Chapter 12- communicable diseases Flashcards
What are physical plant defences against pathogens
-callose is deposited in cell wall and membrane including plasmodesmata. Acting as a barrier and prevents pathogen from spreading
- calloseblocks sieve plates in phloem preventing spread of pathogens
- login added to callose/cell wall making the barrier thicker and stronger
- callose seals off infected cells fro, healthy cells to to prevent prevent the pathogens from spreading
What are 5 chemical plant defences against pathogens?
-insect repellent e.g. citronella
- insecticides e.g. caffeine which is toxic to insects and fungi
- antibacterial compounds e..g antibiotics (contains lysosomes, especially which contains enzymes that break down bacterial cell walls )
- antifungal compounds e.g. phenol and chitanasws (enzymes that break down chitin in fungal cell walls)
- toxins e.g. cyanide which is toxic to most living things
What are the 4 non specific animal defences for keeping pathogens out.
- Skin= covers the body and prevents entry of pathogens. It has microorganisms that outcompete pathogens for space on the body’s surface. The skin also produces sebum (an oily substance which inhibits growth of pathogens)
- Mucous membranes= line many of the body tracts e.g. airways, they secrete sticky mucus. This traps microorganisms and contains lysosomes which destroy pathogens
- Lysosomes= in tears, urine and acid in our stomach prevents pathogens getting into our bodies
- blood clotting
- inflammatory response
describe blood clotting and wound repair. (non- specific response)
blood clotting prevents loss of blood and prevents entry of pathogens. If the endodermis is damaged, for example the skin is cut, then platelets are exposed to proteins outside the endothelium, this activates platelets and now trigger blood clotting. Platelets release chemicals like thromboplastin (enzyme), catalyzing the formation of insoluble fibrin which forms a mesh which traps red blood cells, forming a blood clot. They also release serotonin, which causes the smooth muscle cells in blood vessel wall to contract narrowing blood vessel, reducing blood flow to the damaged area. The body can now start to repair the damaged blood vessel. Tissue damage can also result in inflammation. When tissue is damaged, mast cells release a chemical called histamine, causes nearby blood vessels to dilate or widen (vasodilation), increasing blood flow to the area so it feels hot and red (reducing pathogen ability to reproduce, and causes pain due to increased tissue fluid). Mast cells also release cytokines which attract phagocytes to damaged tissue for phagocytosis.
describe the inflammatory response. (non- specific response)
There is inflammation at the site of wound, it is characterized by pain, heat, redness and swelling.
Mast cells are activated in damaged tissue and release chemical called histamines and cytokines.
Histamines make the blood vessels dilate, causing heat and redness preventing pathogens from reproducing
Histamines do this by making blood vessel walls leakier so blood plamas is forced out, this become tissue fluid which causes swelling and pain. This delivers immune cells in blood to site of infection, fluid dilutes toxins
Cytokines attract white blood cells. They dispose of pathogens by phagocytosis.
Complete the following sequence (5 steps) to outline how a vaccine gives an individual immunity. The
first two steps have been completed for you.
Step 1: A vaccine is produced that is a safe form of an antigen.
Step 2: A small amount of vaccine is injected into blood of the individual to be vaccinated
step 3
antigen presentation /
antigen binds to specific, B / T, lymphocyte / cell ✓
steps 3 or 4
clonal selection /
clonal expansion /
plasma cells produced /
produce antibodies
primary immune response ✓
step 5
ref. memory cells /
secondary immune response ✓
what is meant by the term autoimmune disease?
abnormal immune response ✓
against tissues normally in the body ✓
name the different types of pathogen that can cause communicable diseases in plants and animals
bacteria – tuberculosis (TB), ring rot (potatoes, tomatoes)
viruses – HIV/AIDS (human), influenza (animals), Tobacco Mosaic Virus (plants)
protoctista – malaria, potato/tomato late blight
fungi – black sigatoka (bananas), athlete’s foot (humans).
define the term clonal selection
activated T helper cells bind to the B cell APC. then a B cell with the correct antibody is selected for cloning
define the term clonal expansion
The activated B cell divides by mitosis to give clones of plasma cells and memory cells
describe the role of T helper cells (t lymphocyte)
they have CD4 receptors on their cell surface membranes which bind to surface antigens on the APC’s. They produce interleukins which is a type of cytokines ( cell signalling molecule). They stimulate the activity of B cells which increase antibody production.
describe the role of T killer cells (t lymphocyte)
They destroy the pathogen carrying the antigen. They produce a chemical called perforin, which kills the pathogen by making holes in the cell membrane so it is freely permeable
describe the role of B effector cells (B lymphocyte)
these divide to form the plasma cell clones
describe the role of B plasma cells (B lymphocyte)
produce antibodies to a particular antigen and releases them into circulation
outline how a virus replicates
the virus attaches to a specific receptor on the host cell surface. then passes through the cell membrane. the virus then copies itself using enzymes in the host cell. Then they leave the host cells, infect other cells and continue reproducing
outline how a fungus replicates
fungi obtain nutrients by releasing enzymes and digesting the material around them. the products of digestion are then absorbed back into the fungal cells. this causes damage to the host cells and tissues. they release fungal spores to spread
describe what is meant by the humoral response
increases B cells and effective against pathogens present in bodily fluids
describe what is meant by the cell mediated response
primarily mediated by T cells. this response is effective against pathogens that have entered body cells such as viruses or against abnormal cells like cancer cells.
give the role of cytokines
act as cells signaling molecules informing other phagocytes that the body is under attack and to move to the site of inflammation
give the role of phagosomes
vesicles inside a phagocyte that contain the pathogen keeping it contained
give the role of lysosomes
filled with digestive enzymes. break down and digest the pathogen
what is the potential for personalized medicine
a combination of drugs that work with your specific combination of genetics- and disease by analyzing the entire human genome
what is synthetic biology
using techniques of genetic engineering, we can develop populations of bacteria to produce rare, not available, expensive drugs, this has great potential in medicine.
what are benefits and risks of using antibiotics to manage a bacterial infection?
benefits:
- selective toxicity= antibiotics interfere with the metabolism of bacteria without affecting the metabolism of human cells
risks:
- bacteria are becoming less effective as they are becoming resistant to more and more antibiotics. they rapidly mutate and reproduce. this is a particular problem in hospitals where often antibiotics are needed
