The Fetal Pig Circulatory System 12 05 2013 VESSELS What type of vessel carries blood away from the heart Arteries In which type of vessel does gas exchange occur Capillaries Which type of vessel carries blood back to the heart Veins Arteries contain several layers An outer layer of connective tissue called the serosa a middle layer of smooth muscle called the muscularis and an inner layer of epithelial cells called the endothelium Which layer is the thickest Muscularis What does this suggest about the artery s job in managing blood flow That it uses muscle contractions to move the blood away from the heart in the body Veins have the same layers as arteries Which layer is thickest in veins Serosa ANATOMY OF CIRCULATORY SYSTEM THE MAJOR VESSELS Anterior superior vena cava drains blood from the chest forelimbs neck and head The internal jugular vein and the external jugular vein carry blood from the head and neck to the anterior vena cava The posterior inferior vena cava brings blood up from the posterior regions it disappears into the liver The umbilical vein empties into the posterior vena cava inside the liver Renal veins drain the kidneys Adrenal gland is an endocrine organ pressed against the kidney Hepatic portal system involves blood traveling through two sets of capillaries before returning to the heart Arterial blood travels to the stomach intestine and spleen where it goes through the first capillary bed Nutrients and other materials are picked up and the blood travels into the liver by the hepatic portal vein Blood then goes through the second set of capillaries in the liver as nutrients are picked up and other components of the blood are adjusted by the liver cells Blood leaves the liver tissue in hepatic veins which empty into the posterior vena cava inside the liver Does the hepatic portal vein carry blood rich in nutrients in the fetal pig No Arteries are deeper down than veins while veins are more superficial Are the umbilical arteries in the fetus carrying blood high or low in nutrients High FETAL CIRCULATION Differences arise in fetal circulation because the fetus doesn t have direct access to the outside world for exchange of gases nutrients and wastes the functions are provided by the placenta via the umbilical vein Most of the circulatory differences involve mechanisms that shunt the fetal blood away from the liver and the lungs Ductus venosus shunts blood away from the liver directly to the posterior inferior vena cava about half of the blood in the umbilical vain away from the liver Foreman ovale shunts blood away from lungs between the two atria allows some of the blood to go directly from the right atrium to the left atrium Ductus arteriosus is a junction between the pulmonary trunk and the aorta that allows more blood to bypass lungs Blood enters the right atrium the chamber on the upper right side of the heart When the blood enters the right atrium most of it flows through the foramen ovale into the left atrium Blood then passes into the left ventricle lower chamber of the heart and then to the aorta the large artery coming from the heart From the aorta blood is sent to the heart muscle itself in addition to the brain After circulating there the blood returns to the right atrium of the heart through the superior vena cava About two thirds of the blood will pass through the foramen ovale as described above but the remaining one third will pass into the right ventricle In the fetus the placenta does the work of breathing instead of the lungs As a result only a small amount of the blood continues on to the lungs Most of this blood is bypassed or shunted away from the lungs through the ductus arteriosus to the aorta Most of the circulation to the lower body is supplied by blood passing through the ductus arteriosus This blood then enters the umbilical arteries and flows into the placenta In the placenta carbon dioxide and waste products are released into the mother s circulatory system and oxygen and nutrients from the mother s blood are released into the fetus blood The Fetal Pig Urogenital System 12 05 2013 EXCRETORY SYSTEM The urogenital system consists of the urinary and reproductive systems Whenever amino acids are oxidized for energy ammonia is formed as nitrogenous waste The liver combines the ammonia ammonium ions with carbon dioxide to form molecules of urea The kidney is the main excretory organ that removes urea other wastes and excess materials from the body as it produces urine Kidneys remove nitrogenous wastes adjust blood volume and indirectly blood pressure and maintain blood pH by adjusting amount of Cl ions The area where the renal artery and renal vein attach to the kidney is called the renal hilum here the ureter connects to the kidney The ureter is a hollow tube that carries urine to the urinary bladder The renal pelvis is the open area at the middle of the kidney that drains into the ureter Urine is produced in the nephrons that make up the bulk of the kidney tissue Each nephron begins in the outer region or cortex of the kidney loops into the inner region or medulla then back to the cortex where it empties into a collecting duct The collecting ducts then empty into the renal pelvis THE FEMALE REPRODUCTIVE SYSTEM Ovaries produce eggs estrogen and progesterone Closely attached to the side of the ovary is a tiny twisted tube called an oviduct Fallopian tube uterine tube The ovary is not directly attached to the oviduct so the egg is released by the ovary must find its way into the oviduct which is achieved with the help of fimbriae which sweep the egg into the oviduct the oviduct then carries the egg to the uterus by ciliary action If sperm is present the eggs will be fertilized in the oviduct The female pig and the human female reproductive structures are somewhat different Uterine horn a small junction where each oviduct joins to a much larger uterus in human females The embryo moves from the oviduct through the uterine horn and implants in the lining or endometrium of the uterine wall where it develops until birth In female pigs the uterine horns are much larger and the uterus is much smaller fertilized eggs are from the oviducts move into the uterine horns where the implant in the endometrium and develops In female pigs the uterus is a passageway connecting the two uterine horns to the vagina Uterine horns extensions of uterus toward oviducts and fetus develops here in some mammals so there is more space to hold more babies fetal