BIO 360 - Exam 4 - Chapter 19 Review Questions Flashcards
List and explain the significance of the five characteristics of urine that can be found by physical examination.
color (concentration), odor (infection or excreted substances), clarity (presence of cells), taste (presence of glucose), and froth (presence of proteins)
List and explain the six major kidney functions.
(1) regulation of extracellular fluid volume (to maintain adequate blood pressure)
(2) regulation of osmolarity,
(3) maintenance of ion balance (neuron function)
(4) regulation of pH (proteins denature if pH not maintained) (5) excretion of wastes and foreign substances (to prevent toxic effects)
(6) production of hormones (that regulate RBC synthesis, Ca2+ and Na+ balance)
At any given time, what percentage of cardiac output goes to the kidneys?
20–25%
List the major structures of the urinary system in their anatomical sequence, from the kidneys to the urine leaving the body. Describe the function of each structure.
nephrons through ureters to urinary bladder (storage), leaving through the urethra
Arrange the following structures in the order that a drop of water entering the nephron would encounter them:
(a) afferent arteriole
(b) Bowman’s capsule
(c) collecting duct
(d) distal tubule
(e) glomerulus
(f) loop of Henle
(g) proximal tubule
(h) renal pelvis
(a), (e), (b), (g), (f), (d), (c), (h)
(a) afferent arteriole
(e) glomerulus
(b) Bowman’s capsule
(g) proximal tubule
(f) loop of Henle
(d) distal tubule
(c) collecting duct
(h) renal pelvis
Name the three filtration barriers that solutes must cross as they move from plasma to the lumen of Bowman’s capsule. What components of blood are usually excluded by these layers?
Glomerular capillary endothelium, basal lamina, and epithelium of Bowman’s capsule.
Blood cells and most plasma proteins are excluded.
What force(s) promote(s) glomerular filtration? What force(s) oppose(s) it? What is meant by the term net driving force?
Capillary hydrostatic pressure promotes filtration. Fluid pressure in Bowman’s capsule and colloid osmotic (oncotic) pressure of plasma oppose it. Net driving force is the sum of these pressures.
What does the abbreviation GFR stand for? What is a typical numerical value for GFR in milliliters per minute? In liters per day?
GFR—glomerular filtration rate. 125 mL/min or 180 L/day.
In which segment of the nephron does most reabsorption take place?
When a molecule or ion is reabsorbed from the lumen of the nephron, where does it go?
If a solute is filtered and not reabsorbed from the tubule, where does it go?
70% occurs in the proximal tubule.
Reabsorbed molecules go into the peritubular capillaries and the systemic venous circulation.
If filtered and not reabsorbed, a molecule is excreted in the urine.
List three solutes secreted into the tubule lumen.
penicillin, K+, and H+
What solute that is normally present in the body is used to estimate GFR in humans?
creatinine
What is micturition?
urination
Define, compare, and contrast the items in the following sets of terms:
(a) filtration, secretion, and excretion
(b) saturation, transport maximum, and renal threshold
(c) probenecid, creatinine, inulin, and penicillin
(d) clearance, excretion, and glomerular filtration rate
(a) Filtration and secretion both move material from blood to tubule lumen, but filtration is a bulk flow process while secretion is a selective process.
Excretion is also bulk flow but involves movement from the
kidney lumen to the outside world.
(b) Saturation—all transporter binding sites are occupied by ligand.
Transport maximum—the maximum rate at which carriers are saturated by substrate.
Renal threshold—plasma concentration at which saturation occurs.
(c) Creatinine and inulin—compounds used to determine GFR. Penicillin and probenecid—xenobiotics that are secreted.
(d) Clearance—rate at which plasma is cleared of a substance (mL plasma cleared of substance X/min).
GFR—filtration rate of plasma (mL plasma filtered/min).
Excretion—removal of urine, mL urine/min.
What are the advantages of a kidney that filters a large volume of fluid and then reabsorbs 99% of it?
Allows rapid removal of foreign substances that are filtered but not reabsorbed.
If the afferent arteriole of a nephron constricts, what happens to GFR in that nephron? If the efferent arteriole of a nephron constricts, what happens to GFR in that nephron? Assume that no autoregulation takes place.
Afferent arteriole constricts, GFR decreases.
Efferent arteriole constricts, GFR increases.
