Urinary System Anatomy

General Features of the Urinary System

The urinary system is responsible for filtering blood, removing waste, and regulating fluid and electrolyte balance. Key anatomical structures include the kidneys, ureters, bladder, and urethra.

• Kidney: Filters blood to produce urine; regulates water, electrolyte, and acid-base balance.

• Ureter: Transports urine from the kidney to the bladder.

• Bladder: Stores urine until excretion.

• Urethra: Conducts urine from the bladder to the outside of the body.

• Renal artery: Supplies oxygenated blood to the kidney.

• Renal vein: Drains deoxygenated blood from the kidney.

Kidney Structure

The kidney is divided into several distinct regions and structures, each with specific functions in urine formation and blood filtration.

• Renal capsule: Tough, fibrous covering that protects the kidney.

• Cortex: Outer region containing glomeruli and convoluted tubules; site of filtration.

• Medulla: Inner region containing renal pyramids; involved in urine concentration.

• Renal pyramids: Cone-shaped structures in the medulla; contain nephron loops and collecting ducts.

• Renal columns: Extensions of cortex between pyramids; contain blood vessels.

• Renal papilla: Tip of pyramid where urine drains into minor calyx.

• Minor calyx: Collects urine from renal papilla.

• Major calyx: Formed by convergence of minor calyces; drains into renal pelvis.

• Renal pelvis: Funnel-shaped structure collecting urine from calyces; leads to ureter.

Blood Flow Through the Kidney

Blood flow through the kidney is essential for filtration and urine production. The pathway involves several arteries and veins.

• Renal artery → Segmental arteries → Interlobar arteries → Arcuate arteries → Cortical radiate arteries → Afferent arteriole → Glomerulus → Efferent arteriole → Peritubular capillaries → Venules → Cortical radiate veins → Arcuate veins → Interlobar veins → Renal vein

Key Formula:

Nephron Structure

The nephron is the functional unit of the kidney, responsible for filtering blood and forming urine.

• Glomerular capsule (Bowman's capsule): Surrounds the glomerulus; collects filtrate.

• Proximal convoluted tubule: Reabsorbs water, ions, and nutrients from filtrate.

• Nephron loop (Loop of Henle): Concentrates urine by reabsorbing water and salts.

• Distal convoluted tubule: Further adjusts filtrate composition.

• Collecting duct: Final site for water reabsorption; delivers urine to renal papilla.

• Afferent arteriole: Brings blood to glomerulus.

• Glomerulus: Capillary network for filtration.

• Efferent arteriole: Drains blood from glomerulus.

• Peritubular capillaries: Surround tubules for reabsorption and secretion.

Urine Flow Through the Kidney

Urine is produced in the nephron and flows through a series of structures before exiting the body.

• Nephron → Collecting duct → Renal papilla → Minor calyx → Major calyx → Renal pelvis → Ureter → Bladder → Urethra

Reproductive System Anatomy

Male Reproductive Anatomy

The male reproductive system produces and delivers sperm. Key structures include:

• Testes: Produce sperm and testosterone.

• Epididymis: Stores and matures sperm.

• Ductus deferens (vas deferens): Transports sperm from epididymis to urethra.

• Penis: Organ for copulation and urine excretion.

• Prostate gland: Secretes fluid that nourishes and protects sperm.

• Prostatic urethra: Portion of urethra passing through prostate.

Female Reproductive Anatomy

The female reproductive system produces eggs and supports fetal development. Key structures include:

• Ovaries: Produce eggs (ova) and hormones (estrogen, progesterone).

• Uterus: Site of implantation and fetal development.

• Body of uterus: Main portion of uterus.

• Horns of uterus: Extensions of uterus in some mammals (e.g., pigs).

• Uterine tubes (fallopian tubes): Transport eggs from ovary to uterus.

Summary Table: Key Urinary and Reproductive Structures

Additional info:

• The list of structures provided covers all major anatomical features required for identification in laboratory settings, including those visible in dissection, models, and software.

• Understanding the flow of blood and urine through the kidney is essential for comprehending renal physiology and pathology.

• Comparative anatomy (e.g., fetal pig vs. adult pig) is often used in lab to illustrate structural differences and similarities.