B5b- circulatory systems and the cardiac cycle

Question 1

What is an open circulatory system?

Answer 1

doesn’t include blood vessels

Question 2

What is a closed circulatory system?

Answer 2

does include blood vessels to transport liquid

Question 3

What is a single circulatory system?

Answer 3

one circuit of blood vessels from the heart

Question 4

What is a double circulatory system?

Answer 4

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

Question 5

Why don’t all animals have a circulatory system?

Answer 5

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

Question 6

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

Answer 6

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

Question 7

What did Harvey discover in the 17th century?

Answer 7

• 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

Question 8

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

Answer 8

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

Question 9

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

Answer 9

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

Question 10

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

Answer 10

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

Question 11

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

Answer 11

materials can be transported around the body more quickly

Question 12

what is the cardiac cycle?

Answer 12

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

Question 13

Describe the sequence of events in the cardiac cycle?

Answer 13

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

Question 14

How does exercise affect heart rate?

Answer 14

heart pumps faster to deliver more oxygenated blood to your muscles

Question 15

How do hormones affect heart rate?

Answer 15

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

Question 16

What is a pulse?

Answer 16

a measure of the heart beat

Question 17

What is a pacemaker?

Answer 17

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

Question 18

What is an ECG?

Answer 18

electrocardiogram - shows electrical activity of the heart

Question 19

What is an echocardiogram?

Answer 19

an ultrasound scan of the heart

Question 20

What can an ECG show?

Answer 20

irregular heartbeats
heart attacks
general health of heart

Question 21

What can an echocardiogram show?

Answer 21

enlarged heart
decreased pumping ability
valve function

Question 22

What are the two pacemakers in the heart?

Answer 22

SAN

AVN

Question 23

What does the SAN do?

Answer 23

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

Question 24

What does the AVN do?

Answer 24

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

Question 25

What is an artificial pacemaker?

Answer 25

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

Question 26

How are the SAN and the AVN coordinated?

Answer 26

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