Urinary System Review

These flashcards cover key concepts from the urinary system, including kidney function, anatomy, urine production, and disorders.

What are the general functions of the urinary system?

The urinary system filters blood, removes waste, and regulates fluid balance, electrolytes, and blood pressure.

What substances do the kidneys eliminate?

The kidneys eliminate waste products such as urea, creatinine, and excess salts.

What is the function of calcitriol?

Calcitriol helps regulate calcium and phosphate levels in the blood.

What is the function of erythropoietin (EPO)?

EPO stimulates the production of red blood cells in the bone marrow.

What ions are regulated by the kidneys?

The kidneys regulate ions such as sodium, potassium, calcium, and phosphate.

How do kidneys regulate acid-base levels?

The kidneys regulate acid-base levels by excreting hydrogen ions and reabsorbing bicarbonate.

How do kidneys regulate blood pressure?

Kidneys regulate blood pressure by controlling blood volume and releasing renin.

What is gluconeogenesis?

Gluconeogenesis is the process of synthesizing glucose from non-carbohydrate sources.

What are the two distinct regions of the kidney?

The cortex and the medulla are the two distinct regions of the kidney.

Trace urine flow from the minor calyces to the urethra.

Minor calyces -> Major calyces -> Renal pelvis -> Ureter -> Bladder -> Urethra.

Define nephron.

A nephron is the functional unit of the kidney responsible for filtering blood.

What are the two major structures of the nephron?

The renal corpuscle and the renal tubule.

Describe the structure of the renal corpuscle.

The renal corpuscle consists of a glomerulus surrounded by Bowman's capsule.

List the components of a renal tubule.

The renal tubule includes the proximal convoluted tubule, loop of Henle, and distal convoluted tubule.

What types of epithelial tissue are found in the nephron?

Simple squamous epithelium, cuboidal epithelium, and columnar epithelium.

What is the function of microvilli in the proximal convoluted tubule (PCT)?

Microvilli increase surface area for reabsorption in the PCT.

Compare the two types of nephrons.

Cortical nephrons are primarily in the cortex, while juxtamedullary nephrons extend deep into the medulla.

What is the juxtaglomerular apparatus?

A specialized structure that regulates blood pressure and the glomerular filtration rate.

Describe the action of granular cells.

Granular cells secrete renin in response to low blood pressure.

What is the function of the macula densa?

The macula densa detects sodium chloride concentration and regulates glomerular filtration rate.

What do extraglomerular mesangial cells do?

Extraglomerular mesangial cells support the glomerulus and participate in filtration.

Differentiate between peritubular capillaries and vasa recta.

Peritubular capillaries surround the nephron while vasa recta surround the loop of Henle.

What is the difference between filtrate, tubular fluid, and urine?

Filtrate is the fluid in the renal corpuscle; tubular fluid is in the nephron tubules; urine is excreted.

Trace the fluid from its formation at the renal corpuscle until it exits the body through the urethra.

Filtrate -> tubular fluid -> urine -> exits through urethra.

Define filtration, reabsorption, and secretion.

Filtration is the process of blood plasma being filtered into the nephron; reabsorption is taking substances back into the blood; secretion is the transfer of materials from blood into the nephron.

What are the three layers of the glomerular filtration membrane?

The layers are the endothelium, basement membrane, and podocytes.

What are fenestrae?

Fenestrae are small openings in the capillary endothelium that allow for filtration.

What are podocytes?

Podocytes are specialized epithelial cells with foot-like extensions that help form the filtration slits.

What are filtration slits?

Filtration slits are gaps between the foot processes of podocytes, allowing filtered substances to pass.

What substances can pass through the glomerular filtration membrane?

Small molecules such as water, ions, and small solutes can pass through.

What is the function of mesangial cells?

Mesangial cells help regulate glomerular filtration and provide structural support.

What are the components of filtrate?

Components include water, electrolytes, urea, creatinine, and glucose.

Define glomerular hydrostatic pressure (HPg).

HPg is the pressure exerted by blood in the glomerulus, driving filtration.

Why is HPg higher than pressure in other capillaries?

HPg is higher due to the large afferent arteriole and the constricted efferent arteriole.

Name two pressures that oppose HPg.

Capsular hydrostatic pressure and blood colloid osmotic pressure.

How do you calculate net filtration pressure?

Net filtration pressure = HPg - (capsular hydrostatic pressure + blood colloid osmotic pressure).

Define glomerular filtration rate (GFR).

GFR is the volume of filtrate formed in the kidneys per minute.

What factors influence GFR?

Factors include blood pressure, blood volume, and the resistance of afferent/efferent arterioles.

What is renal autoregulation?

Renal autoregulation is the kidney's ability to maintain GFR despite changes in systemic blood pressure.

What are the two mechanisms of renal autoregulation?

The myogenic mechanism and tubuloglomerular feedback.

What is the myogenic mechanism?

The myogenic mechanism is where smooth muscle in afferent arterioles responds to changes in blood pressure.

What is tubuloglomerular feedback?

A feedback mechanism where the macula densa senses changes in NaCl concentration to regulate GFR.

What is the limitation to maintaining GFR?

If systemic blood pressure fluctuates too much, it can affect renal perfusion and filtration.

What happens if systemic blood pressure increases too much?

It may lead to increased GFR and potential damage to glomeruli.

What happens if systemic blood pressure decreases too much?

It may lead to decreased GFR, impairing waste removal.

How does extrinsic control affect GFR?

Extrinsic control involves neural and hormonal influences to maintain systemic blood pressure and fluid balance.

What stimulates neural control of GFR?

Neural control is stimulated by low blood pressure or sympathetic nervous system activation.

What is reabsorption in the renal tubules?

Reabsorption is the process where substances are absorbed back into the bloodstream from the tubules.

What is secretion in the renal tubules?

Secretion is the transfer of materials from the bloodstream into the renal tubules.

Define transport maximum.

Transport maximum is the maximum amount of substance that can be reabsorbed or secreted by the nephron.

What happens if a substance is above the transport maximum?

If above, the substance will be excreted in urine instead of being reabsorbed.

What is an osmotic diuretic?

An osmotic diuretic is a substance that increases urine output by causing excess water to be retained in the tubules.

What is renal threshold?

Renal threshold is the plasma concentration at which a substance begins to appear in the urine.

What substances are found in filtrate?

Substances in filtrate include water, electrolytes, nutrients, and waste products.

What occurs in the proximal convoluted tubule?

Reabsorption of water, glucose, amino acids, and ions occurs.

Define obligatory water reabsorption.

Obligatory water reabsorption is the process where water is reabsorbed in response to osmotic gradients.

What substances are reabsorbed in the nephron loop?

Sodium, chloride, and water are reabsorbed in the nephron loop.

What is the permeability of the descending limb?

The descending limb is permeable to water but not to solutes.

What is the permeability of the ascending limb?

The ascending limb is impermeable to water but actively transports sodium and chloride.

What is the countercurrent multiplier?

The countercurrent multiplier is a mechanism that creates a concentration gradient in the renal medulla.

What is the role of the vasa recta in the countercurrent exchange system?

The vasa recta supply blood to the medulla while preserving the osmotic gradient.

How does urea recycling contribute to the concentration gradient?

Urea recycling helps to maintain the osmotic gradient in the renal medulla.

What is regulated reabsorption?

Regulated reabsorption is when the reabsorption of water and ions is adjusted based on the needs of the body.

What hormones are involved in regulated reabsorption?

Antidiuretic hormone (ADH), aldosterone, and atrial natriuretic peptide (ANP) are involved.

How does ADH affect urine concentration?

ADH increases water reabsorption, resulting in more concentrated urine.

How is pH regulated in the collecting duct?

pH is regulated by secreting hydrogen ions and reabsorbing bicarbonate.

What other substances are secreted along the tubule?

Other substances include potassium, hydrogen ions, and certain drugs.

Why are renal function tests important?

They assess the health of the kidneys and their ability to filter blood.

What is the procedure for measuring glomerular filtration rate?

GFR can be measured using a substance such as inulin or creatinine clearance.

What is the normal adult GFR?

Normal adult GFR is approximately 90-120 mL/min.

What might a lower GFR indicate?

A lower GFR may indicate impaired kidney function or renal disease.

Define renal plasma clearance.

Renal plasma clearance is the volume of plasma from which a substance is completely removed by the kidneys per unit time.

Why is creatinine used in clearance tests?

Creatinine is used because it is produced at a constant rate and is freely filtered by the kidneys.

What other tests diagnose kidney disease?

Tests include blood urea nitrogen (BUN), urinalysis, imaging studies, and kidney biopsy.

Define kidney failure.

Kidney failure is the inability of the kidneys to maintain normal function.

What might cause kidney failure?

Causes include diabetes, hypertension, glomerulonephritis, and acute kidney injury.

What are the consequences of renal failure?

Consequences include accumulation of waste products, electrolyte imbalances, and fluid overload.

What is the composition of urine?

Urine consists of water, urea, creatinine, uric acid, and various ions.

What are some normal constituents of urine?

Normal constituents include water, urea, and creatinine.

What are abnormal constituents of urine?

Abnormal constituents include glucose, protein, and blood.

What is the clinical term for abnormal constituents in urine?

The clinical term is urine abnormalities or abnormal urinalysis findings.

What is the normal daily volume of urine?

The normal daily urine volume is about 800-2000 mL.

What factors can affect urine volume?

Factors include hydration levels, diet, medications, and exercise.

Define polyuria.

Polyuria is the production of an abnormally large volume of urine.

What causes oliguria?

Oliguria is caused by dehydration, kidney disease, or urinary obstructions.

Define anuria.

Anuria is the absence of urine production.

What causes anuria?

Anuria can be caused by severe kidney failure, shock, or dehydration.

What is the normal urine pH?

Normal urine pH ranges from 4.6 to 8.0.

How does diet affect urine pH?

Diet can influence urine pH; protein-rich diets tend to make urine more acidic.

What is specific gravity in urine?

Specific gravity measures the concentration of solutes in urine.

What is the normal color of urine?

Normal urine is typically light yellow to amber.

What factors can alter the color and smell of urine?

Factors include hydration, diet, medications, and disease.

What are the structures of the urinary tract?

The urinary tract includes the kidneys, ureters, bladder, and urethra.

What is the function of rugae in the bladder?

Rugae allow for expansion of the bladder as it fills with urine.

What type of epithelial tissue is found in the bladder?

The bladder is lined by transitional epithelium.

What is the function of the detrusor muscle?

The detrusor muscle contracts to expel urine from the bladder.

How do the female and male urethra differ?

The female urethra is shorter and more susceptible to infections than the male urethra.

What is the internal urethral sphincter?

The internal urethral sphincter is an involuntary muscle that controls urine flow from the bladder.

What is the external urethral sphincter?

The external urethral sphincter is a voluntary muscle that provides conscious control over urination.

What pathogen causes urinary tract infections (UTIs)?

Escherichia coli (E. coli) is the most common pathogen causing UTIs.