1. Blood Vessels
interpret and explain electrocardiogram (ECG) traces, with reference to normal and abnormal heart activity;
describe, with the aid of diagrams and photographs, the structures and functions of arteries, veins and capillaries;

2. Blood Vessels
interpret and explain electrocardiogram (ECG) traces, with reference to normal and abnormal heart activity;
describe, with the aid of diagrams and photographs, the structures and functions of arteries, veins and capillaries;

3. Open Circulatory Systems
In mammals blood never gets out into the body cavity, it is always in vessels
Some animals, like insects have an open circulatory system where blood is not held in vessels, instead the blood fluid circulates through the body cavity so the tissues and cells are bathed in blood

4. Open Circulatory Systems
In some animals the action of the body muscles during movement may help to circulate the blood
In insects, there is a muscular pumping organ like a heart
It is a muscular tube that lies under the upper surface of the insect
Blood enters this through pores called ostia- the heart then pumps the blood towards the head by peristalsis (squeezing like toothpaste from a tube)
The blood then pours into the body cavity
Larger insects sometimes have open-ended tubes attached to their heart which directs some blood towards specific parts of their body e.g. wing or leg

5. Why don’t all animals have open systems?
An open system works when an organisms is small- the blood doesn’t have to travel far
Also, their blood does not transport oxygen or carbon dioxide- they use a separate transport system for this
Larger organisms rely on the blood to transport oxygen and carbon dioxide
An open system means that blood remains at low pressure and the flow is slow- it would not be sufficient to supply the muscles in a large, active animal

6. Closed Circulatory Systems
In larger animals the blood stays entirely inside vessels
A fluid called tissue fluid bathes the tissues and cells
The heart can therefore pump blood at a higher pressure

8. Blood Vessels
Task: Find images of an artery, vein and capillary and annotate (label) it to show the features of each vessel