Which of the following pathways best represents the expected flow of blood from the human heart to an organ?
A.
Blood pumped from the heart first enters arterioles that then merge to form arteries that deliver blood to the organ.
B.
Blood pumped from the heart first enters arteries that then narrow to form veins that deliver blood to the organ
C.
Blood pumped from the heart first enters arteries that then narrow to form arterioles that deliver blood to capillaries of the organ
D.
Blood pumped from the heart first enters veins that then narrow to form venues that deliver blood to arteries of the organ.
The correct answer and Explanation is :
The correct answer is:
C. Blood pumped from the heart first enters arteries that then narrow to form arterioles that deliver blood to capillaries of the organ.
Explanation:
The pathway of blood flow from the heart to an organ follows a specific sequence:
- Arteries: Blood is pumped from the heart into large blood vessels known as arteries. These arteries are responsible for carrying oxygenated blood (except for pulmonary arteries, which carry deoxygenated blood to the lungs) away from the heart under high pressure. They have thick, muscular walls to handle the pressure and to help regulate blood flow.
- Arterioles: As arteries move away from the heart, they progressively branch into smaller vessels called arterioles. Arterioles play a critical role in regulating blood flow into specific organs and tissues by constricting or dilating. They are smaller and have thinner walls than arteries but still help in controlling the blood flow to various regions.
- Capillaries: The arterioles further branch into even smaller vessels called capillaries. Capillaries form an extensive network of tiny vessels that surround and infiltrate the organs and tissues. Their thin walls (one cell layer thick) facilitate the exchange of gases (oxygen and carbon dioxide), nutrients, and waste products between the blood and the cells of the organ.
- Venules and Veins: After passing through the capillaries, blood is collected by venules, which are small veins. Venules merge to form larger veins, which return deoxygenated blood back to the heart.
In summary, the correct flow of blood from the heart to an organ starts with arteries, which then branch into arterioles, and finally lead to the capillaries where exchange occurs. This pathway ensures that organs receive oxygen and nutrients necessary for their function while removing waste products efficiently.