digestive, reproduction, and urination

Digestive System Overview

  • Functions: Breaks down food, absorbs nutrients, and eliminates waste.

  • Processes:

    • Ingestion (eating)

    • Propulsion (swallowing, peristalsis)

    • Mechanical Breakdown (chewing, churning, segmentation)

    • Digestion (chemical breakdown of carbs, lipids, proteins)

    • Absorption (nutrients enter bloodstream)

    • Defecation (elimination of waste)

Alimentary Canal (GI Tract) Organs (7 total)

  1. Mouth: Entry point; includes oral vestibule, oral cavity, labia (lips), cheeks, labial frenulum (inferior/superior), palate (hard/soft), uvula.

  2. Pharynx: Nasopharynx, oropharynx, laryngopharynx.

  3. Esophagus: Propels food; passes through diaphragm.

  4. Stomach: Regions include cardia, fundus, body, pyloric sphincter, greater/lesser curvature, rugae.

  5. Small Intestine: Major absorption site; duodenum (5%), jejunum (40%), ileum (60%); major duodenal papilla (entry for bile and pancreatic enzymes).

  6. Large Intestine: Water absorption; includes teniae coli, haustra, epiploic appendages, ileocecal valve, cecum, appendix, colon (ascending, transverse, descending, sigmoid), flexures (hepatic, splenic), rectum, anal canal, internal/external sphincters.

  7. Anus: Terminal outlet.

Accessory Organs (6 total)

  1. Teeth: 20 deciduous (baby teeth), 32 permanent.

  2. Tongue: Contains taste buds (filiform, fungiform, vallate), lingual tonsil, terminal sulcus.

  3. Salivary Glands: Parotid (largest), submandibular, sublingual.

  4. Liver: Largest gland; produces bile, stores glycogen, detoxifies blood; structures include lobes (R, L, caudate, quadrate), diaphragmatic/visceral surfaces, ligaments (falciform, round, ligamentum venosum), bile duct, porta hepatis, hepatic portal vein, common hepatic duct.

  5. Gall Bladder: Stores bile; cystic duct joins common hepatic duct to form bile duct.

  6. Pancreas: Endocrine (insulin/glucagon) and exocrine (digestive enzymes); tail, main pancreatic duct (joins bile duct at major duodenal papilla).

Key Anatomical Features

  • Mouth: Oral vestibule (front of teeth), oral cavity (behind teeth), labial frenulum connects lips to gums, palate (hard aids chewing, soft closes nasopharynx).

  • Stomach: Regions and features (e.g., cardia, fundus); rugae (folds aiding expansion).

  • Small Intestine: Longest organ, divided into duodenum (enzymes from liver/pancreas), jejunum, and ileum.

  • Large Intestine: Haustra (pouches), teniae coli (muscle strips), epiploic appendages (fat).

  • Liver: Divided into lobes and ligaments; major vessels/nerves enter at porta hepatis.

  • Gall Bladder: Bile storage; cystic duct critical for bile flow.

Pancreas: Delivers enzymes to the small intestine via pancreatic duct.

Urinary System Overview

  • Function: Filters blood to remove toxins, regulates blood volume and electrolyte balance, and stores/eliminates urine.

Organs

  1. Kidneys:

    • Function: Filters blood, regulates blood volume and electrolytes, forms urine.

    • Anatomy:

      • Renal Cortex: Outer layer of the kidney.

      • Renal Medulla: Inner region containing the renal pyramids.

      • Renal Pyramids: Cone-shaped structures within the medulla; contain nephrons.

      • Renal Columns: Extensions of the cortex separating the pyramids.

      • Renal Pelvis: Funnel-shaped structure; collects urine and directs it to the ureter.

      • Calices (Minor/Major): Cup-like structures that collect urine from the pyramids and drain it into the renal pelvis.

  2. Ureters:

    • Function: Tubes that transport urine from the kidneys to the bladder.

    • Structure: Enter the bladder obliquely, preventing backflow of urine.

  3. Bladder:

    • Function: Stores urine.

    • Capacity: Holds up to 500 mL (approximately 2 cups) when full.

  4. Urethra:

    • Function: Drains urine from the bladder to the exterior of the body.

Key Anatomical Features

  • Kidneys:

    • Renal cortex and medulla are major functional zones.

    • Pyramids contain nephrons, the functional units for filtering blood.

    • Columns support the pyramids structurally and separate them.

    • The renal pelvis acts as the collection center for urine before it passes into the ureters.

    • Minor calices collect urine from the pyramids, which flow into major calices and then the renal pelvis.

  • Ureters: Oblique entry into the bladder prevents urine reflux.

  • Bladder: Elastic organ that expands to store urine.

  • Urethra: Final pathway for urine elimination.

General Reproductive System

  • Purpose: Ensures sexual maturation and produces gametes (oocytes/eggs in females, sperm in males).

  • Primary Organs (Gonads):

    • Male: Testes (produce sperm and androgens).

    • Female: Ovaries (produce eggs and estrogen/progesterone).

Male Reproductive System

Organs to Know:

  1. Testes:

    • Located in the scrotum.

    • Surrounded by layers: Tunica vaginalis (serous sac) and Tunica albuginea (fibrous capsule).

    • Contains seminiferous tubules (site of sperm production).

    • Muscles:

      • Dartos muscle: Wrinkles scrotal skin (temperature regulation).

      • Cremaster muscle: Elevates testes (temperature regulation).

    • Spermatic cord: Contains ductus deferens, blood vessels, and nerves.

  2. Duct System:

    • Epididymis (head, body, tail): Matures and stores sperm.

    • Ductus (vas) deferens: Transports sperm; joins seminal gland to form ejaculatory duct.

    • Ejaculatory duct: Empties into the urethra.

    • Urethra: Passageway for urine and semen.

  3. Accessory Glands:

    • Seminal glands: Produce 60% of semen (nourishes sperm).

    • Prostate gland: Produces fluid enhancing sperm motility.

    • Bulbo-urethral glands: Secretes mucus for lubrication.

  4. Penis:

    • Parts: Root, body, glans (tip), prepuce (foreskin).

    • Erectile tissue:

      • Corpus spongiosum: Surrounds the urethra.

      • Corpora cavernosa: Paired structures aiding erection.

Pathway of Sperm:

Seminiferous tubules → Epididymis → Ductus deferens → Ampulla → Ejaculatory duct → Urethra → Penis.

Female Reproductive System

Organs to Know:

  1. Uterine (Fallopian) Tubes:

    • Parts:

      • Fimbriae: Finger-like projections.

      • Infundibulum: Funnel-shaped end.

      • Ampulla: Site of fertilization.

  2. Uterus:

    • Parts:

      • Fundus, body, cervix (connects to vaginal canal).

      • Cervical canal: Passage through cervix.

    • Layers:

      • Perimetrium: Outer layer.

      • Myometrium: Muscular layer (contracts during childbirth).

      • Endometrium: Inner layer where embryo implants.

  3. Vagina and Vulva:

    • Vagina: Birth canal, receives penis during intercourse.

    • External genitalia (vulva):

      • Mons pubis: Fatty area with pubic hair.

      • Labia majora/minora: Folds of skin (homologous to scrotum).

      • Clitoris: Erectile tissue (homologous to penis).

      • Vaginal orifice: Opening of the vaginal canal.