1. Introduction, fluid compartments Flashcards
1–5. Name the body fluid compartments, based on relative volumes.
- Total body water (TBW)
- Intracellular fluid (ICF)
- Extracellular fluid (ECF)
- Interstitial fluid (ISF)
- Plasma volume (PV)
What is homeostasis?
The maintenance of constant volume and composition of the body fluid compartments (and their temperature in warm-blooded animals and humans)
Ionic composition of the extracellular fluid (ECF) for…
→ Na+?
135-147 mM
Ionic composition of the extracellular fluid (ECF) for…
→ K+?
3.5-5.0 mM
Ionic composition of the extracellular fluid (ECF) for…
→ Calcium? (total? free?)
- 1-2.8 mM (total, blood plasma)
- 1-1.4 mM (free)
Ionic composition of the extracellular fluid (ECF) for…
→ Cl-?
95-105 mM
Ionic composition of the extracellular fluid (ECF) for…
→ HCO3-?
22-28 mM
Ionic composition of the extracellular fluid (ECF) for…
→ Osmolarity?
290 mOsm
Ionic composition of the extracellular fluid (ECF) for…
→ pH?
7.35-7.45
What is steady-state balance?
The process in which the body maintains steady-state balance for water and a number of important solutes
→ This occurs when input into the body equals output from the body
Key concepts of steady-state balance? (3)
- For each solute and water, there is a normal set point.
- Deviations from this set point are monitored (i.e., when input ≠output)
- Effector mechanisms are activated that restore balance.
The sensitivity of the system (i.e., how much of a devia- tion from the set point is tolerated) depends on several factors
→List 3 factors
- The nature of the sensor (i.e., how much of a deviation from the set point is needed for the sensor to detect the deviation),
- The time necessary for generation of the effector signals
- How rapidly the effector organs respond to the effector signals.
2 sources for water input of human body?
- Ingested (liquid & in food)
- Generated from cellular metabolism
4 sources for water output of human body?
- Lungs
- Skin
- GI tract
- Kidneys
Regulation of extracellular potassium ion concentration.
→ How is the set point set?
genetically encoded
Regulation of extracellular potassium ion concentration.
→ mechanism to monitor the deviations from the set point
glomerulosa cells of the adrenal gland
Regulation of extracellular potassium ion concentration.
→ elevation of extracellular potassium ion concentration caused by?
aldosterone production
Regulation of extracellular potassium ion concentration.
→ aldosterone acts on particular kidney cells, potassium ion excretion from the body is going to ____ (increase/decrease?)
increase
Regulation of extracellular potassium ion concentration
Aldosterone acts on particular kidney cells, potassium ion excretion from the body is going to increase
→ lead to a ____ of extracellular potassium ion concentration
decrease
Regulation of extracellular potassium ion concentration is a ____ (negative/positive?) feed-back control?
It is a negative feed-back control
7 physiological parameters can be regulated?
- concentration of other ions in the extracellular fluid
- pH, glucose concentration of the blood
- osmolarity of the blood
- tensions of various gases (O2, CO2) in the tissues
- arterial blood pressure and volume of the blood
- temperature of the body
- body mass
List 4 Physiological control mechanisms?
- Negative feed-back (set-point) control → maintenance of homeostasis
- Servo-control regulation → set point has been changed (fever, exercise)
- Feed-forward control →effector is also disturbed (thermo-, osmoregulation)
- Positive feed-back → increase of activation (ovulation, gating of ion channel)
What is negative feed-back (set-point) control?
maintenance of homeostasis
What happen to set point in Servo-control regulation?
set point has been changed (fever, exercise)