Question

oxygenated
coronary artery disease
red blood cells
aorta
temperature
tricuspid
inferior vena cava
systole
heart
diastole
mitral
arteries
plasma
capillaries
essential substances
the circulatory system is primarily responsible for transporting
throughout the body.
the muscular organ that pumps blood throughout the body is called the
.
the smallest blood vessels, which facilitate the exchange of nutrients and gases, are called
.

Explanation:

First Sub - Question:

The circulatory system's main function is to transport essential substances (like oxygen, nutrients, hormones, etc.) throughout the body. Among the given options, "essential substances" fits this description.

The heart is a muscular organ that pumps blood to different parts of the body. From the options, "heart" is the organ responsible for this pumping action.

Capillaries are the smallest blood vessels. They have thin walls that allow for the exchange of nutrients, gases (like oxygen and carbon dioxide), and waste products between the blood and the body's cells. So among the options, "capillaries" is the correct answer.

Answer:

essential substances

Second Sub - Question: