Biology 160: Fetal Pig Anatomy and Dissection Review

Comprehensive practice flashcards covering anatomical terminology, organ systems, physiological functions, pathways, dissection landmarks, and comparative features of the fetal pig.

Pinna

The external cartilaginous flap of the ear that functions to capture and direct sound waves into the auditory canal.

Nares

The external nostrils situated on the snout that allow inhaled air to enter the nasal cavity for warming, filtering, and transit to the lungs.

Nictitating Membrane

A translucent 'third eyelid' located at the medial corner of the eye that provides protection and moisture while maintaining visibility.

Mammary Papillae

Nipple-like projections arranged in two parallel rows along the ventral abdomen in both male and female fetal pigs, which in mature females connect to milk-secreting mammary glands.

Umbilical Cord

The flexible vascular cord connecting the fetus to the placenta, carrying two umbilical arteries and one umbilical vein to exchange gases, nutrients, and metabolic wastes.

Urogenital Opening

The external orifice shared by the urinary and reproductive systems; located immediately posterior to the umbilical cord in males and ventral to the anus in females.

Urogenital Papilla

A small, conical fleshy projection covering the urogenital opening located immediately ventral to the anus in female fetal pigs.

Hard Palate

The bony, ridged anterior roof of the mouth that separates the oral cavity from the overlying nasal cavity.

Soft Palate

The fleshy, muscular posterior portion of the roof of the mouth lacking bone, which aids in swallowing by closing off the nasopharynx.

Epiglottis

A leaf-shaped flap of elastic cartilage positioned at the base of the tongue that folds down over the glottis during swallowing to prevent food and liquid from entering the respiratory tract.

Glottis

The slit-like opening at the top of the larynx that serves as the entry point for air passing into the trachea.

Larynx

The cartilaginous 'voice box' situated superior to the trachea that houses the vocal cords and maintains an open airway for respiration.

Trachea

The flexible cartilaginous windpipe reinforced with C-shaped hyaline cartilage rings that conveys air from the larynx toward the bronchi of the lungs.

Lungs

The paired multi-lobed respiratory organs situated within the thoracic cavity where passive gas exchange between alveolar air and pulmonary capillary blood occurs.

Diaphragm

A broad, thin sheet of skeletal muscle separating the thoracic cavity from the abdominal cavity; primary muscle of inspiration whose contraction lowers thoracic pressure and increases intra-abdominal pressure.

Heart

The central four-chambered muscular organ encased in the pericardial sac that generates systemic and pulmonary blood flow.

Atrium (Right and Left)

The two thin-walled superior receiving chambers of the heart; the right collects deoxygenated blood from the venae cavae, while the left collects oxygenated blood from pulmonary veins.

Ventricle (Right and Left)

The two thick-walled inferior pumping chambers of the heart; the right expels blood into the pulmonary trunk, while the left forces oxygenated blood through the systemic aorta.

Coronary Artery

A blood vessel traveling along the anterior surface sulcus of the heart supplying oxygenated blood directly to cardiac muscle tissue.

Superior (Cranial) Vena Cava

A major systemic vein returning deoxygenated blood from the head, neck, and forelimbs into the right atrium of the heart.

Inferior (Dorsal) Vena Cava

A large systemic vein that carries deoxygenated blood from the lower abdomen, pelvic region, and hindlimbs back up to the right atrium.

Aorta (Superior and Abdominal)

The primary, thick-walled systemic artery originating from the left ventricle that arches cranially before descending through the thorax and abdomen to distribute oxygenated blood throughout the body.

Umbilical Vein

The single fetal blood vessel that conveys oxygenated, nutrient-rich blood from the placenta to the fetal liver and ductus venosus.

Umbilical Arteries

Paired vessels flanking the urinary bladder that transport deoxygenated, metabolic-waste-laden blood from the fetal internal iliac arteries back to the placenta.

Esophagus

A collapsible, muscular tube situated dorsal to the trachea that propels swallowed boluses of food from the pharynx to the stomach via peristalsis.

Stomach

A curved, muscular digestive sac that mechanically churns ingestible food and secretes hydrochloric acid and pepsinogen for initial chemical breakdown.

Duodenum

The initial, short C-shaped segment of the small intestine directly receiving acidic chyme from the stomach along with digestive secretions from the liver and pancreas.

Small Intestine

A long, convoluted organ of the digestive tract responsible for finishing enzymatic chemical digestion and absorbing nutrients into the bloodstream and lacteals.

Colon (Coiled Colon)

The portion of the large intestine arranged in a compact spiral mass in the fetal pig responsible for reabsorbing water and electrolytes and compacting indigestible waste into feces.

Cecum

A dead-end pouch located at the junction of the small intestine and large intestine that functions in microbial fermentation of plant cellulose.

Rectum

The terminal straight segment of the large intestine extending through the pelvic cavity that stores fecal material prior to defecation.

Anus

The terminal external muscular opening of the digestive tract through which solid feces are expelled from the body.

Liver

The large, multi-lobed reddish-brown organ of the cranial abdomen that synthesizes bile, metabolizes toxins, stores glycogen, and processes absorbed nutrients.

Gallbladder

A small, green-tinted sac embedded on the underside of the right medial lobe of the liver that stores and concentrates bile until stimulated to contract into the duodenum.

Pancreas

A diffuse, granular glandular organ lying beneath the stomach that secretes alkaline digestive enzymes into the duodenum (exocrine) and insulin/glucagon into the blood (endocrine).

Thymus Glands

Large lymphoid tissue lobes located laterally along the cervical trachea and extending into the anterior mediastinum above the heart; essential for the maturation and differentiation of T-lymphocytes.

Thyroid Gland

A compact, reddish-brown oval endocrine gland positioned ventrally across the trachea inferior to the larynx that produces metabolic hormones.

Spleen

A flat, elongated, tongue-like lymphoid organ attached along the greater curvature of the stomach that filters blood, removes senescent red blood cells, and stores platelets.

Kidneys

Paired retroperitoneal, bean-shaped organs on the posterior abdominal wall that filter nitrogenous wastes from the bloodstream, regulate water and electrolyte balance, and produce urine.

Ureters

Slender, muscular retroperitoneal ducts that conduct urine via peristaltic waves from the renal pelvis of each kidney down to the urinary bladder.

Urinary Bladder

A distensible muscular reservoir situated along the ventral abdominal wall between the two umbilical arteries that stores urine prior to excretion.

Urethra

The single tubular duct leading from the bladder neck through the pelvic canal that transports urine (and semen in males) to the exterior urogenital opening.

Ovaries

The paired female reproductive gonads situated posterior to the kidneys that produce ova (egg cells) and secrete estrogen and progesterone.

Oviducts (Fallopian Tubes)

Small, tightly coiled tubes adjacent to each ovary that capture ovulated eggs and serve as the site of fertilization, transmitting embryos to the uterine horns.

Uterine Horns

Elongated, bilateral extensions of the uterus in litter-bearing animals such as pigs where multiple fetuses implant and develop throughout gestation.

Vagina

The female muscular canal leading from the uterine body to the urogenital sinus, serving as the copulatory organ and birth canal.

Testes

The paired male gonads located in the inguinal area or descended into scrotal sacs that produce spermatozoa and testosterone.

Epididymis

A tightly coiled, crescent-shaped tubular structure wrapped around the surface of each testis where developing sperm undergo maturation and storage.

Pathway of Food

The sequential transit route through the alimentary tract: Oral Cavity (mouth) $\rightarrow$ Pharynx $\rightarrow$ Esophagus $\rightarrow$ Stomach $\rightarrow$ Duodenum (Small Intestine) $\rightarrow$ Jejunum and Ileum $\rightarrow$ Cecum / Coiled Colon (Large Intestine) $\rightarrow$ Rectum $\rightarrow$ Anus.

Pathway of Air

The conduction route for inhaled respiratory gases: External Nares $\rightarrow$ Nasal Cavity $\rightarrow$ Pharynx $\rightarrow$ Glottis (Epiglottis) $\rightarrow$ Larynx $\rightarrow$ Trachea $\rightarrow$ Bronchi $\rightarrow$ Bronchioles $\rightarrow$ Lungs (Alveoli).

Pathway of Urine

The excretory sequence of fluid waste: Renal Nephrons / Cortex and Medulla of Kidneys $\rightarrow$ Renal Pelvis $\rightarrow$ Ureter $\rightarrow$ Urinary Bladder $\rightarrow$ Urethra $\rightarrow$ Urogenital Opening.

Artery versus Vein Structural Distinction

Arteries feature thick, muscular, elastic walls that maintain a circular, open lumen under high pressure; veins exhibit thinner, less muscular walls with larger, easily collapsed lumens and valves to direct low-pressure blood flow toward the heart.

Esophagus versus Trachea Physical Distinction

The trachea lies ventrally and feels rigid due to stiff cartilaginous rings keeping it patent; the esophagus lies directly dorsal to it, consisting of a soft, collapsible muscular tube with no cartilage rings.

Multi-System Impact of the Diaphragm

Acts as the primary inspiratory muscle in the respiratory system; its downward contraction also elevates intra-abdominal pressure to assist in peristalsis/defecation (digestive) and compresses abdominal veins to promote venous return to the heart (circulatory).

Small Intestine Spatial and Absorptive Adaptation

Its extensive length is packed within a compact abdominal cavity through continuous looping and folding anchored by mesentery, while mucosal microvilli, villi, and circular folds maximize absorptive surface area.

Consequence of Gallbladder Removal

Directly impairs the digestion of lipids and fatty foods because the body loses the capacity to store and concentrate bile for intermittent, high-volume release, leaving only continuous dilute bile from the liver.

Sex Determination in the Fetal Pig

Distinguished externally by identifying the urogenital opening: females have an opening immediately ventral to the anus marked by a prominent urogenital papilla; males lack a papilla and have their opening on the mid-ventral belly just posterior to the umbilical cord, along with a posterior scrotum.

Limitations of Fetal Pig Anatomy as an Adult Human Model

Fetal specimens retain temporary fetal circulatory shunts (ductus arteriosus, foramen ovale, ductus venosus) and non-aerated unexpanded lungs, have not engaged in adult feeding or digestion, and possess immature reproductive structures.

Eye Region Dissection (Fetal Pig)

A lateral head view displaying ocular structures including the upper eyelid, the lower eyelid, and the medial nictitating membrane.

Oral Cavity Dissection (Fetal Pig)

An exposed ventral view into the oropharynx identifying the ridged anterior hard palate, the smooth posterior soft palate, and the flap-like epiglottis guarding the glottis.

Ventral Neck Dissection (Fetal Pig)

An anterior cervical view showcasing the prominent larynx, the ringed trachea, the ventral dark thyroid gland, and the flanking lobes of the thymus gland.

Thoracic Cavity Dissection (Fetal Pig)

An open thoracic view highlighting the central four-chambered heart enclosed in pericardium, the multi-lobed right and left lungs, and the transverse muscular diaphragm.

Upper Abdominal Cavity Dissection (Fetal Pig)

A cranial abdominal dissection exhibiting the expansive multi-lobed liver, the underlying green gallbladder, the curved stomach, and the elongated spleen.

Intestinal Dissection (Fetal Pig)

A mid-abdominal view presenting the tightly packed spiral coiled colon (large intestine), multiple loops of the small intestine, and pancreatic tissue situated along the mesentery.

Renal and Retroperitoneal Dissection (Fetal Pig)

A posterior abdominal view exposing the paired retroperitoneal kidneys, the descending ureters, and the central systemic vascular trunk (dorsal aorta and inferior vena cava).

External Urogenital and Pelvic Dissection (Fetal Pig)

A ventral caudal dissection displaying the severed umbilical cord, the elongated urinary bladder flanked by umbilical arteries, and pelvic urogenital structures.