Introduction, Modeling, and Hodgkin Huxley (Test 1) Flashcards
What is the concept of physiological homeostasis?
The ability to maintain a constant internal environment in the face of fluctuations in the external environment that can disturb the body composition.
Where is most of the sodium in the body contained? And potassium?
The Extracellular Fluid Volume (Na) and Intracellular Fluid Volume (K)
Where is most of the body water contained?
The Lean Body Mass
How would a male person weighing 80 kg, with a body water content of 48 liters be categorized?
The body fat would be in normal range (18%).
Four grams of a dye are administered into a subject weighing 80 kg and having a lean body mass of 64 Kg. After equilibration, the plasma concentration is measured to be 0.25 grams per liter. Determine the primary dye distribution (EFV vs IFV).
The dye is distributed primarily in the Extracellular Fluid Volume.
What is the proper order of components in a classic negative feedback control system?
Transducer; Feedback Element; Summing Point; Error Signal; Control Element; Control Signal
What percent of water is contained in the lean body mass?
approximately 73% water.
What happens in response to an infusion of a hypertonic NaCl solution?
There would be an expansion of the extracellular fluid volume and a reduction of the intracellular fluid volume.
A volume of blood is suddenly injected into the circulation, which transiently raises the arterial pressure 50 mmHg instantaneously. However, after the pressure regulating control systems have had time to act, the remaining elevation in pressure is only 5 mmHg. What is the negative feedback gain of this control system?
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A diabetic patient had 2 hour postprandial glucose level at 200 mg/dL. After islet transplant, the value changed to 140 mg/dL. If his fasting glucose level is 120 mg/dL, what is his feedback compensation resulted from the transplant? What is the steady state error? What is his feedback gain?
Feedback compensation = 200 mg/dL-140 mg/dL = 60 mg/dL
(Difference between change in response to stimulus if no feedback is present and change in response to stimulus with feedback present.)
Steady state error (SSE) = 140 mg/dL-120 mg/dL = 20 mg/dL
(Difference between original level and level achieved after compensation.)
Feedback gain = compensation/SSE = 60 mg/dL/20 mg/dL = 3
What is Occam’s razor principle?
Make your model as simple as possible.
What is agent-based modeling?
Most agent-based modeling is stochastic. In a micro scale, each agent automatically controls its behavior, based merely by their current status (Markov chain). Macro scale evaluation will come from the summation of all agents’ behaviors.
In membrane potential equation Em-Er = iRm(1 - e-t/τ) , what is τm?
RmCm.
What does the total current flowing across the neuroplasma membrane at time t equal to?
IR + IC or (Em-Er)/Rm + Cm(dE/dt).
In cable theory of electrotonic potential distribution, what happens when diameter of the neural axon increase?
The space constant λ (lamda) increases.
