Final answer:
Decreased cardiac output and PCWP lead to decreased blood flow to the lungs and decreased oxygen delivery to tissues, while increased PVR results in increased resistance to peripheral blood flow. In systemic capillaries, PO₂ decreases and PCO₂ increases as blood passes from the arteries to the veins within body tissues, facilitating gas exchange.
Step-by-step explanation:
The effects of decreased cardiac output (CO), decreased pulmonary capillary wedge pressure (PCWP), and increased peripheral vascular resistance (PVR) can be understood through their impacts on the cardiovascular system. A decrease in CO can lead to lowered blood volume and pressure within the pulmonary circuit, which implies decreased blood flow to the lungs. Simultaneously, a decrease in PCWP indicates lower pressure within the pulmonary capillaries, opposing the second option. Additionally, an increase in PVR corresponds with increased resistance to blood flow in the peripheral vessels, validating the third option. This combination of factors, particularly the decreased CO and increased PVR, can culminate in decreased oxygen delivery to the tissues, supporting the fourth answer option.
Within the systemic capillaries, PO₂ drops and PCO₂ increases as oxygen is diffused from the blood to tissue cells and carbon dioxide is picked up from tissue cells into the blood (Option d). As blood transitions from arteries to veins within body tissues, these changes in partial pressures facilitate the exchange of gases essential for cellular respiration and waste removal.
Decreased blood volume, such as from water loss, leads to a drop in blood pressure, detected by baroreceptors. This can trigger compensatory mechanisms to increase heart rate and contractile strength in an attempt to maintain adequate blood pressure and flow. Vasoconstriction plays a role in maintaining and even enhancing blood flow despite the increased resistance it presents, particularly in the venous system where it aids in returning blood to the heart. This illustrates the complex balance between pressure, flow, and resistance within the cardiovascular system.