Exam 4 pt. 1

Question 1

What are the major organs of the urinary system? What are each of their functions?

Answer 1

o Kidneys: major excretory organs, create urine
o Ureters: transport urine from kidneys to bladder
o Urinary Bladder: temporarily stores urine
o Urethra: transports urine out of the body

Question 2

How to the kidneys maintain homeostasis?

Answer 2

o Kidneys: the body’s major excretory organs
o Kidneys maintain the body’s internal environment by:
o Regulating total water volume and total solute concentration
o Regulating ion concentrations in extracellular fluid (ECF)
o Ensuring long-term acid-base balance
o Excreting metabolic wastes, toxins, drugs
o Producing erythropoietin to regulate RBC function
o Producing renin to regulate blood pressure
o Activating vitamin D
o Carrying out gluconeogenesis (production of glucose)

Question 3

What is Renin? Erythropoietin?

Answer 3

Producing erythropoietin to regulate RBC function
Producing renin to regulate blood pressure

Question 4

What structures enter/exit the renal hilum?

Answer 4

Renal Hilum: point of entrance/exit for ureters, blood vessels, lymphatics, nerves

Question 5

List the 3 layers surrounding the kidney. Know which layer is the most superficial. Which layer is the deepest?

Answer 5

o Renal Fascia: anchoring outer layer of dense fibrous connective tissue
o Perirenal Fat Capsule: fatty cushion
o Fibrous/Renal Capsule: transparent capsule – prevents spread of infection to the kidneys
(superficial to deepest)

Question 6

Define renal ptosis

Answer 6

o Renal Ptosis: condition in which 1 or both kidneys drop to a lower position
 Caused by loss of surrounding fatty tissue – likely with emaciation or rapid weight loss
 Can lead to a kink in the ureter and the back up of urine into the kidney

Question 7

Define hydronephrosis

Answer 7

o Hydronephrosis: backup of urine into the kidney because of ureteral obstruction or infection
 Can cause kidney damage, tissue death, renal failure

Question 8

Define pyelonephritis

Answer 8

o Pyelonephritis: inflammation or infection of the kidney
 Often extensions of urinary tract infections (UTIs)
 In females, UTIs are generally caused by the spread of fecal bacteria, less often by blood-borne bacteria
 In severe pyelonephritis, the kidney swells, abscesses form, and the pelvis fills with pus

Question 9

How do hydronephrosis and pyelonephritis relate to urinary tract infections and renal calculi?

Question 10

What is dialysis?

Answer 10

Dialysis: process of removing waste and extra fluid from the body when the kidneys are unable to

Question 11

Review gross kidney anatomy – cortex, medulla, major and minor calyces, papillae, pyramids, and pelvis.

Answer 11

 Renal Cortex: lighter color, granular appearance
 Renal Medulla: darker color, contains cone-shaped masses called renal pyramids
* Papilla: the apex of each pyramid
* Renal Columns: projections from the renal cortex that divide the renal pyramids
 Renal Pelvis: funnel-shaped tube, continuous with the ureter
* Major Calyces: branching extensions of the pelvis
* Minor Calyces: subdivisions of the major calyces, enclose the papillae
Review gross kidney anatomy – cortex, medulla, major and minor calyces, papillae, pyramids, and pelvis.

Question 12

Know the order of urine flow from origination in the nephrons to exiting the body through the external urethral orifice.

Answer 12

o Urine is created in the nephrons and drains continuously through the renal papillae.
 Renal Pyramid
 Minor Calyx
 Major Calyx
 Renal Pelvis
 Ureter

Question 13

Memorize the order of arterial blood flow into the kidney starting with the aorta.

Answer 13

o Because the kidneys are responsible for cleaning and adjusting the composition of blood, they have a rich blood supply
o The renal arteries deliver 1/4th of cardiac output to the kidneys each minute!
o Arterial Flow
 aorta -> renal artery -> segmental -> interlobar -> arcuate -> cortical radiate (interlobular)

Question 14

Memorize the order to venous blood flow out of the kidney starting with the cortical radiate veins.

Answer 14

Venous Flow
 cortical radiate (interlobular) -> arcuate -> interlobar -> renal vein -> IVC
 There are no segmental veins!

Question 15

Generally, what is the function of a nephron?

Answer 15

o Nephron: the structural + functional unit of the kidney, forms urine
o > 1 million nephrons per kidney
o Each nephron makes cell-free and protein-free filtrate from blood
o Chemicals are either added and/or subtracted from filtrate
o Filtrate is emptied into collecting ducts where it becomes urine

Question 16

What are the 2 parts of a renal corpuscle?

Answer 16

o Glomerulus: tuft of capillaries composed of fenestrated endothelium - highly porous, allows for efficient formation of filtrate
o Glomerular/Bowman’s Capsule: cup-shaped, hollow structure that surrounds the glomerulus, continuous with the renal tubule
 Parietal Layer: simple squamous epithelium
 Visceral Layer: clings to the glomerular capillaries, contains branching epithelial cells called podocytes
 Podocytes terminate in foot processes
 Filtration Slits: clefts/openings between foot processes. Filtrate passes through these slits and into the capsular space.

Question 17

What type of endothelium makes up the glomerulus? Why is this structure important?

Answer 17

o Glomerulus: tuft of capillaries composed of fenestrated endothelium - highly porous, allows for efficient formation of filtrate

Question 18

What are podocytes? Where are they found? What function do they participate in?

Question 19

What are the 3 parts of the renal tubule? Differentiate between the 2 limbs of the nephron loop.

Answer 19

o Renal Tubule: about 3cm long, consists of a single layer of epithelial cells + basement membrane, each region has a unique histology and function
o Three Major Parts
 Proximal Convoluted Tubule (PCT): closest to the renal corpuscle
 Nephron Loop (Loop of Henle): u-shaped, a hairpin turn; has ascending and descending limbs
 Distal Convoluted Tubule (DCT): furthest from the renal corpuscle; drains into the collecting duct

Question 20

Histologically, what is different or unique about the structure of the different sections of the tubule?

Question 21

What functions are best performed by the different sections of the tubule?

Answer 21

o PCT
 Cuboidal cells with dense microvilli that form a brush border
 Increased surface area
 Large mitochondria
 Functions in reabsorption of water + solutes and secretion of substances
 Confined to renal cortex
o Nephron Loop
 Formerly called the Loop of Henle
 U-shaped structure with two limbs
* Descending Limb: proximal part is continuous with PCT; distal part is the descending thin limb (simple squamous epithelium)
* Ascending Limb: typically thicker, cuboidal + columnar cells
o DCT
 Cuboidal cells with very few microvilli
 Functions more in secretion, less reabsorption
 Confined to renal cortex

Question 22

Be prepared to label the portions of a renal tubule using anatomical landmarks.

Question 23

What is a collecting duct? Fused collecting ducts become….? What are the two major types of cells within it?

Answer 23

o Two Cell Types
 Principal Cells: more plentiful, sparse, short microvilli; maintain the body’s water/Na+ balance
 Intercalated Cells: cuboidal cells with abundant microvilli; exist in types A and B – both help maintain the acid-base balance of blood
o Collecting Ducts run side-by-side through the medullary pyramids and receive filtrate from many different nephrons
o Collecting ducts fuse together to deliver urine through the renal papillae to the minor calyces

Question 24

What are the two classes of nephrons? Be prepared to differentiate between them in a picture.

Answer 24

o Two major categories of nephrons
o Cortical Nephrons (85%)
 entirely in the cortex
o Juxtamedullary Nephrons (15%)
 Originate near the cortex-medulla junction
 Have long nephron loops that deeply invade the renal medulla

Question 25

Compare/contrast the glomerulus and the peritubular capillary – especially in terms of pressure and what that has to do with their function.

Answer 25

o The renal tubule of every nephron is closely associated with two capillary beds:
 Glomerulus: produces filtrate
* Glomerular capillaries are specialized for filtration
* Filtration produces a lot of fluid – 99% will be reabsorbed
* Glomerular capillaries are fed AND drained by arterioles – no O2 is dropped off!
o Afferent arteriole enters glomerulus
o Efferent arteriole leaves glomerulus
* The afferent arteriole arises from the cortical radiate arteries
* The efferent arteriole feeds into the peritubular capillaries/vasa recta
* The afferent arteriole is larger than the efferent arteriole so blood pressure in the glomerulus is high – increased filtration!
 Peritubular Capillaries +/- Vasa Recta: reclaim/reabsorb most of that filtrate
* Lower-pressure, porous capillaries adapted for reabsorption of water and solutes from the filtrate within the renal tubule
* Peritubular capillaries arise from efferent arterioles and cling to any adjacent renal tubules in the cortex
* Peritubular capillaries empty into venules -> cortical radiate veins

Question 26

What keeps the pressure high within a glomerulus?

Answer 26

o Glomerular capillaries are specialized for filtration
o Filtration produces a lot of fluid – 99% will be reabsorbed
o Glomerular capillaries are fed AND drained by arterioles – no O2 is dropped off!
 Afferent arteriole enters glomerulus
 Efferent arteriole leaves glomerulus
o The afferent arteriole arises from the cortical radiate arteries
o The efferent arteriole feeds into the peritubular capillaries/vasa recta
o The afferent arteriole is larger than the efferent arteriole so blood pressure in the glomerulus is high – increased filtration!

Question 27

Where do the nephron’s glomerulus, peritubular capillary, and afferent + efferent arterioles fit into the pathway of blood flow that you memorized above?

Question 28

Define the JGC. What two structures is it connecting?

Answer 28

o Each nephron has one Juxtaglomerular Complex (JGC)
o JGC: region where the most distal portion of the ascending limb of the nephron loop lies against the afferent arteriole feeding the glomerulus
o Both structures are modified at the point of contact
o JGC plays an important role in regulating the rate of filtrate formation and systemic blood pressure

Question 29

What are the 3 cell populations of the JGC? What is the specific function of each group?

Answer 29

o Macula Densa
 Tall, closely packed cells in the ascending limb of the nephron loop
 Chemoreceptors that sense the NaCl content of filtrate entering the DCT
o Granular Cells (Juxtaglomerular Cells)
 Enlarged, smooth muscle cells in the afferent arteriole wall
 Act as mechanoreceptors to sense blood pressure in the afferent arteriole
 Contain secretory granules for the enzyme renin
o Extraglomerular Mesangial Cells
 Located between the arteriole and tubule cells
 Interconnected by gap junctions
 May pass regulatory signals between macula densa and granular cells