Homeostasis

Question 1

Homeostasis

Answer 1

Maintenance of internal milieu

Question 2

Equilibrium vs. Steady state

Answer 2

Equilibrium: Gibbs = 0 (death)

Steady state: Gibbs = enthalpy - temp*entropy (energy regulation

Question 3

Fluid compartments:

Relative sizes

Subcompartments of EC

Answer 3

Intracellular 2x more fluid than extracellular

EC - 20% of body weight

15% Interstitial (protein poor), 5% Plasma (protein rich)

IC - 40% of body weight

Question 4

Fluid compartment ion relativity

Answer 4

IC - K+ & protein-

EC - Na+, Cl-

interstitial (protein poor)

plasma (protein rich)

Question 5

Regulation of physiological systems

(Progression)

Answer 5

1. Disturbance - env, metab, ingest
2. Regulated variable - [X]
3. Sensor - warm, cold
4. Effectors - hormone secretion
5. Sensor-effector
6. Response
7. Correction of initial disturbance via

   neg feedback or pos feedback

Question 6

Gain

Answer 6

How well a physiological system corrects after undergoing a disturbance

Math: Gain = Correction/Error

Correction: no control - control

Error: control

High Gain: systems that cannot tolerate big changes (body temp, blood osmolarity) Gain >= 10

Low Gain: systems that can tolerate bigger changes (glucose infusion) Gain < 10

Question 7

Negative feedback

Positive feedback

Answer 7

Neg: ECF down -> vasopressin up -> urine down

Mechanism acts to suppress initial response to disturbance

Pos: Blood loss

(5L->4L, neg feed; 5L -> 3L, pos feed)

Mechanism perpetuates in the same direction as disturbance

Question 8

Tonicity

Answer 8

Hypertonic - More [solute] outside cell

Hypotonic - More [solute] inside cell

Isotonic - Same effective [solute] inside and outside cell