What is the relationship between the intake and outake of fluids in the body?
In a healthy person, intake = output.
Which bodily output of fluid is highly affected by disease states?
Feces.
In regards to fluid output through the skin and the lungs, what does the term insensible mean?
You are unaware that it is happening.
What are the three body fluid compartments?
1.) Plasma
2.) Interstitial Fluid
3.) Intracellular Fluid
Rank the three fluid comparts in regards to volume (largest to smallest).
1.) Intracellular fluid (28.0L)
2.) Interstitial fluid (11.0L)
3.) Plasma (3.0L)
What solutes are highest in concentration in the intracellular fluid/extracellular fluid?
Intracellular: K+, Phosphates-, Proteins-
Extracellular: Na+, Cl-, HCO3-
What solutes don't cross a capillary membrane?
1.) Large proteins
2.) RBC's
What role does the lymphatic system play?
Most fluid is reabsorbed back into the capillaries after it has filtered out. The smaller amount that remains in the interstitium is returned to vascular circulation via the lymphatic system.
What is the average osmolarity of the inside of a cell?
280 mOsm/L
Between the three fluid compartments, where does fluid tend NOT to accumulate?
The interstitium.
There is a strong pull due to colloid osmotic forces back into the capillaries. There is a weaker force pulling towards the intracellular fliud.
Plasma: 301.8 mOsm/L
ISF: 300.8 mOsm/L
ICF: 301.2 mOsm/L
What is the osmolarity of:
1.) 0.9% saline
2.) D5W solution
1.) 308 mOsm/L
2.) 278 mOsm/L
What does total osmolarity refer to?
The total number of particles in solution.
It does not refer to water. And you must also consider molecules that do or do not ionize.
What are colloids, in regards to oncotic or colloid osmotic pressure?
Suspended proteins in blood plasma. They exert a pressure-like pull on water when there is a gradient across a membrane.
What factors influence the distribution of fluid between plasma and interstitial fluid?
Which forces of fluid distribution are the strongest?
Which are negligable?
Strongest: Pc & IIc
Negligable: Pif & IIif
Why are Pif & IIif negligable?
There is very little fluid in the interstitium to exert a force back into the capillary. Also, most proteins present in plasma (ex. Albumin) do not cross the capillary membrane.
What is the equation for Net Filtration Pressure?
NFP = (Pc + IIif) - (Pif + IIp)
What does a positive value for NFP mean? A negative value?
NFP is positive during filtration.
NFP is negative during absorption.
True or false?
Along a capillary, Pc drops due to resistance.
True.
True or False?
Along a capillary, colloid osmotic pressure drops.
False.
True or False?
In a normal capillary, NET filtration occurs.
True.
What are the functions of the kidneys?
1.) Regulation of ECF volume and BP.
2.) Regulation of osmolarity.
3.) Maintenance of ion balance.
4.) Homeostatic regulation of pH.
5.) Excretion of wastes.
6.) Secretion of hormones.
The functional unit of the kidneys - the nephrons - are mostly located in which part of the kidney?
The renal cortex.
What is a kidney's outermost covering?
A fibrous capsule.
It is fairly inelastic and exerts a pressure on the inside of the kidney.
The two capillary beds of the nephron are arranged:
1.) In series?
2.) In parallel?
In series.
If resistance within a blood vessel increases, what is its effect on capillary hydrostatic pressure?
Capillary hydrostatic pressure decreases.
Glomerular capillaries are arranged:
1.) In series?
2.) In parallel?
In parallel.
What are the peritubular capillaries?
Small capillaries that surround the tubule of the nephron. They are in series with the glomerular capillaries.
True or false:
The tubular portion of the nephron is a blood vessel.
False.
It is a tube of epithelial cells containing the filtrate that will either be reabsorbed or excreted as urine.
Why are there multiple loops in the capillaries of the glomerulus?
For increased surface area, resulting in more rapid filtration.
