Gas exchange takes place in the millions of alveoli in the lungs and the capillaries that envelop them. As shown below, inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli.

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”.

Blood enters the right atrium and passes through the right ventricle. The right ventricle pumps the blood to the lungs where it becomes oxygenated. The oxygenated blood is brought back to the heart by the pulmonary veins which enter the left atrium. From the left atrium blood flows into the left ventricle.

Oxygen and carbon dioxide travels to and from tiny air sacs in the lungs, through the walls of the capillaries, into the blood. Blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs.

Blood comes into the right atrium from the body, moves into the right ventricle and is pushed into the pulmonary arteries in the lungs. After picking up oxygen, the blood travels back to the heart through the pulmonary veins into the left atrium, to the left ventricle and out to the body’s tissues through the aorta.

1 : orderly movement through a circuit especially : the movement of blood through the vessels of the body induced by the pumping action of the heart. 2 : flow. 3a : passage or transmission from person to person or place to place especially : the interchange of currency coins in circulation.

heart

Helpful Tips

1. Get moving. One of the best things you can do to improve circulation is to exercise regularly.
2. Stop smoking. Smoking harms the walls of your arteries and causes plaque.
3. Healthy Diet.
4. Elevate legs.
5. Compression stockings.
6. Manage Blood Pressure.
7. See a Vascular Surgeon.

At each body part, a network of tiny blood vessels called capillaries connects the very small artery branches to very small veins. The capillaries have very thin walls, and through them, nutrients and oxygen are delivered to the cells.

Cellular nutrients come in many forms, including sugars and fats. In order to provide a cell with energy, these molecules have to pass across the cell membrane, which functions as a barrier — but not an impassable one. Figure 2: Cells can incorporate nutrients by phagocytosis.

The oxygen you breathe in goes into your lungs and passes into your blood from there. It is then transported to all the cells in your body through your bloodstream. The lungs are located in the chest region, protected by the ribs in the rib cage.

Every cell in your body needs oxygen to function. Your body cells use the oxygen you breathe to get energy from the food you eat. This process is called cellular respiration. During cellular respiration the cell uses oxygen to break down sugar.

The muscles of the small intestine mix food with digestive juices from the pancreas, liver, and intestine, and push the mixture forward for further digestion. The walls of the small intestine absorb water and the digested nutrients into your bloodstream.

Unlike you, unicellular creatures don’t have mouths to eat with, teeth to chew with, or stomachs to digest with. Cells eat other cells by engulfing them inside their cell membrane. This is called phagocytosis. The cell membrane of the predator cell will fold in or extend out to wrap itself around the prey cell.

Autophagy is the recycling process by which our cells keep themselves young. They continually break down and renew small parts of themselves in a kind of self-digestion; this helps to counteract harmful deposits which may form.

We need to eat and drink to survive, and so do our cells. Using a process called endocytosis, cells ingest nutrients, fluids, proteins and other molecules.

Phagocytosis (the condition of “cell eating”) is the process by which large particles, such as cells or relatively large particles, are taken in by a cell.

The Golgi apparatus, also called Golgi complex or Golgi body, is a membrane-bound organelle found in eukaryotic cells (cells with clearly defined nuclei) that is made up of a series of flattened stacked pouches called cisternae. It is located in the cytoplasm next to the endoplasmic reticulum and near the cell nucleus.

Exocytosis. Exocytosis is the reverse of endocytosis. Quatities of material are expelled from the cell without ever passing through the membrane as individual molecules. By using the processes of endocytosis and exocytosis, some specialized types of cells move large amounts of bulk material into and out of themselves.