27 Questions
What is the approximate resting membrane potential (RMP) for contractile cells?
-90mV
Which ion enters the cell during phase 2 of pacemaker cells, contributing to its characteristic shape?
Ca2+
What type of channels drive the automaticity of the heart by enabling immediate regeneration of pacemaker potential?
Funny channels
What is the approximate refractory period for the heart, allowing time for ion movements to enable restimulation of cells?
250 ms
What does phase 0 of pacemaker cells rely on for depolarization?
Voltage gated channels
What happens when Ca2+ channels close in pacemaker cells?
K+ channels remain open
What allows cardiac muscle to fully relax before it can contract?
Long refractory period
What is the approximate resting membrane potential (RMP) for pacemaker cells?
-60mV
Which ion channels have slow kinetics in pacemaker cells?
$K^{+}$ channels
What is the purpose of the refractory period in muscle cells?
To allow the muscle to fully relax before the next contraction
Why does the heart not need stimulus from the nervous system to beat when removed from the body?
It has automaticity due to the presence of salts and sugars
What is the main difference between pacemaker cells and neurons?
Pacemaker cells are modified cardiac cells, not neurons
Why is it important for the heart to have a refractory period?
To allow the heart to fully relax before the next contraction
What role does conductivity play in the heart's function?
It allows for action potentials to be propagated to muscle cells
Why is it necessary for different parts of the heart to have different action potentials?
To synchronize contractions and maintain efficient pumping
What is the role of Na+ gradient in muscle cell function?
It allows for rapid depolarization during action potentials
Why would it be detrimental for the heart to remain contracted for a prolonged period?
It would prevent the heart from pumping blood effectively
What is the significance of K+ concentration in muscle cells?
It allows for rapid repolarization during action potentials
What happens if the hole in the ovales does not close after the fetus is born?
The heart will work extra hard to meet metabolic needs
What is the average rate of flow when a person is at rest?
Around 5L/min
What organ has a high energetic demand despite not being the largest?
Brain
What allows for the increase in venous return during physical exercise?
Increase in sympathetic activity
What is the approximate amount of blood in the average individual?
$5L$
Where do the electrical events first occur in the heart?
SA node
What system is referred to as a closed system with no leakage?
Cardiac system
What is the source of oxygen for a fetus?
Placenta
What happens if cardiac output increases during exercise?
$20L/min$ is pumped even though there isn't that much blood
Test your knowledge on capillaries and congenital disorders related to heart conditions and the respiratory system. Learn about the exchange of substances in capillaries and the impact of congenital disorders on heart function and blood circulation.
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