Circulation and Respiration
Science

Tiny, thin-walled sacs in the lungs where oxygen and carbon dioxide are exchanged between air and the blood
Alveolus
Tiny, thin-walled sacs in the lungs where oxygen and carbon dioxide are exchanged between air and the blood. Alveolus. An alveolus is a tiny air sac in the lungs that helps your body get oxygen and get rid of carbon dioxide.

The heart, blood, and blood vessels that together transport nutrients to the entire body
Cardiovascular system
The heart, blood, and blood vessels that together transport nutrients to the entire body. Cardiovascular system. The cardiovascular system is like a network of roads in your body that moves nutrients and oxygen around to keep you alive and well.

Blood pressure above the normal range, it is also called high blood pressure
Hypertension
Blood pressure above the normal range, it is also called high blood pressure. Hypertension. Hypertension is when the force of your blood against your artery walls is consistently too high, which can lead to health problems.

The respiratory organ that absorbs oxygen from the air and removes carbon dioxide from the blood
Lung
The respiratory organ that absorbs oxygen from the air and removes carbon dioxide from the blood. Lung. The lung is a vital organ in the body that helps us breathe by exchanging gases with the environment.

A clear tissue fluid that moves between the blood and the lymph vessels, it transports fats and aids the immune system
Lymph
A clear tissue fluid that moves between the blood and the lymph vessels, it transports fats and aids the immune system. Lymph is a fluid that helps the body fight infections and maintain fluid balance.

The flow of blood between the heart and all parts of the body, except the lungs
Systemic circulation
The flow of blood between the heart and all parts of the body, except the lungs, is called systemic circulation. Systemic circulation delivers oxygen-rich blood from the heart to the body's tissues and returns oxygen-poor blood back to the heart.