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Questions and Answers
What is the length of the female urethra?
What is the length of the female urethra?
Which region of the male urethra passes through the prostate?
Which region of the male urethra passes through the prostate?
What type of muscle comprises the external urethral sphincter?
What type of muscle comprises the external urethral sphincter?
How long is the male urethra in total?
How long is the male urethra in total?
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What is the total length of the membranous urethra?
What is the total length of the membranous urethra?
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What is the function of the internal urethral sphincter?
What is the function of the internal urethral sphincter?
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Where is the external urethral orifice located in females?
Where is the external urethral orifice located in females?
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What is the length of the spongy (penile) urethra?
What is the length of the spongy (penile) urethra?
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What is the primary function of the flap of mucosa at the entrance of each ureter?
What is the primary function of the flap of mucosa at the entrance of each ureter?
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How long are the ureters that extend from each kidney to the urinary bladder?
How long are the ureters that extend from each kidney to the urinary bladder?
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Which statement correctly describes the nature of urination?
Which statement correctly describes the nature of urination?
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What is the primary function of the distal convoluted tubule in the kidney?
What is the primary function of the distal convoluted tubule in the kidney?
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What structure follows the ureters in the urinary system?
What structure follows the ureters in the urinary system?
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What role do neural controls play in urine elimination?
What role do neural controls play in urine elimination?
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In what anatomical position do the ureters lie in relation to the bladder?
In what anatomical position do the ureters lie in relation to the bladder?
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Which of the following statements about urine production is correct?
Which of the following statements about urine production is correct?
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Which layer of the ureter is responsible for connecting it to surrounding structures?
Which layer of the ureter is responsible for connecting it to surrounding structures?
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What type of epithelium is found in the mucosa of the ureter?
What type of epithelium is found in the mucosa of the ureter?
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What happens to the muscularis layer of the ureter when urine enters?
What happens to the muscularis layer of the ureter when urine enters?
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Where does the transitional epithelium begin in the urinary system?
Where does the transitional epithelium begin in the urinary system?
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Which of the following statements is true about the lumen of the ureter?
Which of the following statements is true about the lumen of the ureter?
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Which feature of the ureters allows for urine transport?
Which feature of the ureters allows for urine transport?
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How many layers of smooth muscle are typically present in the muscularis layer of the ureter?
How many layers of smooth muscle are typically present in the muscularis layer of the ureter?
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What role does the adventitia play in the structure of the ureter?
What role does the adventitia play in the structure of the ureter?
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Study Notes
Contact Information
- Abdeslem El Idrissi, PhD
- Center for Developmental Neuroscience
- City University of New York
- College of Staten Island
- [email protected]
System Summaries
- Urinary System
- Reproductive System
- Digestive System
- Lymphatic System
- Sensory Organs
Urinary System Histology
- Introduction
- The urinary system removes waste products from the body
- Kidneys regulate blood volume, pressure, and composition
- The urinary system is closely associated with the reproductive system, sharing embryonic development and adult anatomical relationships
Functions of the Kidneys
- Filter blood and excrete toxic metabolic wastes
- Regulate blood volume, pressure, and osmolarity
- Regulate electrolytes and acid-base balance
- Secrete erythropoietin for red blood cell production
- Help regulate calcium levels through calcitriol synthesis
- Clear hormones from the blood
- Detoxify free radicals
Nitrogenous Wastes
- Waste: any substance useless or excessive to the body
- Metabolic waste: waste produced by the body
- Urea formation: proteins → amino acids → ammonia → urea
- Uric acid: product of nucleic acid catabolism
- Creatinine: product of creatine phosphate catabolism
- Blood urea nitrogen (BUN): level of nitrogenous waste in blood
- Normal: 10-20 mg/dL
- Elevated BUN (azotemia): possible renal insufficiency
- Uremia: syndrome due to nitrogenous waste toxicity (diarrhea, vomiting, dyspnea, cardiac arrhythmia)
Excretion
- Excretion: separating and eliminating wastes from body fluids
- Four body systems involved:
- Respiratory system: removes small amounts of gases and water
- Integumentary system: removes water, inorganic salts, lactic acid, and urea in sweat
- Digestive system: removes water, salts, lipids, bile pigments, cholesterol, and other metabolic wastes
- Urinary system: removes many metabolic wastes, toxins, drugs, hormones, salts, and water
Retroperitoneal Position of the Kidney
- The kidneys are located behind the peritoneum
- Various organs and structures surround the kidneys, as shown in a diagram.
Gross Anatomy of the Kidney
- Shape and Size: roughly the size of a bar of bath soap, with a convex lateral surface and a concave medial surface (hilum)
- The hilum receives renal nerves, blood vessels, lymphatics, and ureter.
- Three Protective Coverings:
- Renal fascia: immediately deep to parietal peritoneum, binds kidney to abdominal wall
- Perirenal fat capsule: cushions kidney and holds it in place
- Fibrous capsule: surrounds kidney, protecting it from trauma and infection
Two Zones of Renal Parenchyma
- Outer renal cortex
- Inner renal medulla containing renal columns and pyramids
Kidney Anatomy
- Renal columns: extensions of cortex projecting inward toward sinus
- Renal pyramids (6-10): broad base toward cortex, renal papilla toward sinus
- Lobe of kidney: one pyramid plus its overlying cortex
- Minor calyx: each pyramid's papilla cup, collecting urine
- Major calyx: formed by converging minor calyces
- Renal pelvis: formed by major calyces; a tubular continuation into the ureter, draining urine to the urinary bladder
Renal Circulation
- Blood flow to and from kidneys, including arteries (renal, segmental, interlobar, arcuate) and veins (segmental, interlobar, arcuate, renal)
Microcirculation of the Kidney
- Describes the flow of blood through the cortical and juxtamedullary nephrons, including the glomerulus, PCT, DCT, nephron loop, and collecting ducts.
The Renal Corpuscle
- Vascular pole: where afferent arteriole enters and efferent arteriole leaves
- Urinary pole: where renal tubule begins
- Glomerular capsule: parietal and visceral layers, podocytes, filtration slits, Bowman's capsule
- Glomerulus: capillaries for filtration
Microscopic Anatomy of the Nephron
- Renal corpuscle, glomerulus, and its associated capsule
- Tubules (proximal convoluted tubule, nephron loop, distal convoluted tubule)
- Collecting ducts
Renal Cortex (LM: Medium Magnification)
Renal Corpuscle (LM: High Magnification)
Renal Medulla (LM: Medium Magnification)
Renal Medulla (Longitudinal Section)
Structure of the Glomerulus
- Podocytes, filtration slits, and blood vessels within the glomerulus
The Glomerular Filtration Membrane
- Three layers (endothelium, basement membrane, podocytes) through which fluid passes, excluding cells and large proteins
Podocytes (SEM: High Magnification)
Podocytes (TEM: High Magnification)
Basic Stages of Urine Formation
- Glomerular Filtration, Tubular Reabsorption, Tubular Secretion, Water Conservation
The Proximal Convoluted Tubule
- Reclaims about 65% of glomerular filtrate.
- Active transport of substances into the filtrate.
- High microvilli and mitochondria.
Proximal Convoluted Tubule (TEM: Low Magnification)
The Distal Convoluted Tubule and Collecting Duct
- Reabsorption of water and salt is regulated by several hormones (aldosterone, atrial natriuretic peptide, ADH, and parathyroid hormone).
- Fine-tuning of urine composition
Distal Convoluted Tubule (TEM: Low Magnification)
Urine Storage and Elimination
- Urine produced continuously but eliminates episodically.
- Storage apparatus and neural controls release urine at desired intervals
The Ureters
- Retroperitoneal muscular tubes connecting each kidney to the urinary bladder.
- 25 cm long; pass posterior to bladder and enters from below.
- Flap of mucosa at entrance, acting as a valve
The Ureters (Continued)
- Three layers: adventitia, muscularis (smooth muscle layers), mucosa (transitional epithelium)
- Peristaltic waves move urine.
- Narrow lumen—prone to obstruction (kidney stones)
Ureter (LM: Low Magnification)
Ureter (LM: High Magnification)
The Urinary Bladder
- Muscular sac in the pelvic cavity.
- Covered by parietal peritoneum superiorly.
- Three layers : muscularis (detrusor), mucosa (transitional epithelium).
- Umbrella cells to protect mucosa from urine.
The Urinary Bladder 2
- Trigone: triangular area on the floor with openings for ureters and urethra
- Capacity: moderate fullness is 500 ml, maximum is 700-800 ml
- Highly distensible, expanding as it fills
- Rugae flatten upon filling, epithelium thins
The Urinary Bladder 3
- Location and structure in both female and male anatomy
Urinary Bladder Histology
Urinary Bladder (LM: Low Magnification)
Urinary Bladder (LM: High Magnification)
The Urethra
- Tube conveying urine outside the body
- Female urethra: 3-4 cm long, orifice between vaginal and clitoral orifices.
- External urethral sphincter (skeletal muscle).
The Female Urethra
The Urethra 2
- Male urethra is 18 cm long.
- Three regions:
- Prostatic urethra
- Membranous urethra
- Spongy (penile) urethra
- Internal and external urethral sphincters, thickening of detrusor muscle
The Male Urethra
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Description
Test your knowledge of the human urethra with this quiz, focusing on its anatomy and function. You will answer questions about the lengths of the male and female urethra, the components of the urethral sphincter, and the regions of the urethra itself.
