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Anatomy Exam 3 · Class of 2028

Key Flow Sequences

The named, ordered pathways worth memorizing step-by-step — how filtrate becomes urine, how bile and pancreatic juice reach the duodenum, how food transits the alimentary canal, how sperm and the oocyte travel their respective reproductive tracts, how lymph reaches the venous system, and how the testis migrates into the scrotum during development. (For blood/vascular flow specifically, see the separate Blood Flow & Vasculature Guide.)

Filtrate & Urine Flow Bile & Pancreatic Juice Flow Food/Bolus Transit Sperm Flow Oocyte Flow Lymphatic Drainage Testicular Descent

Filtrate & Urine Flow Nephrology/Urinary

Two stages, exactly as taught: an intrarenal stage (filtrate moving through the nephron's own tubules) followed by an extrarenal / urological stage (urine moving through the collecting system and out of the body).

Intrarenal — filtrate through the nephron

Glomerulus / Bowman's capsule→ Proximal convoluted tubule→ Descending limb (thick & thin)→ Nephron loop (loop of Henle)→ Ascending limb (thin & thick)→ Distal convoluted tubule→ Collecting duct→ Papillary duct→ Renal papilla→ Minor calyx→ Major calyx
Once filtrate reaches the collecting ducts it is officially urine — no further modifications occur past this point.

Extrarenal / urological — urine out of the body

Renal pelvis→ Ureter→ Bladder→ Urethra→ External urethral meatus/orifice
The male urethra is subdivided further along this same path: prostatic urethra (through the prostate) → membranous urethra (pierces the urogenital diaphragm) → penile/spongy urethra (through the penile shaft) → external urethral orifice. The female urethra has no such subdivisions — it's simply "the urethra."

Bile & Pancreatic Juice Flow GI · Endocrine (pancreas)

Two separate secretions that converge on the same final doorway into the duodenum — the ampulla of Vater.

Bile: liver & gallbladder → duodenum

Liver (hepatocytes)→ intrahepatic bile ductules→ right & left hepatic ducts→ Common hepatic duct→ Gallbladder (fundus → body → neck)↔ cystic duct→ Common bile duct (CBD)→ Ampulla of Vater→ Major duodenal papilla
The gallbladder sits between the right and quadrate lobes of the liver and stores/concentrates bile between meals rather than producing it — bile flows into it via the cystic duct and back out the same duct when needed. The common bile duct passes behind the first part of the duodenum, then through the head of the pancreas, before terminating at the ampulla of Vater.

Pancreatic exocrine secretions → duodenum

Pancreatic acini→ small intralobular ducts→ Main pancreatic duct (of Wirsung)→ joins the CBD at the Ampulla of Vater→ Major duodenal papilla
The main pancreatic duct runs left to right through the gland, receiving numerous small ducts, then turns inferior/posterior/right at the neck of the pancreas to join the CBD about 3–4 inches below the pylorus. A separate accessory duct (of Santorini), not universally present, instead empties directly into the duodenum at the minor papilla, bypassing the ampulla. Both ducts arise embryologically from the fusion of a ventral and a dorsal pancreatic duct.

Food/Bolus Transit GI

The full path of ingested material through the alimentary canal, mouth to anus — about 9–10 meters (30 feet) end to end.

Oral cavity→ Oropharynx→ Esophagus→ Stomach (cardia → fundus → body → pyloric antrum/canal)→ Duodenum→ Jejunum→ Ileum→ Cecum→ Ascending colon→ Transverse colon→ Descending colon→ Sigmoid colon→ Rectum→ Anal canal
Key checkpoints along the way: the upper esophageal sphincter (cricopharyngeus, skeletal muscle) and lower/cardiac sphincter (smooth muscle, not a true anatomic sphincter) bound the esophagus; the pyloric sphincter gates stomach-to-duodenum flow; the ileocecal valve gates small-to-large intestine flow; and the internal (smooth muscle, involuntary) and external (skeletal muscle, voluntary) anal sphincters gate the final exit.

Sperm Flow Male Reproductive

From production in the testis to ejaculation — sperm are functionally immature until they finish this entire path.

Seminiferous tubules→ Straight tubules→ Rete testis→ Efferent ductules→ Epididymis (head → body → tail)→ Ductus deferens→ Ampulla of ductus deferens+ excretory duct of seminal gland→ Ejaculatory duct→ Prostatic urethra→ Membranous urethra→ Spongy (penile) urethra→ External urethral orifice
Within the testis, the seminiferous tubules uncoil into straight tubules in the mediastinum, which interconnect to form the rete testis. The tail of the epididymis is where the coiled tubes finally uncoil into the single tube of the ductus deferens. Before entering the prostate, the ductus deferens curves around the bladder and ureter, then expands into the ampulla, which joins the seminal gland's excretory duct to form the ejaculatory duct — the point where the sperm pathway and the accessory-gland secretions finally merge, just before both empty into the prostatic urethra.

Oocyte Flow Female Reproductive

From ovulation to the uterine cavity — note that the uterine tube never physically attaches to the ovary; the fimbriae simply sweep the released oocyte inward.

Ovary (ovulation)→ Fimbriae→ Infundibulum→ Ampulla (fertilization site)→ Isthmus→ Interstitial (intramural) segment→ Uterine cavity
Ciliary movement carries the oocyte through the tube toward the uterus over about 3–4 days; the full trip for a fertilized pre-embryo to reach the uterine lumen takes roughly 5–6 days total. The isthmus is the narrow segment attaching to the uterus, and the interstitial/intramural segment is the short final stretch that actually passes through the uterine wall itself.

Lymphatic Drainage → Venous System cross-topic

Regardless of which organ it starts at, lymph everywhere in the body funnels toward one of two final ducts before rejoining the bloodstream.

Organ / regional nodes→ Lymphatic trunks (follow the arteries)→ Cisterna chyli (abdomen, L1–L2)→ Thoracic duct→ Left venous angle (left subclavian v. + left IJV)
The exception — right lymphatic duct: lymph from the right upper quadrant of the body (right head/neck, right arm, right side of the thorax) skips the cisterna chyli/thoracic duct route entirely and drains via the shorter right lymphatic duct directly into the right venous angle (right subclavian v. + right IJV). The thyroid gland is a good example of an organ whose lymphatics explicitly terminate in both the thoracic duct and the right lymphatic duct, depending on which side of the gland is draining.

Two organ-specific routes worth knowing by name: the ovaries/testes drain to the lumbar (para-aortic) nodes — bypassing the pelvic nodes entirely, since these organs migrate down from near the kidneys in development — before those lumbar nodes feed into the cisterna chyli; and the abdominal GI organs drain to nodes clustered around their corresponding artery (celiac nodes for foregut, superior mesenteric nodes for midgut, inferior mesenteric nodes for hindgut) before likewise reaching the cisterna chyli.

Testicular Descent (developmental migration, not a fluid flow)

Included here because it's taught as a staged, ordered path just like the fluid flows above — the testis physically migrates from its site of formation to its final home in the scrotum.

Forms near the kidneys (intra-abdominal)→ Pulled inferiorly by the gubernaculum→ Passes through the inguinal canal→ Scrotum
The gubernaculum testis anchors the testis early on; as the fetus grows in length, the gubernaculum itself does not elongate, so it effectively pulls the testis inferiorly relative to the lengthening body. The ductus deferens, blood vessels, lymphatics, and nerves all stay bundled to the descending testis, forming the spermatic cord, and travel with it through the inguinal canal. Along the way the testis picks up its tunica vaginalis — a peritoneal pouch dragged down during descent that becomes the serous lining of the scrotal cavity. Two temperature notes tie directly to why this migration happens: testicular development requires ~98.6°F (hence forming inside the warmer abdominal cavity first), while sperm development requires ~96.6°F, about 2°F cooler than core body temperature (hence finishing in the cooler extra-abdominal scrotum).