A&P II Ch. 24 Urinary System

kidneys *The kidneys are the organs that produce urine. The urinary tract stores urine and eliminates it. The kidneys are not part of the urinary tract.

increased parasympathetic activity *Elevated parasympathetic activity decreases peripheral resistance, decreases cardiac output, and decreases blood volume. These all lower blood pressure.

Regulation of leukocyte production *The urinary system is involved in the regulation of erythrocyte production, because the kidneys release the hormone erythropoietin, but it does not regulate production of leukocytes.

afferent arteriole *The afferent arteriole is located between the interlobular artery and the glomerulus

cortical *The renal corpuscles of cortical nephrons are situated in the outer renal cortex, and t. They have very short nephron loops that either just dip into the superficial part of the renal medulla, or never leave the cortex.

tubular reabsorption *Tubular reabsorption transports nutrients back into the blood. The nutrients were filtered due to their small size, allowing them to go through the filtration membrane.

glomerulus *Filtration happens as blood flows through the glomerular capillaries.

epithelial cells of the glomerular capsule *Filtrate collects inside the glomerular capsule, but the capsule itself is not part of the filtration membrane.

albumin *Albumin is a plasma protein and is too large to pass through the filtration membrane.

Glomerular hydrostatic pressure (GHP) *Glomerular hydrostatic pressure (GHP) is the force with which blood pushes on the walls of glomerular capillaries and it drives filtration.

GHP - (GCOP + CHP) *NFP is equal to the force that drives filtration (GHP) minus the combination of forces that oppose filtration (CHP + GCOP)

Glomerular hydrostatic pressure (GHP) *The GHP is largely determined by the systemic blood pressure.

juxtaglomerular cells *The juxtaglomerular cells in the wall of the afferent arteriole release renin in response to low blood pressure.

constriction of the efferent arteriole *Constriction of the efferent arteriole increases GFR and ensures filtration will continue even when systemic blood pressure is low.

the sympathetic nervous system would be inhibited *If you prevent the sympathetic branch from working, there will be less activation of Angiotensin II and therefore blood pressure will stay low. Indeed one of the newest treatments for hypertension involves surgery to interfere with sympathetic innervation of the kidneys. Similarly, a common drug prescribed to patients with high blood pressure inhibits components of the RAAS system.

The GFR would temporarily increase due to dilation of the renal arteries and afferent arterioles. *Blood pressure medication will increase the GFR temporarily by increasing the glomerular hydrostatic pressure due to the dilation of renal arteries and afferent arterioles.

squamous epithelial cells of the glomerular capsule *The parietal layer of the glomerular capsule is not part of the filtration membrane. Instead it forms the chamber in which filtrate is collected.

constriction of the afferent arteriole *Constriction of the afferent arteriole and dilation of the efferent arteriole are the mechanisms of myogenic autoregulation, which will cause a decrease in GFR

lower Na and Cl ion concentration in the distal tubule *Because less filtrate moves slower through the tubule and allows for more reabsorption, fewer sodium and chloride ions are delivered to the macula densa cells of the distal tubule. This activates the tubuloglomerular feedback mechanism, resulting in an increased GFR

provides increased surface area for filtration *The combined area of all glomerular capillaries in one kidney combined is about 65 square feet. This large surface area makes filtration a very efficient process.

angiotensin-II (A-II)

antidiuretic hormone (ADH)

angiotensin-II (A-II)

renin

atrial natriuretic peptide (ANP)

angiotensin converting enzyme (ACE)

Plasma proteins *Plasma proteins, like albumin, are too large to pass through the filtration membrane.

increase in GFR *ANP increases the GFR. High GFR leads to more fluid loss and therefore decreases blood volume and effectively lowers blood pressure.

GFR *The glomerular filtration rate is about 125 ml/min.

Dilation of the afferent arteriole *Vasodilation of the afferent arteriole will allow more blood to get into the glomerular capillaries, therefore increasing GHP and GFR.

GFR decreases

Net filtration would decrease

blood cells and large particles *Yes, both blood cells and large particles, such as proteins, are not allowed to filter through a healthy glomerular membrane

hydrostatic pressure of blood (blood pressure) *Yes, the hydrostatic pressure of blood forces fluid out of the glomerular capillaries.

protein *Yes, large proteins are not normally filtered by a healthy glomerular membrane.

net filtration would decrease *Yes, because osmotic pressure opposes filtration, increasing osmotic pressure would decrease net filtration.

25 mm Hg *Yes, 60 - (25 + 10) = 25 mm Hg. The two pressures that oppose filtration must be subtracted from the force favoring filtration.

reabsorption and secretion *Facultative reabsorption and secretion take place in the distal tubule of the nephron.

Aldosterone *Aldosterone from the adrenal cortex stimulates Na (and indirectly water) reabsorption and K secretion.

a drug that blocks the effect of aldosterone •If Aldosterone is inhibited, there will be less Na reabsorption, less water reabsorption, and less potassium secretion. Therefore, there will be increased water loss in urine, while potassium is "spared" and remains in blood.

Facilitated transport only *Pumps or carriers are always required for secretion.

from filtrate to blood *Reabsorption reclaims substances from filtrate back to blood.

glucose *Glucose and other nutrients are rapidly reabsorbed in the proximal tubule. If not, they would be lost in the urine.

paracellular *The paracellular route of reabsorption involves passage of substances between adjacent tubular cells.

urine volume will increase *If ADH is reduced, there will be less water reabsorption, therefore more water will remain in the filtrate, and therefore more urine will be produced.

proximal tubule *The proximal tubule is responsible for the reabsorption of nearly 100% of nutrients such as glucose, amino acids, and other organic substances.

transcellular *Yes, most substances are reabsorbed first through the luminal and then through the basolateral membranes of the proximal convoluted tubule.

an increase in the osmolarity of the interstitium

the sodium-potassium ATPase pump in the basolateral membrane *Yes, this pump moves sodium out of the cell into the interstitium, thus decreasing intracellular sodium.

sodium *Yes, the active transport of sodium out of the cell, across the basolateral membrane into the interstitium, provides the driving force for reabsorption of both water and solutes.

Na+-H+ countertransport *Yes, because this is a countertransporter, Na+ is transported into the cell and H+ is transported out of the cell into the lumen.

number of transport carriers in the luminal membrane *Yes, the number of carriers is the rate-limiting factor. For example, in Diabetes Mellitus, plasma glucose levels are very high, and the sodium-glucose transporter cannot transport (reabsorb) all the glucose passing through the proximal tubule. Glucose is therefore found in the urine.

ions, such as Na and Cl

water

The pH of urine would decrease.

translucent

the simple squamous epithelium is extremely thin, would not provide adequate protection, and be more prone to tearing

stretch receptors in the wall of the blade *The stretch receptors send a signal via sensory afferent fibers to the sacral portion of the spinal cord.

opening of the external urethral sphincter

hydrostatic

glomerulus; podocytes

Size of the substance

All these choices are correct. excrete nitrogenous wastes regulate acid-base balance produce renin maintain water balance

nephron

Glomerular filtration

Proximal tubule

Distal tubule

Proximal tubule