Keynote Lecture 1 Flashcards
The increase of cardiac output in evolution
Do most animals die of ischemic heart disease?
No
Why do other animals not die of ischemic heart disease?
Their heart muscles consists of tiny strands with red blood cells in the cavities. Thus they do not depend on the coronary arteries
Which animals are warm blooded?
Mammals and birds
What is the difference between warm and cold blooded animals?
Warm blooded animals have a high metabolic rate and have higher heart rates. They can die of ischemic heart disease
Does the cardiac output change when the heart rate increases?
Not necessarily, it will stay the same if the amount of blood that goes into the heart stays the same
What is the volume per beat for mammals?
0.99 ml/kg
What is the volume per beat for reptiles?
0.88 ml/kg
What does the myocardium need more than the rest of the body?
ATP, it is thus metabolically expensive
What is peculiar about the heart of a giraffe?
It has a small relative stroke volume and a thicker wall that leads to normal tension on the heart wall
When is the Law of Laplace used?
In combination with talking about hypertrophy
What is the Law of Laplace?
T = aPr
T = tension
P = hypertension (pathological)
r = exercise (good)
What is the main reason for the difference in cardiac output between mammals and reptiles?
The difference in heart rate
What is a normal ejection fraction in humans?
55-60
How do you calculate the ejection fraction?
The stroke volume divided by the end-diastolic volume
What are recesses?
These are small cavities where blood can pool in the heart
What happens to recesses in the systole?
They are compressed
What is the ejection fraction of reptiles?
Around 90
What does a high ejection fraction indicate in humans?
That there is bad hypertrophy
What is the relative human ejection fraction and heart rate compared to reptiles?
A low ejection fraction and a high heart rate
What is the muscle structure of reptiles?
They have a fine muscle structure (in other words a small radius)
What is the consequence of the muscle structure of reptiles?
There is more resistance, thus the heart fills less fast, leading to a lower heart rate
What is different ECG wise comparing animals with a higher heart rate to those with a lower heart rate?
Animals with a higher heart rate have a shorter PR/QT interval. But a longer PT interval to have more time for filling
What changes are made in small animals that makes the heart capable of beating so fast?
Changes in the sarcomeres
What is a word to describe the human heart?
Efficacious (effective)
