Calculus of the Lungs and Heart Flashcards
How do you find the amount of a component from its concentration and the total volume of gas?
amount = concentration * volume
What is the general lung DTDS?
C(t + 1) = (1 - W/V)Ct + (W/V)CA
V = lung volume
W = breath volume
CA = ambient concentration of gas
Ct = concentration of gas in lungs after t breaths
What is the equlibrium for gas exchange problems?
The ambient concentration
In gas exchange problems, is the equilibrium stable or unstable?
It is always stable
What is the sinoatrial (SA) node?
A node in the heart that emits electrical signals at regular time intervals
What is the atrioventricular (AV) node?
A node that recieves electrical signals from the SA node and converts them to electrical potential
What must occur to trigger a heartbeat?
The electrical potential must be at or below a certain threshold, Vc
If there is a heartbeat, what subsequently happens to electrical potential in the AV node?
It increases by a factor of u
What is the equation for the graph of electrical potential decay?
e^-ατ
Heart: what does τ represent?
The time between electrical signals from the SA node
Heart: what does α represent?
The rate of decay of electric potential
Heart: what is the equation for c?
e^-ατ
Heart: what does Vc represent?
The threshold potential in the AV node
Heart: what does Vt represent?
The electrical potential in the AV node after heartbeat t.
Heart: what does u represent?
The increase in electrical potential occurring after a heartbeat
What is the general DTDS for heart dynamics when the heart beats?
V(t +1) = cVt + u, if cVt ≤ Vc
What is the general DTDS for heart dynamics when the heart doesn’t beat?
V(t + 1) = cVt, if cVt > Vc
Heart: when the updating function does not cross y = x, what condition is represented?
2:1 AV block, the heart beats once every two signals
If the updating function does not cross y = x, what kind of equilibrium is there?
No equilibrium
Heart: when the tip of the updating function touches y = x, what is the condition represented?
Wenckeback phenomenon: the heart mostly beats normally but skips an occasional beat
When the heart is healthy, is there stable equilibrium?
Yes
When the heart exhibits 2:1 AV block, is there stable equilibrium?
There is no equilibrium
When the heart exhibits Wenckeback phenomenon, is there stable equilibrium?
Yes
