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?
general health of heart
What can an echocardiogram show?
decreased pumping ability
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