Unit 11 – Physiology of Human Body Systems
M5 – explain how lymphatic system protects the body
Macrophages and phagocytosis:
A macrophage is a special type of leukocyte that engulfs particles. The bone marrow where stem
cells are located creates a cell called a monocyte. This monocyte is the largest type of leukocyte and
moves through the bloodstream. Once leaving the bloodstream and entering into tissues, the
monocyte matures into a macrophage. This macrophage is able to locate, engulf and destroy any
foreign substances in the airways, blood and lymph which positively affects our immune system. For
a macrophage to carry out it’s role, it goes through a process called phagocytosis.
Phagocytosis is the process of which a cell, known as a phagocyte, engulfs and digests foreign
particles. The process is a defensive response made by the body, so no infections are likely to
become worse. Within the lymphatic system, the pathogens release signals molecules called
cytokines which the macrophage recognises and then makes its way to the infected site via
chemotaxis. The macrophage detects the unknown particle which is done by pattern recognition
receptors (PRRs) which are produced by the macrophage. These receptors recognise and bind to the
pathogen-associated molecular patterns (PAMPs) which have different structures. Because these
patterns are not on any other cell in our body, besides the pathogen, this lets the macrophage know
that it will be a destroying a particle unknown to the human body and not a healthy cell. Once the
macrophage and the pathogen have bonded together, the macrophage uses pseudopods which are
extensions on the cytoplasm. These extensions slowly start to surround the pathogen creating and
indentation and pulling the pathogen into the macrophage. The two ends of the indentation then
close together creating a phagosome where the pathogen has been engulfed entirely into the
macrophage inside of a vacuole. Inside the macrophage are lysosomes, which fuse together with the
phagosome to create a phagolysosome. The phagolysosome then lowers the pH of the cell to
become very acidic, this then kills the pathogen inside making it unable to infect the cell it resides in.
Enzymes are released that break-up the neutralised pathogen and the residual body is released out
of the cell.
T-lymphocytes and cell medicated immunity:
T-lymphocytes are a type of leukocyte, specifically lymphocyte. As with all cells, it starts off in the
bone marrows stem cells where lymphocytes will be developed, and then these cells move into the
thymus gland where they mature into T-lymphocytes. There are three types of T-lymphocytes;
cytotoxic T-lymphocyte, helper T-lymphocyte and suppressor T-lymphocyte. These cells help protect
the body as they carry out immune response and are very important for cell mediated immunity, as
they respond to antigens on pathogens.
M5 – explain how lymphatic system protects the body
Macrophages and phagocytosis:
A macrophage is a special type of leukocyte that engulfs particles. The bone marrow where stem
cells are located creates a cell called a monocyte. This monocyte is the largest type of leukocyte and
moves through the bloodstream. Once leaving the bloodstream and entering into tissues, the
monocyte matures into a macrophage. This macrophage is able to locate, engulf and destroy any
foreign substances in the airways, blood and lymph which positively affects our immune system. For
a macrophage to carry out it’s role, it goes through a process called phagocytosis.
Phagocytosis is the process of which a cell, known as a phagocyte, engulfs and digests foreign
particles. The process is a defensive response made by the body, so no infections are likely to
become worse. Within the lymphatic system, the pathogens release signals molecules called
cytokines which the macrophage recognises and then makes its way to the infected site via
chemotaxis. The macrophage detects the unknown particle which is done by pattern recognition
receptors (PRRs) which are produced by the macrophage. These receptors recognise and bind to the
pathogen-associated molecular patterns (PAMPs) which have different structures. Because these
patterns are not on any other cell in our body, besides the pathogen, this lets the macrophage know
that it will be a destroying a particle unknown to the human body and not a healthy cell. Once the
macrophage and the pathogen have bonded together, the macrophage uses pseudopods which are
extensions on the cytoplasm. These extensions slowly start to surround the pathogen creating and
indentation and pulling the pathogen into the macrophage. The two ends of the indentation then
close together creating a phagosome where the pathogen has been engulfed entirely into the
macrophage inside of a vacuole. Inside the macrophage are lysosomes, which fuse together with the
phagosome to create a phagolysosome. The phagolysosome then lowers the pH of the cell to
become very acidic, this then kills the pathogen inside making it unable to infect the cell it resides in.
Enzymes are released that break-up the neutralised pathogen and the residual body is released out
of the cell.
T-lymphocytes and cell medicated immunity:
T-lymphocytes are a type of leukocyte, specifically lymphocyte. As with all cells, it starts off in the
bone marrows stem cells where lymphocytes will be developed, and then these cells move into the
thymus gland where they mature into T-lymphocytes. There are three types of T-lymphocytes;
cytotoxic T-lymphocyte, helper T-lymphocyte and suppressor T-lymphocyte. These cells help protect
the body as they carry out immune response and are very important for cell mediated immunity, as
they respond to antigens on pathogens.
