Dissection Test Abdominal Cavity

Stomach

Temporarily stores ingested food and begins chemical digestion. Secretes hydrochloric acid (HCl) to denature proteins and kill pathogens. Releases pepsinogen, which becomes pepsin, an enzyme that breaks down proteins. Mechanically churns food using muscular contractions, converting it into chyme, a semi-liquid mixture passed to the small intestine.

Cardiac Sphincter Muscles

Controls the opening between the esophagus and stomach. Prevents acid reflux by ensuring that stomach contents do not flow back into the esophagus. Maintains one-way flow of ingested materials.

Pyloric Sphincter Muscles

Regulates the passage of chyme from the stomach to the duodenum (first part of the small intestine). Ensures chyme is released in small, controlled amounts for optimal digestion and nutrient absorption. Prevents the contents of the small intestine from re-entering the stomach.

Small Intestine

Duodenum: First segment, receives chyme from stomach, bile from liver/gall bladder, and enzymes from the pancreas. It neutralizes stomach acids using bicarbonate and initiates fat emulsification and enzyme activity. Jejunum: Main site for chemical digestion and nutrient absorption into the bloodstream. Its inner lining has villi and microvilli to increase surface area. Ileum: Absorbs vitamin B12, bile salts, and remaining nutrients. Contains immune structures (Peyer's patches) for pathogen monitoring.

Ileocecal Junction

A valve between the ileum (small intestine) and cecum (large intestine). Regulates flow of chyme into the large intestine. Prevents backflow of bacteria and waste material from large intestine into the sterile environment of the small intestine.

Mesentery

Suspends and supports the small intestines within the abdominal cavity. Contains blood vessels, nerves, and lymphatic vessels that supply the intestines. Enables nutrient transport from the intestines into systemic circulation.

Abdominal Aorta

Main arterial highway in the abdomen; supplies oxygen-rich blood to major abdominal organs (liver, kidneys, intestines). Branches into arteries like the renal arteries (to kidneys) and mesenteric arteries (to intestines). Essential for delivering nutrients and oxygen for metabolic processes.

Pancreas

Exocrine function: Produces digestive enzymes (amylase, lipase, trypsin) that break down carbohydrates, fats, and proteins in the small intestine. Secretes bicarbonate to neutralize stomach acid in the duodenum. Endocrine function: Produces insulin and glucagon to regulate blood glucose levels.

Spleen

Part of the lymphatic and immune system. Filters and recycles old or damaged red blood cells. Stores white blood cells (lymphocytes) and helps produce an immune response against pathogens in the blood. Can store blood and release it during hemorrhage or stress.

Liver

Produces bile (a fluid that helps emulsify fats). Detoxifies harmful substances (e.g., drugs, ammonia, toxins). Metabolizes nutrients from digestion (e.g., converts glucose to glycogen). Stores vitamins and minerals (e.g., vitamin A, iron). Produces blood-clotting factors and plasma proteins.

Gall Bladder

Stores and concentrates bile. Releases bile into the duodenum to aid fat digestion when triggered by fatty meals.

Kidneys

Filter nitrogenous wastes, toxins, and excess substances from blood to form urine. Maintain homeostasis by regulating electrolyte balance, pH, and water levels. Produce erythropoietin, a hormone that stimulates red blood cell production.

Ureters

Transport urine from kidneys to urinary bladder through peristaltic contractions.

Urinary Bladder

Temporarily stores urine until it is excreted. Composed of transitional epithelium, allowing expansion. Signals the need to urinate when stretch receptors detect fullness.

Large Intestine (Colon)

Absorbs water and electrolytes from undigested food. Houses gut bacteria that produce vitamins (e.g., vitamin K). Compacts waste into feces.

Rectum

Stores feces until elimination. Contains stretch receptors that trigger the defecation reflex.

Umbilical Arteries

Carry deoxygenated blood and waste from fetal pig to the placenta.

Umbilical Vein

Carries oxygenated blood and nutrients from placenta to the fetus. Crucial for fetal circulation before the lungs and digestive system are functional.

Cecum

Serves as a fermentation chamber for cellulose digestion in herbivorous animals. In fetal pigs, it's relatively small but still functions as a junction between small and large intestines.

Appendix

Minimal function in pigs; in humans, may play a role in immune system and gut flora maintenance.

Testes

Produce sperm (via spermatogenesis) and testosterone (promotes male secondary sex characteristics).

Penis

Delivers sperm into the female reproductive tract; also functions in urine excretion.

Ovaries

Produce ova (eggs) and hormones like estrogen and progesterone.

Uterine Horns

Site of embryo implantation and development; allow for multiple offspring (litters), unlike the single uterine body in humans.