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Flashcards in Renal Function And Development Deck (50)
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Accessory renal arteries

Usually arise from the aorta and can superior or inferior to the main renal artery

*sometimes crosses anterior to a ureter and obstructs it causing hydronephrosis (distention of the pelvis and chalices with urine)*

**if an accessory artery is present and gets injuried = ischemia in the region supplied by the accessory artery


Unilateral renal agenesis
(only has 1 kidney)

1:1000 occurrence rates with 2x more likely in males

Usually occurs with the left kidney and causes the other kidney to undergo spontaneous hypertrophy in order to compensate.
- can still live just fine, however future kidney damage is now more severe

Caused by a failure of the ureteric bud to develop at all. Never penetrates the mesonephric mesenchyme = Nothing there


Bilateral renal agenesis
(both kidneys are missing)

Always associated with oligohydroamnios, twisted skin and facial, renal failure in utero and pulmonary hypoplasia (Potter sequence)

1:3000 occurrence rates, 3x more likely in males and is incompatible with life

**can also lead to multi cystic dysplastic kidneys (without penetration form ureteric buds the metanephrogenic blastoma sometimes doesnt degenerate and intends forms cysts). This is usually unilateral though, but if bilateral also leads to potter sequence**

*is caused by failure of both ureteric buds to form at all*


Cystic kidney disease

Most common type is autosomal dominant polycystic kidney disease (ADPKD)
- 1: 500 occurrence rates

Causes mutations in the PKD-1/2 genes respectively
- function is to sit receptors on the primary cilia of the kidney and detect urine flow through the tubules

**results in numerous cysts that reduce normal kidney function


Malrotation of kidneys

Results in any of the following positions fo the kidneys (all of which reduce kidney function)
- hilum faces anteriorly = no rotation

- hilum faces posteriorly = too much rotation

- hilum faces laterally = medial rotation has occurred

** all of which have incidence rates in ectopic kidneys


Ectopic kidneys

One or both of the kidneys are located in abnormal compartments

**most common is in the pelvis of the kidney


Crossed fused ectopia

One kidney will cross over to the other side kidney and possibly cause fusion into 1 large kidney (called unilateral fused kidneys)


Horseshoe kidney

Most common renal fusion defect
(seen in 0.2% of population)
- Poles of the kidneys are fused together, usually at the inferior poles

*Often found in the pelvis just below the inferior mesenteric artery*

**Does NOT affect function and each has its own ureter and blood supply**

Often asymptomatic but increases risk of renal stones, cancer and infections

***15% of people with Turner syndrome have this***


Ectopic ureter

The ureter of one kidney does not enter the urinary bladder and instead enters another part of the pelvis

Caused by the ureter being carried caudally with the mesonephric duct during fetal development

* results in incontinence of leakage of urine unconsciously from urethra or vagina*


Urachal cysts/sinus and fistula

All are resulting from a remnant of the urachal lumen remaining present (typically inferior)

Cysts = remnants of the epithelial lining of the urachus condenses and forms cysts (benign)

Sinus = patent inferior end of the urachus dilates to form a urachal sinus (causes pus leakage from the umbilicus

Fistula = entire urachus remains and forms a fistula and allows urine to escape from the umbilical orifice (causes urine leakage from the umbilicus)


Exstrophy of the bladder

Severe and rare defect 1:30,000. Predominantly seen in females

Causes exposure and protrusion of the mucosal surface of the posterior wall of the bladder, trigone of the bladder and ureteric orifices
- will look like an exerted buldging mass just inferior to the umbilicus
- causes spontaneous urine leakage

**believed to be caused by failure of the mesenchymal cells to migrate between ectoderm and endoderm of the abdominal wall during the 4th week**

* almost always sees epispadias and seperation of the pubic bones as well



A birth defect in which the urethra opens on the dorsum of the penis



Inflammation of the glomeruli usually steaming from a humoral immune reaction
- con include deposition of antibody-antigen complexes within glomeruli or circulating antibodies binding to either glomerular antigens or extraneous antigens.

* always presents with proteinuria due to inflammation causing increased permeability of the glomerulus to proteins


Diabetic glomerulosclerosis

Thickening and loss of function in the GBM produced as part of the systemic microvascular sclorosis caused by diabetes mellitus

**is the leading cause of irreversible end-stage kidney disease in the United States**

Treatment requires kidney transplants or artificial hemodialysis


Sickle cell nephropathy

A common problem related to sickle cells disease in which affected erythrocytes “sickle” (get stuck) in the vasa recta of the kidney.
- this is due to the low oxygen tension in here

Results from renal infarcts in the renal papillae/pyramids


Renal calculi (renallithiasis/ kidney stones)

Are stones that are formed in the renal pelvis usually made up of excess calcium salts and uric acid
- calcium salt stones = large and jagged
- uric acid stones = small and smooth

Can be asymptomatic or cause extreme pain will urinating on the affected side

Treatment = surgical removal or lithotripsy


Kidney gross anatomy

Bilateral pair of retroperitoneal organs that are located in the abdominal cavity

- capsule = fibrous protective outer layer of the kidney.

- hilum = kidney site of the renal neuro vasculature and outflow of urine into the ureter

- cortex = Light colored cortical tissue that contains the vascular supply of the kidney. Site of glomerular filtration and where modification of tubular fluid occurs (reabsorption of proteins, macronutrients, electrolytes, metabolites)

- medulla = dark-colored medullary tissue that is primarily involved with concentrating the tubular fluid and contains the medullary portion of the collecting ducts which transports the final urine to the minor calyces


Broad functions of the kidneys

1) osmoregulation between water/electrolytes/acids-base balances

2) excretion of production of urine by kidneys which passes through the ureters for temporary storage in the bladder before its releases to the exterior by urethra
- metabolic wastes and bioactive substances

3) endocrine functions
- renin = protease used to cleave angiotensin -> angiotensin 1
- erythropoietin = glycoprotein that stimulates erythrocyte production in red bone marrow when O2 is low

Conversion of vitamin D to active form (1,25 dihydroxyvitamin D3/ calcitrol)



Functional divisions of the kidney

Renal lobe: consists of a single renal pyramid and the associated minor calyx and the adjacent renal Columns
- is the functional unit of the kidney (8-15 renal lobes per kidney)

Renal lobules: consists of a medullary ray (collecting duct) and the surrounding cortical tissues (vascular supply and nephrons)


What is the functional excretory unit of the kidney?

A nephron

* are classified based on the location of the renal corpuscles and the depth of the nephron loop


Types of nephrons

1) Juxtamedulary nephrons (8-10% of total nephrons)
- renal corpuscles located deep in the cortex near the corticomedullary junction
-nephron loops extend only deep into the medullary tissue
- produce the MOST concentrated (hypertonic) tubular fluid

2) midcortical nephrons
- renal corpuscules and nephrons both extend in between the subscapularis and juxtamedullary nephrons
- variable tubular fluid concentrations

3) subcapsular nephrons
- corpuscles are located most superficially
- nephron loops extend only a short distance into medullary tissues
- produce the LEAST concentrated (almost completely isotonic) tubular fluid


Parts of a renal corpuscle

1) glomerulus - a tuft of arteriole vasculature

2) bowmans capsule = surrounds the glomerulus with a inner visceral and outer parietal layer of epithelium
- continuous with the lumen of the renal tubule


What is a uriniferous tubule?

The nephron plus the associated connecting tubule and collecting duct

**it is NOT synonymous with nephron**


How is the renal blood circulation broken down

Arteriole supply:
Renal artery -> segmental artery -> interlobar artery -> arcuate artery -> interlobular artery -> afferent arteriole -> glomerulus -> efferent arteriole -> vasarecta (covers the loop of henle) and peritubular capillaries (cover PCT/DCT)

Venous supply:
Vasarecta/peritubular capillaries -> interlobular vein -> arcuate vein -> interlobar vein -> renal vein


Difference between cortical and medullary filtration function

Cortical = tubular reabsorption is primarily to conserve nutrients/minerals and ions needed by the body and to remove excessive and/or toxic substances

Medullary function = tubular reabsorption and secretion occurs primarily for concentration of urea/osmoregulation and acid-base balance


What are the 3 factors associated with the glomerular filtration rate (GFR) of kidneys

1) glomerular surface area

2) permeability of glomerular filtration barrier

3) net filtration pressure
- sum of hydrostatic and osmotic pressure between glomerulus and capsular space


What are the 3 factors to altering hydrostatic pressure gradient?

1) alter systemic blood pressure

2) alter glomerular pressure
- how much blood is coming in vs how much blood is going out

3) alter tubule pressure


How to differentiate proteinuria causes?

Larger proteins in the urine = Problem with the GBM

Smaller proteins in the urine =
Problem with the PCT


Broad major functions of each section of the kidney

1) Proximal convoluted tubule (PCT)
- located in cortex
- reabsorption of all organic nutrients, all proteins and most water and electrolytes
- secretion of organic anions and cations (H+/NH4+)

2) thin limb of Henle
- located in medulla
- passive reabsorption of Na+/Cl-

3) thick ascending limb of Henle
- located in medulla
- active reabsorption of electrolytes

4) Distal convoluted tubule (DCT)
- located in the cortex
- passive reabsorption of electrolytes


Cells of the collecting system of the kidney

1) principal cells
- found in medullary rays and medulla
- most abundant cell type**
- is cuboidal/columnar and pale staining
- function = reabsorption of water and electrolytes. Regulates selection of potassium

2) intercalated cells
- found in medullary rays
- are few columnar and stain darker than principal cells
- function = reabsorption of potassium