Organ Systems & Fetal Pig Dissection In the following laboratory exercise, you will examine in some detail the external and internal anatomy of a fetal pig (Sus scrofa).  As the pig is a mammal, many aspects of its structural and functional organization are identical with those of other mammals, including humans.  Thus, a study of the fetal pig is in a very real sense, a study of humans.            The fetuses you will use in the following weeks were salvaged from pregnant sows being slaughtered for food.  They are not raised specifically for dissection purposes.  The fetuses are removed from the sow and embalmed with a preservative, which is injected through the umbilicus.  Following this, the arterial and venous systems are injected under pressure with latex, a rubber-like compound.  Arteries (red) are injected through the umbilicus; veins (blue) are injected through one of the jugular veins at the base of the throat.

Dissection Rules! First, be aware that "to dissect" does not mean "to cut up," but rather primarily "to expose to view."  Actual cutting should be kept to a minimum.  Tissues are picked and teased apart with needle probes, forceps, and blunt probes in order to trace the pathways of blood vessels, nerves, muscles, and other structures. Never cut or move more than is necessary to expose a given part.  Second, pay particular attention to the spatial relationships of organs, glands, and other structures as you expose them.  Realize that their positions are not random.  Third, we encourage you to engage in collaborative discussions with your classmates and compare dissections.

Wipe down your bench with disinfectant! Everyday. Don’t put your hands in your mouth! Wash your hands before leaving the lab. Wear Safety Goggles! Wear closed toed shoes! No food or drink in the Lab. Wear gloves. Paper towels go in regular trash. All other parts need to remain with the specimen so that they can be disposed of properly. Be sure to bag your specimen properly at the end of each class, be sure it is labeled and placed in the refrigerator. Rinse off your dissecting tools and let them dry on paper towel. Wipe down your bench with disinfectant! Everyday. CLEAN OUT THE DRAIN IN THE SINK! Wash your hands before you leave the room. Practice safe hygiene when dissecting.  Do not place your hands near your mouth or eyes while handling preserved specimens.  Although most of the preservatives in use today are non-toxic to the skin, they may cause minor skin irritations.  If the preservative gets on your skin, wash with soap and warm water.2.      If the preservative gets in your eyes, rinse them thoroughly with the safety eyewash.3.      Never splash the preservative in the pig buckets.4.      Wear lab gloves.  Small, medium, and large sizes are available.  These gloves are expensive--please don't waste them.5.      Lab gloves and paper towels go in the regular trash.  Skin and pieces of pig go into the red plastic bag at the front of the room (not down the disposal).6.      After bagging your pig and placing it in the mortuary cabinet, rinse your tray and stack it neatly by the sink.  Wipe up your station.

CRANIAL/CAUDAL CRANIAL CAUDAL

TRANSVERSE/SAGITTAL/FRONTAL Sagittal – side to side not necessarily in half Frontal-ventral and dorsal SAGITTAL

VENTRAL/DORSAL DISTAL/PROXIMAL | VENTRAL PROXIMAL | DISTAL Proximal close to midline Distal farther from midline

Symmetry

Approximate Age (Days) How old is your pig? To determine the age of your pig. Measure the pig from rump to snout in cm._____ Compare length to chart below: Length of Fetus (cm.) Approximate Age (Days) 1.1 21 1.7 35 2.8 49 4.0 56 22.0 100 30.0 Full term (112-115)

Sex determination Male Female Male

External features Pinna External auditory meatus Nictitating membrane Rooter/Snout Vibrissae Umbilical cord Genital papilla Urogential orifice Scrotum Mammary papilla Anus

Organ Systems Digestive Respiratory Circulatory Urinary Reproductive

DIGESTIVE SYSTEM FUNCTION: The main role of the digestive system is to breakdown and absorb nutrients that are necessary for growth and maintenance. Important organs: Mouth, esophagus, stomach, small and large intestines.

EPIGLOTTIS The cartilaginous flap that covers the glottis to prevent food from entering the larynx and trachea while swallowing.

Digestive system 1 11. Anus Stomach Small intestine Duodenum Large intestine (colon) Caecum Rectum Glands Submaxillary gland Parotid Sublingual gland 38. Thymus Thymus Liver Gallbladder Pancreas Spleen Adrenal gland

Digestive system 2

RESPIRATORY SYSTEM FUNCTION: The main role of the respiratory system is to provide gas exchange between the blood and the environment.  Primarily, oxygen is absorbed from the atmosphere into the body and carbon dioxide is expelled from the body. Important Organs: Nose, trachea and lungs.

Respiratory Respiratory Epiglottis (mouth number) Answers Digestive, glands and Respiratory Respiratory Epiglottis (mouth number) Nasopharynx (mouth number) Glottis (mouth number) 120. Lung Diaphragm Larynx Trachea

Circulatory System Function: The main role of the circulatory system is to transport nutrients, gases (such as oxygen and CO2), hormones and wastes through the body.  Important Organs: Heart, blood vessels and blood. Circulation through the heart

Semi Lunar Valves Right Atrium Bicuspid valve Tricuspid valve

Heart Coronary arteries and veins Right atrium Right ventricle Answers Heart Coronary arteries and veins Right atrium Right ventricle Left atrium Left ventricle Pulmonary trunk Ductus arteriosus Aortic arch Aorta Precava Postcava

Urinary System [Excretory System] Function: The main role of the excretory system is to filter out cellular wastes, toxins and excess water or nutrients from the circulatory system.  Important Organs: Kidneys, ureters, bladder and urethra.

Excretory (Urinary system)1 Urogential opening male (see sex determination) Kidney Hilus Ureter Bladder Urethra Cortex Medulla Pelvis of kidney Calyx Renal pyramid opening urethra female(see sex determination)

Excretory (Urinary system)2 Urogential opening male (see sex determination) Kidney Hilus Ureter Bladder Urethra Cortex Medulla Pelvis of kidney Calyx Renal pyramid opening urethra female(see sex determination)

Reproductive System Function: The main role of the reproductive system is to manufacture cells that allow reproduction.  In the male, sperm are created to inseminate egg cells produced in the female. Important Organs Female: ovaries, oviducts, uterus, vagina and mammary glands.  Male: testes, seminal vesicles and penis. 

Female Reproductive system 1

Female Reproductive system 2 Genital papilla Ovary Oviducts Horns of uterus Uterus Cervix Vagina Urogential sinus Opening of urethra

Female Reproductive system 3 Genital papilla Ovary Oviducts Horns of uterus Uterus Cervix Vagina Urogential sinus Opening of urethra

Male Reproductive system 1

Male Reproductive system 2 Urogential opening Scrotum Testical or testes Epididymus Gubernaculum Vas deferens Inguinal canal Penis (Urethra) Cowper’s gland -- Seminal vesicles Prostate gland

Male Reproductive system 3 Urogential opening Scrotum Testical or testes Epididymus Gubernaculum Vas deferens Inguinal canal Penis (Urethra) Cowper’s gland -- Seminal vesicles Prostate gland

Male Reproductive system 4 Urogential opening Scrotum Testical or testes Epididymus Gubernaculum Vas deferens Inguinal canal Penis (Urethra) Cowper’s gland -- Seminal vesicles Prostate gland

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