Dr. Maha Al-Sedik
Objectives:
 Anatomy, physiology of the renal system.
 Patient Assessment.
Anatomy and Physiology
The Urinary System
 Paired kidneys
 A ureter for each kidney
 Urinary bladder
 Urethra
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Functions of the kidney
Removal of excess water and
electrolytes
Removal of excess toxins and
metabolites
Control of RBCs production and blood
pressure through production of
hormones
Main Functions of Urinary System
 Removal of nitrogenous wastes from blood eg. urea, uric
acid and creatinine.
 Produces erythropoietin, which regulates RBC production.
 Removal of excess water and electrolytes.
Kidneys
 Located in the retroperitoneal space.
 Lateral surface is convex
 Medial surface is concave
 Hilus is cleft: vessels, ureters and nerves enter and leave
 Adrenal glands lie superior to each kidney
 Ureters transport urine from the kidneys to the bladder.
 One fourth of the body’s systemic cardiac output flows through
the kidney each minute.
Nephrons
 In the cortex.
 Structural and functional units in the kidney that form urine.
 Each kidney in the human contains about 1 million nephrons,
each capable of forming urine.
 The kidney cannot regenerate new nephrons. Therefore, with
renal
injury, disease, or normal aging, there is a gradual
decrease in nephron number.
Each nephron contains :
 A tuft of glomerular capillaries called the glomerulus, through
which large amounts of fluid are filtered from the blood.
 A long tubule in which the filtered fluid is converted into urine on
its way to the pelvis of the kidney.
 The substance is freely filtered but is also partly reabsorbed from
the tubules back into the blood.
 For each substance in the plasma, a particular combination of
filtration, reabsorption, and secretion occurs.
 The rate at which the substance is excreted in the urine depends on
the relative rates of these three basic renal processes.
 Most substances that must be cleared from the blood, especially
the end products of metabolism such as urea, creatinine, uric acid,
and urates, are poorly reabsorbed and are excreted in large
amounts in the urine.
Filtration
• Glomeruli
Reabsorption
• Proximal and loop of henle
secretion
• Distal tubule
The rates at which different substances are excreted in the urine
represent the sum of three renal processes,
(1) glomerular filtration,
(2) reabsorption of substances from the renal tubules into the
blood
(3) secretion of substances from the blood into the renal tubules.
Urinary excretion rate =
Filtration rate - Reabsorption rate + Secretion rate
B
A
D
C
E
F
Answer
A: proximal tubule.
B: Bowman capsule.
C: Glomerulus.
D: Distal tubule.
E: Loop of Henle.
F: Collecting duct.
Urine
collecting
ducts
calyces
renal
pelvis
ureters
Urinary
bladder
Ureters

the ureters are tubes made of smooth muscle fibers that propel
urine from the kidneys to the urinary bladder.
 In the adult, the ureters are usually 25- 30 cm long .
Urinary Bladder
 Collapses when empty
 Expands when full.
 The brain controls the urge to void.
 External urinary sphincter remains contracted until conditions
are favorable
Urethra
 Part of the lower urinary
tract.
 Expels urine.
 Male urethra is divided into
three regions.