Lymphatic System Anatomy

Antigen

A molecule that stimulates an immune response by activating lymphocytes, which are white blood cells that fight disease.

Thoracic duct

A type of lymphatic duct, it drains lymph into the blood at the junction of the left subclavian and internal juglar veins.

Antibody

Also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the pathogen, called an antigen.

Histology. Peyer's patches in the ileum

Are clusters of MALT located in the terminal portion of the small intestine, which is called the ileum. This portion of the small intestine is continuous with the large intestine, which contains a large number of bacteria. The small intestine is sterile (contains no bacteria) so these peyer's patches play an important role in protecting it from any bacteria that migrate in from the large intestine.

Lymph-collecting vessel

Contains valves to ensure that lymph flows in a single direction. Lymph collecting vessels drain into larger lymph trunks.

Lymph node

Dosen't secrete any product instead they act as filters that remove potential pathogens from the lymph before it is delievered to the blood.

Right lymphatic duct

Drains the right upper limb and the right side of the head, neck, and thorax.

Tonsil

Found in the posterior oropharynx and nasopharynx. Because of their locataion (throat and palate) they can stop germs entering the body through the mouth or nose. The tonsils also contain a lot of white blood cells which are responsible for killing germs.

Mucosa-associated lymphatic tissue

Initiates immune responses to specific antigens encountered along all mucosal surfaces. MALT inductive sites are secondary immune tissues where antigen sampling occurs and immune responses are initiated.

Tracing the flow of lymph through the body. Intestines (with fat)

Instestines (with fat)- Lacteal capillary- Intestinal lymphatic capillaries- Intestinal lymph collecting vessels - Intestinal lymph node- Intestinal trunk- Cisterna chyli- thoracic duct- junction of left internal jugular and left subclavian veins- superior vena cava

Histology. Palatine tonsil

Internally they consist of lymphoid follicles with germinal centers. Externally they are lined with stratified squamous epithelium and feature deep indentations called tonsillar crypts that help to trap pathogens in the oral cavity.

Histology. Lymph node

Lymph nodes have an outer cortex that contains spherical clusters of immune cells (primarily B lymphocytes) called lymphoid follicled. In the center of the follicle is a lighter-staining region consisting of B lymphocytes, dendritic cells, and macrophages called a germinal center. Deep to the lymphoid follicles we find an area of the cortex that houses primarily T lymphocytes. The innermost region of the node, called the medula, houses primarily marcrophages. The entire lymph node is surrounded by a capsule made of dense irregular collagenous connective tissue.

Lymph

Once inside the lymph capillaries the fluid is called lymph and is delievered to larger lymph-collecting vessels.

Spleen

Resides in the upper left quadrant of the abdominopelvic cavity that filters the blood and houses phagocytes.

Tracing the flow of lymph through the body. Right arm

Right arm- Right arm lymphatic capillaries- Right arm lymph collecting vessels- Right axillary lymph nodes- Right axillary trunk- Right lymphatic duct- Junction of the right internal jugular and right subclavian veins- Superior vena cava

Humoral (antibody-mediated) immunity

Secretes antibodies to fight against antigens. It's rapid/ quick in their action against antigens.

Cell-mediated immunity

Secretes cytokines and no antibodies to attack the pathogens, they show a delay through permanent action against any pathogens.

Thymus

Secretes the hormones thymosin and thymopoietin that stimulate T lymphocyte maturation. The thymus is largest and most active in infants and young children.

Tracing the flow of lymph through the body. Right foot

Start: Right foot - Right foot lymphathic capillaries - Right leg lymph collecting vessels- Right inguinal lymph nodes- Right inguinal lymph trunk- Cisterna chyli- Thoracic duct- Junction of the left internal jugular and left subclavian veins- Superior vena cava

Lymphatic capillary

Surround blood capillary beds. Lymph capillaries have highly permeable walls that allow large substances and large volumes of fluid to enter and exit.

Inflammation

The inflammatory response occurs when tissues are injured by bacteria, trauma, toxins, heat, or any other cause. The damaged cells release chemicals including histamine, bradykinin and prostaglandins. These chemicals cause blood vessels to leak fluid into the tissues, causing swelling.

Innate immunity

The second line of defense, it consists of the responses of the cells and proteins which reacts the same way to any invading organism or cellular injury. We are born with these responses, they don't require exposure to a foreign cell or molecule to be produced.

Histology. Spleen

The spleen consists of two types of tissue: red pulp, which is involved in the destruction of old and worn-out red blood cells. white pulp, which contains phagocytes and lymphocytes that play a role in the immune system.

Adaptive immunity

The third line of defense consists of the responses of the cells and proteins, which responds to foreign cells and molecules with a unique set of cells and molecules for each individual threat. The components of adaptive immunity do require exposure to a foreign agent to be produced and for this reason they are often referred to as an aquired immunity.

Lymph Trunk

There are 9 main lymph trunks that drain lymph from major body regions. -Juglar trunks -Subclavian trunks -bronchomediatinal trunks -intestinal trunk -lumbar trunk -lymph ducts - right lymphatic duct -thoracic duct -cisterna chyli