Dr Laxman Khanal

BPKIHS

07-06-2013

Anatomy of Urinary System

Urinary system

Where is the micturation center in the brain??Which of the following is found exclusively in the renal

medulla?a.Proximal convoluted tubules b. Distal convoluted tubules c. Collecting ducts d. Thin loops of Henle

Space for enlargement of bladder is …………. a. Space of Reitzius b. Verumontanum c. Urogenital raphe d. Pelvic space In kidney the less vascular area separating anterior and

posterior segment is known as…………. a. Brodie’s line b. Canton’s line c. Calot’s line d. Seshachalam’s line

Test yourself

life expectancy of individual with a single kidney is the same as those with two kidneys. ( T/F)

Most common position of ectopic kidney is hypogastric region of abdomen. ( T/F)

Widest and most dilated part of urethra is………….

a. Membranous b. Prostatic c. Penile d. External

meatus

T/F

Key feature of kidneysRelationship of kidneysRenal fascia and its extensionMacroscopic study of kidneyStructure and function of urineferous tubulesKey relation and constrictions of UretersSupport of bladder and its relationshipNeural pathway of micturation

Objectives of class

• Formation of urine• Regulate volume and chemical composition of

blood (water, salts, acids, bases).• Produce-

Renin – regulates BP/ kidney function Erythropoeitin – stimulates RBC production from

marrow.• Metabolism of Vitamin D to active form ( by

PCT).

Functions

• Two Kidneys– Perform all functions except actual excretion.

• Two Ureters– Convey urine from Kidneys to Urinary Bladder

• Urinary Bladder– Holds Urine until excretion

• Urethra– Conveys urine from bladder to outside of body

Components of urinary system

A pair of bean shaped organs located against posterior abdominal wall retro-peritoneally.

Each kidney presents 2 surfaces, 2 ends and 2 borders.

Long axis of kidney is directed downward and laterally so upper end is nearer to the midline.

Extend from T12 to L3

kidneys/ key features

Left kidney is nearer to midline and to diaphragm than the right one.

Medial border presents a concavity called as hilum.

Transpyloric plane passes through the upper part of right hilum and lower part of left hilum

kidneys/ key features

Position of kidneys

Anterior relation

Anterior relation

Posterior relation

Posterior relationship

Ribs-11and 12 for left and 12th for rightMuscles- 3 muscleNerves- 3 nervesDiaphragm

Remember

Angle between the lower border of the 12th rib and lateral border of erector spinae.

It overlies the lower part of kidney.Tenderness can be felt in this area in case of

perinephric abscess.

Renal angle

Fibrous capsule ( true capsule)Perinephric fatRenal fascia( fascia of Gerota)Paranephric fat

Covering of the kidneys

Fibrous capsule formed by condensation of fibrous stroma of the kidney.

In nephropexy, fibrous capsule is divided and sutured with the posterior abdominal wall.

Perinephric fat is abundant along the border of kidneys, in lower pole and in the renal sinus.

Renal fascia is made up of condensation of extra-peritoneal connective tissue.

Covering of the kidneys

Consists of two layers1. Anterior layer or fascia of Toldt2. Posterior layer of Fascia of Zuckerkendl Laterally both layer fused and continued

with the fascia transversalis Medially , anterior layer is continuous with

the similar layer of the opposite side in front of the aorta and IVC.

Renal Fascia or fascia of Gerota

Medially posterior layer covers the back of kidney and renal vessels and blends with the psoas fascia.

Above , both layer fuse and re-split to cover suprarenal gland. At the upper end of the gland two layers fuse and continuous with the subdiaphrgmatic fascia forming the suspensory ligaments of suprarenal gland.

Coverings of kidney

Below, two layer do not fuse , extend downward along the ureter and are finally lost in extra-peritoneal connective tissue of iliac fossa.

Paranephric fat is located in between the renal fascia and anterior layer of thoraco-lumbar fascia.

Coverings of kidneys

Macroscopic structure

When splited longitudinally it presents 2 parts

Kidney proper – it is made up of outer cortex and inner medulla.

Cortex lies in between renal capsule and renal pyramid ( cortical arch), and extends in between pyramid as renal column.

Medulla is made up of renal pyramid.Renal sinus

Macroscopic structure

The urineferous tubules are the microscopic structures of the kidneys. It is made up of nephrons and collecting tubules.

Nephron is the functional unit of the kidney, responsible for the actual purification and filtration of the blood.

About one million nephrons in each kidney.

Two types of nephrons Cortical – 85%- responsible for Na resorptionJuxtramedullary – 15%- for water resorption

Microscopic structure

The main differences in the two types of nephrons are-

1. the length to which the loop of Henle extends into the kidney. 

2. Position of renal corpuscle3. Functions

Parts of the Nephrons-

Renal corpscle = Bowman capsule + GlomerulusPCTLoop of HenleDCT

Microscopic structure

3 phases of urine formation

Renal Corpuscle(Malphigian body) (Glomerular plexus + Bowman’s capsule)

Visceral layer of renal corpuscle

Filtration membrane

Filtration

Nephrotic syndrome

Protinuria; hypoalbuminemia and edema

At the urinary pole of a renal corpuscle, the simple squamous epithelium of the parietal layer of Bowman's capsule undergoes an abrupt change to become the tall cuboidal epithelium with microvilli ( brush border appearance)of the proximal tubule.

PCT

It has descending and ascending limbs , each having thick and thin part.

Thin part makes a hair-pin bend in the deeper plane of medulla .

Due to the close association of two limb, opposite flow of filtrate and variable permeability to the water is responsible for the counter-current multiplier mechanism.

Loop of Henle

Counter-current system

Distal tubule cells possess their own type of Na+ transporter protein called the amiloride-sensitive epithelial Na+ channel (ENaC). Aldosterone, can increase the abundance of ENaC channels at the cell surface, thereby stimulating Na+ reabsorption.

Part of the DCT that comes in contact with the afferent arteriole of glomerulus specialized for sppecial function .this special portion is called as macula densa.

Epithelial lining is simple cuboidal.

DCT

Juxtra-glomerular apparatus

Function of juxtra-glomerular apparatus

Collecting tubules are composed of a simple cuboidal epithelium containing two distinct cell types: principal (light) cells and intercalated (dark) cells.

Principal cells of collecting tubules possess receptors for ADH on their plasma membranes.

Intercalated cells adjust urinary pH by secreting either H+ ions or bicarbonate ions. These cells are also noteworthy because they synthesize a peptide called atrial natriuretic peptide (ANP) , responsible for relaxation of afferent arteriole and less reabsorption of sodium by collecting tubules.

These tubules join to form – duct of Bellini , which is received by the minor calyces at the apex of renal pyramid.

Collecting tubules

Diabetes Insipidus

Renal vasculature

Renal arteries arises at the level of L1- L2

In crossing the midline to reach the IVC, the longer left renal vein traverses an acute angle between the SMA anteriorly and the abdominal aorta posteriorly. Downward traction on the SMA may compress

The syndrome may include hematuria or proteinuria, abdominal pain, nausea and vomiting (indicating compression of the duodenum), and left testicular pain in men (related to the left testicular vein draining into the left renal vein proximal to the compression).

Renal Vein Entrapment Syndrome“nutcracker syndrome”

Brodel’s Line

Segmentation of kidneys

Branching generations after segmental artery

Lobar artery

Interlobar artery

Arcuate artery

Interlobular artery

Function?

Development

These are pair of muscular tubes( 25 cm) that are continuous superiorly with the renal pelvis, which is a funnel-shaped structure in the renal sinus.

Consists of three parts- renal pelvis, abdominal part and pelvic part.

Descend retroperitonealy and cross pelvic brimEnter posterolateral corners of bladderRun medially within posterior bladder wall

before opening into interiorThis oblique entry helps prevent backflow of

urine

Ureter

Important relationship of Ureters : They run Inferior to the ductus deferens in males and inferior to the uterine artery in females.

At three points along their course the ureters are constricted.

the first point is at the ureteropelvic junction, just inferior to the kidney.

the second point is where the ureters cross the common iliac vessels at the pelvic brim.

the third point is where the ureters enter the wall of the bladder. It is the narrowest one.

Ureteric constrictions

arteries supplying the ureters divide into ascending and descending branches, which form longitudinal anastomoses.Lymphatic drainage

Upper part- lumbar nodeMiddle part- common iliac nodesLower part- ext. and internal iliac

nodesNerve supply- T10 to L1/ S2-S4

Ureter

Innermost mucus membrane- transitional epithelium

Middle layer of smooth muscle -inner longitudinal and outer circular layer.In lower part additional outer longitudinal

layer present.Outer layer is tunica adventitia- made up of

connective tissue.

Histology

Excessive distension or spasm of muscle caused by a stone (calculus) provokes severe pain (ureteric colic), particularly if the obstruction is gradually forced down the ureter.

It is referred to cutaneous areas innervated from spinal segments which supply the ureter and shoots down and forwards from the loin to the groin.

it may extend into the proximal anterior aspect of the thigh by projection to the genitofemoral nerve (L1, 2).

The cremaster, which has the same innervation, may reflexly retract the testis.

Referred pain of ureteric colic

The bladder is the most anterior element of the pelvic viscera. Although it is entirely situated in the pelvic cavity when empty, it expands superiorly into the abdomen when full.

An empty bladder is somewhat tetrahedral and has a base (fundus), neck, apex, a superior and two inferolateral surfaces..

Urinary Bladder

Parts of bladder- Male

Parts of bladder- Female

Base of Bladder in male

Base of Bladder- female

The neck of the bladder surrounds the origin of the urethra.

The neck is the most inferior and also the most 'fixed' part of the bladder. It is anchored into position by a pair of tough fibromuscular bands pubovesical ligaments in female and

puboprostatic ligaments in male.

Neck of Urinary Bladder

Interior of bladder

Interior of bladder and trigone

Space of Retzius

Ligaments of Bladder•Lateral true ligaments•Lateral Pubo-prostatic ligaments•Medial Pubo-prostatic ligaments ( pubo-vesical ligaments in female)•Median umbilical ligaments •Posterior ligaments of bladderMedian umbilical

foldMedial umbilical foldLateral false ligamentsPosterior false ligaments

Histology of urinary bladder

Arterial supply- superior and inferior vesical artery( B/O internal iliac artery)Uterine and vaginal artery instead of inferior

vesical artery in female.Venous drainage- vesical venous plexus

on inferolateral surfaces of bladder.Lymphatics- external iliac and lateral aorticNerve supply- T11-L2/S2-S4

Micturation is a reflex action involving sensory and motor pathway mediated by lower micturation center( spinal cord S2-S4).

Neurogenic bladder- bladder disorders due to nerve damage.

Automatic or reflex bladder-due to transection of cord above the lower micturation center(S2-S4).

Voluntary control is lost but reflex is intact.Autonomous bladder- destruction of lower

micturation center(S2-S4).Both voluntary and reflex control is lost

These are really important!!!

Mucosa of Trigone – mesonephric duct( mesoderm)

Remaining mucosa- vesicouretharal part of cloaca ( endoderm).

Apex – allantoic diverticulumMusculature part- Splanchnic layer of

lateral plate mesoderm which surrounds the cloaca.

Development

The male urethra is a muscular tube approximately 20 cm in length. The urethra in men extends from the neck of the bladder( preprostatic urethra) through the prostate gland (prostatic urethra) to the urogenital diaphragm of the perineum (membranous urethra), and then to the external opening of the glans (penile or spongy urethra).

The female urethra is approximately 4 cm in length and extends from the neck of the bladder to the external urethral orifice of the vulva

Urethra

Thank you Visit – www.slideshare.com for this slide and for similar slides

Where is the micturation center in the brain??- ponsWhich of the following is found exclusively in the renal

medulla?a.Proximal convoluted tubules b. Distal convoluted tubules c. Collecting ducts d. Thin loops of Henle

Space for enlargement of bladder is …………. a. Space of Reitzius b. Verumontanum c. Urogenital raphe d. Pelvic space In kidney the less vascular area separating anterior and

posterior segment is known as…………. a. Brodie’s line b. Canton’s line c. Calot’s line d. Seshachalam’s line

Test yourself

life expectancy of individual with a single kidney is the same as those with two kidneys.

Most common position of ectopic kidney is hypogastric region of abdomen.( it is pelvis)

Widest and most dilated part of urethra is………….

a. Membranous b. Prostatic c. Penile d. External

meatus

T/F