Circulatory System
Circulatory System
The circulatory system (or cardiovascular system) is is an organ system that moves nutrients, gases, and waste to and from cells, helps fight diseases and helps stabilize body temperature.
The main components of the human circulatory system are the heart, the blood, and the blood vessels.
The circulatory system includes:
Pulmonary circulation, a “loop” through the lungs where blood is oxygenated and waste Carbon Dioxide removed.
Systemic circulation, a “loop” through the rest of the body to provide oxygenated blood to all organs and tissues.
the heart & Blood Vessels
The heart has four chambers and works as a highly effective pump. The two upper chambers (right and left atria) receive incoming blood. The lower chambers (right and left ventricles), pump blood out of the heart. The heart valves, which keep blood flowing in the right direction, are one-way gates at the chamber openings.
The heart first pumps blood to your lungs. The blood picks up oxygen from the air that you have breathed in and then travels back to the heart.
The heart then pumps the blood out to the body to the various organs and tissues. The blood travels back to the heart and it all begins again.
Pumping of the heart muscle is controlled by an electrical conduction system. This complex system controls the precise contraction of the muscles and creates the pumping sequence that moves blood between the individual chambers and around the body. The entire heart muscle does not contract all at once but in synchronisation, all controlled by a built-in pacemaker (the sinoatrial node, or SA node). This node creates the stimulus that results in a normal adult heartbeat of 60-90 beats per minute.
blood vessels
Blood vessels are a series of tubes inside your body that move blood to and from your heart.
Arteries
The arteries are the tubes that carry oxygen rich blood away from the heart to the body’s cells. They are strong and elastic to withstand the pressure of being pumped from the heart and are able to constrict and expand to provide more or less oxygenated blood to different areas of the body.
The pulmonary is an exception to the above as it carries de-oxygenated blood from the heart to the lungs for oxygen replenishment.
Veins
Veins carry blood back to the heart after the oxygen has been used by the cells. Veins contain one-way valves to ensure the blood (no longer under pressure from the heart) keeps flowing towards the heart.
Deep inside your chest the Pulmonary Vein is slightly different as it carries oxygenated blood to the heart, ready to be pumped around the body.
Capillaries & Capillary Refill Check
Capillaries are tiny blood vessels that transfer oxygen and nutrients to the cells in the body and take waste carbon dioxide for it to be transferred to the lungs.
A useful circulation check is to squeeze the tip of a finger or toe until it becomes pale and then let it go. How long it takes for the colour to return (capillary re-fill check) will determine adequate or reduced circulation to that limb.
As a guide it should take as long as it does to say ‘Capillary Refill’ to come back to colour.
The Pulse
Checking a person’s pulse can help to identify how fast the heart is beating and whether it is working within the normal range. Although not required in first aid guidelines, if you know how to take a pulse it can provide more evidence during a secondary survey. The best place for a first aider to take a pulse are the neck (carotid), or the wrist (radial).
- Adult – resting heart rate 60 – 100 beats per minute
- Child 1 to 12 years – resting heart rate 90 – 100 beats per minute
- Infant under 1 – resting heart rate 110 – 160 beats per minute
