The Immune System Flashcards
What is the function of the 1st line of defense?
Keep pathogens out
What is the function of the 2nd line of defense?
General defense against pathogens that make it in
What is the function of the 3rd line of defense?
Memory of previous pathogens and will attack if seen again
What kind of immunity is considered 1st and 2nd line of defense?
Nonspecific immunity
What is the main difference between nonspecific and specific immunity?
Specific immunity has memory of the pathogens
Describe characteristics of nonspecific immunity
present at birth, doesn’t recognize specific pathogen
Desrcibe characteristics of specifc immunity
recognizes and attacks foreign substances, keeps memory of the pathogens
Name the 1st line of defense techniques
Skin, mucous membranes, chemical secretions, reflexes
How does skin protect?
physical barrier, lysozymes break down bacterial cell walls in sweat, acidity of sweat inhibits bacterial growth, sebum is oily and acidic
How do mucous membranes protect?
mucus traps dusts and pathogens, respiratory mucosa has cilia which moves dirt and pathogens
What do chemical secretions do?
destroy pathogens, stomach juice contains HCl. Saliva, tears, and nasal secretions contain lysozyme, and body openings are acidic
What are your protective reflexes?
blinking, coughing, sneezing, vomiting, urination, defecation
Name the 2nd line of defense techniques
Leukocytes, antimicrobial proteins, natural killer cells, inflammation, fever,
Name the leukocytes involved in the 2nd line of defense
neutrophil, macrophages, eosinophils, basophils
What is the function of neutrophils?
transported via chemotaxis. they dissolve the basement layer of the capillary to enter infected tissue
Define diapedsis
when the neutrophil leaves the capillary to go to the infection site through dissolving the basement layer of the capillary
What is the function of macrophages?
to wander and find pathogens or to gather in a likely place for a pathogen (also uses chemotaxis)
What is the function of eosinophils?
destroy allergens and parasites
What is the function of basophils
secrete Histamine and Heparin to aid in mobility and actions of WBCs
What is the function of Leukotrienes?
activate and attract WBCs
What does Histamine do?
vasodilate to increase blood flow
What does Heparin do?
inhibits formation of blood clot
Describe the process of phagocytosis
Infection occurs -> neutrophils/monocytes go to area ->monocytes enlarge and develop into macrophages ->neutrophils attach to capillary and diapedsis happens ->antigen ingested to form phagosome ->phagosome fuses with lysozome ->antigen ingested and exocytosis occurs
Define interferon
antiviral protein that fills healthy cells to prevent them from being taken over by the virus infecting. helps prevent replication
What is the complement system?
plasma proteins from blood that attack viruses, bacteria, and parasites and cause bacteria to swell and burst.
What is the membrane attack complex?
group of proteins form in rings and puts a hole through bacterium.
Define Opsonization
coating of pathogens to make them more attractive to phagocytes. It stimulates inflammation and binds to basophils
Describe the function of natural killer cells
circulate blood checking for sick cells, lyse and kill sick cells, attacks a larger number of enemies
Define cytolysis
Killing of a cell like when granzymes enter and it dies
Why does inflammation occur?
response to tissue injury
List the four signs of inflammation
redness, heat, swelling, and pain
List the 5 stages of inflammation
- histamine/heparin are released
- hyperemia
- vasodilation increases permeability of capillaries
- pain may be caused by pressure on nerves or injury of neurons
- phagocytic mobilization/containment
- tissue repair (increased rate of mitosis)
Define hyperemia
increased blood flow
What is the function of a fever?
promotes activity of interferon, kills bacteria/viruses, increases metabolic rate, high fever (+106) denatures proteins
List the steps of a fever
- neutrophils/macrophages secrete pyrogen
- pyrogen makes hypothalamus increase body’s temp
- bpdy shivers to produce heat and constricts blood vessels
- body sweats and dilates skin vessels
B cells, T cells, and antibodies are indicators of
specific immunity
Define immunogloblins
antibodies found in plasma and are made by B cells
Define specificity
each B or T cell has receptors that are antigen-specific
Define systemic response
lymphocytes that are sensitive to the antigen will clone themselves and spread through the body
How does memory work in specific defense?
after the initial exposure, lymphocytes make memory cells which then launch a faster and stronger attack against it
Define immunocompetence
ability of the body to produce normal immune response to an antigen
Describe T cells
- make up 80% of lymphocytes
2. mature in the thymus
What are the three types of T cells
- cytotoxic (CD8+)
- helper (CD4+)
- suppressor (regulatory)
What is the function of the cytotoxic cells?
attacks host body infected with virus or cancer
What is the function of helper cells?
stimulates both B and cytotoxic cells (HIV attacks these )
What is the function of supressor cells?
modulates immune system, maintain tolerance to self-antigens, prevents autoimmune disease
Describe B cells
- mature in bone marrow
- humoral immunity
- when stimulated they turn into plasma cells and produce antibodies
Define antigen
proteins on cells membranes that have to be seen as foreign
Define epitope
aka antigen determinants. immunogenic. each antigen has multiple epitopes so it can be recognized by many b or t cells
When are epitopes presented?
During antigen presentation
Where do T cells gain specific antigen receptors?
in the thymus
Where do B cells gain specific receptors?
in the bone marrow
How many epitopes can each lymphocyte bind to?
one
Which cells need antigens to be presented to?
T cells
What are phagocytes usually called and what are they?
professional APCs & macrophages, dendritic cells, B cells
When do normal cells become APCs
when they are infected or have cancer
What happens with a professional APC encounters a pathogen?
it will engulf it, process it, and then display a fragment of the antigen on its surface with MHC II
