BMED 3106Integrated Body Systems III

Renal System, Fluids, & Electrolytes

Department of Health & Biomedical Sciences

Anatomy of Renal/Urinary System

Kidneys

• 2 kidneys– One on each side of

the vertebral column at the level of T12-L3 vertebrae

• Lie retroperitoneally on the posterior abdominal wall

Kidneys• Enclosed by the renal fascia• Surrounded by perinephric fat

Kidneys

• Superiorly, the posterior aspect of the kidneys are associated with the:– diaphragm, which separates them from the

pleural cavities and the 12th pair of ribs.

• Inferiorly, the posterior aspect of the kidneys are related to the:– Psoas muscle medially and quadratus lumborum

muscle

Kidneys• Right kidney slightly lower than left kidney• At the hilum: renal artery, renal vein, and renal pelvis• Blood supply: Renal arteries (branches of abdominal

aorta) and renal veins (drain into IVC)

The medial surface of the kidney is concave with a hilum carrying renal nerves and blood vessels.

The renal parenchyma is divided into an outer cortex and inner medulla.

Extensions of the cortex (renal columns) project toward the sinus, dividing the medulla into 6-10 renal pyramids. Each pyramid is conical with a blunt point called the papilla facing the sinus.

The papilla is nestled into a cup called a minor calyx, which collects its urine. Two or three minor calyces merge to form a major calyx. The major calyces merge to form the renal pelvis.

The Nephron

• Functional unit of the kidney• Each kidney contains ~ 1 million nephrons• Glomerulus

– Filters blood and eventually all waste carried away (filtered)

in the urine, and a small blood vessel returns all filtered substance back to the body.

Nephrons are connected to renal artery/vein and ureter.

A nephron consists of :

A. blood vessels• afferent arteriole• glomerulus• efferent arteriole

B. renal tubules• proximal convoluted tubule• loop of Henle• distal convoluted tubule

The Nephron proximal convoluted tubule

glomerulus

Loop of Henle

afferent arteriole

distal convoluted tubule

efferent arteriole

Urinary Organs

• Include:– Ureters: carry urine

from the kidneys– Urinary bladder:

temporarily stores urine– Urethra: conducts urine

from the bladder to the exterior

Ureters

• Muscular ducts• Transport urine to the urinary bladder• Normally constricted to a variable degree in three places:1. Ureteroplevic junction2. Where cross external iliac vessels3. When enter the bladder

Ureters

• Posteriorly– Surface marking of the ureter is lateral to L1 spinous

process and posterior aspect of superior iliac spine

• Branches off inferiorly from apex of renal pelvis at the hila of the kidneys, passing over the pelvic brim at the bifurcation of the common iliac arteries. – Continues to run along lateral wall of pelvis and enter

the urinary bladder

Urinary Bladder• Hollow viscus with muscular walls composed of detrusor muscle

• When empty its location is in the lesser pelvis and when filled it’s located in the greater pelvis

• Consists of:– Apex– Fundus– Body– Neck

• Arterial and Venous supply– Superior and inferior vesical arteries

• Innervation– Parasympathetic and sympathetic fibers

Urethra

Male

• 18-22 cm long• Function:

– Conveys urine from internal urethral orifice to external urethral orifice

– Exit for semen

• Two parts:– Intermediate part– Spongy urethra

• Arterial and Venous supply– Prostatic branches of rectal arteries

and prostatic venous plexus

• Innervation– Prostatic plexus (sympathetic and

parasympathetic fibers)

Female

• 4 cm long and 6 mm diameter• Function:

– Conveys urine from internal urethral orifice to external urethral orifice

• Arterial and venous supply:– Internal pudendal and vaginal

arteries

• Innervation:– Vesical nerve plexus and pudendal

nerve

Difference betweenFemale and Male Urethra

Suprarenal Glands

• Also referred to as adrenal glands

• Yellowish appearance• Pyramid shaped• Sit above the kidneys• Surrounded by connective

tissue containing perinephric fat.

Suprarenal Glands

• Enclosed by renal fascia• Separated from the kidneys by CT• Divisions: Cortex & Medulla• Blood supply: Suprarenal arteries & veins• Nerves: celiac plexus and abdominopelvic splachnic nerves

Renal Arteries and Veins

• Renal arteries– Arise between L1 and L2 vertebrae– Longer right renal artery passes posterior to the IVC– At the hilum, the renal arteries divided into 5 segmental

arteries• Superior segmental artery• Anterosuperior segmental artery• Anteroinferior segmental arteries• Inferior segmental artery• Posterior segmental artery

• Renal veins drain into each kidney– Unite to form the right and left renal veins

Renal Arteries and Veins

Arterial Supply and Venous Drainage of Ureters

• Arterial branches to the abdominal portion of the ureter arise consistently from the renal arteries.– Form anastomoses

• Veins draining the abdominal part of the ureters drain into the renal and gonadal veins.

Suprarenal Arteries and Veins

• Suprarenal arteries branch freely before entering each adrenal gland– Arteries arise from 3 sources

• Superior suprarenal arteries• Middle suprarenal arteries• Inferior suprarenal arteries

• Suprarenal veins– Large and serve as the venous drainage of suprarenal

glands• Right suprarenal vein and left suprarenal vein

Lymphatics of Kidneys, Ureters,and Suprarenal Glands

• The lymphatics follow the path of the renal veins and drain into:– Right and left lumbar lymph nodes

• Lymphatics of ureters – Drain into common, external,

internal iliac lymph nodes

• Lymphatics of suprarenal glands– Drains into the lumbar lymph

nodes

Nerves of Kidneys, Ureters, and Suprarenal Glands

• Kidneys are primarily supplied by:– Renal nerve plexus

• Sympathetic and parasympathetic fibers• Supplied by fibers from abdominopelvic

splanchnic nerves

• Ureters are primarily supplied by:– Renal, abdominal, aortic, and superior

hypogastric plexuses– Visceral afferent fibers

• Convey pain sensation

• Suprarenal glands are primarily supplied by:– Celiac plexus and abdominopelvic

splanchnic nerves

Questions