Mastering A & P 19

The functions of the nephron include all of the following

tubular reabsorption tubular secretion glomerular filtration

Which of the following should NOT be found in the filtrate in the Bowman's capsule?

white blood cells * Found: -glucose -sodium -potassium

Approximately how much plasma moves through the kidneys of an adult during a 24-hour period?

180 L (120 mL of plasma is filtered each minute in 24 hours but 20% passes)

Calculate the net filtration pressure if capillary hydrostatic pressure is 60 mm Hg, capillary osmotic pressure is 25 mm Hg, and capsular hydrostatic pressure is 10 mm Hg.

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

Which of the following is required for filtration?

Both a membrane and a hydrostatic pressure gradient are required

Blood leaves the glomerulus via which vessel?

Efferent arteriole

Altering the radii of the afferent and efferent arterioles provides for _______.

glomerular filtration rate homeostasis and glomerular hydrostatic pressure homeostasis

What is the name for the "ball" of capillaries found in the renal corpuscle?

glomerulus

What is(are) the driving force(s) for filtration in the nephron?

hydrostatic pressure gradients and osmotic pressure gradients

The correct units for clearance of substance M are:

mL plasma cleared/min

The functional unit of the kidney is the ________.

Nephron

What are the two main parts of the nephron?

the renal corpuscle and the renal tubule

Which of the following correctly indicates the direction of the different forces causing filtration in the renal corpuscle (of fluid flow into or out of Bowman's capsule from the glomerular capillaries)?

* Blood hydrostatic pressure-(out), * Blood colloid osmotic pressure-(in), * Hydrostatic fluid pressure of the Bowman's capsule - (in)

Secretion into the nephron is a/an ______ process because the direction is _____ the concentration gradient.

Active; against

Where does all filtration take place in the kidneys?

Glomerulus

Which changes would cause an increase an in afferent arteriolar resistance due to paracrine signaling from the macula densa?

Greater sodium concentration in the distal tubule

What is the primary driving force (pressure) that produces glomerular filtration?

Hydrostatic pressure of blood (blood pressure)

What causes the internal urethral sphincter to open?

Increasing urinary pressure due to contraction of the full bladder

Why is inulin administration an effective way of measuring renal clearance rates?

Inulin is neither secreted nor reabsorbed

An example of filtration occurs in the kidney and:

Ions and glucose filtered from the capillary into the kidney tubule

Why is the regulation of extracellular fluid osmolarity so important?

It strongly influences cell volume

Using what you know about renal handling of Na+, predict the renal clearance of Na+.

Na+ clearance is less than the GFR.

If the osmotic pressure in the glomerular capillaries increased from 28 mm Hg to 35 mm Hg, would net filtration increase or decrease?

Net filtration would decrease because osmotic pressure opposes filtration, increasing

Which substance would be found in higher concentration if the membrane were damaged?

Proteins - Large proteins usually aren't filtered by a healthy glomerular membrane

Most reabsorption of fluid from the filtrate back into the blood occurs from the______.

Proximal convoluted tubule

What is the most important function of the kidneys (in the sense that loss of this function results in serious medical problems before causing functional problems in other systems)?

Regulation of water and ions content of the blood

The presence or absence of a solute int he filtrate depends on _______.

The molecular weight and size of the solute as well as the MWCO and pore size of the membrane.

Which combination of changes would increase the glomerular filtration rate (GFR) the most?

Vasodilation (relaxation) of the afferent arteriole and vasoconstriction (contraction) of the efferent arteriole

If you know that the renal clearance of substance X is zero, which of the following can you say is true about how the kidney handles X?

X is either not filtered or filtered and completely reabsorbed

Which of the following describes the order in which blood flows through the nephron?

afferent arteriole, glomerulus, efferent arteriole

Which of the following substances is not normally found in filtrate?

blood cells and large particles

What is the primary determinant of the net driving force for filtration in the glomerulus?

capillary hydrostatic pressure

Which part of the nephron is responsible for the greatest possible increase in urine concentration?

collecting duct

Which of the following is NOT a function of the kidneys?

exchange of oxygen and carbon dioxide with the tissues. * Functions: -maintenance of acid-base balance of the blood. -maintenance of plasma osmolarity. -maintenance of electrolyte balance in the body.

Which equation correctly describes the relationship between excretion, filtration, reabsorption, and secretion?

excretion = filtration - reabsorption + secretion

Of the following, which is the most likely reason that GFR would fall below normal?

hypotension

Which of the following would decrease glomerular filtration rate?

increasing the efferent arteriole radius and/or decreasing the afferent arteriole radius

Because the alteration of the afferent or efferent arteriole occurs within the nephron, we refer to this mechanism as _______.

intrinsic

Approximately what percent of the total filtered volume is excreted as urine each day?

less than 1%

What unique epithelial cells of Bowman's capsule allow for the final stage of filtration?

podocytes

Which unique epithelial cells of Bowman's capsule are involved in filtration?

podocytes

The kidneys function to produce hormones, excrete wastes, regulate blood pressure, and maintain ion balance. Which of the following is another function of the kidneys?

regulate osmolarity

In this activity, the drain beaker (second beaker in the flow) simulates the _______.

renal vein

Which word means to selectively move molecules from the blood and add them to the tubule lumen?

secretion