Pathophysiology: Chapter Thirty Three

What are the four organs of the urinary system?

Two kidneys, two ureters, one urinary bladder, and one urethra.

What is the primary function of the urinary system?

Maintaining homeostasis by managing the volume and composition of fluid reservoirs, primarily blood.

What is the function of the kidneys?

They filter blood and produce urine while helping maintain fluid homeostasis.

What is the function of the ureters?

Thin muscular tubes that transport urine from each kidney to the urinary bladder.

What is the function of the urinary bladder?

A hollow muscular organ that stores and eliminates urine.

What is the function of the urethra?

Transports urine from the bladder to the outside of the body.

Where are the kidneys located?

At the back of the abdominal cavity.

What is the renal capsule?

The thin outer covering of the kidney.

What structures are found in the renal cortex?

Renal corpuscles and portions of the renal tubules.

What structures are found in the renal medulla?

Cone-shaped structures called renal pyramids.

What is the function of the renal calyces?

Cup-shaped structures that collect urine from the renal pyramids.

What is the renal pelvis?

A funnel-shaped cavity inside the kidney that collects urine before it enters the ureter.

What is a nephron?

The structural and functional unit of the kidney responsible for producing urine.

What are the three major processes of urine formation?

Glomerular filtration, tubular reabsorption, and tubular secretion.

What is glomerular filtration?

Movement of protein-free plasma across the glomerular membrane, driven by hydrostatic pressure.

What is tubular reabsorption?

Movement of fluid and solutes from the tubular lumen into the peritubular capillaries.

What is tubular secretion?

Transfer of substances from the peritubular capillaries into the tubular lumen.

What is glomerular filtration rate (GFR)?

The volume of fluid filtered from the blood by both kidneys per minute.

What is the average normal GFR in a healthy adult according to the lecture?

Approximately 120–125 mL/minute.

What is renal autoregulation?

The ability of the kidneys to maintain a relatively constant GFR despite changes in systemic blood pressure.

What are the two main mechanisms of renal autoregulation?

The myogenic mechanism and tubuloglomerular feedback.

How does the myogenic mechanism respond to increased arterial blood pressure?

The afferent arteriole stretches, causing smooth muscle contraction and limiting blood flow into the glomerulus.

What is the purpose of afferent arteriole constriction during increased blood pressure?

To limit glomerular blood flow and help maintain a relatively constant GFR.

Which cells participate in tubuloglomerular feedback?

Macula densa cells of the distal tubule.

What do macula densa cells detect?

Sodium chloride (NaCl) delivery.

What happens when NaCl delivery to the macula densa increases?

The macula densa signals afferent arteriole constriction, decreasing glomerular blood flow and GFR.

What happens when NaCl delivery to the macula densa decreases?

The afferent arteriole dilates.

How does angiotensin II affect renal arterioles according to the lecture?

It constricts afferent and efferent arterioles.

How does atrial natriuretic peptide (ANP) affect the afferent arteriole?

It dilates the afferent arteriole.

How does strong sympathetic nervous system stimulation affect GFR?

It constricts afferent arterioles, reducing renal blood flow.

What is urinary frequency?

Frequent need to urinate.

What is urinary urgency?

A sudden and persistent need to urinate.

What is dysuria?

Burning or painful urination during or immediately after voiding.

What is nocturia?

Waking up frequently at night to urinate.

What is urinary incontinence?

Involuntary or accidental leakage of urine.

What is hematuria?

Visible or microscopic blood in the urine.

What is proteinuria?

Excess protein in the urine.

What is bacteriuria?

Presence of bacteria in the urine.

What is pyuria?

A high number of leukocytes in the urine.

What are urinary casts?

Tube-shaped microscopic structures formed in the renal tubules.

What does the presence of urinary casts indicate?

A disorder originating in the kidney nephrons.

What is renal agenesis?

A congenital condition in which one or both kidneys fail to develop before birth.

What is unilateral renal agenesis?

Absence or severe underdevelopment of one kidney.

What is bilateral renal agenesis?

Absence of both kidneys.

What is renal hypoplasia?

Failure of one or both kidneys to develop to normal size.

What is an ectopic kidney?

A kidney located in an abnormal position.

What is a pelvic kidney?

An ectopic kidney that remains in the pelvic region.

What is a crossed ectopic kidney?

A kidney located on the opposite side of the body.

What is a horseshoe kidney?

A congenital condition in which the lower poles of the kidneys fuse, forming a U-shaped structure.

What are cystic kidney diseases?

Disorders characterized by the formation of fluid-filled sacs in the kidney.

What is a renal cyst?

A dilated nephron tubule that forms a fluid-filled sac.

How can an enlarged renal cyst damage the kidney?

It can compress renal blood vessels, cause renal tissue degeneration, and obstruct tubular flow.

What are the characteristics of a simple renal cyst?

It is usually harmless and asymptomatic and generally does not require treatment.

In which population are simple renal cysts commonly seen according to the lecture?

Elderly patients, including patients receiving dialysis.

What is medullary sponge kidney?

A rare, benign congenital condition in which collecting ducts in the renal medulla become dilated.

Why is medullary sponge kidney called sponge-like?

Dilation of collecting ducts gives the inner kidney a sponge-like appearance.

What complications are associated with medullary sponge kidney?

Renal calculi and urinary tract infections.

What is adult polycystic kidney disease (APKD)?

An inherited disorder characterized by numerous fluid-filled cysts developing in the kidneys.

What is the inheritance pattern of adult polycystic kidney disease?

Autosomal dominant.

When do manifestations of adult polycystic kidney disease usually begin?

Usually around age 40; children and young adults may have no indications.

Why do multiple cysts develop in adult polycystic kidney disease?

Abnormality in tubular cell differentiation.

How do cysts damage the kidneys in adult polycystic kidney disease?

They enlarge the kidneys, compress and destroy renal tissue, and may cause chronic renal failure.

What are common manifestations of adult polycystic kidney disease?

Hypertension, flank pain, hematuria, infected kidneys, and UTIs.

Why can adult polycystic kidney disease cause hematuria?

Rupture of a renal cyst.

What is a urinary tract obstruction?

A condition that prevents urine from flowing normally through the urinary tract.

What can urinary tract obstruction cause?

Urine backup, urinary retention, and hydronephrosis.

What is an upper urinary tract obstruction?

An obstruction involving the kidneys, renal pelvis, or ureters.

What is a lower urinary tract obstruction?

An obstruction involving the lower urinary tract, such as the bladder or urethra.

What is hydronephrosis?

Abnormal backup of urine within the kidney because urine cannot drain properly into the bladder.

What happens during hydronephrosis?

Urine backs up and causes distention of the renal calyces and renal pelvis.

Why is hydronephrosis clinically important?

It is one of the most damaging effects of urinary obstruction.

What is urolithiasis?

Formation or presence of stones anywhere in the urinary tract.

Where can urinary stones develop?

In the kidneys, ureters, bladder, or urethra.

What are common predisposing factors for urolithiasis?

Excessive solutes in filtrate, insufficient fluid intake, UTIs, and high animal protein consumption.

When do manifestations of urolithiasis primarily occur?

When stones obstruct urine flow.

How are urinary stones classified?

According to their chemical composition.

What is the most common type of urinary stone?

Calcium stones, including calcium oxalate and calcium phosphate stones.

What factors predispose a person to calcium stones?

High oxalate diet, dehydration, and hyperparathyroidism.

What are struvite stones associated with?

UTIs caused by urease-producing bacteria.

How do urease-producing bacteria contribute to struvite stones?

Urease converts urea to ammonia, promoting struvite stone formation.

What is a staghorn calculus?

A large branching urinary stone that may develop with struvite stones over weeks.

What are uric acid stones associated with?

A high-purine diet, including animal protein consumption.

Are kidney or bladder stones always symptomatic?

No. Stones in the kidney or bladder are often asymptomatic.

What symptoms can urinary stones cause?

Urgency, frequency, dysuria, and hematuria.

What is renal colic?

Intense spasmodic pain caused by obstruction of the ureter.

Where does renal colic pain typically radiate?

From the flank into the groin.

What other manifestations may accompany renal colic?

Hematuria, nausea, vomiting, cool moist skin, and rapid pulse.

How may small urinary stones be treated?

They may eventually pass spontaneously.

What is lithotripsy (ESWL)?

A treatment that uses extracorporeal shock waves to break urinary stones.

What other treatments may be used for urinary stones?

Medications to partially dissolve stones or surgery.

How can urolithiasis be prevented?

Treat underlying conditions, adjust urine pH through dietary changes, and consistently increase fluid intake.

What is a urinary tract infection (UTI)?

An infection involving any part of the urinary system.

Where do UTIs most commonly occur?

In the lower urinary tract, particularly the bladder and urethra.

What is cystitis?

Inflammation of the urinary bladder.

What is urethritis?

Inflammation of the urethra.

What is pyelitis?

Inflammation of the renal pelvis.

What is pyelonephritis?

Inflammation and infection involving kidney tissue and the renal pelvis.

What is the most common cause of uncomplicated UTIs?

Escherichia coli (E. coli).

What other pathogen can cause uncomplicated UTIs?

Staphylococcus saprophyticus.

Which pathogens may cause complicated UTIs?

Proteus mirabilis, Klebsiella pneumoniae, Pseudomonas, and Staphylococcus aureus.