This document provides an overview of the anatomy and physiology of the urinary system. It describes the key organs (kidneys, ureters, urinary bladder, urethra), their locations, coverings, and structures. It explains urine formation through glomerular filtration, reabsorption, and secretion in the nephrons. It also discusses blood flow in the kidneys, development of the urinary system, and changes with aging. The goal is to provide a comprehensive review of the main components and functions of the urinary system.
3. ORGANS OF THE URINARY SYSTEM
Kidneys
Ureters
Urinary bladder
Urethra
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4. LOCATION OF THE KIDNEYS
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Against the dorsal body wall
At the level of T12 to L3
The right kidney is slightly lower than the left
Attached to ureters, renal blood vessels, and
nerves at renal hilus
• Atop each kidney is an adrenal gland
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5. COVERINGS OF THE KIDNEYS
• Renal capsule
– Surrounds each kidney
• Adipose capsule
– Surrounds the kidney
– Provides protection to the kidney
– Helps keep the kidney in its correct location
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6. REGIONS OF THE KIDNEY
• Renal cortex – outer region
• Renal medulla – inside the cortex
• Renal pelvis – inner collecting tube
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8. KIDNEY STRUCTURES
• Medullary pyramids – triangular regions of
tissue in the medulla
• Renal columns – extensions of cortex-like
material inward
• Calyces – cup-shaped structures that funnel
urine towards the renal pelvis
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15. NEPHRONS
• The structural and functional units of the
kidneys
• Responsible for forming urine
• Main structures of the nephrons
– Glomerulus
– Renal tubule
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19. GLOMERULUS
• A specialized capillary bed
• Attached to arterioles on both sides
(maintains high pressure)
– Large afferent arteriole
– Narrow efferent arteriole
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22. TYPES OF NEPHRONS
• Cortical nephrons
– Located entirely in the cortex
– Includes most nephrons
• Juxtamedullary nephrons
– Found at the boundary of the cortex and medulla
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24. PERITUBULAR CAPILLARIES
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Arise from efferent arteriole of the glomerulus
Normal, low pressure capillaries
Attached to a venule
Cling close to the renal tubule
Reabsorb (reclaim) some substances from
collecting tubes
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25. URETERS
• Slender tubes attaching the kidney to the
bladder
– Continuous with the renal pelvis
– Enter the posterior aspect of the bladder
• Runs behind the peritoneum
• Peristalsis aids gravity in urine transport
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27. LINING OF THE URETER
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28. URINARY BLADDER
• Smooth, collapsible, muscular sac
• Temporarily stores urine
• Trigone – three openings
– Two from the ureters
– One to the urethrea
• Urinary Bladder Wall
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ANATOMY
Three layers of smooth muscle (detrusor muscle)
Mucosa made of transitional epithelium
Walls are thick and folded in an empty bladder
Bladder can expand significantly without increasing
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31. URETHRA
• Thin-walled tube that carries urine from the
bladder to the outside of the body by
peristalsis
• Release of urine is controlled by two
sphincters
– Internal urethral sphincter (involuntary)
– External urethral sphincter (voluntary)
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32. URETHRA GENDER DIFFERENCES
• Length
– Females – 3–4 cm (1 inch)
– Males – 20 cm (8 inches)
• Location
– Females – along wall of the vagina
– Males – through the prostate and penis
• Function
– Females – only carries urine
– Males – carries urine and is a passageway for sperm
cells
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33. DEVELOPMENTAL ASPECTS OF THE URINARY SYSTEM
• Functional kidneys are developed by the third
month
• Urinary system of a newborn
– Bladder is small
– Urine cannot be concentrated
• Control of the voluntary urethral sphincter
does not start until age 18 months
• Urinary infections are the only common
problems before old age
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34. AGING AND THE URINARY SYSTEM
• There is a progressive decline in urinary
function
• The bladder shrinks with aging
• Urinary retention is common in males
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