Goal- Immune Sytem Flashcards
Barrier defences
such as the skin and mucous membranes, which act instantaneously to prevent pathogenic invasion into the body tissues
nonspecific innate immune response,
The rapid but nonspecific innate immune response, which consists of a variety of specialized cells and soluble factors
adaptive immune response
The slower but more specific and effective adaptive immune response, which involves many cell types and soluble factors, but is primarily controlled by white blood cells (leukocytes) known as lymphocytes, which help control immune responses
lymphatic system
The lymphatic system is the system of vessels, cells, and organs that carries excess fluids to the bloodstream and filters pathogens from the blood.
The swelling of lymph nodes during an infection and the transport of lymphocytes via the lymphatic vessels are but two examples of the many connections between these critical organ systems.
A major function of the lymphatic system is to drain body fluids and return them to the bloodstream. Blood pressure causes leakage of fluid from the capillaries, resulting in the accumulation of fluid in the interstitial space.
The lymphatic system drains the excess fluid and empties it back into the bloodstream via a series of vessels, trunks, and ducts.
Lymph
the term used to describe interstitial fluid once it has entered the lymphatic system. When the lymphatic system is damaged in some way, protein-rich interstitial fluid accumulates in the tissue spaces. This inappropriate accumulation of fluid referred to as lymphedema may lead to serious consequences.
Lymphatic capillaries
also called the terminal lymphatics, are vessels where interstitial fluid enters the lymphatic system to become lymph fluid.
Located in almost every tissue in the body, these vessels are interlaced among the arterioles and venules of the circulatory system in the soft connective tissues of the body. Exceptions are the central nervous system, bone marrow, bones, teeth, and the cornea of the eye, which do not contain lymph vessels.
thymus
The thymus is a specialised primary lymphoid organ of the immune system.
Within the thymus, thymus cell lymphocytes or T cells mature. T cells are critical to the adaptive immune system, where the body adapts specifically to foreign invaders. The thymus is in the upper front part of the chest, in the anterior superior mediastinum, behind the sternum, and in front of the heart.
It is made up of two lobes, each consisting of a central medulla and an outer cortex, surrounded by a capsule.
Lymph nodes
Lymph nodes function to remove debris and pathogens from the lymph and are thus sometimes referred to as the “filters of the lymph”.
Any bacteria that infect the interstitial fluid are taken up by the lymphatic capillaries and transported to a regional lymph node. Dendritic cells and macrophages within this organ internalize and kill many of the pathogens that pass through, thereby removing them from the body.
The lymph node is also the site of adaptive immune responses mediated by T cells, B cells, and accessory cells of the adaptive immune system.
Cellular Components of the Immune System
The cells of the blood, including all those involved in the immune response, arise in the bone marrow via various differentiation pathways from hematopoietic stem cells.
In contrast with embryonic stem cells, hematopoietic stem cells are present throughout adulthood and allow for the continuous differentiation of blood cells to replace those lost to age or function. These cells can be divided into three classes based on function:
Phagocytic cells, which ingest pathogens to destroy them
Lymphocytes, which specifically coordinate the activities of adaptive immunity
Cells containing cytoplasmic granules, which help mediate immune responses against parasites and intracellular pathogens such as viruses
Phagocytic cells
which ingest pathogens to destroy them
Lymphocytes
which specifically coordinate the activities of adaptive immunity
lymphocytes are the primary cells of adaptive immune responses.
The two basic types of lymphocytes, B cells and T cells, are identical morphologically with a large central nucleus surrounded by a thin layer of cytoplasm. They are distinguished from each other by their surface protein markers as well as by the molecules they secrete. While B cells mature in red bone marrow and T cells mature in the thymus, they both initially develop from bone marrow. T cells migrate from bone marrow to the thymus gland where they further mature. B cells and T cells are found in many parts of the body, circulating in the bloodstream and lymph, and residing in secondary lymphoid organs, including the spleen and lymph nodes.
cytoplasmic granules
help mediate immune responses against parasites and intracellular pathogens such as viruses
B Cells
B cells are immune cells that function primarily by producing antibodies. An antibody is any of the group of proteins that binds specifically to pathogen-associated molecules known as antigens. An antigen is a chemical structure on the surface of a pathogen that binds to T or B lymphocyte antigen receptors. Once activated by binding to antigen, B cells differentiate into cells that secrete a soluble form of their surface antibodies. These activated B cells are known as plasma cells.
T Cells
The T cell, on the other hand, does not secrete antibody but performs a variety of functions in the adaptive immune response. Different T cell types have the ability to either secrete soluble factors that communicate with other cells of the adaptive immune response or destroy cells infected with intracellular pathogens. The roles of T and B lymphocytes in the adaptive immune response will be discussed further in this chapter.
