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)
What happen to effector in feed-forward control?
effector is also disturbed (thermo-, osmoregulation)
What is Positive feed-back?
increase of activation
(ovulation, gating of ion channel)
Negative feed-back (set-point) control maintains the Homeostasis of the internal environment
→ Give 6 examples
- blood pressure
- temperature
- blood glucose
- ionic composition
- pH
- osmotic concentration
Set-point changes during servo-control
→ Give 2 examples
- blood pressure during exercise
- fever
Feed-forward control is related to Rapid reaction
→ Give 2 examples
- thermoregulation
- osmoregulation – drinking
What is the advantage of Positive feed-back?
Advantage: very fast response
- action potential
- calcium-induced calcium release
- blood clotting cascade
Positive feed-back has very fast response
→ Give 3 examples illustrating this advantage
- action potential
- calcium-induced calcium release
- blood clotting cascade
Positive feed-back can be an advantage during pathological disease.
→ Give an example
hypotension during circulatory shock
(The cardiovascular system responds to hypotension and hypovolemic shock by increasing the heart rate, increasing myocardial contractility and constricting peripheral blood vessel)
Composition of the plasma membrane (3)
Lipids + Proteins + Carbohydrates
Structure of phospholipid
- Hydrophilic region: Alcohol + phosphate
- Hydrophobic region: 2 fatty acids
Structure of glycolipid
- Hydrophilic region: Sugar (e.g, galactose)
- Hydrophobic region: 2 fatty acids
Structure of cholesterol
- Hydrophilic region: OH- group
- Hydrophobic region: Steroid region + fatty acid “tail”
3 Functions of the plasma membrane lipids
– Transport of molecules
– Source of second messengers
– Surface
5 examples of phospholipids
- phosphatidylcholine
- sphingomyelin
- phosphatidylethanolamine
- phosphatidylserine
- phosphatidylinositol
5 examples of phospholipids
- phosphatidylcholine
- sphingomyelin
- phosphatidylethanolamine
- phosphatidylserine
- phosphatidylinositol
→ Their localizations?
- phosphatidylcholine
- sphingomyelin
- phosphatidylethanolamine
- phosphatidylserine
- phosphatidylinositol
Main function of sphingomyelin?
lipid raft
Main function of sphingomyelin?
signal transduction
An example of Glycolipid? Its localization and function?
glycosylphosphatidylinositol
→ localization: outer leaflet
→ Function: protein-anchor
localization(s) and function(s) of cholesterols?
Cholesterol
→ localization: inner/outer
→ Function: membrane fluidity; lipid raft
3 types of plasma membrane proteins
- Integral membrane proteins
- Lipid-anchored proteins
- Peripherial proteins
An example of Integral membrane proteins
transmembrane proteins
2 examples of Lipid-anchored proteins
GPI-bound proteins
lipid modification (palmytoilation)
5 functions of the plasma membrane proteins
– Selective transport of molecules
– Cell recognition via surface antigens
– Cell communication (plasma membrane receptors)
– Tissue organization through adhesion molecules
– Enzymatic activity
– Determination of cell shape by linking the cytoskeleton to the
membrane
Ionic composition of the intracellular fluids for
→ Na+?
10-15 mM
Ionic composition of the intracellular fluids for
→ K+?
120-150 mM
Ionic composition of the intracellular fluids for
→ Calcium?
100 nM (free)
Ionic composition of the intracellular fluids for
→ Cl-?
20-30 mM
Ionic composition of the intracellular fluids for
→ HCO3-?
12-16 mM
Ionic composition of the intracellular fluids for
→ Osmolarity?
290 mOsm
Ionic composition of the intracellular fluids for
→ pH?
7.2
Relationship between the volumes of the various body fluid compartments.
Calculate the total body water (TBW)?
TBW = 0.6 x body weight
(70kg x 0.6 = 42L)
Relationship between the volumes of the various body fluid compartments.
Calculate the amount of extracellular fluid (ECF)?
- 4 x the body weight
(0. 4 x 70kg = 28L)
Relationship between the volumes of the various body fluid compartments.
Calculate the amount of intracellular fluid (ICF)?
- 2 x the body weight
(0. 2 x 70kg = 14L)
The fluid compartments of a prototypic adult human weighing 70 kg
→ Identify
The fluid compartments of a prototypic adult human weighing 70 kg. → Total body water is divided into four major compartments which are…
- intracellular fluid (green)
- interstitial fluid (blue)
- blood plasma (red)
- transcellular water such as synovial fluid (tan).
5 examples of Transcellular fluids
- cerebrospinal fluid
- ocular fluid
- synovia (joint fluid)
- fluids in the pleural cavity
- fluids in the peritoneal cavity
Measurements of the volume of various fluid compartments:
Formula for dilution method
V(volume) = m(mass)/c(concentration)
