2.3.1 blood circulatory system  (Page 23/8)

Useful links

Cardiovascular system: http://www.biologyinmotion.com/cardio/index.html

Khan: Red blood cells http://www.khanacademy.org/video/red-blood-cells?playlist=Biology

Khan: Circulatory system and the heart http://www.khanacademy.org/video/circulatory-system-and-the- heart?playlist=Biology

YouTube video: Circulatory system http://www.youtube.com/watch?v=D3ZDJgFDdk0

Blood flow animation http://health.howstuffworks.com/human-body/systems/circulatory/adam-200078.htm

Blood Flow animation http://www.sumanasinc.com/webcontent/animations/content/human_heart.html

The heart and circulation (interactive activity): http://www.kett6.net/adulteducation/heartanimations.html

Circulation animation: http://www.bbc.co.uk/schools/gcsebitesize/pe/appliedanatomy/0_anatomy_circulator ysys_rev1.shtml

Overview

All living cells require nutrients and oxygen to survive. Cells produce metabolic waste, which must be removed and excreted. The circulatory system isresponsible from providing nutrients and removing metabolic waste.

Unicellular organisms have a simple system to allow for this and it is by diffusion where substances move from a high concentration to a low concentration.

Most invertebrates like a grasshopper have an open circulatory system , where blood (haemolymph) bathes the body organs.

By comparison, mammals have a closed circulatory system since blood is contained within blood vessels.

Pulmonary and systemic circulatory systems

Open circulatory system

blood is pumped into a heamocoel (an open space or cavity) that surrounds to organs. Muscle movement also helps to pump then blood. Blood diffuses back theheart. Blood movement is sluggish. There is no difference between the blood and the interstitial fluid. Interstitial fluid is the fluid that surrounds thecells. Blood is not contained within capillaries.

Closed circulatory system

blood is pumped from the heart through arteries and returns to the heart via veins. Blood never leaves the vascular system (arteries, veins andcapillaries). Nutrients, water and metabolic waste diffuses out of the vascular system and into the interstitial fluid. Interstitial fluid and blood areseparated, by the vascular system. Interstitial fluid returns to circulation through the lymphatic system.

The human circulatory system

All mammals have a closed blood circulatory system - blood always flows inside blood vessels.

A double circulatory system = blood passes through the heart twice:

1. Pulmonary circulation: the blood is pumped from the heart to the lungs to oxygenate the blood and then back to the heart.
2. Systemic circulation (to all the systems): the blood is pumped from the heart to all parts of the body and back to the heart again.
3. Coronary circulation : is a circulatory system that supplies the heart muscle with the blood itrequired in order to function.

Very simple simulation of blood flow through the systemic and pulmonary circulatory systems. The illustration shows each of these circulatory systemsto be separate loops leaving from one side of the heart and returning to the other.