Renal Structure and Function

Question 1

Two main functions of the kidneys

Answer 1

Rid the body of waste that is either ingested or produced by metabolism
Control the volume and electrolyte composition of the blood

Question 2

The average kidney in an adult weighs about _____.

Answer 2

150 grams (⅓ pound)

Question 3

T/F the kidneys lie on the posterior wall of the abdominal cavity, outside of the peritoneum

Answer 3

T

Question 4

The outside layer of the kidney is a tough, fibrous _______, which is protective

Answer 4

Renal Capsule

Question 5

the Renal Cortex is where the ___ and ___ are located

Answer 5

glomeruli and arterioles

Question 6

Within the renal medulla, each kidney contains 8-10 cone-shaped structures called _____

Answer 6

Renal Pyramids

Question 7

The major calyces join in the middle of the kidney to form the _____

Answer 7

Renal Pelvis

Question 8

T/F The ureter is a contractile structure

Answer 8

T

Question 9

urine is stored until emptied through the Urethra by_____

Answer 9

micturition

Question 10

Motor _____ fibers from S2-S4 initiate bladder contraction

Answer 10

parasympathetic

Question 11

Which fibers cause contraction of external sphincter muscles, preventing urination until “it’s time” ?

Answer 11

Pudendal somatic motor fibers (under cerebral and brainstem control)

Question 12

Each human kidney contains roughly _____ urine-creating Nephrons

Answer 12

0.8 - 1 million

Question 13

T/F The kidneys are continuously generating new nephrons if they become diseased or injured

Answer 13

F - The kidneys are not able to generate new nephrons if they become diseased or injured.

Question 14

By 80 years of age, a healthy individual will have about ____ of nephrons left

Answer 14

40%

Question 15

a tuft or ball of capillaries in each nephron, through which large volumes of fluid are filtered from the blood

Answer 15

Glomerulus

Question 16

The efferent arteriole of the nephron becomes a complex network called the _____

Answer 16

Peritubular Capillaries

Question 17

The renal circulation is unique in having ____

Answer 17

two capillary beds

Question 18

Purpose of the bowmans capsule

Answer 18

Collects the filtrate

Question 19

From Bowman’s Capsule, the filtrate flows into the _____

Answer 19

Proximal Convoluted Tubule

Question 20

From the Loop of Henle, the fluid passess right by the glomerulus and then reaches the _____ back in the renal cortex.

Answer 20

Distal Convoluted Tubule

Question 21

Each large collecting duct collects urine from as many as _____ nephrons

Answer 21

4000 nephrons

Question 22

Two types of nephrons

Answer 22

Cortical Nephrons
Juxtamedullary Nephrons

Question 23

No matter how deep a nephron lies within the kidney, the _____ is found within the renal cortex

Answer 23

glomerulus

Question 24

Which loop of henle extend deeper? Cortical or Juxtamedullary?

Answer 24

Juxtamedullary
20-30% of all the nephrons are Juxtamedullary and have long Loops of Henle that extend very deep.

Question 25

Draped over and through these long Loops of juxtoglomeruler nephrons are a specialized peritubular capillary called _____

Answer 25

Vasa Recta

Question 26

Blood flow to the kidneys accounts for about ___% of total cardiac output.

Answer 26

22

Question 27

Arcuate Arteries and Veins run ____ of the renal medulla and renal cortex

Answer 27

along the border

Question 28

The Peritubular Capillaries drain into the ____

Answer 28

Interlobular Veins

Question 29

Three excretion processes

Answer 29

Glomerular Filtration Tubular Reabsorption Tubular Secretion

Question 30

Filtrate in Bowman’s Capsule is almost identical to _____.

Answer 30

the plasma

Question 31

Of all the plasma passing through the glomerulus, ____% of the plasma is filtered

Answer 31

20

Question 32

the glomerular capillaries have a _____ intravascular pressure

Answer 32

Higher Systemic capillaries- About 17 mmHg Glomerular capillaries- About 60 mmHg

Question 33

The Glomerular Filtration Rate (GFR) is the volume of fluid that _____

Answer 33

filters into Bowman’s Capsule per unit of time.

Question 34

In an average, healthy adult, the GFR is about_____

Answer 34

125 mL/min

Question 35

T/F less than 1% of the plasma is eventually excreted in the urine

Answer 35

T

Question 36

The Filtration Membrane is 3 layers thick:

Answer 36

Capillary Endothelium Basement Membrane Epithelial (Podocyte) Cells

Question 37

The Capillary Endothelium allows for a high rate of filtration because the wall is perforated by thousands of small holes called ____

Answer 37

Fenestrations

Question 38

What is found in the capillary entothelium?

Answer 38

Contains negatively charged membrane proteins as well (repels plasma proteins)

Question 39

The Basement Membrane is made of a meshwork of ___ and ____

Answer 39

collagen and negatively charged proteoglycans

Question 40

As filtered fluid (filtrate) leaves Bowman’s Capsule and moves through the Tubules, it is modified in two different ways:

Answer 40

Reabsorption of water and specific solutes back into the blood Secretion of other substances from the capillaries into the tubules

Question 41

all three layers of the filtration membrane have some degree of a ____ charge because of membrane proteins or proteoglycans.

Answer 41

negative

Question 42

There are two main advantages of a high GFR (125 mL/min or 180 L/day)

Answer 42

It allows the kidneys to rapidly remove waste products It allows all body fluids to be filtered several times each day.

Question 43

An example of a waste that is not reabsorbed at all is ____, so essentially all that is filtered gets excreted

Answer 43

Creatinine

Question 44

Substances that are partially reabsorbed from the tubules back into capillary blood, rate of excretion < rate of filtration

Answer 44

This pattern is typical for many electrolytes, such as Sodium, Chloride, & Bicarb ions

Question 45

Substances that are freely filtered and not excreted because they are 100% reabsorbed

Answer 45

most of the nutritional substances in the blood, such as glucose, amino acids

Question 46

Substances freely filtered, not reabsorbed at all, but additional quantities are secreted from the blood into the tubule as the fluid moves along, leading to an excretion rate greater than that of the filtration rate

Answer 46

acids and bases

Question 47

secretion plays a large role in regulation of the amount of ____ and ____ ions (and others) excreted in the urine

Answer 47

Potassium and Hydrogen

Question 48

T/F Most waste products of metabolism (such as Urea, Creatinine, Uric Acid, etc.) are easily filtered but poorly reabsorbed (if at all), so excretion rates are high as long as GFR remains high.

Answer 48

T

Question 49

How are solutes reabsorbed into the capillaries?

Answer 49

Solutes are transported through the cells (transcellular path) by passive diffusion or active transport, or between the cells (paracellular path) by diffusion.

Question 50

How is water reabsorbed into the capillaries?

Answer 50

Water is transported through and between the cells by osmosis.

Question 51

The Glomerular Filtration Rate can be increased or decreased depending on alterations to certain variables, including

Answer 51

Glomerular Hydrostatic Pressure Bowman’s Capsule Pressure Glomerular Colloid Osmotic Pressure Capillary Permeability Relative Resistance of Afferent or Efferent Arterioles

Question 52

The Net Filtration Pressure is the sum of the ____

Answer 52

Hydrostatic and Colloid Osmotic forces across the glomerular capillaries that either favor or oppose the process of filtration.

Question 53

What is the primary means of physiologic GFR regulation?

Answer 53

Glomerular Hydrostatic Pressure

Question 54

Increasing the hydrostatic pressure in the glomerulus ____ the GFR

Answer 54

increases

Question 55

3 main things than can increase (or decrease) glomerular pressure:

Answer 55

1) Increasing (or decreasing) arterial blood pressure; 2) Afferent arteriole resistance; 3) Efferent arteriole resistance (more to come)

Question 56

increase in Colloid Osmotic Pressure works to ___ GFR.

Answer 56

decrease

Question 57

This pressure works against filtration as it directly pushes back on the Glomerular Hydrostatic Pressure

Answer 57

Bowman’s Capsule Hydrostatic Pressure

Question 58

decreasing the permeability of the capillary membrane will ____ the GFR.

Answer 58

decrease

Question 59

When required, the kidneys are capable of producing urine that is ___ times the osmolarity of the plasma

Answer 59

4-5

Question 60

Requirements for excreting concentrated urine

Answer 60

High levels of Antidiuretic Hormone (ADH) Hyperosmotic Renal Medulla

Question 61

ADH effect on the kidneys

Answer 61

Increases the permeability to water by stimulating the insertion of Aquaporins into the tubular membrane, thereby opening a channel for water diffusion This increases the reabsorption of water into the blood and results in small volumes of concentrated urine.

Question 62

By a process called the _____, the Loop of Henle is used to produce a hyperosmotic renal medulla

Answer 62

Countercurrent Multiplier System