Fetal and Peripheral Circulation PDF

Fetal Circulation and Peripheral Circulation Paria SHOJAOLSADATI, assistant professor in human anatomy Istanbul Yeditepe University School of Medicine Department of Anatomy Placenta The placenta is a temporary organ that connects the developing fetus via the umbilical cord to the uterine wall allow...

Fetal Circulation and Peripheral Circulation Paria SHOJAOLSADATI, assistant professor in human anatomy Istanbul Yeditepe University School of Medicine Department of Anatomy Placenta The placenta is a temporary organ that connects the developing fetus via the umbilical cord to the uterine wall allow nutrient uptake, thermo-regulation, waste elimination, and gas exchange via the mother's blood supply. Fetal Circulation Fetal Circulation Fetal Circulation Umbilical cord 2 umbilical arteries: return non-oxygenated blood, fecal waste, and CO2 to placenta. 1 umbilical vein: brings oxygenated blood and nutrients to the fetus. Fetal Circulation Fetus depends on placenta to meet nutrition and O2 needs while organs continue formation. Oxygenated blood flows from the placenta to the fetus via the umbilical vein. After reaching fetus the blood flows through the inferior vena cava. Fetal Circulation Blood continues to travel from the ductus venosis to the inferior vena cava. Ductus Venosis Small amount of blood routed to growing liver. Increased blood flow leads to large liver in newborns. Fetal Circulation In the fetus, the ductus venosus (Arantius' duct after Julius Caesar Aranzi) shunts less than a third of the blood flow of the umbilical vein directly to the inferior vena cava. Thus, it allows oxygenated blood from the placenta to bypass the liver. In conjunction with the other fetal shunts, the foramen ovale and ductus arteriosus. It plays a critical role in preferentially shunting oxygenated blood to the fetal brain. Fetal Circulation Blood continues to travel up the inferior vena cava. Empties into the right atrium of the heart. The blood then passes to the left atrium through the foramen ovale. Fetal Circulation Foramen ovale Small opening in the septum of the heart. Completely bypasses the non-functioning lungs. Blood continues journey to the left ventricle, blood is then pumped into the aorta. Blood is circulated to the upper extremities. Blood then returns to the right atrium. Fetal Circulation From the right atrium, the blood goes to the right ventricle then to the pulmonary arteries. Pulmonary arteries Small amount goes to the maturing lungs. Rest of blood is shunted away from the lungs by ductous arteriosus back to the aorta. Fetal Circulation Blood travels back from aorta to the two umbilical arteries to the placenta. The placenta will re-supply the blood with oxygen and nutrition. Fetal circulation is a low-pressure system. Fetal Circulation Low pressure system Lungs are closed. Most oxygenated blood flows between the atria of the heart through the foramen ovale. This oxygen rich blood flows to the upper limbs, head and neck through the aortic arch. Conversion of Fetal to Infant Circulation At birth Clamping the cord shuts down lowpressure system. Increased atmospheric pressure (increased systemic vascular resistance) causes lungs to inflate with oxygen. Lungs now become a low-pressure system. Pressure from increased blood flow. Conversion of Fetal to Infant Circulation In the left side of the heart causes the foramen ovale to close. More heavily oxygenated blood passing by the ductus arteriosus causes it constrict. Functional closure of the foramen ovale and ductus arteriosus occurs soon after birth. Overall anatomic changes are not complete for weeks. Conversion of Fetal to Infant Circulation What happens to these special structures after birth? Umbilical arteries atrophy. Umbilical vein becomes part of the fibrous support ligament (lig. venosum, venous ligament) for the liver. The foramen ovale, ductus arteriosus, ductus venosus atrophy and become fibrous ligaments. Overview of Conversion Umbilical cord is clamped. Loose placenta. Closure of ductus venosus Blood is transported to liver and portal system. Fetal vs. Infant Circulation Fetal Infant Low pressure system Right to left shunting Lungs non-functional Increased pulmonary resistance Decreased systemic resistance High pressure system Left to right blood flow Lungs functional Decreased pulmonary resistance Increased systemic resistance Fetal vs. Infant Circulation Facilitates the exchange of materials between fetus and mother. The fetus picks up oxygen and nutrients from // eliminates carbon dioxide and wastes through the maternal blood supply by means of the placenta. Blood passes between the fetus and the placenta via: Two umbilical arteries One umbilical vein At birth fetal circulation are no longer needed: The ductus arteriosus becomes the ligamentum arteriosum. The foramen ovale becomes the fossa ovalis. The umbilical vein becomes the ligamentum teres (round ligament). The Umbilical arteries become the medial umbilical ligaments. The ductus venosus becomes the ligamentum venosum. Flow Chart of Fetal Circulation Postnatal development of circulation Fetal circulation The circulatory system of a human fetus works differently from that of born humans, mainly because the lungs are not in use: the fetus obtains oxygen and nutrients from mother through the placenta and the umbilical cord. Blood from the placenta is carried by the umbilical vein. About half of this enters the ductus venosus and is carried to the inferior vena cava, While the other half enters the liver proper from the inferior border of the liver. Fetal circulation The blood then moves to the right atrium of the heart. In the fetus, there is an opening between the right and left atrium (the foramen ovale) and most of the blood flows from the right into the left atrium, thus bypassing pulmonary circulation (which aren't being used for respiration at this point as the fetus is suspended in amniotic fluid). The majority of blood flow is into the left ventricle from where it is pumped through the aorta into the body. Some of the blood moves from the aorta through the internal iliac arteries to the umbilical arteries, and re-enters the placenta, where carbon dioxide and other waste products from the fetus are taken up and enter the mother's circulation. Some of the blood from the right atrium does not enter the left atrium, but enters the right ventricle and is pumped into the pulmonary artery. In the fetus, there is a special connection between the pulmonary artery and the aorta, called the ductus arteriosus, which directs most of this blood away from the lungs. Postnatal development of circulation With the first breath after birth, the pulmonary resistance is dramatically reduced. More blood moves from the right atrium to the right ventricle and into the pulmonary arteries, and less flows through the foramen ovale to the left atrium. The blood from the lungs travels through the pulmonary veins to the left atrium, increasing the pressure there. The decreased right atrial pressure and the increased left atrial pressure pushes the septum primum against the septum secundum, closing the foramen ovale, which now becomes the fosse ovalis. This completes the separation of the circulatory system into the left and the right. The ductus arteriosus normally closes off within one or two days of birth, leaving behind the ligamentum arteriosum. The umbilical vein and the ductus venosus closes off within two to five days after birth, leaving behind the ligamentum teres and the ligamentum venosus of the liver respectively. Postnatal development of circulation Adult remnants of fetal vascular structures Fetal Structure Adult remnant 1. Foramen ovale fossa ovalis 2. ductus arteriosus ligamentum arteriosum 3. extra-hepatic portion of the fetal left umbilical vein ligamentum teres hepatis ("round ligament of the liver") 4. intra-hepatic portion of the fetal left umbilical vein (ductus venosus) ligamentum venosum Umblical arteries Ligamentum umblicale and superior vesical artery 5. Peripheral Circulation and major vesseles (arcus aorta,aorta ve venae cava) 31 What is the cardiovascular system? The cardiovascular system consists of a network of vessels that circulates blood throughout the body, motored by the action of the heart. We will concentrate here on the circulatory system. Basic Anatomy of Circulatory routes Carry blood towards the heart Connect capillaries to veins Arteries Veins Carry blood away from the heart Arterioles Venules Capillaries Allow for “exchange” (filtration/reabsorption) of O2/CO2, nutrients/wastes Control blood flow into capillaries & help regulate BP The Heart: Associated Great Vessels  Aorta  Leaves left ventricle  Pulmonary arteries  Leave right ventricle  Vena cava  Enters right atrium  Pulmonary veins (four)  Enter left atrium Slide Structure of arteries and veins From the lumen to the outer wall of the blood vessels , the layer are; 1) 2) 3) Tunica intima Tunica media Tunica adventitia Valves Veins having diameters greater than 2 mm contain valves that allow blood to flow toward the heart but not in the opposite direction The valves consist of folds in the tunica intima that form two flaps that are shaped and function like the semilunar valves of the heart. Circulatory Routes Systemic Circulation: Blood flow from the L ventricle to the body & back to the R atrium. Pulmonary Circulation: Blood flow from the R ventricle to the lungs and back to the L atrium. Pulmonery circulation The heart pumps blood from the right ventricle into the pulmonary trunk. This short vessel, 5 cm long, branches into the right and left pulmonary arteries, one transporting blood to each lung. Within the lungs, gas exchange occurs between air in the lungs and the blood. Two pulmonary veins exit each lung and enter the left atrium. Pulmonery circulation Right atrium Right ventricule Pulmonary artery Lungs Pulmonary vein Left atrium Pulmonery circulation Right pulmonary artery Left pulmonary artery Pulmonary trunk 42 Pulmonery circulation Right pulmonary artery : Left pulmonary artery : Superior lobar a. Superior lobar a. Midle lobar a. Inferior lobar a. Inferior lobar a. Pulmonery circulation Right superior pulmonary vein Right inferior pulmonary vein Left superior pulmonary vein Left inferior pulmonary vein Left atrium 44 SYSTEMIC CIRCULATION Systemic circulation Oxygenated blood entering the heart from the pulmonary veins passes through the left atrium into the left ventricle and from the left ventricle into the aorta. Blood flows from the aorta to all parts of the body. Systemic circulation Left atrium Left ventricule Aorta body inf. & sup. Vena cava Right atrium Systemic circulation AORTA; All arteries of the systemic circulation are derived either directly or indirectly from the aorta , which usually is divided into three general parts: a) Ascending aorta (passes superiorly from the heart) coronary arteries ASCENDING AORTA miyocardium b) Aortic arch 3 main braches carry blood to head, neck and upper limb c) Desending aorta - Thoracic aorta -Abdominal aorta Whole body exclude head, neck and upperlimb AORTİC ARCH 48 Walking Stick Thoracic aorta Abdominal aorta Ascending aorta It’s approximately 5 cm long has only two arteries branching from it: the right and left coronary arteries, which supply blood to the cardiac muscle Branche of ascending aorta The coronary (encircling the heart like a crown) arteries, which are the only branches of the ascending aorta. Left coronary artery Right coronary artery 51 Coronary Circulation  Blood in the heart chambers does not nourish the myocardium  The heart has its own nourishing circulatory system  Coronary arteries  Cardiac veins  Blood empties into the right atrium via the coronary sinus Right coronary artery: coni arteriosy branchVieussens circule Brach to SA nod Brach to AV nod Post. Interventricular artery ( PDA) Right marginal artery Left coronary artery: Circumflex artery Left marginal artery Ant. Interventricular artery (LAD) Veins draining blood from the heart The major vein draining the tissue on the left side of the heart is the great cardiac vein, and a small cardiac vein drains the right margin of the heart. These veins converge toward the posterior part of the coronary sulcus and empty into a large venous cavity called the coronary sinus, which in turn empties into the right atrium. A number of smaller veins empty into the cardiac veins, into the coronary sinus, or directly into the right atrium. SINUS CORONARIUS Great cardiac vein Small cardiac vein Midle cardiac vein 56 Aortic arch The aorta then arches posteriorly and to the left as the aortic arch. Three major branches, which carry blood to the head and upper limbs. Aotic arch Brachiocephalic trunk Left commun carotis artery Left subclavian artery Branches of aortic arch 1. Left sommon carotid artery (Puls) - Left external carotid artery - Left internal carotid artery 2. Left subclavian artery 3. Brachiocephalic Trunk - Right common carotid artery (Puls) - Right subclavian artery The branches of aotic arch carry blood to head, neck and upper limb. 59 COMMON CAROTİD ARTERY: Level of Carotid Bifurcation: Upper border ofThyroid cartilage (*C4 vertebra) Branches of aortic arch The branches of aotic arch carry blood to head, neck and upper limb. Subclavia artery Common carotid artery External carotid artery Head and neck Upper Limb İnternal carotid artery Only for brain 62 Branches of subclavian artery: I. Vertebral atery: II. Thyrocervical trunk: III. Internal thorasic artery: IV. Costocervical trunk: Thyrocervical trunk Vertebral artery Costocervical trunk Subclavian artery Intenal thoracic atery AXILLARY ARTERY: BRACHIAL ARTERY Descending aorta The next part of the aorta is the longest part, the descending aorta. It extends through the thorax in the left side of the mediastinum and through the abdomen to the superior margin of the pelvis. Thoracic aorta The thoracic aorta is that portion of the descending aorta located in the thorax. It has several branches that supply various structures between the aortic arch and the diaphragm. The branches of the thoracic aorta are divided into two groups: the visceral branches supplying the thoracic organs, and the he inner surface of the anterior thoracic wall. The posterior intercostals are derived as bilateral branches directly from the descending aorta. (Th4-Th12) Abdominal aorta The abdominal aorta is that part of the descending aorta between the diaphragm and the point at which the aorta ends by dividing into the two common iliac arteries. The abdominal aorta has several branches that supply the abdominal wall and organs. Its terminal branches, the common iliac arteries, supply blood to the pelvis and lower limbs. (Th 12-L4) branches of the abdominal aorta The branches of the abdominal aorta, like those of the thoracic aorta, are divided into; 1. visceral branches Three major unpaired branches exist: the celiac trunk, the superior mesenteric artery and the inferior mesenteric artery. Each has several major branches supplying the abdominal organs. 2. parietal braches 71 COELIAC TRUNK: 72 SUPERIOR MESENTERICA ARTERY: 73 INFERIOR MESENTERIC ARTERY 74 Parietal branches of the abdominal aorta Suprarenal artery RENAL artery GONADAL ARTERY (testicular/ovarica) lumbalarteries 75 The arteries of the lower limb form a continuum similar to that of the arteries of the upper limb. The external iliac artery becomes the femoral artery in the thigh, which becomes the popliteal artery in the popliteal space. PULS The pulse is important clinically because one can determine heart rate, rhythmicity, and other characteristics by feeling it. A pulse can be felt at 10 major locations on each side of the body where large arteries are close to the surface. Veines Veins of thorax The thoracic drainage to the brachiocephalic veins is through the anterior thoracic wall by way of the internal thoracic veins. They receive blood from the anterior intercostal veins. Blood from the posterior thoracic wall is collected by posterior intercostal veins that drain into the azygos vein on the right and the hemiazygos or accessory hemiazygos vein on the left. Veins of upper limb Veins of lower limb