Immune and lymphatic systems
The spleen is a brown, flat, oval-shaped lymphatic organ that filters and stores blood to protect the body from infections and blood loss.
Protected by our ribs, the spleen is located between the stomach and the diaphragm in the left hypochondriac region of the abdominal body cavity. The splenic artery branches off from the aorta and the celiac trunk to deliver oxygenated blood to the spleen, while the splenic vein carries deoxygenated blood away from the spleen to the hepatic portal vein. A tough connective tissue capsule surrounds the soft inner tissue of the spleen.
The thymus gland, despite containing glandular tissue and producing several hormones, is much more closely associated with the immune system than with the endocrine system. The thymus serves a vital role in the training and development of T-lymphocytes or T cells, an extremely important type of white blood cell. T cells defend the body from potentially deadly pathogens such as bacteria, viruses, and fungi.
The thymus is a soft, roughly triangular organ located in the mediastinum of the thoracic cavity anterior and superior to the heart and posterior to the sternum. It has two distinct but identical lobes that are each surrounded by a tough, fibrous capsule. Within each lobe is a superficial region of tissue called the cortex and a histologically distinct deep region called the medulla. Epithelial tissues and lymphatic tissues containing dendritic cells and macrophages make up the majority of both regions of the thymus.
The immune and lymphatic systems are two closely related organ systems that share several organs and physiological functions. The immune system is our body’s defense system against infectious pathogenic viruses, bacteria, and fungi as well as parasitic animals and protists. The immune system works to keep these harmful agents out of the body and attacks those that manage to enter.
The lymphatic system is a system of capillaries, vessels, nodes and other organs that transport a fluid called lymph from the tissues as it returns to the bloodstream. The lymphatic tissue of these organs filters and cleans the lymph of any debris, abnormal cells, or pathogens. The lymphatic system also transports fatty acids from the intestines to the circulatory system.
The immune and lymphatic system of the head and neck includes the tonsils, several sets of lymph nodes, countless lymphatic vessels, and red bone marrow. All of these structures work together to drain, filter and cleanse the interstitial fluids of the head and neck and destroy harmful pathogens that may infect this region.
The adenoids, also known as the pharyngeal tonsils, are a part of the lymphatic system located in the back of the throat and up into the nasal cavity. Much like the tonsils (palatine tonsils), the adenoids are made up of folded lymphatic tissue, lined with epithelial cells, house mucosal glands, and are covered in cilia and mucus. One single such fold is termed an adenoid.
The cervical nodes are one of the six major locations of lymph nodes. They are grouped along the lower border of the jaw, in front of and behind the ears, and deep in the neck along the larger blood vessels. They drain the skin of the scalp, face, tissues of the nasal cavity, and the pharynx. All lymph nodes have the primary function of the production of lymphocytes, which help defend the body against microorganisms and against harmful foreign particles and debris from lymph before it is returned to the blood stream.
The lingual tonsil is a small mound of lymphatic tissue located at the back of the base of the tongue. Two lingual tonsils are in the mouth, one on each side of the tongue. They are composed of lymphatic tissue that functions to assist the immune system in the production of antibodies in response to invading bacteria or viruses. If the tonsils are repeatedly swollen or infected over an extended period of time, they may need to be removed.
The palatine tonsils are located at the back of the throat. One tonsil is located on the left side of the throat and the other is located on the right side. The tonsils play a role in protecting the body against respiratory and gastrointestinal infections.
The upper torso contains many important structures of the lymphatic and immune systems including many lymph nodes, the lymphatic ducts, thymus gland, and red bone marrow. These structures work together to perform the vital functions of producing immune responses to deadly pathogens; producing blood cells; transporting lymph and lipids; and filtering contaminants from lymph.
A vast network of lymph nodes and lymphatic vessels spreads throughout the diverse tissues of the upper torso. This lymphatic network performs the vital task of draining interstitial fluid from the tissues of the thorax and returning it to the blood supply. Many lymphatic vessels also carry lymph to the upper torso from the limbs, abdomen, head and neck.
The axillary nodes are a group of lymph nodes located in the axillary (or armpit) region of the body. They perform the vital function of filtration and conduction of lymph from the upper limbs, pectoral region, and upper back.
The axillary lymph nodes are a group of twenty to thirty large lymph nodes located in the deep tissues in and around the armpit. These nodes are arranged into five distinct groups: pectoral (anterior), lateral, subscapular (posterior), central (intermediate), and subclavicular (medial). Each group of lymph nodes receives lymph from a specific region of the body or from another group of lymph nodes.