cells and tissues of immune system Flashcards
what gives rise to cells in blood
haematopoietic stem cells (HSCs) give rise to haematopoietic progenitor cells which give rise to mature haematopoietic cells
the haematopoietic system is responsible for all the cells in blood
what parts of blood are involved in immune function
all parts of blood except erythrocytes and platelets (white blood cells) are involved in the immune system
how many immune cells are produced per day, how is this beneficial
10^9 lymphocytes, 10^10 granulocytes
large turnover of cells means the system is very flexible about regulating cell numbers which helps during infection
describe speed of translocation of immune cells
very motile, fastest in the body
what happens if the entire immune system is destroyed
immune system is renewable, if it is completely destroyed and stem cells are replaced the whole immune system will be repopulated
where are immune stem cells produced
stem cells emerge from bone marrow to blood where they develop, they then locate themselves in either
immunological organs (specialised organs made of immune cells, most of decision making happens here e.g how to react to foreign bodies e.g lymph nodes and spleen)
or non immunological organs (everything else), immune cells exist in all tissues.
what are sites that are most likely to be exposed to pathogens
through skin and gut
where do T lymphocytes develop
thymus, which is a primary lymphoid organ
what immune system responds to microbes
both innate and adaptive systems
what cells are granulocytes
neutrophils, eosinophils and basophils
describe neutrophil function
they are the major circulating white blood cell/ most common
main function is phagocytosis
they are recruited from blood to tissue during inflammation
they are short lived, have a strangely shaped nucleus
they convert free oxygen into oxygen free radicals, which are very potent toxins used to kill microbes
what do granulocytes produce
tiny amount of bleach when they kill bacteria
describe macrophage physiology/function
they are phagocytes
precursor is monocyte which exists in blood, develops into macrophages in tissues
when tissue is not infected macrophages clean up dead cells
macrophages are long lived and are specialised for the tissue they inhabit
macrophages in the liver are called kuppfer cells, in the brain they are called microglia
5% of blood cells are monocytes
killing molecules of macrophages are only made when they are activated by microbes
describe the physiology of lymphocytes
they are the cells of the adaptive immune system, they are very long lived and are responsible for specific immunity (how vaccines work)
what are functions of different types of lymphocytes
B cells are effectively big sacks of endoplasmic reticulum which it uses to produce lots of antibodies, produces the most protein per cell per minute than any cell
T cells circulate in blood, however constantly leave blood to enter tissues, they can enter tissues through inflammed tissues or through lymph nodes.
A T cell that is going to kill an infected cell is an effector T cell, secrete chemicals which make endothelium sticky for lymphocytes which helps them cross
naive cells (never seen pathogen before) and memory cells leave the blood stream to enter lymphoid tissue to search for antigen.
what are dendritic cells
antigen presenting cells, help with adaptive immunity
