A 29-year-old man presents to his primary care provider complaining of testicular pain. He reports a four-day history of dull chronic pain in his left testicle that is worse with standing. His past medical history is notable for asthma and major depressive disorder. He takes inhaled albuterol as needed and sertraline. He is sexually active with a single female partner and always uses barrier protection. His temperature is 99.2°F (37.3°C), blood pressure is 125/75 mmHg, pulse is 85/min, and respirations are 17/min. Physical examination reveals a non-tender twisted mass along the left spermatic cord that disappears when the patient lies supine. This patient’s condition most likely stems from decreased laminar flow at which of the following vascular junctions?

Left testicular vein – Left renal vein

Descending aorta – Left testicular artery

Left testicular vein – Left suprarenal vein

Left testicular vein – Inferior vena cava

Left testicular vein – Left internal iliac vein

On cardiology service rounds, your team sees a patient admitted with an acute congestive heart failure exacerbation. In congestive heart failure, decreased cardiac function leads to decreased renal perfusion, which eventually leads to excess volume retention. To test your knowledge of physiology, your attending asks you which segment of the nephron is responsible for the majority of water absorption. Which of the following is a correct pairing of the segment of the nephron that reabsorbs the majority of all filtered water with the means by which that segment absorbs water?

Proximal convoluted tubule via passive diffusion following ion reabsorption

Distal convoluted tubule via passive diffusion following ion reabsorption

Distal convoluted tubule via aquaporin channels

Thick ascending loop of Henle via passive diffusion following ion reabsorption

Collecting duct via aquaporin channels

A 75-year-old male presents to the emergency room complaining of severe lower abdominal pain and an inability to urinate. He reports that he last urinated approximately nine hours ago. When asked to urinate, only a few drops dribble from the tip of his penis. Further questioning reveals that the patient has experienced progressively worsening difficulty with urinating over the past two years. He has lived alone for five years since his wife passed away. He has not seen a doctor in that time. His temperature is 98.8°F (37.1°C), blood pressure is 145/90 mmHg, pulse is 115/min, and respirations are 22/min. He appears to be in severe pain. Physical examination reveals a distended bladder and significant tenderness to palpation over the inferior aspect of his abdomen. Which of the following sets of lab values would most likely be found in a urinalysis of this patient?

Urine osmolality 300 mOsmol/kg H2O, Urine Na+ 45 mEq/L, FENa 5%, no casts

Urine osmolality 550 mOsmol/kg H2O, Urine Na+ 15 mEq/L, FENa 0.9%, red blood cell casts

Urine osmolality 400 mOsmol/kg H2O, Urine Na+ 25 mEq/L, FENa 1.5%, no casts

Urine osmolality 200 mOsmol/kg H2O, Urine Na+ 35 mEq/L, FENa 3%, muddy brown casts

Urine osmolality 600 mOsmol/kg H2O, Urine Na+ 15 mEq/L, FENa 0.8%, hyaline casts

A 40-year-old sailor is brought to a military treatment facility 20 minutes after being involved in a navy ship collision. He appears ill. He reports a sensation that he needs to urinate but is unable to void. His pulse is 140/min, respirations are 28/min, and blood pressure is 104/70 mm Hg. Pelvic examination shows ecchymoses over the scrotum and perineum. There is tenderness over the suprapubic region and blood at the urethral meatus. Digital rectal examination shows a high-riding prostate. Abdominal ultrasound shows a moderately distended bladder. X-rays of the pelvis show fractures of all four pubic rami. Which of the following is the most likely cause of this patient's symptoms?

Tearing of the posterior urethra

Tearing of the anterior urethra

Rupture of the corpus cavernosum

A 22-year-old Caucasian male is stabbed in his left flank, injuring his left kidney. As the surgeon undertakes operative repair, she reviews relevant renal anatomy. All of the following are correct regarding the left kidney EXCEPT?

The left kidney has a longer renal artery than the right kidney

The left kidney has a longer renal vein than the right kidney

The left kidney underlies the left 12th rib

The left kidney moves vertically during deep breathing

The left kidney lies between T12 and L3

Urinary system overview for USMLE Step 2 CK: High-Yield Anatomy Lessons

System Overview - The Body's Filter

Primary Role: Filters blood to produce urine, removing waste while retaining essential substances. Regulates blood volume, pressure, pH, and electrolyte balance.
Key Components:
- Kidneys: Paired, bean-shaped organs; the primary filtration units.
- Ureters: Tubes carrying urine from kidneys to the bladder.
- Bladder: Muscular sac for urine storage.
- Urethra: Tube for urine excretion.

Male and Female Urinary Systems

⭐ The kidneys are retroperitoneal organs (except for the anterior surface), making them accessible from a posterior surgical approach, which avoids entering the peritoneal cavity.

📌 Mnemonic (Retroperitoneal Organs): SAD PUCKER

Kidney Gross Anatomy - Bean-Shaped Powerhouse

Kidney cross-section with internal structures and vessels

Location: Retroperitoneal, at T12-L3 level. The right kidney is slightly lower than the left.
Structure (External to Internal):
- Renal Capsule: Fibrous outer covering.
- Cortex: Outer parenchyma containing glomeruli and convoluted tubules.
- Medulla: Inner parenchyma arranged in pyramids, containing Loops of Henle and collecting ducts. Renal columns are cortical extensions between pyramids.
Urine Flow: Papilla → Minor Calyx → Major Calyx → Renal Pelvis → Ureter.
Hilum (Anterior → Posterior): Renal Vein, Artery, Ureter. 📌 Mnemonic: VAU.

⭐ The left renal vein is longer than the right and passes between the superior mesenteric artery (SMA) and the aorta. This anatomical course makes it susceptible to compression, leading to "Nutcracker Syndrome".

Ureters, Bladder, Urethra - The Plumbing Crew

Ureters: Muscular tubes carrying urine from kidneys to bladder; retroperitoneal.
- Three constrictions (sites of stone impaction): ureteropelvic jct (UPJ), pelvic inlet, ureterovesical jct (UVJ).
- 📌 Mnemonic: "Water (urine) flows under the bridge (uterine a. / vas deferens)."
Bladder: Hollow organ with detrusor muscle; stores urine.
- Lined by transitional epithelium (urothelium).
- Trigone: Smooth triangular area between ureteric orifices and internal urethral orifice.
Urethra: Drains urine from bladder.
- Female: Short (~4 cm); ↑ risk of UTIs.
- Male: Long (~20 cm); 3 parts (prostatic, membranous, spongy).

Male and Female Urinary System Anatomy

⭐ High-Yield: The most common site for kidney stone obstruction is the ureterovesical junction (UVJ), the narrowest point of the ureter.

Vasculature & Innervation - Power and Control

Arterial Supply: Follows a precise path to the glomerulus.

Venous Drainage: Mirrors the arterial path, exiting via the renal vein into the IVC.

Renal Vasculature: Arterial Supply and Venous Drainage

Innervation: Primarily autonomic.
- Sympathetic (T10-L1): Vasoconstricts afferent arterioles → ↓ RBF & GFR. Stimulates renin release.
- Parasympathetic (Vagus/Pelvic Splanchnic): Vagal fibers to kidney (role unclear); pelvic splanchnics (S2-S4) cause detrusor contraction for micturition.

⭐ Exam Favorite: Kidneys receive 20-25% of the total cardiac output, highlighting their immense filtration role.

The kidneys are retroperitoneal organs located at the T12-L3 vertebral level; the right kidney is typically lower than the left.

From anterior to posterior, the structures at the renal hilum are the Renal Vein, Renal Artery, and Renal Pelvis (VAP).

Ureters have three physiological constrictions where stones often lodge: the ureteropelvic junction (UPJ), the pelvic brim, and the ureterovesical junction (UVJ).

The left renal vein is longer and passes between the superior mesenteric artery (SMA) and the aorta.

The adrenal glands sit superior to the kidneys but are embryologically and functionally distinct.

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