Ch. 51 The Immune System in Animals Flashcards
pathogen
disease-causing organism
(ie) bacteria, parasite, microbe, virus or prion
immune system
the system whose primary function is to defend the host organism against pathogens
- includes several types of cells (leukocytes)
- lymph nodes & thymus
organs of the immune system
1) lymph nodes
2) thymus
observations biologists investigated about how animals stay healthy
1) wounds usually heal even if they become infected
2) most people who contract a bacterial/viral illness eventually recover w/out medication
3) people who acquire bacterial in viral infections and recover frequently do not contract the same disease again
immunity
a resistance to or protection against disease-causing pathogens
- prevents individuals from contracting disease more than once
immunization
the conferring of immunity to a particular disease by artificial means
(ie) vaccination
vaccination
artificially producing immunological memory against a pathogen by introducing a weakened/altered pathogen to prime the body’s immune system so it fights later infections effectively
Edward Jenner
physician who observed milkmaids did not get smallpox b/c they were exposed to cowpox
innate immunity
a set of barriers to infection & generic defenses against broad types of pathogens
- immediate response
- involves many leukocytes
- often activate an inflammatory response
- ready to respond to foreign invaders @ all times
- nonspecific
- responds in the same way to all antigens
antigen
any foreign molecule (often a protein) that can stimulate an innate or adaptive response by the immune system
adaptive immunity
immunity to a particular pathogen or antigen
- based on interactions btwn specific immune system cells & a specific antigen
- B & T cells
- specific
- diverse
- memory
- self-nonself recognition
(aka) adaptive immune response
* we get this from our mom
types of immunity
1) innate immunity
2) adaptive immunity
characteristics of innate immunity
- occurs in all animals
- has both cell-mediated & secreted components
- rapid response
- broadly specific response against types of pathogens
- response does not vary when infections recur (no memory)
- born w/
characteristics of adaptive immune
- occurs only in vertebrates
- has both cell-mediated & secreted components
- slow response
- specific response against pathogen strains
- response is more rapid & efficient when infection recur (memory)
- learned
barriers to invasion/entry
1) non-specific physical/chemical defenses
2) innate immunity (natural)
3) adaptive immunity (acquired)
* if pass #3, you’re screwed, you will die
types of barriers in the animal kingdom
1) insects - armored body
2) soft-bodied animals - covered w/ mucus
3) human skin - dead cells filled w/ keratin
how does the human skin act as a barrier against invasions?
1) shingled dead layer of cells filled w/ keratin acts as a protective layer
2) skin covered w/ oil (fatty acids), which lowers pH, making it difficult for pathogens to grow
mucus
a proteoglycan-rich solution secreted by epithelial cells
- serves as a barrier to protect surfaces from infection
how are gaps in the body protected?
*excluding mucous layers
via wax & lysozyme
wax
a class of lipid w/ extremely long, saturated hydrocarbon tails - harder & less greasy than fats
lysozyme
an enzyme that digests bacterial cell walls
- innate immunity
- occurs in lysozomes of phagocytes
- secreted in saliva, tears, mucus & egg white
flu virus
contain enzyme on their surface that disrupts the mucous lining of the respiratory tract
- sialic acid (originated from chickens)
- cross species disease
cells involved in the innate immune response
1) leukocytes
2) mast cells
3) macrophages
4) neutrophils
how are innate immune response leukocytes alerted by the presence of foreign invaders?
antibodies bind to antigens, labeling them as invaders
- binding cites are only found in invaders, not host cells
Innate response is nonspecific, but will respond to groups of pathogens such as _______ and ______
bacteria & fungi
pattern-recognition receptor
(leukocytes) a class of membrane proteins that bind to molecules commonly associated w/ foreign cells & viruses
- signal responses against broad types of pathogens
- innate immune response
- activated by pathogen-specific compounds
- serve as “on” switches by imitating cell response
(ie) Toll protein
Toll protein receptor (TLR)
“amazing”
acts as a receptor to signal a pathogen is present
- responds to antigens
- pattern-recognition receptors
(flies) signal production
1) fly detects a fungus infection: signal cascade activates secretion of antimicrobial peptides that act as antibodies
2) human TLR4 is activated, signal cascade promotes secretion of cytokines
3) when a virus attacks a cell, TLR7 detects signal promoting the secretion of a specific cytokine, interferon
cytokine
a group of signal proteins
- secreted by immune system
- stimulates leukocyte production
- recruits cells to site of infection, tissue repair & fever
- regulate type, intensity & duration of an immune response
(1st response) inflammatory / innate response in humans
- occurs @ site of an injury
1) skin breaks, pathogens enter a wound
2) platelets release blood-clotting proteins @ wound site
3) wounded tissues & macrophages @ wound site secrete chemokines, signaling molecules that assault immune cells by forming a gradient to mark the path to the site
4) mast cells release chemical messengers that constrict blood vessels near the wound–reducing blood flow & thus blood loss
5) neutrophils & macrophages remove pathogens by phagocytosis
6) macrophage secrete cytokines that attract other immune system cells to the site & activate cells involved in tissue repair; also induce fever
platelet
a small membrane-bound cell fragment in vertebrate blood
- FCN: blood clotting
- derived from large cells in the bone marrow
chemokine
a subset of cytokine
- acts as a chemical signal
- attracts leukocytes to a site of tissue injury or infection
- produced by: injured tissues & macrophages in tissues
- received by neutrophils & macrophages
- mark path to wound
- promote division & increased permeability of blood vessels
mast cell
a type of leukocyte
- stationary (embedded in tissue)
- triggers inflammatory response
- triggers secretion of histamine to infection or injury
- important in allergic response & defense against parasites
histamine
a molecule released from mast cells during an inflammatory response
- high concentrations: blood vessels constrict, reduced blood loss from tissue damage
- produced by: mast cells
- received by: blood vessels
neutrophil
a type of leukocyte
- capable of moving through body tissues
- engulfs & ingests pathogens & otro foreign particles
- secretes various compounds that attack bacteria & fungi
macrophage
a type of leukocyte
- participates in inflammatory response
- secretes cytokines & phagocitizing invading pathogens & apoptotic cells
- serves as an antigen-presenting cell to activate lymphocytes
phagocytosis
uptake by a cell of small particles or cells by invagination & pinching off of the plasma membrane to form small, membrane-bound vesicles
- engulf & digest
fever
elevated body temperature that aids in healing
innate immunity in invertebrates
innate responses make up the entire immune system observed in millions of species of invertebrates
- not fully functioning
examples of invertebrate innate immunity
1) cells respond to pathogen by synthesizing &;secreting peptides w/ potent antibacterial or antifungal properties
2) sea stars have specialized cells similar to neutrophils & macrophages; secrete cytokines or engulf & destroy pathogens by phagocytosis
key characteristics of the adaptive immune response
1) specificity
2) diversity
3) memory
4) self-nonself recognition
antibody
a protein produced by B cells
- bind to a specific part of an antigen
- tags antigen for removal by the immune system
- consist of 2 light chains & heavy chains
(aka) immunoglobulin
specific
adaptive immune response
antibodies & otro components of the adaptive immune system bind only to specific sites on specific antigens
diversity
adaptive immune response
the adaptive response recognizes an almost limitless array of antigens
memory
adaptive immune response
the adaptive response can be reactivated quickly if it recognizes antigens from a previous infection
self-nonself recognition
adaptive immune response
molecules that are produced by an individual do not act as antigens, so the adaptive immune system can distinguish btwn self and nonself
*major problem in organ transplants
lymphocyte
a cell that circulates through the bloodstream & lymphatic system
- responsible for development of adaptive immunity
- produced in bone marrow
- may also originate in the spleen
- belongs to either B cells or T cells
*unspecific like undergrad
inflamed lymph nodes
- sick
- high B or T cell concentration
*massage increase B or T cell movement, decreasing inflammation
types of lymphocytes
1) B cells
2) T cells
bone marrow
the soft tissue filling the inside of large bones
- contains stem cells that develop into RBC & leukocytes throughout life
spleen
a dark red organ found near the stomach of most vertebrates
- filters blood
- stores extra RBC in case of emergency
- plays a role in immunity
- lymphocytes may originate from here
B cell
a type of lymphocyte
- matures in the bone marrow (most animals) or bursa (birds)
- responsible for adaptive immunity
- produces antibodies
- functions in antigen presentation
*specializes in bone marrow like specialization in grad school
T cell
a type of lymphocyte
- matures in the thymus
- responsible for adaptive immunity
- involved in activation of B cells
- destroys infected cells
*specializes in thymus like specialization in grad school
B cells in chickens are produced in the _____.
bursa
bursa
organ that is necessary for B cell development in birds