AS EDEXCEL BIOLOGY UNIT 1 NOTES - THE HEART & BLOOD VESSELS

THE HEART

• Most cells get energy via anaerobic respiration.
• Glucose and Oxygen are needed for this - the body needs to supply this to all cells.

In single-celled organisms they can diffuse across the cell membrane to the cell. Rate of diffusion = quick as they only have a short distance to travel.

In multi-cellular organisms diffusion across the membrane is too slow - the distance is too far.

SO THEY HAVE A MASS TRANSPORT SYSTEM (OR CICULATORY SYSTEM)

• to carry raw materials from exchange organs to body cells.
• to remove waste EG carbon dioxide.
• in mammals blood is used to transport substances around the body.

THE HEART PUMPS BLOOD AROUND THE BODY - EACH PART OF IT IS ADAPTED FOR ITS JOB.

• LEFT VENTRICLE: thicker than right ventricle, as it needs to pump blood all the way around the body. Right only pumps blood…