transport in animals
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what does the circulatory system do?
provides oxygen and nutrients to the different parts of the body and removes carbon dioxide and other waste material
the circulatory system consists of:
• a pump (the heart) to keep the blood moving • blood vessels to carry the blood • valves to make sure that the blood flows in one direction only
the 3 types of blood vessels
arteries, veins and capillaries
2 types of circulation
single circulation eg. in fish, where: heart → gills → rest of the body → heart - double circulation eg. in humans, where: heart → lungs → heart → rest of the body → heart
advantages of double circulation
higher pressure, therefore; - The greater the flow of blood - The further the blood can travel in the body
the heart is divided into two halves by a…
septum
the upper chamber is called an…
atrium
the lower chamber is called a…
ventricle
blood is pumped away from the heart in…
arteries
blood returns towards the heart in…
veins
where are semi-lunar valves found?
found at the exits of the heart
what do semi-lunar valves prevent?
blood flowing back from arteries to ventricles
where are atrioventricular valves found?
found between the atrium and the ventricle
what do atrioventricular valves prevent?
blood flowing back from ventricles to atria
the walls of the _____ are thicker than the walls of the _____
• ventricles • atria
why are the walls of the ventricles thicker than the walls of the atria?
• The thickness of the wall chamber is proportional to the amount of force the chamber must generate. • The atria only pumps blood to the ventricle, therefore not a lot of force must be generated • The ventricles, however, must pump blood to the rest of the body, so they need to generate more force
why are the walls of the left ventricle thicker than the walls of the right ventricle?
the right ventricle only pumps blood to the lungs, whilst the left ventricle has to pump blood all the way up to the head (against gravity) and all the way down to the toes (long distance), so it needs to generate a greater force
actions in a heartbeat (5)
• Blood flows from veins into the atria • The atria contract, pushing blood to the ventricles • The atrioventricular valves close due to the fall in pressure in the atria • The ventricles contract, pushing blood to the arteries • The semilunar valves close due to the fall in pressure in the ventricles
what does coronary heart disease refer to?
• refers to the disease that arises when the coronary arteries are unable to supply oxygen rich blood to the heart muscles due to blockages in them • The blockages decrease the diameter of the coronary arteries, making it difficult for blood to pass through
risk factors for CHD
• age • diet • genetic predisposition (whether or not there is a family history of CHD) • gender • smoking • stress
arteries characteristics
small lumen, thick walls, oxygen-rich blood, high pressure
capillaries characteristics
very small lumen, very thin walls, blood cells flow in a single file
veins characteristics
large lumen, thin walls, valves, deoxygenated blood, low pressure
to the heart
pulmonary vein (from lungs) vena cava (from the body)