Question

Match the descriptions to the circuit in the key. Answers may be used more than once. Key: a. pulmonary circuit b. systemic circuit c. both pulmonary and systemic Arteries carry blood away from the heart, and veins carry blood toward the heart.

Short answer

The provided description "Arteries carry blood away from the heart, and veins carry blood toward the heart" applies to both pulmonary and systemic circuits. In the pulmonary circuit, pulmonary arteries carry deoxygenated blood away from the heart to the lungs, and pulmonary veins carry oxygenated blood towards the heart from the lungs. In the systemic circuit, systemic arteries carry oxygenated blood away from the heart to the body, and systemic veins carry deoxygenated blood back to the heart from the body. Therefore, the correct match is \(c. both \: pulmonary \: and \: systemic\).

Step-by-step solution

Understand Pulmonary and Systemic Circuits

There are two types of circuits in the human circulatory system: the pulmonary circuit and the systemic circuit. The pulmonary circuit involves blood flow between the heart and the lungs. In this circuit, deoxygenated blood from the heart is carried to the lungs by pulmonary arteries for gas exchange (oxygen is taken in and carbon dioxide is released). The oxygenated blood then returns to the heart through pulmonary veins. The systemic circuit is responsible for blood flow between the heart and the rest of the body, excluding the lungs. In this circuit, oxygenated blood from the heart is carried to the rest of the body organs and tissues by systemic arteries. The blood gives up oxygen and collects carbon dioxide before returning to the heart through systemic veins as deoxygenated blood.

Match the Description to the Circuits

Description: "Arteries carry blood away from the heart, and veins carry blood toward the heart." Considering both pulmonary and systemic circuits, we find that arteries carry blood away from the heart in both circuits. In the pulmonary circuit, pulmonary arteries carry deoxygenated blood away from the heart to the lungs. In the systemic circuit, systemic arteries carry oxygenated blood away from the heart to the body. Veins also have a similar role in both circuits. In the pulmonary circuit, pulmonary veins carry oxygenated blood towards the heart from the lungs. In the systemic circuit, systemic veins carry deoxygenated blood back to the heart from the body. Based on this understanding, the correct match for the provided description is "c. both pulmonary and systemic."

Key concepts

Pulmonary Circuit

The pulmonary circuit is a crucial part of the circulatory system responsible for oxygenating the blood. As the heart pumps, deoxygenated blood is sent from the right ventricle into the pulmonary arteries. These arteries are unique because, unlike most arteries that carry oxygen-rich blood, they transport oxygen-poor blood to the lungs.

Once in the lungs, the blood undergoes gas exchange in tiny air sacs called alveoli. Oxygen from the inhaled air diffuses into the blood, and carbon dioxide, a waste product, is expelled during exhalation. This newly oxygenated blood then travels back to the heart via the pulmonary veins, completing the circuit. This part of the circulatory system is exclusive to the oxygenation process and does not deliver blood to other body tissues.

Systemic Circuit

The systemic circuit functions to distribute oxygen-rich blood to all body tissues and organs, except for the lungs. Beginning at the left ventricle, the heart pumps oxygenated blood into the aorta, the body's main artery. From there, a network of systemic arteries and smaller arterioles direct the blood to various regions of the body.

As these arteries branch further, oxygen and nutrients are delivered to cells, and waste products like carbon dioxide are collected. The now deoxygenated blood is then transported back to the heart through systemic veins. The largest of these veins, the superior and inferior vena cava, empty into the right atrium of the heart, thus closing the systemic circuit. This circulation is essential for sustaining the life and function of body tissues.

Arteries and Veins

Arteries and veins are two types of vessels in the circulatory system, each serving a distinct role. Arteries, characterized by their thick, elastic walls, are responsible for carrying blood away from the heart. The high pressure in arteries as blood is pumped out of the heart requires them to be strong and flexible.

Veins, on the other hand, have thinner walls and less elasticity because they do not have to withstand the same high pressures. They carry blood back toward the heart, aided by valves that prevent backflow and the squeezing action of muscles during movement. Both arteries and veins are involved in the pulmonary and systemic circuits, but they carry different types of blood according to the circuit they belong to: deoxygenated blood in the pulmonary arteries and veins, and oxygenated blood in the systemic arteries and veins.

Blood Flow

Blood flow refers to the continuous movement of blood through the circulatory system, driven by the pump action of the heart. The heart consists of four chambers, and the sequential contraction of these chambers propels blood throughout the body. The flow of blood is a vital process as it transports oxygen, nutrients, and hormones to cells, and removes waste products.

The rate and distribution of blood flow change according to the body's needs. For instance, during exercise, blood flow increases to the muscles, skin, and lungs to meet the higher demand for oxygen and nutrients and for more efficient temperature regulation. This regulation of blood flow is achieved by varying the diameter of blood vessels and the rate at which the heart beats.