Circulatory System
Sooooo. Circulatory system....this is to do with blood and
moving it around the body (circulating).
Ok, lets start at
the beginning. Blood is the red stuff that comes out when you cut yourself…Shall
we go into a little more detail now?
Blood is
essential for the body to work. Within blood all manner of essential things are
carried around the body, serving the various organs. Blood flows through vessels
such as arteries (large vessels which take blood away from the heart), veins
(large vessels which take blood to the heart) and capillaries (small vessels
which allow water and chemicals to move in and out of the
blood).
A main function of the circulatory
system is to move blood from one part of the heart, to the lungs, where
oxygen is picked up and carbon dioxide is dropped off (see respiratory
system). This blood is then moved from the lungs to a different part of the
heart and from there it is moved around the body. As the blood moves around the
body, its oxygen is passed on to different cells, which also put waste carbon
dioxide into the blood. The blood then is moved back to the first part of the
heart, so the whole process can be repeated again and again and again and...well
I think you get the point that hopefully this goes on for a long time.
All this moving of the blood is done by the heart,
which despite what you romantics may think, is just a pump (though a very
important pump at that).
At the top of the heart are 2
chambers called the left and the right atria and at the bottom of the heart are
2 chambers called the left and the right ventricles. Before the heart contracts
(to cause blood to move around the body), blood flows into the atria and
then into the ventricles. The left side (atrium and ventricle) gets oxygen rich
blood from the lungs and the right side gets oxygen depleted (though carbon
dioxide rich) blood from the rest of the body. Valves then shut between the
ventricles and the atria, so that blood cant move back that way. The ventricles
then contract, pushing the blood out. Blood from the left ventricle is
sent around the body via the aorta and blood from the right ventricle is
sent to the lungs via the pulmonary artery. The atria and ventricles then relax
and fill with blood again.
moving it around the body (circulating).
Ok, lets start at
the beginning. Blood is the red stuff that comes out when you cut yourself…Shall
we go into a little more detail now?
Blood is
essential for the body to work. Within blood all manner of essential things are
carried around the body, serving the various organs. Blood flows through vessels
such as arteries (large vessels which take blood away from the heart), veins
(large vessels which take blood to the heart) and capillaries (small vessels
which allow water and chemicals to move in and out of the
blood).
A main function of the circulatory
system is to move blood from one part of the heart, to the lungs, where
oxygen is picked up and carbon dioxide is dropped off (see respiratory
system). This blood is then moved from the lungs to a different part of the
heart and from there it is moved around the body. As the blood moves around the
body, its oxygen is passed on to different cells, which also put waste carbon
dioxide into the blood. The blood then is moved back to the first part of the
heart, so the whole process can be repeated again and again and again and...well
I think you get the point that hopefully this goes on for a long time.
All this moving of the blood is done by the heart,
which despite what you romantics may think, is just a pump (though a very
important pump at that).
At the top of the heart are 2
chambers called the left and the right atria and at the bottom of the heart are
2 chambers called the left and the right ventricles. Before the heart contracts
(to cause blood to move around the body), blood flows into the atria and
then into the ventricles. The left side (atrium and ventricle) gets oxygen rich
blood from the lungs and the right side gets oxygen depleted (though carbon
dioxide rich) blood from the rest of the body. Valves then shut between the
ventricles and the atria, so that blood cant move back that way. The ventricles
then contract, pushing the blood out. Blood from the left ventricle is
sent around the body via the aorta and blood from the right ventricle is
sent to the lungs via the pulmonary artery. The atria and ventricles then relax
and fill with blood again.
One of the really cool things about all this is the way that each chamber is made to contract and relax. After all, the heart is nothing special, its just a muscle. First, at the top of the atria is the Sino atrial node (also called the pacemaker), which sends out nerve impulses, causing the atria to contract and blood to move from the atria to the ventricles. Because the node is at the top of the atria, it means that they contract from top to bottom, squeezing blood down and into the ventricles below. Activity from the Sino atrial node reaches the atrioventricular node, which delays it from passing further for a moment, so the atria can empty fully. The nerve impulse is then passed down the centre of the heart by the atrioventricular bundle, which splits into the left and right atrioventricular branches. Until now the ventricles have not been caused to contract, until the atrioventricular branches pass the nerve impulse on to the Purkinjie fibres (at the bottom of the ventricles). This then causes the ventricles to contract from the bottom to the top, squeezing blood out of the aorta and the pulmonary artery.
So how clever is that, your heart (which does such a vital job), works without you thinking about it (the Sino atrial node sets it off) and it does it in the most efficient way (contracting first the atria from top to bottom and then the ventricles from bottom to top)!
Blood and the circulatory system is important because it links many other body systems. Blood carries glucose, nutrients and minerals, obtained from food via the digestive system. Blood contains red blood cells, which carry oxygen around the body for use by cells and this oxygen is taken from outside of the body via the respiratory system. Blood carries hormones, chemicals made in parts of the body called glands and which affect other parts of the body, all part of the endocrine system. White blood cells (which fight infections) and platelets (which make the blood clot, so if you get cut, the blood goes thick and sticky, then dries to form a scab and you don’t bleed to death!) are carried in the blood and are part of the immune system. Blood is enriched by the lymphatic system, which transports white blood cells (which fight infection), fluid and fatty acids in and out of the blood. Also blood is kept clean by the urinary system.
*Read more about these systems elsewhere on this website.
So blood is pretty important. It takes things around the body, which are required by different cells and organs and it also carries waste chemicals so that they can be removed from the body. Blood also carries defense against infection.
Another cool thing is that if you get a load of blood (eg from a pig), mix it with fat, oatmeal and spices, then boil it in a sausage skin, you can make your own black pudding. Yum yum! *probably shouldnt try this with human stuff though, or should you....discuss!
So how clever is that, your heart (which does such a vital job), works without you thinking about it (the Sino atrial node sets it off) and it does it in the most efficient way (contracting first the atria from top to bottom and then the ventricles from bottom to top)!
Blood and the circulatory system is important because it links many other body systems. Blood carries glucose, nutrients and minerals, obtained from food via the digestive system. Blood contains red blood cells, which carry oxygen around the body for use by cells and this oxygen is taken from outside of the body via the respiratory system. Blood carries hormones, chemicals made in parts of the body called glands and which affect other parts of the body, all part of the endocrine system. White blood cells (which fight infections) and platelets (which make the blood clot, so if you get cut, the blood goes thick and sticky, then dries to form a scab and you don’t bleed to death!) are carried in the blood and are part of the immune system. Blood is enriched by the lymphatic system, which transports white blood cells (which fight infection), fluid and fatty acids in and out of the blood. Also blood is kept clean by the urinary system.
*Read more about these systems elsewhere on this website.
So blood is pretty important. It takes things around the body, which are required by different cells and organs and it also carries waste chemicals so that they can be removed from the body. Blood also carries defense against infection.
Another cool thing is that if you get a load of blood (eg from a pig), mix it with fat, oatmeal and spices, then boil it in a sausage skin, you can make your own black pudding. Yum yum! *probably shouldnt try this with human stuff though, or should you....discuss!