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Physiology BIOL224 Chapter 18 - Urinary
Terms in this set (91)
What is the difference between the renal cortex and the renal medulla?
Cortex - Light colored superficial region
Medulla - Reddish brown deeper region
Cone-shaped tubules that transport urine from the cortical, or outer, part of the kidney, where urine is produced, to the calyces, or cup-shaped cavities in which urine collects before it passes through the ureter to the bladder.
Medullary extension of the renal cortex in between the renal pyramids. It allows the cortex to be better anchored
What is the relationship between minor calyces, major calyces, and the renal pelvis?
The minor calyces surround the apex of the renal pyramids.
Urine formed in the kidney passes through a renal papilla at the apex into the minor calyx;
two or three minor calyces converge to form a major calyx, through which urine passes before continuing through the renal pelvis into the ureter.
Which structure is associated with the papilla of a renal pyramid?
The renal papilla is the location where the renal pyramids in the medulla empty urine into the minor calyx in the kidney.
Histologically marked by medullary collecting ducts converging to form a papillary duct to channel the fluid.
Which structure is continuous with the ureter?
What artery delivers blood to the kidney?
Approximately what percentage of the total cardiac output is delivered to the kidneys each minute under resting conditions?
What vein drains blood from the kidney and returns it to the inferior vena cava?
What is the structural and functional unit of the kidney? How many units in each kidney?
> 1 million
What two structures make up a renal corpuscle?
Describe the structure of the glomerular capsule:
parietal layer, visceral layer, and capsular space
Which layer of the glomerular capsule contains simple squamous epithelium?
Which layer of the glomerular capsule is made up of podocytes?
the three major parts of the renal tubule in the order that filtrate passes through them:
Proximal convoluted tubule
loop of Henle
distal convoluted tubule
type of epithelium forms the walls of the proximal convoluted tubule?
Cuboidal epithelial cells with dense microvilli
What is the function of microvilli on the surfaces of the cells in proximal convoluted tubule?
What parts of a nephron are located entirely within the renal cortex?
proximal, and distal convoluted tubules
What part of a nephron extends into the renal medulla
Descending loop of Henle
What part of a nephron empties into a collecting duct?
Distal convoluted tubule
What structure do the collecting ducts empty into?
What are the structural differences between juxtamedullary and cortical nephrons?
Cortical - 85% of Nephrons Almost entirely in cortex
Juxtamedullary - Long loops of Henle extend deep into medulla
Which type of nephron is important in producing concentrated urine?
What vessels feed and drain the glomerulus?
Afferent and Efferent Arterioles
What is the function of the glomerulus?
Tiny blood vessels, supplied by the efferent arteriole, that travel alongside nephrons allowing reabsorption and secretion between blood and the inner lumen of the nephron are:
A series of straight capillaries in the medulla that lie parallel to the loop of Henle.
What is the function of the macula densa cells of the JGC?
monitor the NaCl content of the filtrate entering the distal convoluted tubule.
What is the function of the granular cells of the JGC?
Three processes of urine formation
Movement of water and solutes from glomerular capillaries into glomerular capsule refers to:
Movement of water and solutes from filtrate back into blood refers to:
Movement of substances from blood into filtrate refers to:
what percentage of the filtrate produced actually leaves the body as urine?
Kidneys process ~180 L of filtrate daily, but < 1% (1.5 L) leaves body as urine
everything in blood plasma except proteins is called
water + unneeded substances (excess salts, metabolic wastes) is called
Fenestrated endothelium of glomerular capillaries, Basement membrane, and Foot processes of podocytes of glomerular capsule are the three layers of what?
What substances pass freely through the filtration membrane?
Molecules < 3 nm (water and solutes) pass freely from blood into glomerular capsule
What substances do not freely pass through the filtration membrane?
Molecules > 5 nm (blood cells, plasma proteins) are not filtered
Hydrostatic pressure in glomerular capillaries (HPgc)
Equal to glomerular BP (about 55 mm Hg)
Diameter of efferent arteriole << diameter of afferent arteriole --> high resistance
Chief force pushing water and solutes out of blood
Hydrostatic pressure in the capsular space (HPcs)
Pressure exerted by filtrate in capsule (about 15 mm Hg)
Colloid osmotic pressure in glomerular capillaries (OPgc)
Pressure exerted by proteins in blood (about 30 mm Hg)
Net Filtration Pressure
NFP = outward pressures - inward pressures
= (HPgc) - (HPcs + OPgc)
= (55) - (15 + 30)
= 10 mm Hg
volume of filtrate formed per minute by both kidneys (120-125 ml/min)
Directly proportional to net filtration pressure
Glomerular filtration rate (GFR)
Two types of controls regulate GFR:
Renal autoregulation (intrinsic controls) - act locally within kidney
Extrinsic controls - act outside kidney
Ability of kidney to maintain constant GFR despite fluctuations in systemic blood pressure by
Two mechanisms by which renal autoregulation is accomplished
Tubuloglomerular feedback mechanism
Increased BP = vasoconstriction of afferent arteriole= GFR Decrease
Decreased BP = vasodilation of afferent arteriole = Increased GFR
Increased GFR leads to Increased NaCl concentration in filtrate (due to insufficient reabsorption time)
Tubuloglomerular feedback mechanism
The tubuloglomerular feedback mechanism involves the ________________ cells of the juxtaglomerular complex
Macula densa cells
elevated NaCl levels and release signaling molecules = vasoconstriction of afferent arteriole = decreased GFR
When BP drops, granular cells of JGC release renin describes
Two types of Tubular Reabsorption
Two types of Active Tubular reabsorption
Three types of passive tubular reabsorption
How does the Na+-K+ ATPase pump in the basolateral membrane promote the entry of Na+ at the apical membrane?
primary active transport
How does the active transport of Na+ from the tubule cells create the conditions necessary for reabsorption of solutes by secondary active transport?
Creates strong electrochemical gradient that favors Na+ entry at apical membrane via secondary active transport carriers
Substances reabsorbed by secondary active transport:
glucose, amino acids, some ions, vitamins
Active transport of Na+ creates strong osmotic gradient = water reabsorbed by osmosis through
In passive tubular reabsorption, As water leaves tubule, concentration of solutes in filtrate increases = solutes move down concentration gradients. What solutes?
(lipid-soluble substances, some ions, urea)
Site of most reabsorption
100% of glucose and amino acids
65% of Na+ and water
Most ions (Cl-, K+, Mg2+,Ca2+, HCO3-)
Proximal convoluted tubule
Reabsorptive capabilities of the loop of henle
Water can leave descending limb but not ascending limb (aquaporins scarce or absent)
Solutes can leave ascending limb but not descending limb
Plays key role in kidney's ability to form dilute or concentrated urine
Which hormone targets the collecting duct and promotes insertion of aquaporins into apical membrane
Which hormone targets the DCT and collecting duct and promotes synthesis of apical Na+ and K+ channels and basolateral Na+-K+ ATPase pumps
Which peptide targets the collecting duct and elsewhere and inhibits reabsorption of Na+ when blood pressure or blood volume rise
Atrial natriuretic peptide (ANP)
Which hormone targets the DCT and increases reabsorption of Ca2+
Parathyroid hormone (PTH)
movement of selected substances from blood into filtrate is called
What substances are secreted in tubular secretion?
Substances secreted: H+, K+, foreign organic compounds
Disposes of substances (e.g., drugs) bound to plasma proteins
Eliminates undesirable substances passively reabsorbed (e.g., urea)
Rids body of excess K+
Controls blood pH by altering amounts of H+ or HCO3- in urine
are all functions of what?
concentration of solute particles per kg of H2O is called
Kidneys maintain osmolality of plasma at
~ 300 mOsm
Occurs when fluid flows in opposite directions in two adjacent segments of same tube connected by hairpin turn
interaction of filtrate flow in ascending/descending limbs of loops of Henle of juxtamedullary nephrons is called
blood flow in adjacent parallel sections of vasa recta is called
Establish and maintain osmotic gradient (300 mOsm to 1200 mOsm) from cortex through medulla and Allow kidneys to vary urine concentration
are functions of
How much urine is secreted per day
What creates yellow color of urine
urochrome from heme breakdown
Range and average of urine pH
ranges from 4.5 to 8.0
ratio of the mass of a volume of a substance to the mass of an equal volume of distilled water is called
What is the specific gravity of urine
1.001 to 1.035, depending on solute concentration
H2O = 1.0
Chemical Composition of Urine
what Nitrogenous wastes are found in urine
Urea - breakdown of amino acids
Uric acid - breakdown of nucleic acids
Creatinine - breakdown of creatine phosphate
if found in urine are considered?
What are the three layers of the ureter wall?
Mucosa - lined by transitional epithelium
What pushes urine from ureters toward bladder
smooth, triangular area outlined by openings for two ureters and urethra is called
Three layers of bladder wall
Detrusor Muscle - three layers of smooth muscle
Maximum capacity of the urinary bladder
Muscular tube from bladder to body exterior; opens to outside at external urethral orifice
How long is the female urethra?
How long is the male urethra and what are its three parts?
Micturition reflex involves three simultaneous events: What are they and what nervous system controls them?
Detrusor muscle contracts (ANS)
Internal urethral sphincter relaxes (ANS)
External urethral sphincter relaxes (somatic nervous system)
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