6.3 DEFENSE AGAINST INFECTIOUS DISEASE Flashcards
ESSENTIAL IDEA
the human body has structures and processes that resist the continuous threat of invasion by pathogens
PATHOGEN
disease causing organism bacteria protozoa viruses fungi
PRIMARY DEFENSE AGAINST PATHOGENS THAT CAUSE INFECTIOUS DISEASE
skin
mucous membranes
SKIN AS A DEFENCE
continuous: hard to find an opening
many layers/tough
dry
pH: not favourable to pathogens
lysozyme: enzyme break down pathogens
natural organisms: competitive exclusion by non-harmful microbes
MUCOUS MEMBRANE AS A DENFENCE
sticky mucous: traps invaders
pH: not favourable to pathogens
lysozyme: enzymes break down pathogen
natural organisms: competitive exclusion by non-harmful microbes
CLOTTING FACTORS
cause a series of reactions which end with fibrin (a protein) fibres forming a mesh across the wound site
PLATELETS
small cell fragments
alongs with damaged tissue release clotting factors in response to a wound
FIBRIN FIBRES
capture blood cells and platelets forming a clot
in the presence of air the clot dries to form a scab which shields the healing tissue underneath
WHY DOES BLOOD CLOT?
to prevent blood loss and the entry of pathogen
BLOOD CLOT SUMMARY
platelet/ cell damage clotting factors thrombin fibrinogen--> fribin fibres captures erythrocytes clot
BLOOD CLOT CONVERSION
the cascade results in the rapid conversion of fibrinogen to fibrin by thrombin
CAUSES AND CONSEQUENCES OF BLOOD CLOT FORMATION IN CORONARY ARTERIES
cholesterol deposit plaques atherosclerosis blood clots heart attack death
LEUKOCYTES
WBC
phagocytes
–> engulf
lymphocytes
- -> B cells
- -> T cells
- -> killer cells
INGESTION OF PATHOGENS BY PHAGOCYTIC WBC
gives non- specific immunity to diseases
PHAGOCYTOSIS
involves a phagocyte
PHAGOCYTOSIS STEP 1
detecting and moving towards a foreign material (pathogen) using chemotaxis
PHAGOCYTOSIS STEP 2
foreign material is ingested by endocytosis
PHAGOCYTOSIS STEP 3
lysosomes attach to the ingested vesicle (which encloses the foreign material) and release enzymes into it
PHAGOCYTOSIS STEP 4
the enzyme digests/ breaks down the foreign material
PHAGOCYTOSIS STEP 5
the remains of the foreign material are expelled from the phagocyte
INADEQUATE PHAGOCYTIC RESPONSE
if the infection becomes widespread
then lymphocytes which control the specific immune response are used
ANTIGENS
substance or molecule that causes antibody formation
ANTIBODY
globular protein that recognises a specific antigen and binds to it as part of an immune response
ANTIBODIES ARE SPECIFIC TO
certain antigens
