Upload
kristin-douglas
View
215
Download
0
Embed Size (px)
Citation preview
8/13/2019 HIS 2 Body Fluid Compartments
1/3
HIS2 Body fluid compartments, osmolality- Learning Outcomes
Describe the distribution and composition of body fluids
Male: 60% Water, 40% Solids (Fats, carbs, proteins, minerals) Water (60%)
o 40% intracellular fluido 20% extracellular fluid (5% plasma and 15% interstitial fluid)
Also consist of electrolytes, small quantities of amino acids/glucoseo ICF: Na+, Cl-, HCO3- o ECF: K+, PO43-
Discuss how the composition of body fluids is maintained at a constant level
The composition is essential for cell function (ECF= homeostasis ICF= cell mechanisms) ECF = Glucose increases after a meal = increased secretion of insulin which decreases the
amount of glucose in the plasma. Other examples: blood pressure, pH, temperature
ICF has a selectively permeable cell membrane to water and small but not large ions/small solutes. Na/K transporter pump where K is pumped back in the cell and kept constant
Explain how the osmotic pressure of body fluids is determined
Water moves down its concentration gradient, from area of low solute concentration to ahigh solute concentration, water will always move to dilute a solution.
Typically ECF is similar to ICF in osmotic pressure, because there's no net movement ofwater into or out of the cells, it remains relatively constant.
Differentiate between osmolarity and osmolality
Osmolarity = A concentration of a solution is expressed in Osmol/L of solutiono Body fluid is 283 mOsmol/L because of ECF: K+, PO43- ICF: Na+, Cl-
Osmolality= A concentration of a solution expressed in Osmol/kg of solventExplain how the tonicity of solutions is determined
Tonicity is the measure of the osmotic pressure gradient of two solutions separated by asemi permeable membrane.
Effected by solutes that cannot pass the membrane (Na, K, etc.) Hypertonic = Shrink and shrivel (Water escapes the cell, ECF < ICF ) Isotonic= No net effect (5% glucose or 0.9% saline ECF = ICF) Hypotonic= Swell and burst (Water enters the cell, ECF > ICF)
8/13/2019 HIS 2 Body Fluid Compartments
2/3
Describe the effects of water balance disturbances
Water balance disturbances associated with changes in body fluid osmolarity.o Osmotic movement of water into or out of the cell
Water moves from low osmolarity to a high osmolarity.Diabetes mellitus Type 1 and Type 2
Results from absolute or functional deficiency of circulating insulin (hyperglycemia) Glucose is osmotically active (↑ ECF osmolarity = water shift ECF to ICF = dehydration) Urinary glucose excretion (glycosuria) and kidney glucose excretion. Symptoms: polyuria, intra/extracellular dehydration, increased thirst.
Dehydration:
Insufficient H2O intake (desert travel, difficulty swallowing. Symptoms mainly neurological as water lost from brain cells leads to shrinkage of cells.
Mild cases Moderate cases Severe cases Non-neural
symptoms
Dry skin and
tongue, sunken
eyeballs
Mental confusion
and irrationality
Delerium,
convulsions, coma
Circulatory
disturbances (vary
from slight lower
BP, circ shock, and
death
Underhydration
Excessive H2O loss (heavy sweating, vomiting, diarrhea, diseases such as cholera, diabetesinsipidus)
Overhydration
Any surplus of water is excreted so it does not generally occur. Patients with renal failure (cannot excrete dilute urine and become hypotonic upon
consuming more water than solutes)
Low body mass infants Marathon runners who only drink water Over-heating (overexertion/MDMA-Ecstacy) Syndrome of inappropriate vasopressin/ADH secretion (SIADH) Excess water dilutes ECF → ECF osmolarity decreases → water moves by osmosis throughcell membrane → ICF osmolarity decreases → disrupts cell function Symptoms: Related to water entering brain cells / swelling of brain cells leading to a
decrease in cell fluid osmolarity. = confusion, lethargy, headache, dizziness, vomiting and
severe cases coma/death. Also weakness (muscle cell swelling) and plasma volume increase
Diabetes Insipidus
Deficiency in vasopressin (ADH/antidiuretic hormone) Normal for reduction in urine output, conserves water in the body. Patients can produce up to 20 L of urine (normal is 1.5L)
8/13/2019 HIS 2 Body Fluid Compartments
3/3
Relate the clinical use of IV solutions
Chemically prepared solutions for patients, by injection or infusion to blood. Used to replace lost fluid and aid in IV medication delivery
Colloid
solutions
High molecular weight solutions Ex: albumin or other which do not
readily cross the semi-permeable membrane.
They stay longer than crystalloid (3-6h). Reduces abnormal
accumulation of fluid in interstitial compartment (edema) because
they draw fluid from interstitial/intracellular to vascular components.
Crystalloid
solutions
Clear solutions consisting of sterile water and electrolytes which
cross a semi-permeable membrane into interstitial space and achieve
equilibrium in 2-3 hours. The principle one for IV therapy and
classified based on tonicity.
Given to patients undergoing surgery (IV drip of saline), used to
rehydrate or admin drugs. Isotonic saline can also be given to patients
with low ECF volume (dehydrated).
Hypertonic: 3% - 5% saline which may be given to patients with low
plasma osmolarity and as a result water has moved into the cells
Hypotonic: 0.45% saline which may be given to patients whose body
fluids are hyperosmotic or with renal disease and cannot rehydrate
but do not need additional sodium.
Blood products