1. Red blood cells (Erythrocytes): These cells are responsible for carrying oxygen from the lungs to the rest of the body. They contain hemoglobin, a protein that binds to oxygen.

2. White blood cells (Leukocytes): These cells are part of the immune system and help fight infection. There are different types of white blood cells, each with a specific role in the immune response.

3. Platelets (Thrombocytes): These small cell fragments are responsible for blood clotting. They help stop bleeding by forming a plug at the site of injury.