Blood
Your blood is a fluid connective tissue. Its plasma is combined mostly of water with a wide variety of dissolved substances including nutrients, wastes, enzymes, plasma proteins, hormones, respiratory gases and ions. It also contains red blood cells, white blood cells and platelets. Red blood cells transport oxygen from the lungs to body cells, while removing carbon dioxide from cells to the lungs for exhalation. Blood carries nutrients from the gastrointestinal tract, and hormones from the endocrine cells to other body cells. Blood also transports heat and waste products to various organs for elimination. White blood cells and platelets are some of the building blocks of your immune system, aiding in defense against foreign bodies (viruses and bacteria, for example), and tissue repair. Blood acts to protect by clotting, which creates a barrier against excessive loss from the cardiovascular system after injury, and white blood cells are involved in immune responses. These immune responses include injury recovery, allergy response, and phagocytosis (or consumption and destruction of dead cells and other noxious substances). In addition, several blood proteins like antibodies, act to protect us against disease in a variety of ways.

Cardiovascular System
Your cardiovascular system (cardio = heart; vascular = blood & blood vessels) consists of the blood, blood vessels & heart. Your heart pumps to circulate blood through your vascular system. The first organ your blood passes after being pumped from the heart are the lungs. The vessels leaving the heart, most often carrying oxygen rich blood to the rest of the body are known as arteries, while the vessels carrying blood that’s most often low in oxygen, after distributing it throughout the body, and travelling back to the heart and lungs are known as veins.

Obesity and your cardiovascular system
As your body grows, so must your network of arteries and veins in order to supply new tissues with oxygen and to remove waste. Your heart is responsible for pumping blood through all of these vessels no matter how vast the network may grow. As you gain weight (and tissue), your heart must pump harder and/or faster in order to maintain your body’s blood supply and to regulate circulation. This helps explain why blood pressure and other heart related issues are so closely related to obesity.