Immune system Flashcards
The three components of the immune system
lymphoid tissue
various immune cells
chemical signals that coordinate responses
Functions of the immune system
protect against pathogens
foreign substances
remove damaged cells
remove abnormal cells
Types of immune system pathologies
autoimmune diseases
overactive immune responses
lack of immune responses
what are the two lines of defense
Physical or chemical barrier : skin, cilia epitheal linings, acids, mucus, lysozymes.
Immune defenses:
name the two types of immune responses
Innate immunity: Non-specific- responds to a range of signals
- It is an immediate response
Acquired/adaptive immunity
specific: responds to specific signals
- Slower but stronger response
- Keeps memory for if the pathogen attacks again
Physical and chemical barriers
Physical/mechanical barriers: skin, mucous membrane, lacriminal apparatus ( produces tears ), saliva, epiglottis.
Chemical
sebum: secreted by sebacious glands and has a low pH that inhibits microbial growth
Perspiration: Flushes skin of micobes and has lysozymes
Gastric juice: low pH and has enzymes
Urine
The timeline for response
for the first 6hr: innate response Epitheal barriers phagocytes complement NK cells
After: Adaptive immunity: B lymphocytes T lymphocytes antibodies Effector T cells
the four steps to immune responses
detection of the foreign substance
communication with other immune cells
Recruitment of other immune cells
destruction or suppression of the invader cells
Lymphatic system
a system that collects tissue fluid from cells and returns it the blood.
Lymph is constantly monitored for pathogens0
Types of lymphoid tissues
primary lymphoid tissues: Bone marrow , thymus
encapsulated lymphoid tissues : lymph nodes, spleen.
diffuse lymphoid tissues/ lymph nodules
The thymus gland
this is a 2 lobed organi located above the heart.
It produces: T-lymphocytes and
peptides: thymosin,
thymopoietin, thymulin .
theses are necessary for the maturaion of T lymhocytes
Grows to its full size i adolescence then it shrinks and turns into adipose
lymphoid nodules
Loose connective tissue with densely packed lymphocytes
not surrounded by a capsule
germinal centre is where lymphocytes divide
Their size is highly dependant on the amount of lymphocytes in them
where are lymphoid nodules found
under the epithileal layers of organs connected to the outside world eg. the digestive, resporatory and urinary tract
interferons
signaling proteins produced by a virus infected cell to alert nearby cells to heighten their viral defences
parts of lymph nodes
afferent and efferent lymph vessels
Paracortical area( has mostly T-Cells
Medullary (macrophages and plasma cells)
primary lymph follicle (b cells mostly)
Leukocytes
Granulocytes
Neutrophils
basophils
eusonophils
Agranulocytes
Monocytes
lymphocytes
dendritic cells
macrophages
Act by phagpcytosis and bactericidal mechanisms
antigen presentation
dendritic cells
antigen uptake in perpheral sites
antigen presentation
neutrophil
phagocytosis and activation of bactericidal mechanisms
mast cells
release granules containing histamine and active agents
eusinophil cells
killing antibody coated parasites
Natural killer cells
release lytic granules that kills some virus infected cells
they induce apoptosis
they attack tumor cells
they secrete interferons alpha and beta that stop viral replication
Interferon gamma activates microphages
First line of defence
barriers that keep the pathogens from entering physically or with chemicals eg the skin, mucous membranes and secretions of the stomach, that are acidic
what is the difference between the way pathogens with and those without caosules are phagocytosisized
those without are directly and those with have antibodies that attach first and then they are ( well you know the word)
how are ingested pathogens killed
with lysozymal enzymes
How do Anitgen presenting cells work
they ingest the pathogen, break it down and then they present them on the surface of the cell.
Inflammation
this is a local non specific response to infection
beneficial roles of inflammation
attract immune cells to the site of infection
create a physical barrier so that infection does not spread
promote tissue repair
steps to inflammatory responses
cytokines are released to the site
acute phase proteins help prevent damage
cytokine encourage the production of histamine from mast cells which cause vasodilation to allow more white blood cells faster and edema due to osmotic effect of the plasma proteins
action of cytokines
small roteins that are produced by macrophages they increase permiability and cause fever and attract other immune cells
other chemicals in inflammatory responses
interleukins- subset of cytokines. They cause fevers and blood vessels become more permeable to WBC and proteins , acute phase proteins
Bradykinin: cause pain and swelling
complement proteins: are inactive as plasma proteins
the complement cascade produces membrane attack complex that inserts into foreign cells and results in lysis.
how does the membrane attack complex act
complement proteins insert themselves in the membrane of pathogens and water and ions go in and cause lysis
immune response chemicals functional classes
acute phase proteins : enhane the inflammatory response and act as opsonins
chemotaxins: they attract phagocytes to infection sites
cytokines : affect growth and activity of other cells
opsonins : coat pathogen
pyrogens: fever producing
acquired immuntity
acts to and reacts to a specific antigen
the difference between active and passive immunity
active: when the lymphocytes are exposed to foreign antigens in the body
Passive when we receive foreign antibodies from elsewgere
Memory cells are also produced
Mechanism of adaptive responses
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