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Questions and Answers
What is the pH range necessary for maintaining homeostasis in blood?
What is the pH range necessary for maintaining homeostasis in blood?
Which system primarily maintains acid-base balance in the body?
Which system primarily maintains acid-base balance in the body?
At what age does control of the voluntary urethral sphincter typically begin?
At what age does control of the voluntary urethral sphincter typically begin?
What happens to the bladder as a person ages?
What happens to the bladder as a person ages?
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Which of the following statements about urinary function is true for newborns?
Which of the following statements about urinary function is true for newborns?
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What is the primary process through which water and solutes smaller than proteins are forced through capillary walls?
What is the primary process through which water and solutes smaller than proteins are forced through capillary walls?
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Which of the following materials is typically reabsorbed by the peritubular capillaries?
Which of the following materials is typically reabsorbed by the peritubular capillaries?
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What is a characteristic of urine related to its composition?
What is a characteristic of urine related to its composition?
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What role does peristalsis play in the urinary system?
What role does peristalsis play in the urinary system?
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Which anatomical structure collects filtrate before it moves to the renal tubule?
Which anatomical structure collects filtrate before it moves to the renal tubule?
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Which of the following substances is not typically reabsorbed in the kidneys?
Which of the following substances is not typically reabsorbed in the kidneys?
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What is the specific gravity range of normal urine?
What is the specific gravity range of normal urine?
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Which process is described as reabsorption in reverse?
Which process is described as reabsorption in reverse?
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What percentage of water is typical in young adult males?
What percentage of water is typical in young adult males?
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What happens to water levels when electrolyte balance changes?
What happens to water levels when electrolyte balance changes?
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Which hormone is primarily responsible for preventing excessive water loss in urine?
Which hormone is primarily responsible for preventing excessive water loss in urine?
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What happens to urine concentration when excessive water intake occurs?
What happens to urine concentration when excessive water intake occurs?
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What are the two main sources of water output from the body?
What are the two main sources of water output from the body?
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Which of the following is a key function of aldosterone in maintaining water balance?
Which of the following is a key function of aldosterone in maintaining water balance?
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What can impair cellular activity during changes in water balance?
What can impair cellular activity during changes in water balance?
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What is the typical percentage of water in the body of elderly individuals?
What is the typical percentage of water in the body of elderly individuals?
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What is the primary function of the urinary bladder?
What is the primary function of the urinary bladder?
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Which layer of the urinary bladder wall is responsible for its ability to expand significantly?
Which layer of the urinary bladder wall is responsible for its ability to expand significantly?
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Which sphincter is under voluntary control?
Which sphincter is under voluntary control?
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What distinguishes the female urethra from the male urethra?
What distinguishes the female urethra from the male urethra?
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What is the primary function of the glomerulus?
What is the primary function of the glomerulus?
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What structure surrounds the glomerulus?
What structure surrounds the glomerulus?
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What is the role of peritubular capillaries?
What is the role of peritubular capillaries?
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What initiates the relaxation of the internal urethral sphincter during micturition?
What initiates the relaxation of the internal urethral sphincter during micturition?
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Which type of nephron is primarily located in the cortex?
Which type of nephron is primarily located in the cortex?
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What is located at the trigone of the bladder?
What is located at the trigone of the bladder?
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What is the typical length of the male urethra?
What is the typical length of the male urethra?
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What is the effect of the narrow efferent arteriole attached to the glomerulus?
What is the effect of the narrow efferent arteriole attached to the glomerulus?
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Which function is performed solely by the female urethra?
Which function is performed solely by the female urethra?
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What is NOT one of the processes involved in urine formation?
What is NOT one of the processes involved in urine formation?
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Where do juxtamedullary nephrons primarily reside?
Where do juxtamedullary nephrons primarily reside?
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What type of pressure do peritubular capillaries operate under?
What type of pressure do peritubular capillaries operate under?
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What is NOT a function of the urinary system?
What is NOT a function of the urinary system?
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Which organ is NOT part of the urinary system?
Which organ is NOT part of the urinary system?
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Where are the kidneys located?
Where are the kidneys located?
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What is the primary functional unit of the kidney responsible for urine formation?
What is the primary functional unit of the kidney responsible for urine formation?
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Which region of the kidney is the outer part?
Which region of the kidney is the outer part?
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What structure funnels urine towards the renal pelvis?
What structure funnels urine towards the renal pelvis?
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Which statement about the kidneys is correct?
Which statement about the kidneys is correct?
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Which of the following is NOT a homeostatic function of the urinary system?
Which of the following is NOT a homeostatic function of the urinary system?
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Study Notes
Urinary System Functions
- Eliminates waste products, including nitrogenous wastes, toxins, and drugs.
- Regulates homeostasis, including water balance, electrolytes, acid-base balance in the blood, blood pressure, red blood cell production, and vitamin D activation.
Urinary System Organs
- Kidneys
- Ureters
- Urinary bladder
- Urethra
Kidney Location
- Located against the dorsal body wall.
- Situated 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 the renal hilus.
- An adrenal gland sits atop each kidney.
Kidney Regions
- Renal cortex (outer region)
- Renal medulla (inside the cortex)
- Renal pelvis (inner collecting tube)
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 toward the renal pelvis.
Blood Flow in the Kidneys
- Blood flows from the aorta to the renal artery, then to segmental arteries, lobar arteries, interlobar arteries, arcuate arteries, interlobular arteries, afferent arterioles, glomerulus, efferent arterioles, peritubular capillaries, and then to the renal vein.
Nephrons
- Structural and functional units of the kidneys.
- Responsible for forming urine.
- Consist of glomerulus and renal tubule.
Glomerulus
- Specialized capillary bed attached to arterioles on both sides (maintains high pressure).
- Contains afferent (large) and efferent (narrow) arterioles.
- Sits within a glomerular capsule (first part of the renal tubule).
Renal Tubules
- Glomerular (Bowman's) capsule.
- Proximal convoluted tubule.
- Loop of Henle.
- Distal convoluted tubule.
Types of Nephrons
- Cortical nephrons: located entirely in the cortex (most common).
- Juxtamedullary nephrons: located at the boundary of the cortex and medulla.
Peritubular Capillaries
- Arise from efferent arterioles of the glomerulus.
- Normal, low-pressure capillaries.
- Attached to a venule.
- Cling closely to the renal tubule.
- Reabsorb substances from collecting tubes.
Urine Formation Processes
- Filtration: nonselective passive process where water and solutes smaller than proteins are forced through capillary walls; filtrate collects in the glomerular capsule.
- Reabsorption: peritubular capillaries reabsorb water, glucose, amino acids, and ions (mostly active transport).
- Secretion: some materials move from peritubular capillaries into the renal tubules (e.g., hydrogen and potassium ions, creatinine).
Materials Not Reabsorbed
- Nitrogenous waste products (urea, uric acid, creatinine).
- Excess water.
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 in urine transport.
Urinary Bladder
- Smooth, collapsible, muscular sac.
- Temporarily stores urine.
- Trigone: three openings (two from the ureters, one to the urethra).
- Walls are thick and folded in an empty bladder.
- Bladder expands significantly without increasing internal pressure.
Urethra
- Thin-walled tube carrying urine from the bladder to the outside of the body via peristalsis.
- Release controlled by two sphincters: internal (involuntary) and external (voluntary).
Urethra Gender Differences
- Length: Females (3-4 cm); Males (20 cm).
- Location: Females (along vagina wall); Males (through prostate and penis).
- Function: Females (only urine); Males (urine and sperm passageway).
Micturition (Voiding)
- Both sphincter muscles open to allow voiding.
- Internal sphincter relaxes after bladder stretching.
- Activation from impulse sent to spinal cord and back via pelvic splanchnic nerves.
- External sphincter is voluntarily relaxed.
Maintaining Water Balance
- Intake must equal output.
- Water sources: ingested foods/fluids, metabolic processes.
- Water output sources: vaporization (lungs), perspiration, feces, urine.
- Dilute urine if excessive intake; concentrated urine if water loss.
- Proper electrolyte concentrations are crucial for water balance.
Regulation of Water/Electrolyte Reabsorption
- Primarily regulated by hormones such as ADH and aldosterone.
- ADH prevents excessive water loss in the urine.
- Aldosterone regulates sodium ion content of extracellular fluid and is triggered by the rennin-angiotensin mechanism.
- Kidney and hypothalamus cells are active monitors.
Maintaining Acid-Base Balance
- Blood pH must be between 7.35 and 7.45 to maintain homeostasis.
- Most acid-base balance is maintained by the kidneys.
- Other systems include blood buffers and respiration.
Developmental Aspects of the Urinary System
- Functional kidneys develop by the third month.
- Newborn bladder is small; urine cannot be concentrated.
- Voluntary urethral sphincter control starts after 18 months.
- Urinary infections are common problems before old age
Aging and the Urinary System
- A progressive decline in urinary function occurs.
- The bladder shrinks with aging.
- Urinary retention is common in males.
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Description
Test your knowledge on the urinary system, including its functions and the structure of the kidneys. This quiz covers the organs involved, their locations, and specific kidney regions and structures. Enhance your understanding of how the urinary system maintains homeostasis and eliminates waste.
