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Questions and Answers
What are the four main roles of the kidneys in maintaining blood composition?
What are the four main roles of the kidneys in maintaining blood composition?
The right kidney is slightly higher than the left kidney due to the position of the liver.
The right kidney is slightly higher than the left kidney due to the position of the liver.
False
What is the name of the triangular region of the urinary bladder base that is based on three openings?
What is the name of the triangular region of the urinary bladder base that is based on three openings?
Trigone
The ______ is the functional unit of the kidney.
The ______ is the functional unit of the kidney.
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What are the three major processes involved in urine formation?
What are the three major processes involved in urine formation?
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What is the name of the hormone that helps regulate blood composition and blood volume by acting on the kidney?
What is the name of the hormone that helps regulate blood composition and blood volume by acting on the kidney?
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The thirst mechanism is triggered by a decrease in blood volume only.
The thirst mechanism is triggered by a decrease in blood volume only.
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The kidneys begin to develop in the third month of embryonic life.
The kidneys begin to develop in the third month of embryonic life.
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What is the main function of the ureters?
What is the main function of the ureters?
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Study Notes
Urinary System Overview
- The urinary system consists of organs that filter blood, remove waste, and regulate fluid balance
- Kidneys filter blood and produce urine
- Ureters transport urine from kidneys to bladder
- Urinary bladder stores urine
- Urethra carries urine outside the body
Kidney Functions
- Excretion of nitrogenous wastes (e.g., urea, uric acid, creatinine)
- Regulation of blood volume and pressure (via renin)
- Regulation of erythrocyte production (via erythropoietin)
- Regulation of vitamin D activation
- Maintenance of electrolyte balance
- Maintenance of acid-base balance
Kidney Structure
- Retroperitoneal position (behind parietal peritoneum)
- Level of T12 to L3 vertebrae (right kidney is slightly lower)
- Three protective layers: fibrous capsule, perirenal fat capsule, renal fascia
- Renal cortex (outer region), renal medulla (deeper region with renal pyramids), renal pelvis (medial region)
- Renal hilum: a medial indentation where structures enter/exit the kidney (ureters, renal blood vessels, nerves)
- Kidneys have a complex blood supply (one-quarter of total blood supply passes through each minute)
- Blood supply enters via renal artery, branches into arterioles, then capillaries
- Blood leaves via renal vein
Nephrons
- Structural and functional units of the kidney
- Contains over a million nephrons per kidney
- Two main structures: renal corpuscle and renal tubule
- Renal corpuscle: glomerulus (knot of capillaries) and glomerular (Bowman's) capsule
- Renal tubule: proximal convoluted tubule (PCT), nephron loop (loop of Henle), distal convoluted tubule (DCT)
Urine Formation
- Three processes: glomerular filtration, tubular reabsorption, tubular secretion
- Glomerular filtration: Nonselective passive process (forces water and small solutes from blood into glomerular capsule)
- Tubular reabsorption: Selective process (reabsorbs water, glucose, amino acids, and ions)
- Tubular secretion: Reabsorption in reverse; moves substances from blood into filtrate (e.g., hydrogen ions, creatinine)
- Urine characteristics: clear and pale to deep yellow, slightly acidic, sterile, slightly aromatic
Ureters
- Slender tubes (25-30 cm) connecting kidneys to bladder
- Continuous with renal pelvis
- Enter posterior aspect of bladder
- Run behind peritoneum
- Peristalsis aids urine transport
Urinary Bladder
- Smooth, collapsible muscular sac
- Stores urine temporarily
- Trigone: a triangular region of the bladder base with openings for ureters and urethra
- Three layers: detrusor muscle (smooth muscle), mucosa (transitional epithelium), external fibrous connective tissue
- Capacity: about 500 ml
Urethra
- Thin-walled tube carrying urine from bladder to exterior
- Length varies (females: 3-4 cm, males: 20 cm)
- Location in females: anterior to vaginal opening; in males: travels through prostate and penis
- Two sphincters: internal (involuntary, smooth muscle) and external (voluntary, skeletal muscle)
Micturition (Voiding)
- Emptying of the urinary bladder
- Two sphincters control urine release
- Impulses cause bladder contractions and relaxation of sphincters to expel urine
Fluid, Electrolyte, and Acid-Base Balance
- Kidneys regulate water balance, electrolyte balance, and acid-base balance of the blood
- Blood composition depends on diet, cellular metabolism, and urine output
Hormonal Control
- Antidiuretic hormone (ADH): regulates water reabsorption in the kidneys
- Aldosterone: regulates electrolyte balance, particularly sodium and potassium
Development and Problems
- Kidneys start developing early in embryonic life and begin excreting urine by the 3rd month
- Common congenital issues: polycystic kidney and hypospadias
- Common urinary system problems (adults): Infections (often from Escherichia coli), urinary retention, incontinence, kidney failure
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Description
This quiz covers the key aspects of the urinary system, including its structure, functions, and the role of kidneys in maintaining bodily homeostasis. Focus on the filtration processes, urine transportation, and the kidneys' regulatory functions. Test your understanding of how these components work together to manage waste and fluid balance.
