he left side of our heart feeds into the systemic circulatory route and the right side feeds into the pulmonary circulatory route (Patton et al., 2011). The systemic side pushes blood to the whole body except the lungs where the left side moves blood back and forth to only the lungs. In order for the heart to achieve proper contraction, it has a conduction system. The heart’s conduction system of the heart includes the sinoatrial node, the atrioventricular node, the AV bundle, and the subendocardial branches (Cleveland Clinic, n.d.). The sinoatrial node which is also called the SA node is located in your right atrium. This node is what sends impulses for your heart to initiate beating. Due to this function, this is sometimes called your heart’s natural pacemaker. The atrioventricular node otherwise known as your AV node is located near the center of your heart. This node is responsible for delaying the SA node’s impulse for a short amount of time to ensure the atria have pushed out all of their blood because it decreases contraction. From the atria, the blood is pushed into the ventricles. The AV bundle is what is stimulated next. The AV bundle is also known as the bundle of his is separated into left and right branches (Conducting System of the Heart – Bundle of His – SA Node, 2019). These bundles send the impulse from the AV node to the subendocardial branches. The right bundle sends it to the subendocardial branches in the right ventricle and the left bundle sends it to the subendocardial branches in the left ventricle. The subendocardial branches are also called Purkinje fibers. The Purkinje fibers are a group of specialized cells. The cells are able to transmit cardiac impulses from the AV nodes to the ventricles. This allows for coordinated contraction through the ventricles. Describe what happens to a person’s heart when they experience a myocardial infarction?
Classmate Question #2:
There is an average of 5 liters of blood in a healthy adult. Men usually have more blood than women but during pregnancy, a woman’s blood volume can increase by 50% (Sharma et al., 2021). Blood volume is regulated by how much sodium and water we intake and how much we excrete (CV Physiology, n.d.). We excrete water and sodium through our kidneys but we can also lose them through our GI tract, skin, and lungs. If our blood volume were to decrease by 5 to 10 percent so would our blood pressure (Betts, 2013). ADH is then released from our pituitary gland. The release of this hormone causes vasoconstriction which helps raise our blood pressure back up. To help restore blood volume this hormone also stimulates aquaporin channels in our kidneys to help restore the volume of water. When blood return to the atria is too elevated cells in the atrial wall secrete ANH (Patton et al., 2011). ANH is called atrial natriuretic hormone. This decreases our blood volume by increasing sodium excretion in the kidneys. When this is stimulated water is also excreted by the kidneys due to the rule of osmosis. The opposite of this would be when the kidneys stop water loss by reabsorbing it from the urine when the antidiuretic hormone is secreted. If there is more antidiuretic hormone present then there is less water excreted from the body which in turn causes an increase in total blood volume. What are two disorders that can affect our total blood volume?
