Fill in the Blank QuestionFill in the blank question.The thick-walled inferior chambers of the heart that pump blood into the arteries are called .

The two upper chambers of the heart that receive blood from the veins.

The heart chamber with the thickest walls is the

The heart is a muscular organ comprising four chambers, two atria and two ventricles, that function synergistically to pump blood through a vast closed network of blood vessels.  The chambers are separated by membranous muscular barriers known as septa.  Oxygenated blood returning from the lungs via the pulmonary veins fills the left atrium and enters the left ventricle, which then pumps the blood into the systemic arteries to supply other organs in the body.  Deoxygenated blood returning from systemic veins first enters the right atrium, then the right ventricle, and is ultimately siphoned into the pulmonary arteries leading to the lungs.  The necessary exchange of oxygen, nutrients, and waste occurs between the thinnest blood vessels (capillaries) and neighboring tissues of the systemic and pulmonary circuits.Blood flow throughout the circulatory system is dictated by blood (hydrostatic) pressure, vascular resistance (force opposing blood flow through a vessel), and cardiac output (blood volume expelled from the ventricles per unit time).  When blood traverses a vessel, it exerts hydrostatic pressure on the vessel walls, which results in the forced movement of fluid out of vessels and into the interstitial space.  The circulating plasma proteins cause the osmotic pressure within the vessel to be higher than that of the interstitial fluid.  In turn, osmotic pressure causes fluid to flow from the interstitial space into blood vessels, opposing hydrostatic pressure.Cardiac output depends in part on heart rate, which is tightly regulated by the sinoatrial (SA) and atrioventricular (AV) nodes, specialized groups of self-depolarizing cells located in the upper right atrium wall and lower interatrial septum, respectively.  Action potentials (APs) generated by SA nodal cells stimulate atrial contraction as they travel to the AV node.  The AV node delays AP transmission to ventricular cells, ensuring ventricular filling is complete prior to heart contraction.A 63-year-old man was admitted to the hospital after he collapsed while exercising.  The patient had an elevated heart rate and an abnormally low blood oxygen level on admission.  X-rays revealed excess fluid in his lungs. Question 20Based on the information in the passage, the excess fluid in the patient's lungs is most likely caused by which of the following at pulmonary sites of gas exchange?A.Increased protein concentration in the blood flowing through pulmonary capillariesB.Decreased solute concentration in the interstitial fluid surrounding the pulmonary capillariesC.Increased hydrostatic pressure within pulmonary capillariesD.Decreased volume of blood flowing through the pulmonary capillariesSubmit

Blood returns from the upper part of the body to the heart via which blood vessel?

Fill in the Blank QuestionFill in the blank question.Blood from the right ventricle flows to the , which then splits into two arteries (left and right) that lead into the lungs.