Intro to Cardio

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What is the approximate resting membrane potential (RMP) for contractile cells?

-90mV (correct)

-60mV

-30mV

-40mV

Which ion enters the cell during phase 2 of pacemaker cells, contributing to its characteristic shape?

K+

Cl-

Ca2+ (correct)

Na+

What type of channels drive the automaticity of the heart by enabling immediate regeneration of pacemaker potential?

K+ channels

Sodium channels

Funny channels (correct)

Calcium channels

What is the approximate refractory period for the heart, allowing time for ion movements to enable restimulation of cells?

250 ms Signup and view all the answers

What does phase 0 of pacemaker cells rely on for depolarization?

Voltage gated channels Signup and view all the answers

What happens when Ca2+ channels close in pacemaker cells?

K+ channels remain open Signup and view all the answers

What allows cardiac muscle to fully relax before it can contract?

Long refractory period Signup and view all the answers

What is the approximate resting membrane potential (RMP) for pacemaker cells?

-60mV Signup and view all the answers

Which ion channels have slow kinetics in pacemaker cells?

$K^{+}$ channels Signup and view all the answers

What is the purpose of the refractory period in muscle cells?

To allow the muscle to fully relax before the next contraction Signup and view all the answers

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 Signup and view all the answers

What is the main difference between pacemaker cells and neurons?

Pacemaker cells are modified cardiac cells, not neurons Signup and view all the answers

Why is it important for the heart to have a refractory period?

To allow the heart to fully relax before the next contraction Signup and view all the answers

What role does conductivity play in the heart's function?

It allows for action potentials to be propagated to muscle cells Signup and view all the answers

Why is it necessary for different parts of the heart to have different action potentials?

To synchronize contractions and maintain efficient pumping Signup and view all the answers

What is the role of Na+ gradient in muscle cell function?

It allows for rapid depolarization during action potentials Signup and view all the answers

Why would it be detrimental for the heart to remain contracted for a prolonged period?

It would prevent the heart from pumping blood effectively Signup and view all the answers

What is the significance of K+ concentration in muscle cells?

It allows for rapid repolarization during action potentials Signup and view all the answers

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 Signup and view all the answers

What is the average rate of flow when a person is at rest?

Around 5L/min Signup and view all the answers

What organ has a high energetic demand despite not being the largest?

Brain Signup and view all the answers

What allows for the increase in venous return during physical exercise?

Increase in sympathetic activity Signup and view all the answers

What is the approximate amount of blood in the average individual?

$5L$ Signup and view all the answers

Where do the electrical events first occur in the heart?

SA node Signup and view all the answers

What system is referred to as a closed system with no leakage?

Cardiac system Signup and view all the answers

What is the source of oxygen for a fetus?

Placenta Signup and view all the answers

What happens if cardiac output increases during exercise?

$20L/min$ is pumped even though there isn't that much blood Signup and view all the answers