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Questions and Answers
What is one of the primary functions of the urinary system?
What is one of the primary functions of the urinary system?
The kidneys help regulate blood pressure by altering the volume of blood in the body.
The kidneys help regulate blood pressure by altering the volume of blood in the body.
True
What is the functional unit of the kidney?
What is the functional unit of the kidney?
Nephron
The structures that transport urine from the kidneys to the bladder are called ______.
The structures that transport urine from the kidneys to the bladder are called ______.
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Match the following components of the kidney with their descriptions:
Match the following components of the kidney with their descriptions:
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Which ions are regulated by the kidneys?
Which ions are regulated by the kidneys?
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The urinary bladder has the capacity to store urine.
The urinary bladder has the capacity to store urine.
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What substances do the kidneys excrete from the blood?
What substances do the kidneys excrete from the blood?
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Higher blood pressure triggers the kidneys to filter out excess ______.
Higher blood pressure triggers the kidneys to filter out excess ______.
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What anatomical position do the kidneys sit in?
What anatomical position do the kidneys sit in?
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What is the primary function of the glomerulus?
What is the primary function of the glomerulus?
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The proximal convoluted tubule has simple squamous epithelium.
The proximal convoluted tubule has simple squamous epithelium.
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What are the two types of nephrons and their major functions?
What are the two types of nephrons and their major functions?
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The __________ vein drains blood from the kidneys to the inferior vena cava.
The __________ vein drains blood from the kidneys to the inferior vena cava.
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Match the kidney structure with its primary function:
Match the kidney structure with its primary function:
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Which part of the nephron is primarily responsible for tubular reabsorption?
Which part of the nephron is primarily responsible for tubular reabsorption?
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The ureters are equipped with valves to prevent backflow of urine.
The ureters are equipped with valves to prevent backflow of urine.
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What condition is characterized by a decrease in glomerular filtration?
What condition is characterized by a decrease in glomerular filtration?
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The __________ muscle is responsible for the contraction of the bladder during urination.
The __________ muscle is responsible for the contraction of the bladder during urination.
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What happens when the macula densa detects a slow filtration rate?
What happens when the macula densa detects a slow filtration rate?
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Study Notes
Urinary System Overview
- The urinary system significantly impacts the cardiovascular system by filtering blood, removing excess water and solutes, and storing urine.
- It regulates blood pressure by controlling blood volume and sodium/water balance. High blood pressure triggers the kidneys to filter excess sodium and water, reducing blood volume and lowering pressure.
- The urinary system regulates blood pH by selectively removing hydrogen ions and reabsorbing bicarbonate ions, which are then excreted in urine.
- It regulates blood glucose levels and blood ion content (Na+, K+, Ca2+, Cl-). Gluconeogenesis plays a role in glucose regulation.
- The kidneys produce endocrine hormones and excrete wastes (ammonia, urea, creatinine) from the blood.
Kidney Anatomy and Function
- External Anatomy: Kidneys are retroperitoneal, reddish due to high blood supply, enclosed by a fibrous capsule, adipose capsule (padding), and renal fascia.
- Internal Anatomy: Composed of cortex (containing renal corpuscles, tubules), and medulla (containing nephron loops, collecting ducts). Fibrous capsule, renal column and pyramids make up renal lobes.
- Nephron: The functional unit of the kidney, filtering blood to create urine. Urine flows from nephrons to collecting ducts, then to calices, the renal pelvis, and then to the ureters.
- Renal Corpuscle: Contains a glomerulus (specialized capillaries) that filter blood plasma, preventing larger molecules (proteins & blood cells) from leaving the capillaries. This process allows water, electrolytes, and small molecules to pass into Bowman's capsule.
- Blood Supply: Kidneys receive 25% of blood flow, via renal arteries branching to segmental, interlobar, arcuate, and cortical radiate arteries; blood returns via corresponding veins back to the inferior vena cava. Glomerular capillaries (afferent/efferent arterioles) are part of this network, feeding into peritubular capillaries and vasa recta.
- Juxtaglomerular Apparatus: A specialized region where afferent and efferent arterioles meet, containing macula densa cells (detect filtration rate) and juxtaglomerular cells (sense blood pressure, regulating renin release).
Nephron Histology and Functions
- Nephron types: Cortical (most common, produce most urine), and juxtamedullary nephrons (concentrate/dilute urine).
- Renal Corpuscle: Composed of the glomerulus and glomerular capsule. The parietal layer (outer) and visceral layer (inner) of the capsule, made of podocytes (specialized cells to filter blood).
- Nephron Tubules: Include proximal convoluted tubule (with microvilli for reabsorption), nephron loop (descending & ascending limbs), distal convoluted tubule, and collecting duct (all varying in epithelium types as they reabsorb or secrete substances depending on the region).
- Filtration: The glomerulus filters water, electrolytes, and small molecules into Bowman’s capsule — this forms the filtrate.
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Reabsorption: Useful substances are reabsorbed from tubules back to capillaries.
- Secretion: specific wastes (like metabolic wastes, toxins, drugs) are pumped from the blood into the tubules.
Other Urinary System Components
- Ureters: Retroperitoneal tubes carrying urine from kidneys to bladder; have transitional epithelium for stretching, and distinct layers for structure and function.
- Urinary Bladder: Anterior to rectum; composed of mucosa (transitional epithelium), submucosa, and muscularis (detrusor muscle) layers. Stores urine.
- Urethra: Transports urine from the bladder out of the body; varies in length and histology (transitional to stratified squamous) between men and women and throughout the urethra; sphincters control urination.
Micturition (Urination)
- Reflex: Stretch receptors in the bladder signal via spinal cord to the micturition center; relaxation of internal sphincter, contraction of detrusor muscle, and inhibition of external sphincter.
- Voluntary Control: External urethral sphincter is under voluntary control.
Aging Effects
- Nephron Loss: 40% reduction in nephron functional capacity by age 85.
- Filtration Decrease: Decreased blood filtration and urine formation.
- Prostate Enlargement: Can constrict the urethra (affects urination).
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Description
Explore the intricate functions of the urinary system, focusing on its vital role in regulating key physiological parameters such as blood pressure, pH, and glucose levels. This quiz also delves into the anatomy of the kidneys, examining both their external and internal structures. Test your knowledge in this essential aspect of human physiology!
