Anatomy and Physiology Chapter 25 & 26
A group of coaches for the local youth leagues have asked you to speak to them about proper hydration for young athletes. Which statement shows the greatest understanding?
"I plan to have plenty of water available on our bench, and I'll have my team take frequent breaks during practice to quench their thirst."
Calculate the net filtration pressure if blood pressure in the glomerulus is unusually high, around 68 millimeters of mercury (mm Hg). Assume the colloid osmotic pressure and capsular hydrostatic pressure are normal.
23 mm Hg
Which of the following would NOT be associated with a rise in K+ concentration in the extracellular fluid (ECF)?
A drop in Na+ reabsorption (Rising levels of K+ directly influence the adrenal cortex. The subsequent release of aldosterone leads to both increased loss of K+ in the urine and increased reabsorption of Na+.)
An increase in blood CO2 levels leads to __________.
A drop in blood pH
The bicarbonate buffer system is one of the chemical buffer systems of the body. How would the bicarbonate buffer system work if sodium hydroxide were added to a solution?
A hydrogen on carbonic acid would dissociate and join the hydroxyl group on the base to form water and sodium bicarbonate.
In severe dehydration or blood loss, what would be the levels of ADH and what would be the urine flow rate?
ADH - high; low urine flow rate (0.25 ml/min)
In overhydration, what would be the levels of ADH (high, normal, or low) and what would be the osmolarity of the urine?
ADH - low; 100 mOsm (urine). (In over-hydration, ADH would be very low and the cells of the collecting duct would be relatively impermeable to water and urea. Thus, the final urine would be dilute, having an osmolarity of about 100 mOsm.)
Which of the following statements about ADH (antidiuretic hormone) is correct?
ADH is released by the posterior pituitary gland.
Through the tubuloglomerular feedback mechanism, how would an increase in filtrate NaCl concentration affect afferent arteriole diameter?
Afferent arteriole diameter would decrease. (High NaCl concentration in the filtrate at the JGA indicates that GFR is too high. By decreasing the diameter of the arteriole delivering blood to the glomerulus, HPg is decreased, resulting in lower GFR.)
The myogenic mechanism of renal autoregulation primarily involves smooth muscle in which blood vessels?
Afferent arterioles
Which of the following statements about aldosterone is NOT correct?
Aldosterone increases sodium reabsorption by increasing the number of Na+-K+ ATPase pumps in the luminal membrane of the proximal tubule. (Aldosterone increases the number of Na+-K+ ATPase pumps in the basolateral membrane of the distal tubules and collecting ducts.
Which of the following processes would be considered as a secretory rather than an excretory activity?
Aldosterone release by the adrenal glands
Which of the following statements is FALSE regarding water intake and output by the body?
An increase in fluid taken by mouth would reduce the amount produced by metabolism. (The water produced by metabolism is a by-product of energy processing. This amount is not dependent on the amount of water taken by mouth.)
During reabsorption of water in the proximal convoluted tubule, what causes water to diffuse from the lumen into the interstitial space?
An increase in the osmolarity of the interstitium.
Suppose the extracellular fluid (ECF) osmolality becomes too high. What hormone would most likely be released to correct this situation?
Antidiuretic hormone (ADH) (High osmolality in extracellular tissue indicates a drop in blood pressure and loss of fluid volume. The hypothalamus monitors ECF osmolality and, if high, triggers the posterior pituitary to release ADH. ADH acts on the kidneys to correct this by reclaiming more water from kidney filtrate.)
What is the primary buffer in the plasma?
Bicarbonate buffer system (Bicarbonate is the form that CO2 is transported in the blood stream. Using carbonic anhydrase to shift between bicarbonate and carbonic acid, the pH of the blood stream can be quickly regulated.)
Which of the following is not an electrolyte?
Carbohydrate (Carbohydrates are held together by covalent bonds, whereas electrolytes are held together by ionic bonds.)
The respiratory system is one of the three systems that regulate acid-base balance in the body. How does it work to decrease an acidosis?
Carbonic acid is broken down into water and CO2; the CO2 is then exhaled.
What is the effect of antidiuretic hormone on the cells of the collecting duct?
Causes aquaporins to be inserted into the apical membranes.
Why do you have to carefully monitor certain patients who are on "loop diuretics" to lower their blood pressure?
Certain diuretics are not specific and in addition to getting rid of excess water, additional ions like potassium will be secreted.
What negatively charged ion is reabsorbed by renal tubules when the blood pH is drawing near its alkaline limit?
Cl-
The__________use the medullary osmotic gradient to concentrate urine.
Collecting ducts
When filtrate flow through the renal tubule increases, reabsorption of sodium chloride by the tubule__________.
Decreases
In what part of the renal tubule does parathyroid hormone (PTH) promote the reabsorption of calcium ions?
Distal Convoluted Tubule (DCT)
Upon reaching what point in the nephron is reabsorption (1) dependent upon the body's needs at the time and (2) regulated by hormones?
Distal-Convoluted Tubule (DCT)
The vasa recta preserve the medullary osmotic gradient and act as counter-current__________.
Exchangers
When the macula densa detects an increase in NaCl concentration in the renal filtrate, what happens to the glomerular filtration rate (GFR)?
GFR decreases.
GFR regulation mechanisms primarily affect which of the following?
Glomerular hydrostatic pressure (HPg) (Hydrostatic pressure within the glomerular capillaries produces net outward movement of fluid. Unique to glomerular capillaries, HPg is consistently higher than other capillaries (~55 mm Hg), which ensures the one-way movement of fluid and solutes out of the glomerulus under normal conditions.)
The chief force pushing water and solutes out of the blood across the filtration membrane is ________.
Glomerular hydrostatic pressure (glomerular blood pressure)
The specialized capillary bed responsible for the pressure that drives filtration is the__________.
Glomerulus
Your patient's urinalysis shows a large amount of protein in the urine. This suggests a problem in the ____________.
Glomerulus (If the glomerular capillary is damaged, large molecules such as proteins can pass through the filtration membrane and appear in the urine.)
Which of these should not normally appear in urine?
Glucose
What is the chief force pushing water and solutes out of the blood and across the filtration membrane of the glomerulus?
Hydrostatic pressure in glomerular capillaries (HPgc)
Which of the following conditions promotes edema?
Hypoproteinemia
What type of water imbalance increases the amount of fluid in both cells and tissue?
Hypotonic hydration
Vasa recta blood osmolality is critical to maintaining the countercurrent mechanisms of the nephron. Where is vasa recta blood osmolality the highest?
In the deep medulla
Which of these combinations of values would help you determine if your patient was suffering from metabolic acidosis?
Increased blood HCO3- levels and decreased pH
Filtrate flow through the renal tubule increases when glomerular filtration rate__________.
Increases
When filtrate flow through the renal tubule increases, the concentration of sodium chloride remaining in the filtrate__________.
Increases
What does a high concentration of NaCl in the renal tubule at the juxtaglomerular apparatus (JGA) most likely indicate?
Insufficient NaCl reabsorption due to high GFR (If the filtrate is moving through the tubule quickly, less reabsorption is possible, so more NaCl gets left behind. This means that at the JGA, the NaCl concentration within the filtrate will be high.)
What is the osmolarity of the filtrate at the end of the proximal tubule?
Isotonic - 300 mOsm
Polycystic kidney disease always affects both kidneys instead of only the right or left kidney because __________.
It is a genetic disease
Renin is released by cells of the__________apparatus in response to afferent arteriole pressure and the degree of stretch of the arteriole wall.
Juxtaglumerular
The long nephron loops of the__________ nephrons are located in the renal__________.
Juxtamedullary; Medulla
Conditions such as diabetes mellitus and starvation are closely linked to __________.
Ketonuria (The liver generates large quantities of ketones, as an alternative to glucose, when glucose stores are depleted (during starvation) or when cells are unable to take up glucose from the blood (as in diabetes mellitus). As ketone production increases, excess ketones appear in the urine, a condition called ketonuria.)
Which of the following is the only logical explanation for why hypocalcemia increases neuromuscular excitability and causes muscle tetany?
Low plasma calcium ion concentration increases the permeability of neuron membranes to sodium ions, thereby causing depolarization that in turn increases the likelihood of action potentials being generated.
The most important renal mechanism for regulating acid-base balance of the blood involves __________.
Maintaining HCO3- balance
A patient is admitted to the hospital with the following plasma values: pH = 7.2, pCO2 = 25 mmHg, and HCO3¯ = 18 mEq/L. What is the acid base imbalance?
Metabolic acidosis with respiratory compensation. (The low bicarbonate indicates this is a metabolic acidosis. Since CO2 is below the normal range, this indicates there is a respiratory compensation.)
Starvation would cause which of the following acid-base conditions? Also, determine what type of compensation (metabolic or respiratory) there would be.
Metabolic acidosis with respiratory compensation. (This is known as a ketosis (due to the breakdown of fat for metabolism), and the respiratory system would increase respiration to compensate for the excess hydrogen ions.)
Diarrhea can lead to which acid/base disturbance? Assuming compensation, would it be a metabolic or respiratory compensation?
Metabolic acidosis with respiratory compensation. (With the loss of bicarbonate ions, this is a metabolic acidosis. If compensated, it would be a respiratory compensation.)
Ingesting too much antacid would cause which of the following acid-base disturbances?
Metabolic alkalosis
Vomiting will cause which type of acid-base disturbance?
Metabolic alkalosis
A patient is admitted to the hospital with the following plasma values: pH = 7.5, pCO2 = 45 mmHg, and HCO3¯ = 30 mEq/L. What is the acid-base imbalance?
Metabolic alkalosis with no compensation. (Since HCO3¯ is 30 (above the normal range of 22 to 26 mEq/L), this is definitely a metabolic alkalosis. There is no respiratory compensation since CO2 is within the normal range.)
A friend has acid indigestion after eating a big meal. Which of the following would act as a buffer and help ease his pain?
Milk of magnesia, with a pH of 10 (Excellent! Excess acid can be buffered by the addition of an alkaline or base.)
The long nephron loops create the medullary osmotic gradient and act as counter-current__________.
Multipliers
Which of the following are mechanisms of intrinsic control of glomerular filtration (renal autoregulation)?
Myogenic mechanism and tubuloglomerular feedback (The myogenic mechanism is mediated by smooth muscle within the afferent arteriole. In contrast, tubuloglomerular feedback is mediated by macula densa cells of the juxtaglomerular apparatus.)
Which of the following transporters in the luminal membrane results in secretion?
Na+-H+ countertransport (Na+ is transported into the cell and H+ is transported out of the cell into the lumen.)
Which of the following substances is a key component of the major buffer system in extracellular fluids?
NaHCO3 (The bicarbonate buffer system is the only important ECF buffer and consists of a solution of carbonic acid (H2CO3) and its salt, sodium bicarbonate (NaHCO3, a weak base)
The structural and functional unit of the kidney is a__________.
Nephron
Which structure is INCORRECTLY matched with a function?
Nephron loop: reabsorption of urea.
If the osmotic pressure in the glomerular capillaries increased from 28 mmHg to 35 mmHg due to dehydration, would net filtration increase or decrease?
Net filtration would decrease.
What is the limiting factor for the reabsorption of most actively transported solutes in the proximal tubule?
Number of transport carriers in the luminal membrane
What area of the nephron is responsible for the reabsorption of most of the water from the filtrate as well as most nutrients?
Proximal convoluted tubule
Where in the nephron does most solute reabsorption occur?
Proximal convoluted tubule
Which of the following is NOT a function of the kidneys?
Regulate body fluid by controlling excretion from sweat glands. (Carry out gluconeogenesis during prolonged fasting, regulate blood volume and osmolality, and maintain acid-base balance, and metabolize vitamin D to its active form are all functions of the kidney.)
When filtrate flow through the renal tubule increases, the macula densa responds by__________vasoconstrictors.
Releasing
Of the three buffering mechanisms in the body, which is the strongest?
Renal system
Granular cells of the juxtaglomerular apparatus (JGA) regulate GFR indirectly through which mechanism?
Renin-angiotensin mechanism (When systemic blood pressure decreases, granular cells release renin which ultimately causes the formation of angiotensin II. Angiotensin II causes widespread vasoconstriction of systemic arterioles and the increase of blood volume due to aldosterone release.)
What is the most important trigger for aldosterone release?
Renin-angiotensin-aldosterone mechanism
A patient is admitted to the hospital with the following plasma values: pH = 7.2, pCO2 = 55 mmHg, and HCO3¯ = 30 mEq/L. What is the acid base imbalance?
Respiratory acidosis with metabolic compensation. (Since pCO2 is above the normal range, it is the cause of the acidosis. HCO3 is increased to compensate, which is a metabolic compensation.)
Emphysema can lead to which acid/base disturbance? What would be the compensation?
Respiratory acidosis; kidneys will retain more HCO3 and excrete H+.
Severe anxiety would cause which type of acid-base disturbance? What would be the compensation?
Respiratory alkalosis; kidneys would excrete HCO3
Approximately 80% of the energy used for active transport is devoted to the reabsorption of __________.
Sodium
The active transport of which ion out of proximal convoluted tubule cells causes the reabsorption of both water and solutes?
Sodium
Which of the following is NOT a property used to establish the medullary osmotic gradient?
The blood flow through the ascending and descending portions of the vasa recta (preserves). (The ascending limb's impermeability to water and permeability to salt, the filtrate flow through the ascending and descending limbs of the long nephron loops of juxtamedullary nephrons, & the descending limb's permeability to water and impermeability to salt all establish the MOG.)
The lab results of a newly admitted patient indicate renal impairment. How might this affect the dosing regimen of drugs that are excreted by the kidney?
The dosage or the dosage interval may need to be reduced.
In a respiratory acidosis the kidney would do which of the following?
The kidney would reabsorb bicarbonate and secrete hydrogen ions.
Hypersecretion of aldosterone results in hypokalemia, which causes hyperpolarization of neurons; this in turn results in ______.
The need for a stronger than normal stimulus in order to trigger an action potential.
The decreased intracellular concentration of sodium in tubular cells during active transport is caused by which of the following mechanisms?
The sodium-potassium ATPase pump in the basolateral membrane
Which of the following best describes glomerular filtration rate (GFR)?
The volume of filtrate created by the kidneys per minute. (Glomerular filtration is driven by glomerular hydrostatic pressure (HPg) and produces ~125 ml of filtrate per minute.)
Which of the following is true of electrolytes?
They are ionic compounds (Electrolytes dissociate, or come apart, in water, releasing ions, which have electrical charges—hence the term "electrolyte.")
Most solutes that are reabsorbed in the proximal convoluted tubule use which of the following pathways?
Transcellular
Which of the following does NOT impact how much sodium is reabsorbed?
Transport maximum of the renal proximal tubule (The transport maximum only describes the max potential for sodium transport. This transport is regulated by hormones that influence transport, especially beyond the proximal convoluted tubule (PCT)
Macula densa cells of the juxtaglomerular apparatus (JGA) regulate GFR through which intrinsic mechanism?
Tubuloglomerular feedback (The JGA is a region of the nephron where the afferent arteriole and its associated tubule are closely apposed. This anatomical arrangement allows macula densa cells to adjust GFR according to the NaCl concentration in filtrate.)
An elevated level of urea in the blood is__________.
Uremia
When filtrate flow through the renal tubule increases, the afferent arteriole responds by__________.
Vasoconstricting
If a person exercises for a long time, lactic acid will start to build up in his or her muscles. Which of the following would you expect to happen as the lactic acid first starts to be formed?
Weak bases in the muscles will act as buffers and resist or minimize any pH change.
Which of the following blood workups would most likely demonstrate metabolic acidosis?
pH: 7.33; PCO2: 30 mmHg; HCO3 -: 20 mEq/L
Which of the following is NOT an effect of PTH?
to decrease Ca2+ absorption in the gut (Calcium has two valence electrons, so it is generally written as Ca2+, or Ca++). (This would have the opposite effect of PTH. PTH works to increase Ca2+ in the blood stream.)