Block I - System Physiology

Question 1

What is the concept of physiological homeostasis?

Answer 1

The ability to maintain a constant internal environment in the face of fluctuations in the external environment that can disturb the body composition

Question 2

Where is most of the sodium in the body contained? Potassium?

Answer 2

Na is in extracellular fluid volume; K is in intracellular

Question 3

Where is most of the body water contained?

Answer 3

Lean body mass

Question 4

*How would a male weighing 80kg with 48L of water be categorized?

Answer 4

Normal range - 18%

* ranges

Question 5

• 4 grams of a dye are administered into 80 kg subject with LBM 64 kg. Plasma concentration is measured to be 0.25 g/L. What is primary dye distribution?

Answer 5

Primarily in EFV * how to work

Question 6

What is the proper order of components in a classic negative feedback control system?

Answer 6

Transducer, feedback element, summing point, error signal, control element, control signal

Question 7

What percent of LBM is water?

Answer 7

About 73%

Question 8

• What happens with an infusion of hypertonic NaCl solution?

Answer 8

Expansion of EFV and reduction of IFV

* examples of how to work this

Question 9

A volume of blood is suddenly injected into circulation, raising pressure 50 mmHg. After regulation, it is only raised 5 mmHg. What is the negative feedback gain?

Answer 9

9

Question 10

A diabetic pt had a 2 hour postprandial CBG of 200. After transplant it was 140, and it is normally 120. What is feedback compensation, steady state error, and feedback gain?

Answer 10

60, 20, 3

Question 11

What is Occam’s razor principle?

Answer 11

Make your model as simple as possible

Question 12

What is agent-based modeling?

Answer 12

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.

Question 13

For Em-Er = iR(1-exp(-t/tau), what is tau?

Answer 13

RmCm… a time constant

Question 14

What does the total current flowing across the membrane at time t equal?

Answer 14

Ir + Ic or (Em-Er)/Rm + Cm(dE/dt)

Question 15

*In cable theory of electronic potential distribution, what happens when the neural axon increases?

Answer 15

The space constant lambda increases

* formulas and effects of various time constants

Question 16

In cable theory of electrotonic potential distribution, what happens when less Na channel expressed on a fixed membrane area?

Answer 16

The space constant lambda increases

Question 17

What does a bigger space constant mean for elctrotonic potential propagation?

Answer 17

The distance of a single stimulation can propagate further

Question 18

Which nerve fiber has a bigger space constant, thinner or thicker?

Answer 18

Thicker

Question 19

Give examples of transport processes using ATP most directly

Answer 19

Na out of cells, K into cells, Ca into ER/SR

Question 20

What factors cause the opening and closing of ion channels?

Answer 20

Voltage, ligand-binding, physical stretch, phosphorylation

Question 21

Give example of transport process that is not chemical specific.

Answer 21

Gas diffusion through cytoplasmic membrane

Question 22

*Which transport process characterizes Na/Ca exchanger’s function of moving intracellular Ca out of cells

Answer 22

Secondary active transport

* see notes, “exchange”

Question 23

*Which protein provides the highest speed for ions moving across the membrane?

Answer 23

Ion channel

* rankings of speeds

Question 24

What is a second messenger?

Answer 24

Few common small intracellular molecules that amplify the hormonal signal inside a cell

Question 25

Is intracellular Ca responsible for action potential propagation along the neuron axons?

Answer 25

No

Question 26

Is cCMP a second messenger?

Answer 26

No

Question 27

What are the cellular functions of cAMP?

Answer 27

PKA activation, regulation of ion channels, regulation of proteins containing NBD (nucleotide-binding domain)

Question 28

What does G-protein refer to?

Answer 28

Guanine-nucleotide binding proteins

Question 29

How does vitamin D move across cytoplasmic membrane?

Answer 29

Simple diffusion because vitamin D is a metabolic product of cholesterol

Question 30

If the two chambers are equal in volume, a diffusible molecule concentration X in chamber 1, 0 in chamber 2 at t=0. What is concentration after equilibrium is achieved? What if the volume of 1 is n-times larger than 2?

Answer 30

X/2; X*n/(n+1)

Question 31

What factors directly determine the amplitude of a voltage gated ion channel current?

Answer 31

Ion concentration gradient and voltage difference across cytoplasmic membrane

Question 32

What effect of increase in intracellular Na concentration will be on the rate of Na/Ca exchanger?

Answer 32

decrease

Question 33

How many different kinds of second messengers have been discovered so far?

Answer 33

Less than 10

Question 34

What is the function of inositol triphosphate (IP3)?

Answer 34

It triggers Ca release from intracellular Ca store

Question 35

Which channel plays the most important role in establishing the resting membrane potential?

Answer 35

Voltage-gated K channel

Question 36

Which of the following processes describes CO2 transport in lung?

Answer 36

Simple diffusion through lipid bilayer

Question 37

What is an antagonist?

Answer 37

A molecule that binds to a specific receptor, but it does not generate a consequential physiological function as the physiological ligand does

Question 38

Give an example of a nuclear receptor.

Answer 38

Vitamin D

Question 39

Give an example of a small G-protein.

Answer 39

G_12/13

Question 40

*Heterotrimeric G-protein consists of alpha, beta, gamma subunits. Which binds to GTP and is separated from the others?

Answer 40

Alpha

* what do other subunits do?