Kidneys Pt.1

Main function of the Urinary system

Exrcretes wastes

regulates blood composition

~ kidneys, ureters, urinary bladder, urethra

Kidneys location?

located retroperitoneally, below the diaphragm

right kidney is slightly lower (displaced by liver)

What’s the size of the kidney

9-12cm Length

5 cm Width

2.5 cm thick

The outer cortex is……

darker due to higher blood perfusion

The inner medulla contains……

pyramids that drain into renal pelvis

What’s the functional unit of the kidney

nephrons

Pyramids of the Kidney

8-18 striated conical masses

base toward cortex; apex (papilla) into minor calyx

arcuate arteries

at pyramid base; separate medulla from the cortex

hilum

area where vessels, nerves, and ureter enter/ exit

Renal Fascia or Gerota fascia

is a layer of connective tissue encapsulating the kidneys

perinephric fat

covers the renal capsule; is below the renal fascia

Perinephric fascia

surrounds the perinephric fat and encloses kidney and adrenal gland

What is anterior to right kidney

right adrenal gland, liver, morison pouch, 2nd part of duodenum, right colic flexure

Anterior to left kidney

left adrenal gland, spleen, stomach pancreas, left colic flexure, jejunum coils

Posterior to Right kidney

diaphragm, pleural recess, 12th rib, psoas, quadratus lumborum, transversus abdominis

Right renal artery travels

from aorta → behind IVC to kidney

left renal artery travels…..

from aorta → directly into renal sinus

Right Renal Vein drains into

IVC

lymphatics

to lateral aortic nodes

Nerves travel from

renal sympathetic plexus

What are components of a nephron

renal corpuscle + renal tubule

Renal corpuscle is made up of

glomerulus and Bowman’s capsule

How does blood flow through a nephron

Afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries

What are the tubule segments of a nephron

Proximal convoluted tubule → Loop of Henle → Distal convoluted tubule → Collecting duct

Function of a nephron

filters blood, returns needed substances, excretes waste as urine

Ureter

25 cm tube from renal pelvis to bladder

Ureter is constricted at

•Leaving renal pelvis

• Crossing pelvic brim

• Entering bladder wall

• Retroperitoneal, obscured by bowel gas

Urinary bladder

large muscular bag with elastic lining

• Openings:

  • Posterior × 2 (ureters)

  • Anterior × 1 (urethra)

Wall thickness of bladder

3-6mm

Function of bladder

collects urine until stretch receptors trigger voiding

Sonographically seen when distended

Urethra

membranous tube from bladder to exterior

not typically seen on ultrasound

Two sphincters of the urethra

internal and external

Test includes

urinalysis, urine pH, specific gravity, blood tests (BUN, creatinine, hematocrit, hemoglobin, protein)

Main waste products are

water, CO2, urea, uric acid, creatinine

Uric Acid

from nucleic acid breakdown

Creatinine

from muscle metabolism

Urea

from amino acids → ammonia → urea (liver→ kidneys

Elevated BUN/creatinine is equal to

renal impairment

Use renal preset because……

• Assess mass characteristics (cystic, solid, complex)

• Detect hydronephrosis, stones, perirenal fluid

• Evaluate renal size, shape, position, and parenchyma

• Detect congenital anomalies

Patient positioning

supine, decubitus, or right posterior oblique

• Use liver/spleen as acoustic window

• Inspiration improves view

Compare renal _______ echogenicity to liver

cortex

columns of bertin

cortical bands extending into renal sinus

parenchymal disease types?

Type 1 and Type 2

Type 1 parenchymal disease

increased cortical echoes; corticomedullary junction visible

Type 2 parenchymal disease

distorted anatomy; loss of corticomedullary differentiation

Renal Anomalies

• Solitary kidney

• Renal hypoplasia

• Pseudotumor: overgrowth of cortical tissue

• Bifid pelvis / duplex system / incomplete duplication

• Ectopic or pelvic kidney,

• crossed renal ectopia,

• horseshoe kidney

Cystic Renal Mass

thin wall, round, anechoic, posterior enchantment

Solid Renal Mass

irregular borders, internal echoes, poor through- transmission

Complex renal mass

mixture of cystic & solid

Bosniak classification

used to grade cysts

stricture

due to fibrosis, stones, inflammation, tumors, or injury

ureterocele

cyst like dilation at distal ureter (congenital or acquired)

Incomplete emptying causes

bladder stones,

blood clots,

trauma,

diabetes,

strictures,

inflammation,

pregnancy,

neurogenic bladder,

tumors,

surgery

or radiation effects

The renal corpuscle, the proximal convoluted tubule, and

the distal convoluted tubule of each nephron are located

within the

renal cortex

The renal arteries are lateral branches of the aorta that are located just _______ to the superior mesenteric artery

inferior