B5b- circulatory systems and the cardiac cycle Flashcards Preview

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Flashcards in B5b- circulatory systems and the cardiac cycle Deck (26)

What is an open circulatory system?

doesn't include blood vessels


What is a closed circulatory system?

does include blood vessels to transport liquid


What is a single circulatory system?

one circuit of blood vessels from the heart


What is a double circulatory system?

two circuits from the heart, one to the body and the other to the lungs


Why don't all animals have a circulatory system?

some small animals have a large surface area to volume ratio so enough oxygen can get into the body through diffusion


What did Galen think about the heart in the 2nd Century?

-knew about the chambers of the heart
-thought blood was made in heart and liver
-thought the heart sucked blood and organs consumed it


What did Harvey discover in the 17th century?

-heart valves stopped back flow of blood
-heart is a pump
-pulse is caused by heart pumping blood into arteries
-same blood was circulated around the body


Why do you need a two chambered heart for a single circulatory system?

one chamber to receive blood and one to pump blood out to the gills and rest of the body


Why do you need a four chambered heart for a double circulatory system?

so blood can be pumped separately to the lungs and the body


Why is the blood pressure in a double circulatory system much higher?

the blood from the lungs returns to the heart before being pumped to the rest of the body


What is the advantage of blood being pumped at a high pressure?

materials can be transported around the body more quickly


what is the cardiac cycle?

the sequence of events in one complete heartbeat (how the heart contracts)


Describe the sequence of events in the cardiac cycle?

1) Blood flows into the atria
2) The atria contract, pushing the blood into the ventricles
3)The ventricles contract, forcing the blood into the aorta and the pulmonary artery
4)The blood then flows along the arteries, the atria fill then the cycle starts over


How does exercise affect heart rate?

heart pumps faster to deliver more oxygenated blood to your muscles


How do hormones affect heart rate?

Adrenaline causes heart rate to increase so muscles have enough oxygen to run away from danger


What is a pulse?

a measure of the heart beat


What is a pacemaker?

a group of cells that tell the heart how fast to beat


What is an ECG?

electrocardiogram - shows electrical activity of the heart


What is an echocardiogram?

an ultrasound scan of the heart


What can an ECG show?

irregular heartbeats
heart attacks
general health of heart


What can an echocardiogram show?

enlarged heart
decreased pumping ability
valve function


What are the two pacemakers in the heart?



What does the SAN do?

(Sino-atrial node) - stimulates the atria to contract


What does the AVN do?

(atrio-ventricular node) - stimulates the ventricles to contract


What is an artificial pacemaker?

a device implanted under skin and has a wire going to the heart. It produces an electric current and is use to control heartbeat if the pacemakers don't work properly


How are the SAN and the AVN coordinated?

The SAN produces an electric current first when then stimulates the AVN to produce one. This means the atria always contracts before the ventricles.