Exam 4 Flashcards
skin and mucosal surfaces
organism must penetrate, adhere, grow
mucus limits direct access to epithelial cells
normal flora
young are more susceptible before stable adult flora develops
diet and drugs can alter flora
antimicrobial secretions
lysozyme & other enzymes kill bacteria in saliva and tears
defensin proteins insert in microbial membranes
blood proteins sequester nutrients
fatty acids on skin lower pH
physical removal
cilia/mucus movement
urine flushing
general host defenses
skin and mucosal surfaces, normal flora, antimicrobial secretions, physical removal, stomach acid
components of the immune system (2nd and 3rd line of defense)
blood and lymph systems, organs and tissues, blood cells, plasma proteins
blood and lymph systems
two interconnected circulatory systems
- blood is closed loop powered by heart
- lymph is a drainage system returning tissue to blood
lymph drainage system
- series of connecting vessels starting with microscopic capillaries
- fluid drains from lymph to surrounding tissue
- movement of fluid powered by skeletal muscle pressing on lymph vessel (one way valves keep lymph moving to chest)
- white blood cells move in and out of lymph vessels (extravasation), WBCs collect in lymph nodes, kill bacteria, remove debris, and interact with other cells of the immune system present there
primary organs/tissues
where lymphocytes develop: thymus and bone marros
secondary organs/tissues
where lymphocytes collect: spleen, lymph nodes, tonsils, adenoids, appendix (MALT GALT SALT)
M cells in skin, tonsils, adenoids, intestines monitor flora
blood cells: erythrocytes
red blood cells, not part of immune system (enucleated, carry oxygen)
platelets
involved in clotting
leukocytes: white blood cells
monocytes, dendritic cells, macrophages, polymorphonuclear leukocytes, mast cells, lymphocytes
monocytes, dendritic cells, macrophages
these are phagocytic, antigen presenting cells
-engulfs foreign cells, viruses, proteins
-break these down and display foreign peptides on their surface
-monocytes circulate in blood
-dendritic cells and macrophages attach to different tissues
polymorphonuclear leukocytes (PNMs or granulocytes in blood)
neutrophils, eosinophils, basophils
PNMs: neutrophils
phagocytic cells, migrate to site of infection (go where they are needed) can use NET (neutrophil extracellular trap) to kill cells
PNMs: eosinophils
anti-protozoan secretions
PNMs: basophils
inflammation mediator
mast cells
mediate inflammation throughout the body, not in blood
lymphocytes
mostly in spleen and lymph nodes:
natural killer cells, T cells, B cells
lymphocytes: T cells
central to adaptive immunity
lymphocytes: B cells
part of adaptive immunity, produce antibodies
lymphocytes: natural killer cells
kill infected or cancerous cells
proportion of blood
plasma proteins (soluble in fluid portion of blood): 55%
blood cells: 45%
plasma proteins
fibrinogen - clotting
antibodies
complementary
iron sequestration and other antibacterial proteins
response: infection via a splinter
resident macrophages engulf pathogens and release cytokines. vasoactive factors and cytokines help deliver additional phagocytes. some cytokines initiate healing as pathogens are destroyed.
inflammatory response
a non specific response to wounds and infection, signs describes 2000 years ago: redness, heat, pain, swelling
detection
triggered by unique signals of invader, bind to toll like receptors (in membrane) or nod-like receptors (in cytoplasm), cause transcription, and release of cytokines
clotting
clotting factors released by platelets, attempt to contain (wall off) infection
phagocytosis
- bacterium binds to the surface of a phagocytic cell. antibody or complement can aid binding
- phagocyte pseudopods extend and engulf the organism
- invagination of phagocyte membrane traps the organism within a phagosome
- lysosome fuses and deposits enzymes into the phagosome. enzymes cleave macromolecules and generate reactive oxygen species, destroying the organism
phagocyte/macrophage engulfs the microbe
invader is recognized because it does not have self antigen (CD4), some pathogens can avoid because of their capsule. antibodies can increase phagocytosis
