Cholera and HIV Flashcards
How is cholera transmitted?
Through ingestion of water or food that’s been contaminated with faeces containing the cholera pathogen
What are the 2 parts of the cholera toxic protein and what do they do?
1st: binds to specific carbohydrate receptors on cell membranes which are only found on epithelial cells in the small intestine
2nd: Enters epithelial cells and causes ion channels to open, causing chloride ions to flood into lumen of small intestine.
What leads to loss of water in cholera?
- Loss of chloride ions raises water potential of epithelial cells, causing water to flood out of them
- Loss of ions creates a concentration gradient, causing ions from blood and surrounding tissues to diffuse into cells. Creates water potential gradient, and water osmoses from blood into small intestine.
What should oral rehydration solution contain?
Water,Sodium,Glucose,Potassium and other electrolytes
What are the problems with ORS
- Excess sodium can cause side effects
- Too little sodium, but too much glucose lowers water potential
- Lowering glucose makes respiration harder
Solved problem with ORS
Use starch as it’s insoluble with no osmotic effect. It’s broken down steadily by amylase and maltase in small intestine into glucose
How does HIV infect a person?
1) attachment protein attaches to receptor molecule on CD4 helper T-cell
2) Capsid releases into cell, uncoats and releases RNA and viral enzymes into cell’s cytoplasm
3) Reverse transcriptase makes DNA from RNA
4) DNA integrated into host cell DNA
5) Host cell enzymes and ribosomes make viral proteins which are assembled. New virus made from cell membrane of host cell.
Why does HIV lead to AIDS?
Damage to helper T-cells which stimulate response means B-cells can no longer receive proper signals, reducing function of immune system
How do attachment and entry inhibitors stop HIV?
Block attachment points of HIV viral protein onto helper T-cell. Some bind to proteins on virus while others bind to cell’s receptors
How do Reverse transcriptase inhibitors stop HIV?
Non-nucleoside bind to region away from active site to change its shape. Nucleoside inhibitors act as alternative nucleotides in synthesis of Viral DNA copy. Polynucleotide chain gets terminated when they incorporate
How do integrase inhibitors stop HIV?
Act on enzyme repsonsible for integration of viral DNA onto Genomic DNA
How do protease inhibitors stop HIV?
Inhibit enzymes responsible for completing modification of proteins incorporated in new virus particles
