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Complete digestive pathway

Oral cavity → Oropharynx → Laryngopharynx → Esophagus → Lower esophageal sphincter → Stomach → Pyloric sphincter → Duodenum → Jejunum → Ileum → Ileocecal valve → Cecum → Ascending colon → Transverse colon → Descending colon → Sigmoid colon → Rectum → Anal canal → Anus

Oral cavity, teeth, and tongue

Chew food, mix it with saliva, moisten it, and form a bolus. Salivary amylase begins starch digestion.

Mechanical digestion

Physical breakdown of food, such as chewing and stomach churning.

Chemical digestion

Breakdown of food by acids and enzymes.

Bolus

A soft mass of chewed food mixed with saliva.

Salivary glands

Secrete saliva that lubricates food and begins carbohydrate digestion.

Salivary amylase

An enzyme that begins starch digestion in the oral cavity.

Pharynx

Uses muscular contractions to push the bolus into the esophagus.

Oropharynx

The first pharyngeal region through which swallowed food passes.

Laryngopharynx

The pharyngeal region that directs food into the esophagus.

Esophagus

Transports the bolus to the stomach through peristalsis.

Peristalsis

Wave-like muscular contractions that move material through a tube.

Lower esophageal sphincter

Allows food to enter the stomach and helps prevent acid reflux.

Stomach

Mixes food mechanically and begins protein digestion using acid and enzymes.

Parietal cells

Stomach cells that secrete HCl and intrinsic factor.

Chief cells

Stomach cells that secrete inactive pepsinogen.

Pepsinogen

The inactive form of pepsin.

Pepsin

The active stomach enzyme that digests proteins.

Chyme

A semi-liquid mixture of partially digested food and stomach secretions.

Pyloric sphincter

Controls the movement of chyme from the stomach into the duodenum.

Small intestine

Performs most chemical digestion and absorbs most nutrients.

Small-intestine order

Duodenum → Jejunum → Ileum.

Duodenum

Receives chyme, bile, pancreatic enzymes, and bicarbonate; a major site of chemical digestion.

Jejunum

The middle small-intestine region and a major site of nutrient absorption.

Ileum

The final small-intestine region; continues absorption and connects to the cecum.

Ileocecal valve

Controls movement from the ileum into the cecum and helps prevent backflow.

Liver

Produces bile and stores nutrients.

Gallbladder

Stores and concentrates bile.

Pancreas

Secretes digestive enzymes and bicarbonate-rich buffer into the duodenum.

Bicarbonate

Neutralizes acidic chyme entering the duodenum.

Large intestine

Absorbs water and compacts indigestible material into feces.

Large-intestine pathway

Cecum → Ascending colon → Transverse colon → Descending colon → Sigmoid colon → Rectum → Anal canal → Anus.

Cecum

The first pouch of the large intestine; receives material from the ileum.

Colon order

Ascending → Transverse → Descending → Sigmoid.

Rectum

Temporarily stores feces.

Anal canal and anus

Allow feces to leave the digestive tract.

Complete kidney blood pathway

Renal artery → Segmental artery → Interlobar artery → Arcuate artery → Cortical radiate artery → Afferent arteriole → Glomerulus → Efferent arteriole → Peritubular capillaries or vasa recta → Cortical radiate vein → Arcuate vein → Interlobar vein → Renal vein.

Afferent arteriole

Carries blood into the glomerulus. Afferent arrives.

Glomerulus

A network of about 50 intertwining capillaries that filters blood.

Efferent arteriole

Carries blood away from the glomerulus. Efferent exits.

Peritubular capillaries

A capillary network surrounding renal tubules; participates in reabsorption and secretion.

Vasa recta

Long capillaries surrounding nephron loops; help maintain the medullary concentration gradient.

Renal corpuscle

Glomerulus plus glomerular capsule.

Glomerular capsule

The expanded beginning of the renal tubule that surrounds the glomerulus and receives filtrate.

Capsular space

The space where newly formed filtrate enters.

Nephron

The basic structural and functional unit of the kidney.

Complete filtrate pathway

Glomerulus → Capsular space → PCT → Descending limb → Ascending limb → DCT → Collecting duct → Papillary duct.

Proximal convoluted tubule, PCT

Begins at the tubular pole and performs most reabsorption.

PCT location

Tubular pole of the renal corpuscle.

Descending limb

Water leaves the filtrate, making the filtrate more concentrated.

Ascending limb

Sodium and chloride leave the filtrate, but water does not.

Nephron loop

Consists of a descending limb and an ascending limb.

Distal convoluted tubule, DCT

Passes the vascular pole and performs regulated reabsorption and secretion.

DCT location

Vascular pole, between the afferent and efferent arterioles.

Collecting duct

Receives fluid from multiple nephrons and performs final water adjustments.

Macula densa

Specialized DCT cells that monitor sodium chloride in tubular fluid.

Juxtaglomerular cells

Modified smooth-muscle cells, mainly in the afferent arteriole, that release renin.

Juxtaglomerular complex

An endocrine structure that helps regulate blood pressure, GFR, and normal filtrate production.

Filtration

Movement from glomerular blood into the capsular space.

Reabsorption

Movement from the renal tubule back into the blood.

Secretion

Movement from the blood into the renal tubule.

Complete urine pathway

Collecting duct → Papillary duct → Renal papilla → Minor calyx → Major calyx → Renal pelvis → Ureter → Urinary bladder → Urethra → External urethral opening.

Renal papilla

The tip of a renal pyramid where urine drains.

Minor calyx

Receives urine from a renal papilla.

Major calyx

Receives urine from several minor calyces.

Renal pelvis

A funnel-shaped region that directs urine into the ureter.

Ureter

A muscular tube about 30 cm long that moves urine from the kidney to the bladder.

Urinary bladder

Temporarily stores urine.

Detrusor muscle

Smooth muscle in the bladder wall that contracts during urination.

Trigone

A triangular bladder area bounded by two ureteral openings and one internal urethral opening.

Urethra

Carries urine from the bladder to the outside.

Ureter versus urethra

Ureter: kidney to bladder. Urethra: bladder to outside.

Complete sperm pathway

Seminiferous tubules → Straight tubules → Rete testis → Efferent ductules → Epididymis → Ductus deferens → Ampulla of ductus deferens → Ejaculatory duct → Prostatic urethra → Membranous urethra → Spongy urethra → External urethral opening.

Seminiferous tubules

The site of sperm production.

Interstitial cells, Leydig cells

Produce testosterone.

Straight tubules

Carry sperm from seminiferous tubules to the rete testis.

Rete testis

A network of channels carrying sperm toward the efferent ductules.

Efferent ductules

Carry sperm from the rete testis to the epididymis.

Epididymis

A highly coiled tube where sperm mature and are stored.

Epididymis epithelium

Pseudostratified columnar epithelium with stereocilia.

Stereocilia

Long, nonmotile microvilli; they are not true cilia.

Ductus deferens

A 40–45 cm muscular tube that transports sperm.

Epididymis versus ductus deferens

Epididymis matures and stores sperm; ductus deferens transports sperm.

Seminal vesicle

A tubular gland that adds fructose-rich fluid to semen.

Ejaculatory duct

Formed by the ductus deferens and seminal vesicle duct; empties into the prostatic urethra.

Prostate gland

Adds prostatic fluid to semen and surrounds the prostatic urethra.

Bulbourethral glands

Secrete lubricating mucus before ejaculation.

Male urethra order

Prostatic urethra → Membranous urethra → Spongy urethra.

Spermatic cord

Contains the ductus deferens, blood vessels, nerves, lymphatics, fascia, and muscle.

Pampiniform plexus

A network of veins that cools blood traveling to the testis.

Dartos muscle

Smooth muscle that wrinkles the scrotal skin.

Cremaster muscle

Raises and lowers the testis.

Dartos versus cremaster

Dartos wrinkles the scrotal skin; cremaster elevates the testis.

Complete oocyte pathway

Ovary → Peritoneal cavity → Fimbriae → Infundibulum → Ampulla → Isthmus → Uterine part → Uterine cavity.

Ovary

Produces oocytes, estrogen, and progesterone.

Ovarian cortex

Contains ovarian follicles.

Ovarian medulla

Contains blood vessels, nerves, and connective tissue.

Uterine tube

A muscular tube that transports the oocyte toward the uterus.

Uterine-tube order

Infundibulum → Ampulla → Isthmus → Uterine part.

Fimbriae

Fingerlike projections that guide the oocyte toward the infundibulum.