inhibits Na+ and water reabsorption and lowers the blood pressure?
Natriuretic peptides
What are possible effects of hypokalemia?
Neurons become hyperpolarized and are less excitable. Reflexes may become depressed. Electrical activity of the heart becomes irregular.
Match the type of fluid replacement with the ideal case in which it could be used.
Normal saline isotonic 0.9% -> Patients with extensive blood loss Ringer's lactate solution -> Patients with acidosis Potassium chloride -> Patients with alkalosis (with no renal failure) and close monitoring of blood pH Plasma volume expanders (i.e. mannitol) -> Patients with seizures or coma (in order to combat hypotonic hydration) Isotonic 5% dextrose-> Patients who cannot eat (for example after severe trauma)
Which type of water loss is output that is relatively unavoidable? Examples include water loss through expired air, cutaneous transpiration, sweat, fecal moisture, and the minimum urine output.
Obligatory
Why can the kidneys neutralize more acid or base than any other buffer in the human body?
Only the kidneys actually expel H+ from the body.
Which is the same in the ICF and in the blood plasma?
Osmolarity
Which triggers the release of ADH?
Osmoreceptors detect the increase in osmotic pressure of body fluids and signal the posterior pituitary.
How does water move from the digestive tract to the bloodstream?
Osmosis
By which means can water move from one fluid compartment to another?
Osmosis Capillary filtration
Which of the following may cause metabolic alkalosis?
Overuse of intravenous bicarbonate solutions or aldosterone hypersecretion
Calcium homeostasis is regulated by which hormones? Select three from the list below.
PTH Calcitonin Calcitriol
Calcium does which of the following?
Participates in muscle contraction Acts as second messenger and activates exocytosis during neurotransmission Participates in bone and tooth development Acts as a factor for blood clotting
Slight deviations from the body's normal ____ range can shut down metabolic pathways as well as alter the structure and function of other macromolecules. Buffer systems help to avoid this.
Ph
Imbalances in which of the following are not as critical as imbalances of other electrolytes?
Phosphate
Which ion acts as an important buffer that helps stabilize the pH of body fluids?
Phosphate
Imbalances in which ion are the most dangerous of all electrolyte imbalances?
Potassium
Which ion is the greatest determinant of intracellular osmolarity and cell volume?
Potassium
Which ion is the most abundant cation of the ICF?
Potassium
Which statements are true regarding potassium homeostasis?
Potassium homeostasis is closely linked to that of sodium. Aldosterone stimulates renal secretion of potassium.
The pH of intracellular fluid is buffered mainly by which of the following?
Proteins
Which are possible complications of volume excess and hypotonic hydration?
Pulmonary edema Cerebral edema
Describe respiratory compensation in response to acidosis.
Pulmonary ventilation rate increases.
A pH below 6.8 or above 8.0 is which of the following?
Quickly fatal
Fluid intake is governed mainly by thirst. Which of the following can make a person thirsty?
Reduced blood pressure
How can the respiratory system compensate for a drop in blood H+ concentrations?
Reduced pulmonary ventilation allows CO2 to accumulate, lowering the pH back to normal.
Which occurs when blood volume and pressure are too high?
Release of ADH is inhibited.
The bicarbonate buffer system would not work very well in the human body if not for the action of the lungs and the kidneys doing which of the following?
Removing CO2 produced by the buffer system
Aldosterone stimulates which of the following?
Renal secretion of potassium Renal reabsorption of sodium
A buffer can be generally defined as a mechanism that does which of the following?
Resists changes in pH
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 which system?
Respiratory
______ acidosis occurs in hypoventilation, when carbon dioxide accumulates in the ECF and lowers its pH.
Respiratory
Which results when CO2 is eliminated faster than it is produced (for example, during hyperventilation)?
Respiratory alkalosis
Prolonged, heavy work increases which of the following? Select all that apply.
Respiratory loss Perspiration
Which physiological buffer system exerts an effect within a few minutes but cannot alter the pH as much as the urinary system?
Respiratory system
Which type of water loss is noticeable output, particularly through the urine and in case of sufficient sweating to produce obvious wetness of the skin?
Sensible
Under conditions do nerve and muscle cells become less excitable?
Slow-onset hyperkalemia Hypokalemia
Match each type of potassium imbalance to its neurological effects.
Slow-onset hyperkalemia -> Voltage-gated sodium channels inactivate. This prevents the firing of action potentials. Hypokalemia -> The concentration gradient for K+ across the membrane becomes steeper, resulting in hyperpolarization. This makes neurons and muscle cells less excitable. Rapid-onset hyperkalemia -> Neurons and muscle cells depolarize suddenly and fire action potentials. Synchronous activation of cardiac muscle cells can lead to cardiac arrest.
Aldosterone, antidiuretic hormone, and the natriuretic peptides help maintain concentrations which of the following?
Sodium
Chloride homeostasis is achieved primarily as an effect of controlling the concentration of which other ion?
Sodium
During dehydration, urine volume decreases and more body water is retained. This is often due to increased reabsorption of which of the following?
Sodium
Which ion is the most significant solute in determining total body water and the distribution of water among fluid compartments?
Sodium
Which ion is the principal cation of the ECF?
Sodium
Which statement is correct regarding the relative abundance of electrolytes in the ECF and ICF?
Sodium is more abundant in the ECF and potassium is more abundant in the ICF.
Changes in urine volume are often linked to adjustments in which of the following?
Sodium reabsorption
Which determines the direction and extent of osmosis between the intracellular and extracellular compartments?
Solute concentrations in the various compartment
An acid such as hydrochloric acid (HCl) that ionizes freely, gives up most of its hydrogen ions, and can markedly lower the pH of a solution is known as what type of acid?
Strong
HCl ionizes freely, gives up most of its hydrogen ions, and can markedly lower the pH of a solution. Because of this it is classified as which of the following?
Strong acid
Hydroxide (OH-) has a great tendency to bind H+ and raise the pH. It is therefore classified as which of the following?
Strong base
Which factors determine the amount of acid or base that can be neutralized by a chemical buffer system? Select two answers below.
The concentration of the buffer The pH of their working environment
Why are infants more vulnerable to dehydration than adults?
The have higher metabolic rates and produce toxic metabolites faster.
Which best describes the role of the kidneys in maintaining water balance during dehydration?
The kidneys can slow down the rate of water and electrolyte loss through changes in urine volume and composition.
Which statements are true?
The kidneys compensate very well for abnormally high fluid intake through diuresis. The kidneys cannot compensate very well for inadequate fluid intake.
How does the phosphate buffer system differ from the bicarbonate buffer system?
The phosphate buffer system has a higher optimal pH. Phosphates are more important in the renal tubules and ICF. The phosphate buffer system has a stronger buffering effect than an equal amount of bicarbonate buffer.
How is the phosphate buffer system different from the bicarbonate buffer system?
The phosphate buffer system has a stronger buffering effect than an equal amount of bicarbonate buffer. Bicarbonates play a larger role in buffering the ECF. Phosphate is more important in the renal tubules and ICF.
True or false: The primary effects of chloride imbalances are disturbances in acid-base balance, but acid-base imbalances can cause chloride imbalances as well.
True
What are the major chemical buffer systems of the body? Select three options from the list below.
The protein buffer system The phosphate buffer system The bicarbonate buffer system
Which statements are true concerning the protein buffer system?
The protein buffer system is especially important in the ICF. Amino groups (-NH2) bind H+ and buffer decreases in pH. Carboxyl groups (-COOH) release H+ and buffer increases in pH.
Describe renal compensation in response to alkalosis.
The renal tubules decrease the rate of H+ secretion.
Describe renal compensation in response to acidosis.
The renal tubules increase the rate of H+ secretion.
Why is it important to maintain the pH of blood and tissue fluids within normal limits?
The structure and function of macromolecules are pH dependent. Slight deviations from normal pH can shut down metabolic pathways.
What must be true in order for tubular secretion of hydrogen ions to take place?
There is a concentration gradient between the renal tubule cell and the tubular fluid.
Why are there are no bicarbonate ions in urine of a person with normal acid-base balance?
They are consumed by neutralizing H+.
Which are functions of chloride ions?
They participate in the chloride shift in that accompanies carbon dioxide loading and unloading. They play a major role in the regulation of body pH. They are important in osmotic balance. They contribute to formation of stomach acid.
Which is an example of insensible water loss?
Transpiration of water from the skin
True or false: Acidosis can cause hyperkalemia, and conversely, hyperkalemia can cause acidosis.
True
True or false: Cold weather has a dehydrating effect on the human body.
True
True or false: In cases of volume depletion, total body water declines but fluid osmolarity is normal.
True
True or false: The ability of a buffer to function effectively (neutralize acids or bases) depends on the pH of the solution and the concentration of the buffer.
True
True or false: The kidneys cannot compensate very well for inadequate fluid intake, but they compensate very well, on the other hand, for abnormally high fluid intake
True
Which processes occur in the kidney during the neutralization of acid?
Tubular cells form ammonia, which acts as a base and reacts with H+ and Cl- to form ammonium chloride (NH4Cl) For every HCO3- that enters the peritubular capillaries, a sodium ion does too The glomerular filtrate contains Na2HPO4 (dibasic sodium phosphate), which reacts with some of the H+
Which system buffers the greatest quantity of acid or base but requires several hours to days to exert an effect?
Urinary system
Which two organ systems form physiological buffers that help stabilize pH by controlling the body's output of acids, bases, or CO2? Select two options from the list below.
Urinary system Respiratory system
Which are the primary effects of aldosterone? Select all that apply.
Urine contains less NaCl. Urine has a lower pH. Urine contains more K+.
Water output is primarily controlled through variations in which of the following?
Urine volume
Which are affected by aldosterone? Choose three answers from the list below.
Urine volume Blood volume Blood pressure
If the body has retained too much sodium and water, but the ECF remains isotonic, the person has which of the following?
Volume excess
Which can result from aldosterone hypersecretion or renal failure?
Volume excess
Sodium is actively pumped across membranes. What compounds passively follow it?
Water and chloride
Which are examples of preformed water? Select all that apply.
Water in a baked potato and steak dinner Water in a glass of milk Water in an apple
Which of the following best defines cutaneous transpiration?
Water loss through skin
Match each type of water loss with its description.
Water loss through the breath and cutaneous transpiration -> Insensible water loss Water loss through minimal urine formation; expired air; cutaneous transpiration; fecal moisture -> Obligatory water loss Water loss through urine and visible sweating matches -> Sensible water loss
Which are examples of sensible water loss? Select all that apply.
Water loss through urination Water loss through profuse sweating
What are possible consequences of hypernatremia? Select all that apply.
Water retention Hypertension Edema
An acid such as carbonic acid (H2CO3-) that ionizes only slightly and keeps most hydrogen in a chemically bound form that does not affect pH, is classified as which type of acid?
Weak
H2CO3 ionizes only slightly and keeps most of its hydrogen in a chemically bound form that does not affect pH. Because of this it is classified as which of the following?
Weak acid
A tissue fluid pH below 7.35 is defined as a state of ______.
acidosis
Respiratory ______ occurs when the rate of alveolar ventilation fails to keep pace with the body's rate of CO2 production. Carbon dioxide accumulates in the ECF and lowers its pH.
acidosis
Respiratory ______ results from hyperventilation, in which CO2 is eliminated faster than it is produced.
alkalosis (Respiratory acidosis occurs when not enough CO2 is eliminated.)
In response to ADH release, collecting duct cells in the kidneys increase their expression of proteins called ___ . These proteins act as water channels and allow the kidneys to reabsorb more water and produce less urine.
aquaporin
Phosphate is a necessary component of which of the following?
cAMP GTP Nucleic acids ATP Phospholipids
Any substance that binds H+ and removes it from solution as its concentration begins to rise, or releases H+ into solution as its concentration falls is classified as a ______ buffer. Examples include proteins, bicarbonate, and phosphate
chemical
Any substance that binds H+ and removes it from solution as its concentration begins to rise, or releases H+ into solution as its concentration falls is classified as a ______ buffer. Examples include proteins, bicarbonate, and phosphate.
chemical
Blood plasma is a type of ______ fluid.
extracellular
Transcellular fluid is a type of ______ fluid.
extracellular
True or false: Most of the water (65%) is found in the extracellular compartment.
false
A person is in a state of fluid ___ when daily gains and losses are equal.
homeostasis
Plasma concentrations of calcium less than 4.5 mEq/L are known as
hypocalcemia
A plasma concentration of chloride less than 95 mEq/L is called _____ and it is usually a side effect of hyponatremia.
hypochloremia
Some tumors of the adrenal cortex secrete excess aldosterone. Paralysis may occur because aldosterone stimulates renal secretion of potassium ions, which may result in a potassium deficiency called
hypokalemia
Where are osmoreceptors found?
hypothalamus
Even though aldosterone ______ the tubular reabsorption of sodium and water, this is offset by a(n) ______ in GFR; thus there is only a small ______ in urine output.
increases; increase; decrease
The loss of water through breathing is a type of ______ water loss.
insensible
Match the pH disorder with its cause.
metabolic acidosis - excess production of organic acids i.e. diabetes meliltus and starvation; hyperkalemia, chronic diarrhea; excessive alcohol consumption; aspirin; laxatives Metabolic alkalosis - rare but can result from chronic vomitting; overuse of antacids; aldosterone hypersecretion respiratory acidosis - hypoventilation; apnea respiratory alkalosis - hyperventilation due to pain or emotions such as anxiety
Fluid intake is governed by thirst and it is regulated by a group of hypothalamic neurons called ___, which respond to angiotensin II and to rising osmolarity of the ECF.
osmoreceptors
If a local imbalance between the intracellular and extracellular fluid occurs, water movement called ______ restores the balance. This depends on the relative concentration of solutes in each compartment.
osmosis
If the osmolarity of the tissue fluid rises, water moves ______ the cells.
out of
Which property of a solution is determined by the concentration of hydrogen ions?
pH
The ______ buffer system is a solution of H(PO4)2 and H2(PO4).
phosphate
A ______ buffer is a system (for example the respiratory or urinary system) that stabilizes pH by controlling the body's output of acids, bases, or CO2.
physiological
Rank the following electrolyte imbalances in terms of how dangerous they are. Start with the most dangerous.
potassium calcium phosphate
Water intake totals about 2500 mL/day. The combination of water from food (about 700 mL) and drink (about 1600 mL) is known as ____ water.
preformed
The ___ buffer system accounts for about three-quarters of all chemical buffering in the body fluids, especially in the ICF.
protein
Dehydration ______ blood volume and ______ blood osmolarity.
reduces, raises
The most abundant solute particles are electrolytes, especially potassium in the intracellular fluid (ICF) and ______ in the extracellular fluid (ECF).
sodium
When a person is thirsty, the osmoreceptor response leads to ______ output from the hypothalamus that inhibits salivation.
sympathetic
True or false: A newborn baby's weight is as much as 75% water, whereas obese and elderly people's weight is as little as 45% water.
true
True or false: Simply moistening the mouth can temporarily inhibit thirst even if no water reaches the stomach.
true
Of the two major physiological buffer systems, the respiratory system can restore the pH quickly, whereas the ___system can take several hours to days to restore the pH.
urinary
Most water is lost daily through ______.
urine
The total water output per day in a resting adult is about 2500 mL. Match the route of water loss with its approximate normal volume
urine -> 1500 feces -> 200 Sweat-> 100 Expired breath -> 300 Cutaneous transpiration -> 400
The most important buffer system in the blood is the bicarbonate buffer, which is a solution of ______ acid and bicarbonate ions.
weak
