SNAB Biology - Topic 6
- Created by: Bambih369
- Created on: 23-06-19 09:58
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- Topic 6 - Immunity, Infection and Forensics
- Forensics
- Forensic entomology
- Determine type of species on the body
- Find the age of larvae on the body and determine the succession of species
- Determine type of species on the body
- Body Temperature
- Body begins to cool after death for 1-2 days
- It depends on the body position, clothing, Body size, humidity and surrounding temperature
- Extent of decomposition
- Enzymes in the gut break down the wall of the gut and surrounding area
- As cells die they release enzymes which break down other tissues
- Discoloration of skin and gas formation allow time of death to be determined
- As cells die they release enzymes which break down other tissues
- Enzymes in the gut break down the wall of the gut and surrounding area
- Rigor Mortis
- Muscles stiffen and become fixed 6-9hrs after death
- This is because contraction relies on ATP
- It wears off after 36hrs
- Muscles stiffen and become fixed 6-9hrs after death
- Forensic entomology
- Antibiotics
- Bactericidal
- Kills bacteria by destroying cell wall
- Bacteriostatic
- Prevents bacteria from diving by inhibiting protein sythesis
- Bacterial growth in cultures
- Sterilize petri dishes using hot agar
- Dip all instruments including forceps, inoculating loop into ethanol and run through the Bunsen burner
- Keep a Bunsen burner on near to the area of experiment to remove all extraneous bacteria
- Dip the loop into bacteria and run through the agar in a zig-zag pattern
- Add in antibacterial coated discs, lifting the lid as little as possible and then tape on three areas
- Dip the loop into bacteria and run through the agar in a zig-zag pattern
- Keep a Bunsen burner on near to the area of experiment to remove all extraneous bacteria
- Dip all instruments including forceps, inoculating loop into ethanol and run through the Bunsen burner
- Sterilize petri dishes using hot agar
- Bactericidal
- DNA profiling
- Forensic Technique for identifying genetic relationships
- Immunity
- Herd immunity
- Enough people vaccinated to stop transmission e.g 90%
- Types of immunity
- Active
- E.g vaccinations
- Natural
- E.g Body's natural response to infection
- Artificial
- E.g Anti serums such as antivenom
- Passive
- E.g antibodies being passed from mother to baby
- Active
- Secondary infection
- Shorter lag time
- Greater production of antibodies produced
- Much more rapid response
- RNA splicing
- Between the process of transcription and translation often mRNA is edited with some sections removed
- Non-coding introns are removed
- Exons remain and are expressed
- This means several proteins can be made from one length of mRNA
- Between the process of transcription and translation often mRNA is edited with some sections removed
- Herd immunity
- Non- specific Responses
- First line of defence
- Skin
- Physical barrier
- Skin flora produce sebum which destroys microbes and out competes other bacteria for space
- Lysozymes
- Enzyme in tears, sweat and mucus
- Stomach
- Stomach acid to break down pathogens
- Gut flora
- Mucus
- Traps pathogens which are broken down when we swallow in the stomach
- Skin
- Second line of defence
- Lysozymes
- An enzyme that kills bacteria by breaking down the cell wall
- Found in nasal secretions, sweat and tears
- Inflammation
- When tissue is damaged mast cells and damaged WBC release histamines
- These cause arterioles to dilate which causes heat and redness
- It makes the walls of the capillaries permeable, forcing plasma, WBC and antibodies out of the capillary to cause swelling
- When tissue is damaged mast cells and damaged WBC release histamines
- Interferons
- When cells are invaded they produce a chemical called interferons
- This diffuses from the cell to surrounding cells where is binds to the receptors on the surface of uninfected cells
- This prevents viral replication
- This diffuses from the cell to surrounding cells where is binds to the receptors on the surface of uninfected cells
- When cells are invaded they produce a chemical called interferons
- Phagocytosis
- The phagocyte produces a pseudopodia which grabs the microbes
- These microbes go inside a vesicle called the phagosome
- This vesicle fuses with the lysosome to produce the phagolysosome
- The enzyme inside called the lysozyme breaks down the microbes and any piece too large leaves via exocytosis
- This vesicle fuses with the lysosome to produce the phagolysosome
- These microbes go inside a vesicle called the phagosome
- The phagocyte produces a pseudopodia which grabs the microbes
- Lysozymes
- First line of defence
- Bacteria vs Viruses
- Viruses
- Dependent on host cell
- No cell bound organelles
- Nucleus
- HIV
- Symptoms include fever, diarrhea and secondary infections
- Treated with anti retroviral drugs
- Spread by sharing infected bodily fluids
- Viruses
- Specific responses
- Cell-mediated response
- The pathogen invades the host cell which then displays the antigens on its MHC- becomming an APC
- T killer cells with complementary receptor (CD4) binds to the APC
- The T killer cell divides into active and memory cells
- Cytokines secreted by T helper cells to stimulate the divide
- Actuve T killer cells bind to the infected cell which releases chemicals causing pores to form in the cell which causes it to fill with water and burst via lysis
- The T killer cell divides into active and memory cells
- T killer cells with complementary receptor (CD4) binds to the APC
- The pathogen invades the host cell which then displays the antigens on its MHC- becomming an APC
- Humoral response
- Bacterium engulfed by macrophage which presents antigens on the surface (APC)
- APC binds to T helper cell with CD4 receptors which activates the T helper cells
- T helper cells divide into active T helper cells and clones of T memory cells
- Antigen binds to the B cell with CD4 receptor (APC)
- Activated T helper cell binds to B cell with CD4 receptors and produces cytokines to stimulate B cell division
- B cells divide into B memory cells and B effector cells
- B effector cells differentiate into plasma cells which secrete antibodies which bind to antigens- identifying them for easier destruction
- B cells divide into B memory cells and B effector cells
- Activated T helper cell binds to B cell with CD4 receptors and produces cytokines to stimulate B cell division
- Antigen binds to the B cell with CD4 receptor (APC)
- T helper cells divide into active T helper cells and clones of T memory cells
- APC binds to T helper cell with CD4 receptors which activates the T helper cells
- Bacterium engulfed by macrophage which presents antigens on the surface (APC)
- Cell-mediated response
- Hospital code of practise
- Take full course and don't oversubscribe
- Reduces selection pressure on organisms and destroys all bacteria causing infection
- Hygiene
- Prevents spread of infection and cuts down the number of places for infection
- Isolating patients and resistant diseases
- Prevents transmission of resistant bacteria between pts
- Screening of pts coming into hospitals
- Person may be infected without showing symptoms so detected and isolated and treated
- Take full course and don't oversubscribe
- Forensics
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