B5b: Circulatory systems and the cardiac cycle Flashcards Preview

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Flashcards in B5b: Circulatory systems and the cardiac cycle Deck (14):
1

Why do many animals need a blood circulatory system

to ensure all their cells receive enough food and oxygen and to remove waste products(e.g. co2)

2

Describe single circulatory systems and where are they found(3+2)

One circuit from the heart

Links to a two-chambered heart
-one to receive and one to distribute blood

Found in fishes
-single blood circuit of the heart, gills and body

3

Describe double circulatory systems and where are they found(3+2)

two circuits from the heart

links to a four-chambered heart
-2 atria to receive blood(1 from lung, 1 from body) and 2 ventricles to distribute blood(1 to lung, 1 to body)

found in mamals
-heart and lung form 1 circuit, heart and rest of body form the other

4

What is the advantage of having a double circulatory system

bloody is under higher pressure compared with a single circulatory system
-allows materials to be transported more quickly around the body

5

What did Galen(2nd century) contribute to our knowledge about the heart(2)

knew about the chambers in the heart and that the heart acted as a pump as well as the importance of the pulse(he cut up animals)

thought arterial blood was made by the heart, while blood in veins were made by the liver

6

What did William Harvey(17th century) contribute to our knowledge about the heart

found out that blood circulated around the body over and over again and the existence of valves and capillaries

7

Describe pressure changes during blood flow(3)

As blood flows through arteries, veins and capillaries the pressure decreases
-veins have valves to stop backflow of blood
-high pressure would damage the fragile walls of the capillaries

8

What is the cardiac cycle

sequence of events as blood enters and leaves the heart

9

Describe the cardiac cycle(4)

blood flows into the two atria

atria contracts and atrio-ventricular valves open, pushing the blood into the ventricles

ventricles contract, atrio-ventricular valves close to prevent backflow into the atria, and semilunar vavles open, pushing the blood into the aorta and the pulmonary artery

semilunar valves close to prevent backflow into the ventricles

10

How does activity affect heart rate

More activity causes greater demand for oxygen and food, heart rate therefore increases to pump more oxygenated blood to your muscles

11

How else can heart rate be increased(3)

By the hormone adrenaline
-released when you get a shock or in danger
-increases heart rate to make sure the muscles have plenty of oxygen

12

How is heart muscle contraction controlled(4)

by a group of cells called the pacemakers
-produce a small electric current that stimulates muscle contraction

impulses from the SAN cause the atria to contract then stimulate the AVN

impulses from the AVN then cause the ventricles to
contract (makes sure that the atria contracts before the ventricles)

13

How can pacemaker cells be replaced

By an artificial pacemaker which controls the heart beat

14

What can be used to investigate heart action(3+3)

ECG(electrocardiogram)
-shows the electrical activity of the heart
-can show heart attacks or irregular heartbeats and general health of the heart
(-practice interpreting graphs)

Echocardiograms
-an ultrasound scan of the heart
-can show enlarged hearts, decreased pumping ability and faulty valves