Kidney

Question 1

What are the 2 borders, 2 surfaces, and 2 poles of the kidney?

Answer 1

Borders:

• lateral (convex)
• medial (concave, with renal hilum)

Surfaces:

• anterior
• posterior

Poles:

• upper
• lower

Question 2

Which structures enter the kidney at the renal hilum, and in which order?

Answer 2

From anterior to posterior:

• renal vein
• renal artery (with ANS nerves and lymphatics)
• renal pelvis

Question 3

Where is the kidney located?

Answer 3

At T12-L3 level on the posterior abdominal wall, with the upper lobes within the floating ribs

• left: rib 11 on upper pole
• right: rib 12 on upper pole

(right lower than left because of liver)

Question 4

What are the tissue layers of the kidney?

Answer 4

Retroperitoneal:
- anterior surface covered by parietal peritoneum

Deep to superficial:

• fibrous capsule
• perinephric fat (cushions kidney)
• renal fascia (anchors kidney and adrenal gland to surrounding structures

Question 5

Which organs lie in relationship to the kidneys?

Answer 5

Posterior surfaces (both kidneys):

• medial: psoas
• intermediate: QL
• lateral: TA

Anterior surface (right):

• hepatic area (superior)
• right colic flexure (middle)
• duodenum (medial)
• small intestine (inferior)

Anteerior surface (left):

• gastric surface (superior)
• pancreatic (middle)
• small intestine (inferior)
• spleen (supero-lateral)
• descending colon (infero-lateral)

Question 6

What are the lobes of the kidney?

Answer 6

There are 8 lobes per kidney

Lobe = medullary pyramid + surrounding cortical tissue

Question 7

Describe the 4 major components of the internal anatomy of the kidney

Answer 7

Cortex:

• external layer of tissue beneath capsule
• inward extensions of cortical tissue form renal columns

Medulla:

• internal component of kidney
• pyramids: have a papilla (apex) and a base, and a striated appearance due to parallel bundles of urine collecting ducts
• renal columns projecting between pyramids from cortex

Chalyces:

• urine drains from papillae of renal pyramids into several minor chalyces
• minor chalyces converge into 2-3 major chalyces, which empty into renal pelvis

Renal pelvis:

• receives urine from the major chalyces
• continuous with ureter leaving hilum

Question 8

Which are the arteries that supply and flow through the kidney, in order from largest to smallest?

Answer 8

Renal arteries
Segmental arteries
Interlobar arteries
Arcuate arteries
Afferent arteriole
(through glomerulus)
Efferent arteriole

Question 9

Describe the steps of blood circulation through the kidney

Answer 9

Renal arteries
Segmental arteries
Interlobar arteries
Arcuate arteries
Interlobular
Afferent arteriole
(through glomerulus)
Efferent arteriole
Peritubular capillaries or vasa recta

Interlobular veins
Arcuate veins
Interlobular veins
Renal vein
Inferior vena cava

Question 10

Briefly describe the renal arteries and renal veins

Answer 10

Renal arteries:

• arise from aorta at L1-2
• (right longer than left)
• enter renal sinus and divide into smaller branches

Renal veins:

• formed by 5-6 interlobular veins
• left longer than right (crosses aorta); and joined by Lt suprarenal v and Lt gonadal v before draining into IVC

Question 11

What is the nerve supply of the kidney?

Answer 11

PNS: CNX Vagus

SNS: T10-12 splanchnic nerves

Visceral afferents

Question 12

What is the lymphatic drainage of the kidney?

Answer 12

Para-aortic nodes (near origins of renal arteries)

Question 13

What is a nephron?

Answer 13

The basic functional unit of the kidney (1 million per kidney)

• made up of a renal corpuscle (glomerulus and glomerular capsule), a renal tubule (proximal convoluted, nephron loop and distal convoluted tubule), and a collecting duct

Question 14

What are the functions of a nephron?

Answer 14

Blood filtration and urine formation

Question 15

What are the components of a renal corpuscle?

Answer 15

Glomerulus and glomerular capsule

Glomerulus:

• a knot of capillaries
• fenestrations (capillary pores) allow for the easy formation of filtrate
• blood supplied by an afferent arteriole and drained by an efferent arteriole

Glomerular capsule:

• encloses glomerulus
• continuous with renal tubule
• podocytes: specialized epithelial cells with foot processes that cling to capillaries

Question 16

What are the components of a renal tubule?

Answer 16

Proximal convoluted tubule
Nephron loop
Distal convoluted tubule

Question 17

Describe the 2 types of nephrons

Answer 17

Cortical

• majority (85%)
• primarily in cortex with only a short extension into medulla
• feed into peritubular capillaries

Juxtamedullary

• minority (15%)
• originate close to cortex-medulla junction and extend deep into medulla
• feed into vasa recta

Question 18

Describe the antaomy of a renal tubule

Answer 18

Proximal convoluted tubule:

• receives filtrate from glomerular capsule
• cuboidal cells have microvilli and mitochondria, which gives the proximal tubule a large reabsorption capacity

Loop of Henle / nephron loop:

• descending limb: squamous cells (thin segment)
• ascending limb: cuboidal / columnar cells (thick segment)

Distal convoluted tubule:

• cuboidal cells
• no microvilli
• conveys urine to collecting ducts

Question 19

Describe the anatomy and function of a collecting duct

Answer 19

• each duct receives filtrate from many nephrons
• passes through medulla for final adjustments to urine concentration and content
• ducts fuse together and deliver urine to minor calyces via renal papilla

Question 20

Describe a juxtaglomerular apparatus

Answer 20

The region where the distal loop of Henle lies against the afferent (and sometimes efferent) arteriole of glomerulus

Question 21

What are the 3 types of cells in a juxtaglomerular apparatus?

Answer 21

Macula densa (MD) cells:

• in wall of tubule
• chemoreceptors
• monitor NaCL content of filtrate entering distal convoluted tubule

Juxtaglomerular (JG) cells:

• in arteriolar walls
• mechanoreceptors
• contain granules of renin

Extraglomerular mesangial cells:

• between tubule and arteriole
• regulate MD and JG cells