We have evolved a very effective immune system, consisting of barriers, non-speficif defence mechanisms and specific ones. If we’re so good at fighting infections, why do we still get ill? Answer: pathogens are evolving as well. So how has TB evolved to beat...
Antibiotics work by targeting prokaryotic features not found in eukaryotic cells, e.g. penicillin targets the cell wall and breaks it down. Penicillin can be taken in large doses by humans because it has no effect on our cells (we have no cell walls). ...
The effectiveness of antibiotics can be measured using a disc diffusion technique. A bacterial lawn is grown on an agar plate (either by spreading the bacteria over the plate, or by using a pour plate). A disc of blotting paper is soaked in antibiotic of...
Bacteria are becoming resistant to antibiotics. Bacteria develop resistance through mutation. A bacteria can mutate and develop resistance by; Having an enzyme that breaks the antibiotic down Having a protein which pumps antibiotic out of the cell...
The evolutionary arms race between bacteria and drug developers is, at the moment, tipped against humans. There are over 100 different types of antibiotic and in the 40years since their development 4 species of bacterium have developed resistance against all of ...
Homeostasis is the maintenance of the body’s internal environment. This is carefully controlled by a series of systems, which aim to keep conditions at a stable controlled level. Body Tempereature Body temperature is carefully regulated to maintain a steady 37.5˚C,...
Barrier Mechanisms include; Skin, Stomach Acid, Normal Flora, Epithelial cells. Skin adaptions for defence The skin is made from 2 layers Outer epidermis layer Inner dermis layer The epidermis provides a physical barrier to invading pathogens. There are 2 layers in...
Both T and B Cells differentiate into Memory Cells, which remain in our lymph nodes and wait until we are re-exposed to the same pathogen. When the Memory B cell is activated by the old antigen it makes large quantities on antibody quickly and kills the...
There are two different types of Immune Response; A Cell-mediated Immune Response B Antibody-mediated Immune Response. NB: ISOLATED VIRUSES DO NOT PRESENT ANTIGENS AND THEREFORE DO NOT TRIGGER EITHER THE CELL- OR ANTIBODY-MEDIATED IMMUNE...
Negative feedback systems aim to keep something (e.g. blood [glucose] or body temperature) at a constant level. Negative feedback works as follows; Signal causes action Action has effect Effect removes original E.g. High...
Pathogens have proteins on their surface that our immune system has learned to recognise as foreign. These proteins are called antigens. T cells, B cells & Macrophages all have the ability to recognise an antigen and once this has happened, they will trigger an...
A typical prokaryot Ribosomes. Same function as eukaryotic cells (protein synthesis), but are smaller (70s rather than 80s). Nuclear Zone. The region of the cytoplasm that contains DNA. There is no nuclear membrane. DNA. Always circular, and not in chromosome...
COURSE OF INFECTION FOR TUBERCULOSIS : Tuberculosis (TB) is caused by the Mycobacterium tubercolusis bacterium. Mycobacterium tuberculosis is inhaled into the lungs in droplets of water & mucus from another person’s lung (droplet infection) TB...
Inflammation: damaged white blood cells and mast cells release histamine at the site of infection. Histamine causes local arterioles to vasodilate, increasing the blood supply to the area. It also causes holes to open between endothelial cells in capillary walls. This...
The identity of a dead person can be ascertained by; Identity papers – Fingerprints Dental records Genetic Fingerprint Fingerprints: The skin on fingers, toes etc is ridged into specific patterns (arches, tented arches, whorls & loops). Sweat and...
The idea that as each organism or group of organisms feeds on a body, it changes the body. This change in turn makes the body attractive to another group of organisms, which changes the body for the next group, and so on until the body has been reduced to a skeleton....
Time of death can be measured using the following factors; Body temperature Extent of rigor mortis Level of decomposition Forensic entomology Body Temperature A body cools following an S-shaped (sigmoid) curve. The initial plateau at 37˚C lasts 30 – 60 min, then the...