L39: Anatomy & Embryology Of Kidneys

Front 1

What are the parts of the urinary system?

Back 1

kidneys, ureters, bladder, and urethra

Front 2

What does the kidney function of "filtration of blood and formation of urine" result in specifically?

Back 2

-Waste excretion

-fluid & electrolytes balance > body fluid volume & blood pressure

-Acid-base balance

Front 3

Which hormones does the kidney form and release? What does each have an effect on?

Back 3

-Renin > blood pressure

-Erythropoietin > red blood cell production

-Calcitrol (vit D) > calcium balance

Front 4

What types of organs are kidneys and where do they lie in the body?

Back 4

The kidneys are primary
retroperitoneal organs
that lie on the posterior
abdominal wall from
T12 to L3 vertebral level.

Front 5

What POSTERIOR structures inside the body are the kidneys related to?

Back 5

Diaphragm & behind > Costodiaphragmatic recess (pleura) & 12th rib (+11th rib, L)*
Psoas major m.
Quadratus lumborum m.
Transversus abdominis m.
Subcostal n.
Iliohypogastric n.
Ilioinguinal n.
Subcostal vessels

Front 6

What ANTERIOR structures is the right kidney related to?

Back 6

suprarenal gland, liver* & hepatorenal recess, 2nd part of duodenum, right colic flexure, small intestine*

*separated by peritoneum

Front 7

What ANTERIOR structures is the left kidney related to?

Back 7

suprarenal gland, spleen*, stomach*, pancreas, left colic flexure, coils of jejunum*

*separated by peritoneum

Front 8

Which kidney is more inferior (lower)?

Back 8

right kidney 1-2 cm lower due to liver

Front 9

What major vessels are between both kidneys?

Back 9

vena cava (right) & descending aorta (left)

Front 10

What is the fibrous capsule of a kidney?

Back 10

surrounds kidney, closely applied to its outer surface

Front 11

What is the perirenal fat of a kidney?

Back 11

covers the fibrous capsule (& adrenal glands)

Front 12

What is the renal fascia (of Gerota) of a kidney?

Back 12

condensation of fibrous connective tissue outside the perirenal fat; encloses kidneys and suprarenal glands except inferiorly >> spread of infection or blood from kidney to pelvis / kidney drop (nephroptosis)

-continuous with fascia transversalis & psoas fascia, diaphragmatic fascia, sheath of renal vessels and periuretic fascia

Front 13

What is pararenal fat of a kidney?

Back 13

external to renal fascia; often in large quantity; part of retroperitoneal fat

Front 14

What are the 2 outermost coverings of the kidneys?

Back 14

Parietal peritoneum & extraperitoneal fat

Front 15

What does the medial border of a kidney contain?

Back 15

hilum, which leads to a cavity, the renal sinus

Front 16

What do the hilum and sinus contain?

Back 16

fat

Front 17

What does the hilum transmit?

Back 17

-renal artery (extrahilar arteries are commons)

-renal vein

-ureter
(VAU anterior to posterior)

-renal lymphatic vessels (follow renal vein & tributaries)

-renal nerve plexus (associated with renal artery & tributaries)

Front 18

What are the 3 main divisions of a kidney?

Back 18

medulla, cortex, renal pelvis

Front 19

What is the medulla of the kidney?

Back 19

8 to 18 discontinuous aggregations of dark triangular-shaped areas > renal pyramids

Front 20

What is the cortex of the kidney?

Back 20

pale outer layer surrounding pyramids

-cortical labyrinths & medullary rays > striations extending from the bases of the renal pyramids into the cortex

-renal column (of Bertin) - extensions of cortex into medulla

Front 21

What is the renal pelvis of the kidney?

Back 21

upper expanded end of the ureter in renal sinus

>Major calyces - 3 or more divisions of renal pelvis

>Minor calyces - 3 or more divisions of each major calyx

>Renal papilla- apical projection of a pyramid into minor calyx

Front 22

What are the functional subdivisions of kidneys?

Back 22

segments, lobes, and lobules

Front 23

What are the segment subdivisions of the kidney?

Back 23

five: superior, inferior, posterior, anterosuperior, anteroinferior

Front 24

What are the lobes of the kidney?

Back 24

a pyramid and surrounding cortical tissue, including renal columns

Front 25

What are the lobules of a kidney?

Back 25

section of cortical & medulla tissue with a medullary ray in the middle

Front 26

How are kidney arteries and veins divided?

Back 26

Arteries & veins follow the same subdivisions:

Renal artery / vein > 5 segmental a. & v. > interlobar a. & v > arcuate a. & v. > interlobular a. & v. >

Front 27

What is a uriniferous tubule?

Back 27

functional unit of the kidney; made up of a collecting tubule and its associated nephrons

Front 28

There are 1-4 million nephrons per kidney in the cortical/juxtamedullary. What are they compose of?

Back 28

A. Renal corpuscle:
glomerulus (arterial capillaries)+
Bowman’s capsule

B. Proximal convoluted tubule

C. Henle’s loop (thick and thin limbs)

D. Distal convoluted tubule

Front 29

What parts of the nephron are in the kidney cortex?

Back 29

-cortical labyrinth: renal corpuscles and proximal and distal convoluted tubules

-Medullary rays: collecting tubules

Front 30

What parts of the nephron are in the kidney medulla?

Back 30

-Renal pyramids: loops of Henle, lower part of collecting tubules & Bellini ducts

-Renal papilla: ducts of Bellini deliver urine to minor calyx

Front 31

What is the renal circulation path for the FILTRATION of blood?

Back 31

Abdominal aorta > renal artery > segmental a. > interlobar a. >> arcuate a. > interlobular a. > afferent glomerular arterioles >> glomeruli (capillaries in renal corpuscules) >> efferent glomerular arterioles >>>

then depending on whether it goes to the cortex or medulla:

-peritubular capillaries (cortex, both nephrons) > stellate veins

OR

-vasa recta spuria (medulla, loop of Henle of mostly juxtamedullary nephron ) > venulae recta

Front 32

What is the renal circulation path of blood that only SUPPLIES the tissues of the kidney?

Back 32

Abdominal aorta > renal artery > segmental a. > interlobar a. >>


-cortical interlobular > aglomerular arterioles> cortical capillary plexus (cortex) > stellate veins

OR

-arcuate a & cortical interlobular a. > vasa recta vera (medulla) > venulae recta

Front 33

What is the renal circulation of veins in the cortex?

Back 33

peritubular capillaries & cortical capillary plexus > stellate veins

Front 34

What is the renal circulation of veins in the medulla?

Back 34

vasa recta > venulae recta


>> interlobular veins > arcuate veins > interlobar veins > renal vein > inferior vena cava

Front 35

At any given time, how much of the cardiac input is going through both kidneys?

Back 35

25%

Front 36

How do renal cell carcinomas spread?

Back 36

-Grow outward of kidney into fat & fascia

-Also invade renal vein

-Spread to inferior vena cava, right atrium, across tricuspid valve into pulmonary artery

Front 37

What is the ureter?

Back 37

25-30 muscular tubes that connect kidneys with bladder

Front 38

Where is the upper half of the ureter?

Back 38

in abdomen on psoas major m. to bifurcation of common iliac aa.

Front 39

Where is the lower half of the ureter?

Back 39

in pelvis in front of internal iliac aa. to ischial spine, crossed by uterine artery (in females), then to post. surface of bladder

Front 40

What does the ureter adhere to?

Back 40

adheres to peritoneum; mobilization of peritoneum puts ureter at risk

Front 41

What are the ANTERIOR relations of the right ureter?

Back 41

duodenum, terminal ileum, right colic and ileocolic vessels, right testicular (ovarian) vessels, mesentery of small intestine

Front 42

What are the POSTERIOR relations of the right ureter?

Back 42

right psoas m., bifurcation of right common iliac a.

Front 43

What are the ANTERIOR relations of the left ureter?

Back 43

sigmoid colon and sigmoid mesocolon, left colic vessels, left testicular (ovarian) vessels

Front 44

What are the POSTERIOR relations of the left ureter?

Back 44

left psoas m., bifurcation of left common iliac a.

Front 45

What are the MEDIAL relations of the left ureter?

Back 45

inferior mesenteric vein

Front 46

What are the normal constrictions of the ureter?

Back 46

Sites where renal calculi (stones) may get impacted:

A. ureteropelvic junction: where renal pelvis joins the ureter

B. as ureter crosses the pelvic brim: at bifurcation of the common iliac aa.

C. ureterovesical junction: where ureter pierces obliquely thru the wall of the urinary bladder

Front 47

What arteries are part of the blood supply to the ureter?

Back 47

Arteries (forms longitudinal anastomoses)
1. upper end: branches of renal a.

2. middle: branches from: testicular (ovarian) a., abdominal aorta, common iliac a.

3. pelvis: branches of internal iliac a. & tributaries

Front 48

What veins are part of the blood supply to the ureter?

Back 48

1. upper: renal v.

2. Middle: gonadal v.

3. Pelvis: branches of internal iliac v.

Front 49

Which lymphatic nodes drain the kidneys?

Back 49

paraaortic (lateral aortic or lumbar) nodes

Front 50

Which lymphatic nodes drain the ureters?

Back 50

-upper: paraaortic (lateral aortic) nodes

-middle: common iliac nodes

-pelvic: external, or internal iliac nodes

Front 51

What does the sympathetic fibers (visceral efferent) supply to the kidneys consist of?

Back 51

T10-T12 (especially least thoracic splanchnic nerve & aorticorenal ganglion)> vasoconstrictrion > glomerular filtration

Front 52

What does the sympathetic fibers (visceral efferent) supply to the ureters consist of?

Back 52

T11-L2 (upper, middle & pelvic* innervation)

Front 53

What does the parasympathetic fibers (visceral efferent) supply to the kidneys and ureters consist of?

Back 53

1. Kidneys: vagus nerve

2. Ureters: vagus & pelvic* splanchnic nerves S2-S4

Front 54

What does the visceral afferent (pain) nerve supply to the kidneys and ureters consist of?

Back 54

follow sympathetic fibers retrograde (via splanchnic nerves) to spinal sensory ganglia and spinal cord levels T10-L2 / refer pain to dermatomes of lumbar & inguinal regions

Front 55

What shape do the suprarenal glands have and what separates them from kidneys?

Back 55

-Right: pyramidal; left: crescentic

-Both glands are separated from kidneys by a thin septum, embedded in perirenal fat and fascia

Front 56

What structures is the right suprarenal gland related to?

Back 56

-Caps upper pole of right kidney

-Extends medially behind IVC

-Lies behind right lobe of liver

Front 57

What structures is the left suprarenal gland related to?

Back 57

-Caps upper pole of left kidney

-Extends along medial border of left kidney to hilum

-Lies behind pancreas, lesser sac, stomach

Front 58

What are the functional subdivisions of the suprarenal glands?

Back 58

capsule, cortex, medulla

Front 59

What zones make up the cortex of the suprarenal glands?

Back 59

Cortex (mesoderm origin): three layers from external to internal

1. Zona glomerulosa: mineralocorticoids >control of fluid & electrolyte balance

2. Zona fasciculata: glucocorticoids >metabolism of carbohydrates, fats, proteins

3. Zona reticularis: androgens > prepubertal development of sex organs

Front 60

What does the medulla of suprarenal glands consist of?

Back 60

(neural crest cells origin)
Chromaffin cells: Catecholamines (epinephrine, norepinephrine

Front 61

What are the 3 main disorders of the suprarenal glands?

Back 61

1. Addison’s disease-adrenal insufficiency

2. Cushing’s syndrome-excessive cortisol

3. Pheochromocytoma-tumor of adrenal medulla

Front 62

What does the arterial blood supply of the suprarenals consist of?

Back 62

1. Superior suprarenal a. <<< inf. phrenic a.

2. Middle suprarenal a. <<< abdominal aorta

3. Inferior suprarenal a. <<< renal a.

Front 63

What does the venous blood supply of the suprarenals consist of?

Back 63

1.Right suprarenal v. >>> IVC

2.Left suprarenal v. >>> left renal v.

Front 64

What does the nerve supply to the suprarenals consist of?

Back 64

Primarily sympathetic:
-Preganglionic fibers (T10-T12 ) pass thru paravertebral ganglia and continue as thoracic (lesser & least) splanchnic nerves

A. Fibers pass thru celiac ganglia (or aorticorenal) & plexus and join periarterial plexus
-Preganglionic fibers end in the adrenal medulla, on chromaffin cells (postganglionic cells) Chromaffin cells secrete catecholamines in bloodstream to produce flight-or-fight response to stress

B. Other preganglionic fibers synapse with neurons in prevertebral ganglia and postganglionic fibers travel through celiac & periarterial plexuses (vasoconstriction)

Front 65

What do the kidneys and ureters develop from (embryology)?

Back 65

Most of the urogenital system, including kidneys & ureters, develop from intermediate mesoderm located on each side of the the median plane along the embryonic posterior abdominal wall.

Front 66

During folding of the embryo, the intermediate mesoderm forms a bulge the, urogenital ridge, which comprises what?

Back 66

-nephrogenic cord or ridge that gives rise to most of the urinary system

-gonadal ridge, on the medial side, that gives rise to most of the genital system

Front 67

Which overlapping kidneys (3) develop in a cranial-caudal sequence during gestation?

Back 67

Pronephros
Mesonephros
Metanephros

Front 68

What gives rise to the pronephros?

Back 68

-Intermediate mesoderm in the cervical region gives rise to pronephros & pronephric duct

Front 69

What is the pronephros?

Back 69

-forekidney

-collection of ~ 7 clusters of cells on both side of median plane that form vestigial excretory tubules

-transitory > appears and disappears during 4th week of gestation


-non-functional structure > tubules do not acquire glomeruli & do not join the pronephric duct

Front 70

What is the pronephric duct?

Back 70

-collecting duct runs caudally

-opens into the urogenital sinus (ventral derivative of cloaca) at the end of 4th week

-becomes mesonephric duct

-plays essential part as inductor of mesonephros

Front 71

What is the mesonephros?

Back 71

-interim kidney

-appears late in 4th week in thoracic & lumbar region of nephrogenic cord and disappears by end of embryonic period (8th week)

-Its excretory tubules have a Bowman’s capsule around an arterial glomerulus but no loop of Henle > filtrate blood

-tubules open into mesonephric duct > carry filtrate

-Some caudal tubules persist to become part of epididymis & efferent ductules of testis

Front 72

What is the mesonephric (wolffian) duct?

Back 72

-derived from pronephric duct & opened into the urogenital sinus (upper & largest part becomes bladder)

-the mesonephric duct persists as ductus deferens in males and form vestigial structures in females

-trigone region of the bladder is derived from caudal end of mesonephric ducts

Front 73

What is the metanephros?

Back 73

-permanent kidney

-appears ~5th week in pelvic area and begins to function 4 weeks later: produce urine, which is added to the amniotic fluid around the 10th week (fetal period)

-develops from 2 sources (both of intermediate mesodermal origin):
--metanephric diverticulum or utereric bud
--metanephric mesoderm or metanephrogenic blastema

Front 74

What is the metanephric diverticulum (or urteric bud)?

Back 74

-outgrowth of mesonephric duct near the cloaca (E)

-which grows into the metanephric blastema and subdivides to become the collecting system (F to I): ureter, renal pelvis, major and minor calyces, and collecting tubules ( reach 1-3 millions) that aggregate into renal pyramids.

-Metanephric blastema induces branching of ureteric bud

Front 75

What is the metanephric mesoderm (or metanephrogenic blastema)?

Back 75

give rise to excretory units > nephrons

-Nephrons are induced to develop from metanephric tissue caps by the collecting tubules (A) ~ 7th week

-Each nephron develops a Bowman’s capsule into which a tuft of capillaries (glomerulus) later grows (B)

-The distal end of Bowman’s capsule lengthens to form the proximal convoluted tubule, loop of Henle, and distal convoluted tubule that establishes an opening into a collecting tubule (C&D)

~1 million nephrons per kidney by 40th week

Front 76

What does the ascent of the kidneys consist of?

Back 76

-initially, kidneys are in the pelvis close together; move later to the abdomen

-“migration” is a relative ascent, resulting from growth of the embryo’s body; “ascent” stops when the kidneys come in contact with the suprarenal glands

-retroperitoneal on post. abd. wall by 9th week

-90 degree medial rotation from facing anteriorly

Front 77

During the ascent of the kidneys, how does the arterial supply to the organs come about?

Back 77

-supplied by arteries closest to them at higher levels while ascending

-caudal arteries normally degenerate and kidneys receive their most cranial branches from the abdominal aorta: the permanent renal arteries

-Accessory renal arteries are common: persistence of embryonic vessels > enter superior or inferior pole of kidney

Front 78

What is the primary remover of nitrogenous waste prior to, and after, birth?

Back 78

Prior to birth, the placenta is the primary remover of nitrogenous wastes from the fetus. After birth, the kidney takes on this role

Front 79

What is the unilateral absence of a kidney?

Back 79

relatively common 1/1000; asymptomatic since one kidney can perform function of missing kidney

Front 80

What is the bilateral absence of a kidney?

Back 80

1/3000, incompatible with postnatal life / associated with oligohydramnios, deficiency in amount of amniotic fluid & neonate exhibits Potter sequence (flattened face, hypoplastic lungs, limb deformities)

Front 81

How does the absence of kidney(s) occur?

Back 81

results when metanephric diverticulum fails to develop or degenerates early --> failure of metanephric diverticulum to penetrate metanephric mesoderm --> no nephrons induced by early collecting tubules to develop from metanephric mesoderm

Front 82

What is renal ectopia?

Back 82

-one or both kidneys in an abnormal position, usually more inferior than usual (pelvis or inferior part of abdomen)

-result from failure of kidneys to “ascend”

-pelvic kidneys may fuse to form a round mass, known as discoid or pancake kidney

Front 83

What is crossed renal ectopia?

Back 83

results when developing kidneys fuse while in the pelvis, then one kidney “ascends” to its normal position, carrying the other one with it

Front 84

What are different ways a kidney can be malrotated?

Back 84

-no rotation > face anteriorly;
-too far > face posteriorly;
--face laterally

Front 85

What does duplication of the urinary tract result from?

Back 85

division of metanephric diverticulum

Front 86

What happens in incomplete division of metanephric diverticulum (vs complete division)?

Back 86

incomplete division --> divided kidney with a bifid ureter


complete division --> double kidney with bifid or separate ureters

Front 87

What does a supernumerary kidney result from?

Back 87

supernumerary kidney with own ureter probably results from formation of 2 metanephric diverticula

Front 88

What is a horseshoe kidney?

Back 88

-results from fusion of poles of kidneys, usually inferior poles

-U-shaped kidney in hypogastrium, anterior to lumbar vertebrae because normal ascent prevented by the root of inferior mesenteric artery

-usually asymptomatic

-Frequent in women with Turner syndrome (45, XO)

-Wilms’ tumor (nephroblastoma) more frequent

-Increased risk of nfection (pyelonephristis)

Front 89

What are ectopic ureteral orifices?

Back 89

-ureters that open anywhere except into the urinary bladder

-usually in bladder neck or prostatic urethra

Front 90

What is common in ectopic ureteral orifices?

Back 90

incontinence common because urine does not enter the bladder but continually dribbles from the urethra and/or vagina in females

Front 91

How do ectopic ureteral orifices develop?

Back 91

results when ureter is not incorporated into the posterior part of the urinary bladder but is carried caudally into the developing prostatic urethra in males and the entire urethra in females

Front 92

What is polycystic kidney disease?

Back 92

-relatively common

-Kidneys contain multiple small to large cysts--severe renal insufficiency

Front 93

What is the difference in autosomal recessive and autosomal dominant inheritance of polycystic kidney disease?

Back 93

-Autosomal recessive (childhood): Cysts develop from the collecting duct > death usually occurs after birth but survival has increased due to hemodialysis and kidney transplants / may produce Potter sequence


-Autosomal dominant (adult): mutation in ADPKD genes (polycystin 1& 2) that play a role in renal tubular development & function / cysts develop from parts of nephron > renal failure in adult

Front 94

What is multicystic dysplastic disease?

Back 94

-Fewer cysts than PKD

-Good outcome, 75% unilateral

-Cysts are wide dilations of parts (Loops of Henle) of otherwise continuous nephrons