Urinary & Reproductive Lab – Comprehensive Study Notes

Urinary System – Gross Overview

• Two intimately related systems covered together in Lab 8: urinary (aka renal) and reproductive ("Uro-Repro").
• No wet‐lab physiology this semester (no urinalysis, no reproductive physiology experiments) – purely structure and pathways.
• Major urinary organs (in “kidney-to-toilet” order)
  • Kidneys → ureters → urinary bladder → urethra.
• “Renal” refers only to kidney; “urinary” includes the whole pathway.

Kidney Anatomy (Macroscopic)

• Bean-shaped retro-peritoneal organs sitting against posterior abdominal wall.
• Superior pole capped by adrenal (suprarenal) glands – fatty, yellowish "dollops" previously studied in endocrine lab.
• Hilum (medial indentation) admits:
  • \text{Renal artery (red)} – carries O$_2$-rich, waste-laden blood in.
  • \text{Renal vein (blue)} – carries cleansed blood out.
  • Ureter – exits inferiorly.
• External zones
  • Renal cortex (outer granular rim).
  • Renal medulla (inner, striated) comprised of renal pyramids.
• Collecting region sequence
  • Renal pyramid tip (papilla) drains → minor calyx → major calyx → renal pelvis → ureter.

Nephron Structure & Urine Formation (Microscopic)

• Functional filtering unit = nephron; >1 million per kidney.
• Vascular component
  • Afferent arteriole (wider) → glomerular capillary tuft → efferent arteriole (narrow) – P{in}>P{out} drives filtration.
• Tubular component (yellow in diagrams)
  • Bowman’s (glomerular) capsule surrounds tuft; together they form the renal corpuscle.
  • Proximal convoluted tubule (PCT).
  • Nephron loop (Loop of Henle) – descending & ascending limbs.
  • Distal convoluted tubule (DCT).
  • Multiple DCTs drain → collecting duct → papillary duct → minor calyx.
• Adjustment of filtrate composition occurs through most segments; once fluid reaches minor calyx it is fixed as "urine" (no more tweaks).

Two Nephron Classes

• Cortical nephrons ≈ 85 %; corpuscle sits high in cortex, short loops – bulk of routine filtration.
• Juxtamedullary nephrons ≈ 15 %; long loops extending deep into medulla – essential for \text{urine concentration} via counter-current multiplier.

Post-Renal Urine Pathway

• Minor calyx → major calyx → renal pelvis → ureter (peristaltic tube) → posteroinferior bladder wall (ureteric orifices) → bladder storage.
• Bladder to sphincters:
  • Internal urethral sphincter (smooth m.; involuntary).
  • External urethral sphincter (skeletal m.; voluntary – learned during potty training).
• Exit via urethra to exterior; length & shared use differ by sex.

Female Urinary Anatomy

• Short (~4 cm) urethra, independent of reproductive tract (separate openings for urethra & vagina).
• Bladder sits anterior to uterus; anteverted uterus compresses bladder – markedly during pregnancy → ↑frequency & urgency.
• Two sphincters as above; urethral orifice located in vestibule anterior to vaginal opening.
• Clinical pearl: shorter urethra → ↑incidence of ascending UTIs (e.g.
  E. coli from fecal contamination).

Male Urinary Anatomy

• Bladder superior to prostate; urethra subdivided:
  • Prostatic urethra (pierces doughnut-shaped prostate).
  • Membranous urethra (through urogenital diaphragm; location of external sphincter).
  • Spongy/penile urethra (within corpus spongiosum → external urethral meatus).
• Catheterization challenge: near 90° bend at urogenital diaphragm.
• Benign prostatic hyperplasia (BPH) narrows prostatic urethra → urinary retention, UTIs.

Reproductive Systems – Common Themes

• Gamete production + pathway to exterior.
  • Eggs (ova) in females; sperm in males.
• Female system adds gestation & lactation roles; male focused on gamete manufacture & delivery.

Female Reproductive Anatomy (Gross)

• Ovaries – intraperitoneal, tethered by broad & round ligaments; not physically fused to uterine tube.
• Uterine (Fallopian) tube regions: fimbriae → infundibulum → ampulla → isthmus → uterine cavity.
  • Fimbriae act as "catcher’s mitt"; open system = risk for ectopic pregnancies & retrograde flow (endometriosis).
• Uterus parts: fundus (dome), body, cervix (cervical canal & external os).
  • Anteverted orientation creates posterior fornix (cul-de-sac) around cervix.
• Uterine wall layers
  • Endometrium – cyclic build-up & shedding (menses) if no implantation.
  • Myometrium – thick smooth muscle for labor contractions.
• Blood supply
  • Ovarian aa. from abdominal aorta.
  • Uterine & vaginal aa. branches – rich vascular bed for pregnancy & menstruation.
• External genitalia (vulva): labia majora, labia minora, clitoris (erectile), vestibule.

Ovarian Cycle Snapshot

• Folliculogenesis visualized ~clockwise:
  • Primordial → primary → secondary → Graafian follicle.
  • Ovulation: follicle ruptures at surface; oocyte expelled.
  • Remainder becomes corpus luteum → corpus albicans.

Mammary Glands & Lactation

• Secondary sex organ supplying neonate nutrition.
• Architecture:
  • Lobes/lobules with secretory alveoli produce milk.
  • Milk drains → lactiferous ducts → lactiferous sinuses → multiple openings in nipple (NOT single orifice).
  • Suspensory (Cooper’s) ligaments support breast within pectoral fat pad.
• Neuro-endocrine reflex:
  • Infant suckling → nipple mechanoreceptors → hypothalamus → posterior pituitary releases oxytocin.
  • \text{Oxytocin} causes myoepithelial cell contraction → "milk let-down" (ejection).
  • Delay ~10 s; bottle-fed infants may choke due to single-hole nipples vs multi-duct flow in breast.

Male Reproductive Anatomy (Gross)

• Testes develop near kidneys, descend through inguinal canal into scrotum (cooler than core body 37^{\circ}\text{C}; sperm require ~34^{\circ}\text{C}).
• Scrotal temperature regulation via cremaster (skeletal) & dartos (smooth) muscles.
• Testis internal structure:
  • Seminiferous tubules (spermatogenesis) converge → rete testis → efferent ductules → epididymis (head–body–tail).
• Epididymis: sperm storage & quality control (defective sperm phagocytosed).

Sperm Pathway ("SEVEn UP" mnemonic)

1. Seminiferous tubules.
2. Epididymis.
3. Vas/ductus deferens (ascends within spermatic cord; loops over ureter).
4. Ejaculatory duct (within prostate; union of vas deferens ampulla + seminal vesicle duct).
5. (nothing for "n")
6. Urethra (prostatic → membranous → spongy).
7. Penis (external release).

Male Accessory Glands & Semen Composition

• Seminal vesicles (posterior to bladder): viscous fructose-rich fluid (≈ 60 % semen volume) – energy + prostaglandins.
• Prostate: slightly alkaline, citrate, enzymes (≈ 30 %). BPH & cancer clinically significant.
• Bulbourethral (Cowper’s) glands (lateral to membranous urethra): clear mucus pre-ejaculate; neutralizes acidic urethra; visible only in posterior view, often absent in midsagittal models.

Erectile Tissue & Mechanism

• Three longitudinal columns:
  • Two corpora cavernosa (dorsal, with central arteries).
  • One corpus spongiosum (ventral, surrounds urethra; expands as glans).
• Sexual arousal → parasympathetic vasodilation → blood engorges cavernosa → erection; venous outflow compressed.

Study & Lab Strategies

• Use Visible Body® modules:
  • Urinary anatomy ID → skip pelvic floor neuromuscular digressions not covered in lecture.
  • Urinary pathologies animations (UTI, renal stones, BPH) – helpful clinical context.
  • Reproductive animations for ovulation, fertilization, erection, lactation.
• Textbook & Visible Body images are congruent; VB offers in-body 3-D spatial perspective.
• Practice pathway questions ("If filtrate exits the nephron loop, which segment next?" "An oocyte just left the fimbriae; where is it now?" etc.).
• Quiz: Urinary & Reproductive Lab (no separate data sheet) – focus on structures highlighted in PowerPoint & pathways.

Key Pathways – Quick Reference

• Urine (microscopic): renal corpuscle → PCT → nephron loop → DCT → collecting duct → papillary duct.
• Urine (gross): renal pyramid → minor calyx → major calyx → renal pelvis → ureter → bladder → urethra (M/F differences).
• Egg: ovary → fimbriae → uterine tube (ampulla most common fertilization site) → uterine cavity → cervix → vagina (if menses).
• Sperm: seminiferous tubules → epididymis → vas deferens (+ampulla) → ejaculatory duct → prostatic, membranous, spongy urethra → external urethral orifice.

Ethical / Clinical Connections

• Catheterization technique variation by sex (risk of urethral trauma in males at 90° bend).
• BPH & prostate cancer impact on urination & fertility.
• UTIs more prevalent in females – hygiene & clinical management.
• Ectopic pregnancy & endometriosis demonstrate open nature of female peritoneal cavity.
• Lactation physiology informs breast-feeding practices and neonatal nutrition.