The human body has a cardiovascular system and a lymphatic system, which are closely connected. The main functions of the cardiovascular system are to transport oxygen, nutrients, and hormones and to remove metabolic wastes (nitrogenous wastes, carbon dioxide, and others) from the cells of the body. Primary structures enabling the cardiovascular system to accomplish these functions include the heart, blood, and blood vessels. The lymphatic system is a major part of the immune system and is composed of lymph, lymph vessels, lymph nodes, and lymph organs, which include the tonsils, spleen, and thymus. Lymph fluid flows through lymphatic vessels into the lymph nodes, where macrophages assist with removal of foreign material. All lymph returns to the blood after passing through the lymph nodes, which can serve as a vehicle to transmit microorganisms between tissues. In healthy people neither the cardiovascular nor the lymphatic system normally hosts microorganisms. The presence of microorganisms, their toxins, or their other secretions in a person's cardiovascular or lymphatic systems indicates a disease state.
At A Glance
- The cardiovascular system includes blood, all of the blood vessels, and the heart.
- The lymphatic system includes lymph, lymph vessels, lymph nodes, and lymph organs.
Causative agents of cardiovascular and lymphatic system disease infect cardiovascular and lymphatic organs and tissues, resulting in diseases that are very difficult for the immune system to fight.
Sepsis occurs when an infection results in a system-wide inflammation response that can be life-threatening.
- Bacteria that infect the cardiovascular system may exploit the life cycles of blood-feeding insects to spread from host to host or may result from inadequately treated infections from elsewhere in the body.
- The three forms of plague include bubonic, pneumonic, and septicemic.
Anthrax is an infection caused by bacterial spores and can occur in three forms: skin, lung, and intestinal.
- Common nonhemorrhagic fever diseases result from bacterial infections and include brucellosis, caused by foodborne Brucella; Q fever, caused by the zoonotic Coxiella burnetii; and Rocky Mountain spotted fever, caused by the tick-borne Rickettsia.
Hemorrhagic fever diseases result from viral infections spread from animal reservoirs.
- Serious protozoan blood infections include the insect-transmitted Chagas disease, caused by Trypanosoma cruzi, and malaria, caused by the apicomplexans of the genus Plasmodium.