Circulatory II

1. Superior Vena Cava / Inferior Vena Cava. 2. Right Atrium. 3. Right Atrioventricular Valve. 4. Right Ventricle. 5. Pulmonary Semilunar Valve. (Semilunar means its traveling out of the heart) 6. Pulmonary trunk, then into the pulmonary artery. 7. Pulmonary Capiollaries at Lungs. 8. From the lungs back into the heart through the Pulmonary Veins. 9. Left Atrium. 10. Left Atrioventricular Valve. 11. Left Ventricle. 12. Aortic Semilunar Valve. 13. Aorta (to the rest of the body).

How blood flows in the heart.. 1. Superior Vena Cava / Inferior Vena Cava. 2. Right Atrium. 3. Right Atrioventricular Valve. 4. Right Ventricle. 5. Pulmonary Semilunar Valve. 6. Pulmonary trunk, then into the pulmonary artery. 7. Lungs.

How blood flows in the heart.. 8. From the lungs back into the heart through the Pulmonary Veins. 9. Left Atrium. 10. Left Atrioventricular Valve. 11. Left Ventricle. 12. Aortic Semilunar Valve. 13. Aorta 14. Target Organs

Key notes The SA Node The AV node Found along the wall of the right atrium Stimulates the simultaneous contraction of the atria Sends a nerve impulse along a nerve to the AV node Called the “pacemaker” of the heart The AV node In the right atrium close to the AV valve When the AV node receives the impulse from the SA node, it fires to initiate the contraction of the LARGE ventricles The AV nodes sends its message via purkinje fibres

How exactly does the heart know when to “beat”? Medulla oblongata (in brain) sends eletrical impulse to right atrium SA node/pacemaker receives message and sends message through both atria to contract Impulse travels to AV node and down long nerve fibres called purkinje fibres Ventricles contract (atria is now relaxed) Entire heart rests

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Fetal Circulation

Fetal Heart As the fetus develops, the heart develops before the lungs The fetus exchanges gases with the placenta, not the lungs Placenta A large disk of tissue attached to the uterine wall It allows for nutrient, waste and gas exchange to occur The blood of mom and baby does not mix Exchange occurs via diffusion

Adaptions umbilical vein Oxygenated blood is joining in the blood vessel.. It can go to the LIVER and it’ll take a while to get out to the other side OR it can go to the shortcut at the DUCTUS VENOSUS and meets up with the inferior vena cava (IVC) (still oxygenated blood) THE IVC meets up with the blood coming from the umbilical vein and mixes with blood that is not as rich.. This is then dumped to the right atrium.

Ductus Venosus and Foramen Ovale Blood is in the atrium and has a couple of options 1.go to the right ventricle -> squeezed into the pulmonary arteries -> lungs (that is not full of air) and because of the increase in pressure, in the Right Atrium some blood flows to the LEFT ATRIUM via the Foramen Ovale -> left ventricle-> arota > umbilical arteries (placenta branch) which takes deoxygenated blood and high in CO2+waste to the placenta Pulmonary artery > arota(via the Doctus Arteriosus)> umbilical arteries

Path of blood through fetus Begins with blood collecting in the right atrium Blood can go into the left atrium via oval opening and into right ventricle through the AV valve Right ventricle to the pulmonary artery Arota to the tissue – umbilical arteries lead to the placenta (where exchange of gases and nutrients occur) Umbilical vein carries O2 rich blood that enters the venous duct and bypasses liver Venous duct joins the inferior vena cava; mixes w/ deoxygenated blood; then mixed blood goes back to the heart

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