Diseases Flashcards
Name a bacteria in:
- Humans
- Plants
- TB
- Ring rot
Name a virus in:
- Humans
- Animals
-Plants
- HIV
- Influenza
- TMV
Name a Protoctista in:
- Humans
- Plants
- Malaria
- Potato late blight
Name a fungi in:
- Humans
- Plants
- Athlete’s foot
- Black sigatoka
Describe physical defences in plants:
- Bark (act as a protective barrier)
- Callose
Callose deposits itself between cell walls and cell membrane, preventing pathogens from infecting cells outside of the site of infection
It blocks phloem sieve tube elements
It deposits in the plasmodesmata between neighbouring cells
Describe chemical responses to plant infection:
- Anti-microbial compounds (antibiotics)
- Anti-fungal compounds (chitinases)
- Toxic compounds (cyanide)
- Insect repellent
Describe how blood clots are formed:
Platelets are tiny fragments of cells with no nucleus. When activated platelets detect damage to the skin, they release chemicals (thromboplastin and serotonin). Serotonin induces vasoconstriction. Thromboplastin + Ca2+ convert prothrombin to an active enzyme thrombin which catalyses the conversion of soluble fibrinogen to insoluble fibrin. This forms a mesh in which blood cells and blood components are caught, creating a blood clot.
What do cytokines do?
Attract phagocytes
What do opsonins do?
Bind to pathogens and increase phagocytosis
What are the three roles of antibodies?
- Agglutinins
- Opsonins
- Anti-Toxins
Describe the process of inflammation:
Mast cells are transported in the bloodstream, when they detect damaged tissue they release histamines and cytokines. Histamines cause vasodilation, redness, heat and swelling. Leaky vessels cause tissue fluid to escape (swelling). Cytokines attract phagocytes.
Name the four types of T cell and their purposes:
- T-Killer cells release perforin and disrupt cell membranes in order to kill them
- T-helper cells select B cells and induce clonal selection and clonal expansion
- T-memory cells remain in the bloodstream and are activated quicker upon secondary infection
- T-regulatory cells regulate the immune response to prevent excess damage
What are some non-specific defences against diseases?
- Expulsive reflexes
- Lysozymes (tears)
- Skin
- Mucous membranes/ Cilia
- Fevers (cause vasodilation and reduce pathogen reproduction)
Explain how phagocytosis works:
The foreign antigen on a pathogen is detected. It is ingested by a phagocyte and enclosed into a vesicle (phagosome). The phagosome then fuses with a vesicle containing hydrolytic enzymes (lysosome) to form a phagolysosome where the pathogen is digested. The antigen can be salvaged and expressed on the cell surface membrane of the phagocyte (antigen-presentation).
What are some differences between macrophages and neutrophils?
- Neutrophils are originally found as monocytes in blood
- Macrophages are APCs
- Neutrophils are short-lived and form pus
- Macrophages usually reside in tissues
