How will you describe capillaries?
a. Capillaries are tiny sacs in your lungs.
b. Capillaries are tiny blood vessels in your lungs.
C. Capillaries are tiny blood cells in your lungs.
d. Capillaries are large blood cells in your lungs.
Answers
Answer:
Capillaries are tiny blood vessels connecting arteries to veins. These blood vessels carry oxygen and nutrients to individual cells throughout the body.
a. These air sacs, called alveoli, are responsible for gas exchange. They look a bit like grapes at the end of the bronchial branches. Healthy lungs have about 300 million air sacs in them. Each air sac is surrounded by a network of fine blood vessels (capillaries)
b. The alveoli are surrounded by tiny blood vessels, called capillaries. The alveoli and capillaries both have very thin walls, which allow the oxygen to pass from the alveoli to the blood. The capillaries then connect to larger blood vessels, called veins, which bring the oxygenated blood from the lungs to the heart.
c. When blood enters the small capillaries of the lung (called the pulmonary capillaries), fresh oxygen enters the blood and carbon dioxide is removed. This is called "gas exchange" or "respiration". Because this is the exchange of gases between the atmosphere and the bloodstream, it is also called "external respiration".
d. Blood Is In the Lungs for Less Than a Second—But That Is Long Enough to Equilibrate the Gases
The total amount of blood in the lung capillaries is normally about 70 mL, approximately one stroke volume of the heart. At a heart rate of 72 bpm, the blood is in the lungs only 60 s min−1/72 min−1=0.83 s. During this short time, venous blood entering the lungs equilibrates
Explanation: