OCR 21st Century B2

  • Created by: madison
  • Created on: 21-06-12 20:38

The Circulatory System

Supplying Blood to your body…

·         Blood is moved around your body in blood vessels.

·         Oxygen & nutrients are carried in blood to body cells, waste (C02) is carried away from the cells.

·         The heart pumps the blood around. It has a double pump

1.      (Right Side) pumps deoxygenated blood to the lungs to pick up oxygen and drop of waste like carbon dioxide.

2.      (Left Side) pumps oxygenated blood around the body.

·         Heart has muscles to keep it beating (&pumping) these muscles need their own blood to supply nutrients and oxygen to keep them working continually.

·         Blood is supplied to heart by 2 coronary arteries which come from the base of the aorta (biggest artery in the body).

Major Types of Blood Vessels

  Arteries- carries blood away from the heart. Comes out at high pressure so the walls are much thicker than veins and are strong but elastic.

  Veins- carry blood back to heart. Bloods at lower pressure so thinner walls. Bigger lumen to help flood flow easily. Have valves to make blood flow in right direction.

Capillaries (branches of microscopic arteries)- carry blood close to cells to exchange substances with them. Have permeable walls so substances can diffuse in and out. They supply nutrients and oxygen but take away waste and co2. Walls are only one cell thick, increases rate of diffusion by decreasing the distances in which it occurs.


·        Antimicrobials are chemicals that inhibit the growth of a microorganism or kill it without seriously damaging your own body.

·        They are good at clearing up infections that your immune system is struggling with.

·        Antibiotics are antimicrobials that can kill bacteria- it cannot get rid of flu/colds as these are viruses.

Resisting Antimicrobials

Ø Some microorganisms can evolve and become resistant to antimicrobials.

Ø They develop random mutations that lead to characteristic change which means its less affected by the antimicrobials- this is a big advantage to the microorganism.

Ø The process of natural selection happens and this mutation gets passed on as it reproduces. This makes it harder to get rid off.

Ø Sometimes new antimicrobials are created and get rid of it, some cant- these are now ‘superbugs’

Antibiotics Course

§  The more often antibiotics are used the more common antibiotic resisrance becomes.

§  Its important to only use them when you need too- they don’t really cause resistance but naturally resistant bacteria have an advantage and increase in numbers. If there not doing you any good don’t use them.

§  Take them for how long it says, if you feel better and stop the course in which they are meant for it increases the risk of antibiotic resistant bacteria emerging.

Drug Trials (basic)

·         Test these drugs on human/animal cells in a lab (check if it’s a possibility)

·         Then


Zara Mahmood


thnks these r really detailed!!!

one question r these good for the higher paper

lisa linsdell


Good for general revision of the OCR 21st Century B2 module. Test yourself section very basic though.



Thank you so much!