ADDITIONAL FUNCTIONS: Addition to oxygen, the circulatory system

Circulatory System
COMPONENTS OF THE CIRCULATORY SYSTEM OPERATION AND FUNCTION Systemic Circulation Pulmonary Circulation Additional Functions Blood Pressure

HEART Anatomy Arrhythmias Cardiac Cycle Cardiac Output Congenital Heart Defect Control Of The Heart Rate Coronary Arteries Coronary Heart Disease Diseases Of The Heart Endocardium Function Of The Heart Generation Of The Heartbeat Heart Failure Heart Valves History Of Heart Research Myocardium Pericardium Heart Structure Heart Valve Malfunction Other Forms of Heart Disease
Blood INTRODUCTION ROLE OF BLOOD COMPOSITION OF BLOOD Plasma Red Blood Cells Blood Type White Blood Cells Platelets and Clotting PRODUCTION AND ELIMINATION OF BLOOD CELLS Red Blood Cell Diseases White Blood Cell Diseases Coagulation Diseases BLOOD BANKS Blood Transfusion Blood Count Blood donation and registry Blood gas analysis Blood sugar tests Blood typing and crossmatching Blood urea nitrogen test Blood-viscosity reducing drugs Blood Culture Blood Clot in the Legs Causes Blood Clot in the Legs Symptoms Blood Clot in the Legs
Digestive system Esophagus Gall bladder Large intestine Lips, cheeks and palate Salivary glands Serous membranes Small intestine Stomach Tunics
Teeth Tongue Digestive Process in Mouth Sleep Right Mouth Guard
Respiratory system
Endocrine system Glandular Structure Gonads Hormones Pancreas Parathyroid Glands Pineal Gland Pituitary Gland Pituitary Hormones Thymus Thyroid Gland


 In addition to oxygen, the circulatory system also transports nutrients derived from digested food to the body. These nutrients enter the bloodstream by passing through the walls of the intestine. The nutrients are absorbed through a network of capillaries and veins that drain the intestines, called the hepatic portal circulation. The hepatic portal circulation carries the nutrients to the liver for further metabolic processing. The liver stores a variety of substances, such as sugars, fats, and vitamins, and releases these to the blood as needed. The liver also cleans the blood by removing waste products and toxins. After hepatic portal blood has crossed the liver cells, veins converge to form the large hepatic vein that joins the vena cava near the right atrium.

 The circulatory system plays an important role in regulating body temperature. During exercise, working muscles generate heat. The blood supplying the muscles with oxygen and nutrients absorbs much of this heat and carries it away to other parts of the body. If the body gets too warm, blood vessels near the skin enlarge to disperse excess heat outward through the skin. In cold environments, these blood vessels constrict to retain heat.

 The circulatory system works in tandem with the endocrine system, a collection of hormone-producing glands. These glands release chemical messengers, called hormones, directly into the bloodstream to be transported to specific organs and tissues. Once they reach their target destination, hormones regulate the body’s rate of metabolism, growth, sexual development, and other functions.

 The circulatory system also works with the immune system and the coagulation system. The immune system is a complex system of many types of cells that work together to combat diseases and infections. Disease-fighting white blood cells and antibodies circulate in the blood and are transported to sites of infection by the circulatory system. The coagulation system is composed of special blood cells, called platelets, and special proteins, called clotting factors, that circulate in the blood. Whenever blood vessels are cut or torn, the coagulation system works rapidly to stop the bleeding by forming clots.

 Other organs support the circulatory system. The brain and other parts of the nervous system constantly monitor blood circulation, sending signals to the heart or blood vessels to maintain constant blood pressure. New blood cells are manufactured in the bone marrow. Old blood cells are broken down in the spleen, where valuable constituents, such as iron, are recycled. Metabolic waste products are removed from the blood by the kidneys, which also screen the blood for excess salt and maintain blood pressure and the body’s balance of minerals and fluids. ©2016.