Monday, 2 February 2015

Nervous System and Reflex Arc

The nervous system helps us to respond to changes in the environment.

nerve cell

central nervous system = brain + spinal cord
stimuli = changes in the environment
receptors = cells that detect stimuli
nerve impulse = electrical message that passes along a neurone
neurone = nerve cells

Five senses:
  1. taste
  2. smell
  3. sight
  4. sound
  5. touch
 Reflex arc
 Reflex actions are automatic and rapid. We need them to avoid danger.


Drugs

A drug is a chemical that changes the way your body works.

Types of drugs:
  • painkillers
  • stimulants 
  • halucinogens
  • antibiotics
Medical drugs make people feel better when they are ill.
Painkillers block nerve impulses.

What is a difference between medical drugs and recreational drugs?
The difference is that medical drugs are used when a person is ill and needs his/her body to function normally and recreational drugs are drugs that are taken by people when they don't need them.

People can become addicted to a drug, which means that it is hard for them to give it up. It can damage the lungs, brain and a liver.

Sometimes drugs are not effective because the body got used to it when taking regularly.

Antibiotics
Antibiotics can't be used to kill viruses because they live in body's cells, so it would have to damage the cell to kill viral pathogens.

Penicilin
Penicilin is an antibiotic discovered by Sir Alexander Fleming in 1928. He left petri dishes with bacteria on in a sink whilst he went on a holiday. After he returned he found some mould and bacteria developing on the petri dish.

This discovery was so important because it saved many soldiers' lives during WW2. The first people who received penicillin were Ernst Chain and Howard Florey.

Drug trials
Drugs must be tested before they can be sold to see if they are safe and effective. This is checked in a series of stages:
  1. in the laboratory using cells and tissues
  2. in clinical trials - this involves usually three phases with healthy volunteers and patients.
Double blind trials are when one patient is given a placebo and the other one a drug. Neither the patients nor the doctors know who received placebo and who received a drug.

Problems with drugs
Some people use drugs recreationally and they can become addicted which can cause a big harm to the body. Some drugs are legal (eg. nicotine), others aren't (eg. heroine). Some people don't take drugs sensibly, they overuse them, eg. sleeping tablets.

Thalidomide
It was developed as a sleeping tablet in first place, but women found it to be effective to make them feel better during morning sickness when pregnant. Although, the drug was not tested for this use, more and more women started taking it. Many babies of those women were born with severe limb abnormalities. It was then banned.
 

  

Sunday, 1 February 2015

MRSA and Semmelweis' Policy

MRSA (methicillin-resistant Staphylococcus aureus)
  • one of the most troublemaking strains of bacteria
  • resistant to even very strong antibiotics
To prevent MRSA, we must practicegood hygiene in hospitals and stop prescribing antibiotics for non-serious infections.

Semmelweis and washing hands
Semmelweis stated that all doctors should wash their hands after each contact with patient, so pathogens don't spread out to other patients.  


 
 

Vaccinations

How vaccines work?
  1. A vaccination is a dead or inactive pathogen.
  2. Vaccination is injected.
  3. The pathogen is detected and white blood cells start producing specific antibodies to kill that particular pathogen.
  4. White blood cells remember the pathogen.
  5. When live pathogen enters the body, white blood cells recognise the pathogen and produce antibodies.
  6. The pathogen is removed before it can develop any symptoms.
MMR vaccine
MMR vaccine is injected to children to protect them against measles,mumps and rubella.

Advantages
  • Epidemics can be prevented as there are fewer number of people who can pass the disease on.
  • By having vaccinations, we can control diseases.
Disadvantages
  • Some people can react badly to the vaccination.
  • Vaccines don't always work.