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B3 - Infection and Response (Human Defences and against Diseases…
B3 - Infection and Response
Human Defences and against Diseases
Preventing Entry of Pathogens
The body has non specific defenses which protect the body against diseases
Nose traps pathogens which may enter the body
Enzymes inside tears KO microorganisms
Glands in stomach make HCL acid which KO bacteria on food
Sheet of mucus traps particles and bacteria
The Immune system
The WBC KO bacteria through phagocytosis, when involves the pathogen being surrounded and engulfed and then digested
The microorganism invades and WBC finds the micro and engulfs it then it ingests it then it has been KO
Antigens the markers on the surface of the microorganism and WBC produce antibodies which lock onto the antigens, this forces the microorganism to clump together making it easy for WBC to digest them
Boosting Immunity
If the same pathogen enters the body the WBC respond quicker
This quick response prevents the person from getting ill and called immunity
If a large proportion of the population can be made immune to the pathogen then the pathogen cannot spread easily
Treating Diseases
Antibiotics
Antibiotics can kill bacteria KO not viruses.
Use antibiotics has reduced deaths
MRSA is a strain of bacteria which is resistant to antibiotics
To reduce the rate at which resistant strains of bacteria develop doctors should not prescribe antibiotic-
unless they are needed
for non-serious infections
for viral infections
Patients should complete their course so all bacteria is killed and non of the resistant bacteria survive and reproduce
Developing new drugs
Digitalis is a heart drug that originates from foxgloves
Aspirin is a painkiller that originates from willow
Penicillin was discovered by Alexander Flemming from the penicillin mould
If a drug is found to be safe it tested on patients to see if it works and to find out the optimum dose
These tests are usually double-blind trials-
some patients are given a placebo
Patients are allocated randomly into two groups
neither the patient or doctor know who has the placebo
New painkiller are designed to treat the symptoms but do not kill the pathogen