8526708 Renal Anatomy

7/28/2019 8526708 Renal Anatomy

http://slidepdf.com/reader/full/8526708-renal-anatomy 1/51

Renal Anatomy and

PhysiologyBy: Wong Ann Cheng

MD (UKM) MRCPCH (UK)

7/28/2019 8526708 Renal Anatomy


Renal Anatomy and Physiology

Macroscopic anatomy Embrology

Gross

Procedures Investigations

Microscopic anatomy Glomerular

Tubular

Physiology

Excretory function

Nitrogenous metabolic

waste: urea, uric acid, creat

Homeostatic function

Water and salt regulation

Renin angiotensin

mechanism

Acid/ base balance

Endocrine function

Erythropoeitin

Prostaglandin

Calcitrol

7/28/2019 8526708 Renal Anatomy


Embrology

Early development andevolution

Pronephros

Mesonephros

Metanephros

Ascent and abnormalities

7/28/2019 8526708 Renal Anatomy


Metanephros –

definitive

kidney The metanephros or

definitive kidney of higher vertebrates, begins when themetanephric ducts (uretericbuds) sprout from the distal

end of the mesonephric ductat about 5 weeks.

The ureteric buds induceintermediate mesoderm in the

sacral region to form ametanephric blastema whichforms the glomeruli andtubules of the nephrons.

7/28/2019 8526708 Renal Anatomy


vo ut on o t e neys:Metanephros

The ureteric buds bifurcate again and again to

form the calyces and collecting duct system of the definitive kidney.

The kidneys begin producing urine by week 12,and it adds to the volume of the amniotic fluid.

The fetus drinks this fluid in utero.

The fetal kidneys are not responsible forexcretion as the placenta serves this function

7/28/2019 8526708 Renal Anatomy


Ascent of the

Kidneys

In the 6th week the kidneys begin to ascend from the sacral regionto their position in the upper abdomen.

The metanephric ducts elongate and become the ureters.

As the kidney ascends it receives new segmental arteries from theaorta and loses those vessels below (“climbing a ladder”). Thussometimes there is more than one renal artery.

Sometimes one kidney fails to ascend => pelvic kidney

Sometimes the left and right kidneys become attached in the pelvis

then the horseshoe kidney can’t ascend above the inferiormesenteric arter

7/28/2019 8526708 Renal Anatomy


Position of

kidneys Kidneys lie on the psoas muscle beside

the vertebral bodies.

The diaphragm and 11th and 12th ribslie behind the upper half of eachkidney.

Therefore they move with breathing Left is higher than right (liver)

Upper poles T12

Hilum is at L1/2

Lower poles at L3 Upper poles are more medial (psoas).

In the hilum: Renal vein is the most anterior.

Followed by renal artery & pelvis/ureter Note that the left renal vein is lon er .

It crosses the aorta

Is crossed by the SMA

Receives left gonadal vein

7/28/2019 8526708 Renal Anatomy


Anterior relations

Right Adrenal

Liver bare area

Hepatorenal pouch

Duodenum

Pancreas

Right colicflexure

Jenunum

Left

Adrenal

Stomach

Spleen

PancreasDescending

Colon

Jenunum

7/28/2019 8526708 Renal Anatomy


Macroscopic anatomy

7/28/2019 8526708 Renal Anatomy


Upper urinary tract

Renal

Lower urinary tract

Nephrology / Urology

7/28/2019 8526708 Renal Anatomy


7/28/2019 8526708 Renal Anatomy


Retroperitoneal organ

Weight: 150gm each

Size: ~clenched fist sizeLocation

Right: hilum at L1-2

Left: hilum at L1

Divided into cortex and medulla

Each ~1million unit nephrons and kidney cannotregenerate new nephrons.

Physiologic anatomy

7/28/2019 8526708 Renal Anatomy


Two Paired Organs:

Early in pregnancy, the kidneys become two distinct but paired organs.

(1 in 1,000) only one kidney develops called congenital agenesis .

Shaped Like Beans:

The kidneys are bean shaped.

(1 in 400), the two kidneys fuse into a single horseshoe kidney

Located in Your Lower Back:

The kidneys lie in the retroperitoneum on either side of the spine.

Some people are born with ectopic kidney , not proper location.

Roughly the Size of Your Fist: On the average, the kidneys are about 11-12 cm in length, 7-8 cm wide, 2-

3 cm thick and weigh about 1/4 to 1/3 pound each.

If large, it suggests congestion or inflammation.

If small, it suggests scarring.

7/28/2019 8526708 Renal Anatomy


Microscopic anatomy

7/28/2019 8526708 Renal Anatomy


7/28/2019 8526708 Renal Anatomy


Total blood flow ~25% cardiac output.(1.2L/min)Renal

artery segmentalinterlobararcuateinterlobularafferent

Glomerulusefferent peritubular (vasa recta) veins

2 capillary bedsHigh presure system

hydrostatic pressure 60mmHg minus (32mmHg oncotic pressure +18 mmHg bowman hydrostatic pressure)

Renal cortex receives the most of the blood flow.

Renal medulla only receives 1-2% total blood flow

Renal blood supply

7/28/2019 8526708 Renal Anatomy


7/28/2019 8526708 Renal Anatomy


GFR depends on

Starling force net pressure

1= capillary hydrostatic pressure.

2= bowman capsule

hydrostatic pressure

3= capillary oncotic pressure

7/28/2019 8526708 Renal Anatomy


GFR depends on

1. Glomerular permeability

-capillary and bowman capsule endothelium, glomerular basement

mambrane.

2. Number of functioning glomeruli and total capillary surface area

3. Glomerular capillary plasma flow

ultrafiltrate: plasma minus protein/fat

7/28/2019 8526708 Renal Anatomy


Use of clearance method to quantify

kidney function

The rates at which different substance are

cleared from plasma provide a useful way of

quantifying the effectiveness of which the

kidney excrete various substances

7/28/2019 8526708 Renal Anatomy


Renal clearance of a substance

Volume of plasma completely cleared of the

substance by the kidney per unit time

Provides a useful way to quantify the excretory

function of the kidneys

Can be used to quantify the rate at which blood

flow through the kidneys as well as the basic

function of the kidney, glomerular filtration rate,tubular reabsorption and tubular secretion

7/28/2019 8526708 Renal Anatomy


Cs x Ps = Us x Vs

Cs = clearance rate of a substance s

Ps = plasma concentration of the substance

V = urine flow rate Us = urine concentration of the substance

7/28/2019 8526708 Renal Anatomy


Cs = Us x V / Ps

Renal clearance of a substance is calculated from

the urinary excretion rate (Us x V) of the

substance divided by its plasma concentration

7/28/2019 8526708 Renal Anatomy


Inulin clearance

Can be used to estimate GFR

Substance existed that was freely filtered, not

absorped or secreted by the renal tubules, then

the rate at which the substance was excreted in

the urine (Us x V) is equal the rate at which the

substance was filtered by the kidneys (GFR x Ps)

GFR x Ps = Us x V

7/28/2019 8526708 Renal Anatomy


GFR = US x V / Ps = Cs

Inulin – polysaccharide molecule which

molecular rate of 5200

Not produced in the body

Found in the roots of certain plants.

Must be administered IV to a patient to measure

GFR

7/28/2019 8526708 Renal Anatomy


Other substances used to estimate

GFR

Radioactive iothalamate

Creatinine

By product of skeletal muscle metabolism

Present in plasma at relatively constant concentration

Does not require IV infusion

7/28/2019 8526708 Renal Anatomy


Creatinine clearance

Most widely used method for estimating GFR clinically

Creatinine not a perfest marker for GFR

A small amount is excreted by the tubules

The amount of creatinine excreted in the urine slightly exceeds the amount filtered

Overestimation of the plasma concentration

The creatinine clearance provides a reasonable estimateof the GFR

7/28/2019 8526708 Renal Anatomy


Formula

GFR ( total plasma volume/min from capillary to bowman capsule ) 38× Ht( cm )/ plasma Creatinine (mcmol/L)

Normal adult- 120ml/min/1.73m2

Creat. clearance ( plasma volume removed /min by kidney ) Urine creatinine (mmol/L) × Urine volume (ml/min)/

plasma creatinine(mmol/L)

Normal: ♂ 90-140ml/min

♀ 80-125ml/min

7/28/2019 8526708 Renal Anatomy


Creatinine clearance

7/28/2019 8526708 Renal Anatomy


Physiologic control of GFR and Renal

blood flow

1. Sympathetic NS activation: all

blood vessels are richly

innervated.

Most important during severe

acute disturbances

2. Hormonal (see table)

Hormone or

autocoid

Effect on GFR

Norepinephrine ↓

Epinephrine ↓

Endothelin ↓

Angiotensin II ↔ (prevents ↓)

Endothelial derived

NO

↑

Prostaglandin ↑

7/28/2019 8526708 Renal Anatomy


7/28/2019 8526708 Renal Anatomy


Renin Angiotensin Aldosterone

System

Powerful mechanism for controlling pressure

Renin: small protein released by kidneys when

arterial pressure falls too low

Synthesized and stored in an inactive form called

prorenin in the JG cells of the kidneys

JG cells are modified smooth muscle cells located in

the walls of the afferent arterioles immediately proximal to the glomeruli

7/28/2019 8526708 Renal Anatomy


Two principal effects of

Angiotensin II that can elevate AP

Vasoconstriction – occursrapidly Intense in the arterioles

and less extent in veins

Constriction in arteriolesincreases peripheralresistance, raising AP

Mild constriction in veins

promotes increase venousreturn to the heart,helping the heart pumpagainst increase pressure

Decreased excretion of both salt and water – slowly increases the ECF

volume, increases AP

over period of hours anddays Even more powerful than

acute vasoconstrictor

mechanism in eventually returning AP back tonormal

7/28/2019 8526708 Renal Anatomy


7/28/2019 8526708 Renal Anatomy


Procedure anatomy

7/28/2019 8526708 Renal Anatomy


Orientation and surroundings The medial border of each kidney is anterior to the lateral

border (psoas). Thus the coronal plane of the kidney is at 30degrees to the coronal plane of the body.

Layers surrounding

the kidney

Outside the renal

capsule is perirenal fat

Then is the renal

fascia which also

surrounds the adrenals

This is embedded in

extraperitoneal fat

(pararenal fat)

7/28/2019 8526708 Renal Anatomy


RENAL BIOPSY

7/28/2019 8526708 Renal Anatomy


Normal anatomy

The kidneys are paired

organs that lie posterior

to the abdomen, in the

area of the lower back.The kidneys make

urine, which is

transported from the

kidneys to the bladder

by the ureters, long

muscular tubes whichconnect the kidneys

with the bladder.

7/28/2019 8526708 Renal Anatomy


Kidney transplant may

be recommended for

patients with kidney

failure caused by:

severe, uncontrollablehigh blood pressure

(hypertension)

infections

diabetes mellitus

congenital

abnormalities of thekidneys

other diseases which

cause renal failure,

such as autoimmune

disease

Donor kidneys are

obtained from either

brain-dead organ

donors, or from living

relatives or friends of

the recipient.

7/28/2019 8526708 Renal Anatomy


Incision

While the patient is

deep asleep and

pain-free (general

anesthesia), an

incision is made in the

lower right quadrant

of the abdomen. The

donor kidney is

transplanted into theright lower pelvis of

the recipient.

7/28/2019 8526708 Renal Anatomy


Procedure

The new kidney is

sutured into place. The

vessels of the new

kidney are connected

to the vessels leadingto the right leg (the iliac

vessels), and the ureter

is sutured to the

bladder.

7/28/2019 8526708 Renal Anatomy


Aftercare

In most cases, therecipient's native

kidneys are left in

place, and the

transplanted kidney

performs all the

functions that both

kidneys perform in

healthy people.

Kidney transplant

recipients are

required to takeimmunosuppressive

medications for the

rest of the lives, to

prevent immune

rejection of the

transplanted organ.

7/28/2019 8526708 Renal Anatomy


7/28/2019 8526708 Renal Anatomy


Kidney StructureNumber of Kidneys: agenesis

Shape of the Kidneys: horseshoe kidney

Location of the Kidneys: ectopic kidney.

Finding Kidney Stones, Cysts, and Masses

Kidney Stones: The kidney ultrasound is a useful screening test for kidney stones. Not all kidney stones can be seen onultrasound, but many can be. If a stone is causing ureter obstruction, there may be hydronephrosis.

Ureter Obstruction: A kidney ultrasound is routinely ordered to rule out obstruction in kidney failure. Impeding the flow of

urine can cause it to back up and dilate the ureters and kidneys. It should be noted that finding hydronephrosis doesn’tnecessarily mean there is an obstruction.

Kidney Cysts: The kidney ultrasound is very good at discovering kidney cysts, most of which are uncomplicated and

incidental findings. Some cysts look complicated or complex and may represent infection, bleeding or cancer. People withpolycystic kidney disease have multiple large cysts that replace normal tissue and destroys the kidneys.

Kidney Masses: The ability of kidney ultrasound to detect a kidney mass depends on its size. It is very good for large

masses (> 3 cm) but not so good for small tumors.

Signs of Kidney Chronic Disease

Kidney Size: On the average, the kidneys are about 11-12 cm in length, 7-8 cm wide, and 2-3 cm in thickness. If they arevery small, it suggests significant scarring and irreversible damage.

Thickness of the Cortex: The cortex is the outer shell of the kidney (about 1 cm in thickness) and contains all the glomeruli.

If it particularly thin, it suggests chronic kidney disease and may make it hard to biopsy. If it is thick, it may mean inflammationand congestion.

Echogenicity of the Cortex: Echogenicity refers to how the sound waves look when they bounce off something. It is often

said that it is not normal if there is a lot of echogenicity (compared to the liver). In reality, it is not a very reliable indicator of

kidney disease.

RENAL ULTRASOUND

7/28/2019 8526708 Renal Anatomy


7/28/2019 8526708 Renal Anatomy


THANK YOU

8526708 Renal Anatomy

Documents

Transcript of 8526708 Renal Anatomy