31 - immune system Flashcards
(21 cards)
what are the lymphatic system structures?
The lymphatic system consists of
- Lymph vessels
- Lymphatic tissues such as the spleen, thymus and lymph nodes.
what is the function of the lymphatic system?
The lymphatic system carries out the body’s immune response by producing and distributing lymphocytes – cells that combat disease.
where does lymph circulate?
Lymph circulates through the body. It begins at interstitial fluid between cells and filters into lymphatic capillaries, following into larger vessels and trunks, and eventually returning to venous blood.
where does lymph empty into the bloodstream?
Lymph empties into the bloodstream from the thoracic duct and right lymphatic duct, at the junction between the subclavian and internal jugular veins.
what is the thoracic duct?
The thoracic duct, or left lymphatic duct, begins at the cisterna chyli and collects lymph from the left upper body beneath the ribs.
what does the right lymphatic duct do?
The right lymphatic duct collects lymph from the right upper body.
what are lymph trunks?
Lymph trunks are major lymphatic vessels that empty into the thoracic and right lymphatic ducts.
where are lymphocytes produced?
B cells are lymphocytes that develop and mature in red bone marrow inside spongy bone, particularly in the vertebrae, sternum, ribs, and pectoral and pelvic girdles. After maturing, they enter the bloodstream, then colonize lymphatic tissues like the spleen and lymph nodes. Some of them stay in the bloodstream until needed.
what happens in the Thymus?
T cells are lymphocytes that develop and mature in the thymus. After maturing, they enter the bloodstream, then colonize lymphatic tissues like the spleen and lymph nodes. Some of them stay in the bloodstream until needed.
what happens in the spleen?
Inside the spleen, abnormal blood cells are consumed by cells called macrophages, and lymphocytes carry out immune responses. The spleen also stores iron from blood cells.
what is the function of the lymph node?
lymph nodes are capsules of tissue that lifter lymph and contain lymphocytes that destroy pathogens.
how are lymph nodes distributed?
lymph nodes are clustered in areas where the head and limbs meet the torso and near the intestines. this distribution defends the torso from pathogens entering from the extremities or from ingested food.
what are the physical defenses of the immune system?
the skin and mucous membranes provide a physical barrier to invading pathogens. tears, saliva, urine, and gastric juices also aid in the destruction and removal of microbes.
what is innate immunity?
innate immunity provides a fast and general defence against invading pathogens.
once infection takes place, fever elevates body temperature to accelerate the immune response. inflammation around the site of injury is from dilated blood vessels, which allows more white blood cells to leave the bloodstream and enter the tissues.
some of the white blood cells are phagocytes, which consume the invading microbes. other white blood cells kill the pathogen by peircing its cell membrane.
what is the innate immune response?
the innate immune response is a general response involving physical defenses, antimicrobial substances, fever, inflammation and phagocytes that consume pathogens.
what is phagocytosis?
when bacteria or other pathogens are present in the body, certain white blood cells categorised as phagocytes consume the microorganisms to protect the body from infection.
the process of consuming the pathogen begins when the phagocyte is attracted to chemicals from the pathogen, and through receptors, binds to it.
the phagocyte ingests the microbe, encasing it in a compartment called a vacuole.
lysosomes in the phagocyte merge with the vacuole.
its enzymes then kill and digest the pathogen, and release any indigestible remains from the cell.
this process, called phagocytosis, protects the body by removing pathogens.
explain the importance of white blood cells
White blood cells, or leukocytes are the component of blood that defends the body against disease.
There are many types of leukocytes.
Together they account for 1 percent of circulating blood; their numbers increase during infection or inflammation.
explain adaptive immunity
Cells in the body can fight unknown invaders by adapting an antibody response or a T cell mediated response. When a B cell with receptors for a specific pathogen recognises the pathogen in the body, the B cell is activated and divides to produce plasma cells and memory cells.
The plasma cell releases antibodies that eliminate the pathogen and memory B cells live on in the body to prepare for the next invasion. During cell-mediated immunity, T cells seek out antigens on infected cells. The T cell’s receptors bind to the cells, then destroy them. Some T cells become memory cells.
what is the adaptive immune response?
The adaptive immune response is a targeted response in which B and T lymphocytes recognise and neutralise invading microbes in the lymphatic system and bloodstream.
what are B cells
B cells develop and mature in red bone marrow before becoming active in the spleen, lymph nodes, and bloodstream. They produce antibodies - substances that recognise the antigens on foreign microbes and act as tags that identify the invaders.
what are T cells?
T cells develop in red bone marrow and mature in the thymus before becoming active in the spleen, lymph nodes, and bloodstream.
Once activated by antigens - the substances on foreign microbes - they seek out and destroy infected cells.
