B5b: Circulatory Systems and the Cardiac Cycle

Our heart beats automatically from before birth until we die; it also adjusts itself to varying levels of activity. The history of discoveries about blood circulation is an interesting story culminating in our increasing use of modern technology. Using video clips to show heart action is an example of using ICT in teaching and learning while ECG traces illustrate the use of ICT in science. 

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What circulatory system does an amoeba have?
It doesn't have one.
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What circulatory system does an insect have?
An open circulatory system
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What circulatory system does a human have?
A closed circulatory system
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What is an open circulatory system?
Their blood flows freely through their body cavity, carrying nutrients to their cells. Oxygen is delivered directly to the insect’s tissues through tiny tubes that open to the outside.
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What is a closed circulatory system?
Vertebrates have closed circulatory systems. Their blood flows through blood vessels and they have a heart to push the blood around their body.
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In the closed circulatory system what blood vessels does their blood flow through?
Veins, arteries and capillaries.
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How does heart muscle cause blood to move?
When the muscle contracts it forces the blood to move.
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What is the heart made of? How are these supplied?
powerful muscles which are supplied with food substances, including glucose, and oxygen by the coronary artery.
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Why does the heart need a constant supply of glucose and oxygen?
The heart needs a constant supply of glucose and oxygen so that its muscle cells can respire and continue to contract.
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What is a pulse?
as a measure of the heart beat (muscle contraction) to put the blood under pressure
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Name three places where a pulse can be detected.
Ear, wrist and temple.
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Why do many animals need a blood circulatory system?
Living cells need to absorb nutrients and oxygen, and to release waste products, such as carbon dioxide. larger, multicellular animals need a circulatory system to transport substances to and from their cells.
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What is a single circulatory system?
one circuit from the heart.
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What is a double circulatory system?
two circuits from the heart.
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What circulatory system does a fish have?
Single circulatory system
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What circulatory system does a mammal have?
Double circulatory system
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Describe the blood flow in a fish's single circulatory system
the blood travels from the heart to the gills, where it absorbs oxygen and releases carbon dioxide. It then flows from the gills to the organs and tissues in the rest of the body, and back to the heart. There is just one circuit from the heart.
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Describe the blood flow in a mammal's double circulatory system.
there are two circuits from the heart:1.blood passes from the heart to the lungs - where it absorbs oxygen & releases carbon dioxide - then back to the heart 2. blood passes from the heart to the organs & tissues in the body, & back to the heart.
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Describe what Galen - a roman doctor - discovered.
He gained knowledge through animal dissections. He understood the importance of the pulse and that blood moved around the body, but he made some mistakes. e.g he thought that the liver made blood for the veins & the heart made blood for the arteries
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Describe William Harvey - a doctor from london - theory of the circulatory system was.
He explained that blood circulates from the heart 2 the lungs,&from the heart 2 the rest of body.He was able to link the pulse in the arteries 2 the contractions of the left ventricle,&he realised that veins have valves to prevent backflow of blood
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Why does a single circulatory system links to a two-chambered heart?
A single circulatory system links to a two-chambered heart. One chamber receives blood from the body and the other pumps it back out.
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Why does a double circulatory system links to a four-chambered heart?
A double circulatory system (such as in humans) links to a four-chambered heart. The right side is involved with moving deoxygenated blood to the lungs, and the left side is involved with moving oxygenated blood to the body.
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Which circulatory system is under more pressure? Single or double? Why is this high pressure good?
Compared to a single circulatory system, blood in a double circulatory system is under higher pressure - which allows materials to be transported more quickly around the body.
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What is the heart?
The heart is a pump which sends some blood to the lungs and some blood to the rest of the body each time it beats. The blood on the left side is kept separate from the blood on the right side.
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What prevents the back flow of blood?
Valves in
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Describe the flow of blood through the heart.
Blood enters the heart through a vein&collects in an atrium. The atrium contracts&the blood is pushed into a ventricle. The ventricle then contracts, and the blood is forced out through an artery towards the lungs or towards the rest of the body
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Name the areas of the heart in order of how blood would flow through the heart
Vein: Vena Cava. R atrium, tricuspid valve, R ventricle, Semi-lunar valve, Pulmonary Artery, Pulmonary Vein, L atrium, bicuspid valve, L ventricle, semi lunar valve, Artery: Aorta
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How is heart rate linked to activity?
The body’s cells need more glucose and oxygen during exercise, and the blood supplies this. The heart rate increases as activity increases, and this is detected as a faster pulse rate. The hormone adrenaline increases heart rate.
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What is heart muscle contraction controlled by?
by groups of cells called the pacemakers which produce a small electric current that stimulates muscle contraction.
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What are artificial pacemakers now commonly used for?
To control heart beat.
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Which two techniques are used to investigate heart action?
ECG (electrocardiograms) and echocardiograms
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Which hormone can be used to increase heart rate?
Adrenaline
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What do electrocardiograms do? (ECG)
measure the heart’s electrical activity
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What do echocardiograms do?
use ultrasound to show possible heart defects
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What type of blood enters the body through the Vena Cava?
Deoxygenated.
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What type of blood enters the body through the pulmonary veins?
Oxygenated
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What happens as the left ventricle contracts?
The semi lunar valve opens and oxygenated blood flows through the body.
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What happens as the right ventricle contracts?
The semi lunar valve opens and deoxygenated blood travels to the lungs.
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What are the two pacemaker cells?
SAN (sino-atrial nodes) and AVN (atrio-ventricular nodes)
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What do pacemaker cells do?
coordinate the contractions of the heart muscles
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What does the SAN do?
causes the atria to contract, and stimulates the AVN
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What does the AVN do?
causes the ventricles to contract
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Talk about the electrical current in one complete heartbeat.
The SAN produces an electric current first, which spreads to the atria (making them contract). The current stimulates thee AVN to produce an electrical current (causing the ventricles to contract). This ensures that the atria always contract first
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Card 2

Front

What circulatory system does an insect have?

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An open circulatory system

Card 3

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What circulatory system does a human have?

Back

Preview of the front of card 3

Card 4

Front

What is an open circulatory system?

Back

Preview of the front of card 4

Card 5

Front

What is a closed circulatory system?

Back

Preview of the front of card 5
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