MOD 3 Integrative body functions Flashcards
What are the forces that move fluid to different body compartments
Osmosis
Hydrostatic Pressure
Osmotic (oncotic) pressure
Osmosis
The movement of fluid through a semipermeable membrane from an area of low solute concentration to a high solute concentration to reach equilibrium
Hydrostatic pressure
PUSHES fluid out of the blood vessel into the tissue on the arterial side of the capillaries
Osmotic (oncotic) pressure
the PULL that attracts fluid out of the tissue back into the blood vessel on the venous side of the capillaries
Molecules with pulling power:
Protein
Glucose
Sodium
Tonicity of IV fluids
Number/ size of molecules in a solution determines which direction fluid flows
Isotonic solutions
MOST COMMONLY USED
this fluid moves equally back and forth across a membrane without increasing or decreasing the cell size.
(preferred for fluid replacement since the tonicity (sodium concentration) is similar to blood)
*I SO perfect to remember isotonic fluids are used for almost all situations
EX: 0.9% normal saline, NS, and LR
Hypertonic solutions
HyperErtonic: the E reminds you that fluid ENTERS the bloodstream. Fluid is attracted from the tissue into the bloodstream by the high concentration of solutes in hypertonic fluid.
-Large molecules like protein and glucose attract water
-SALT SUCKS (sodium attracts water)
-Given in IV when RAPID TISSUE REPLACEMENT is needed
-or when TISSUE IS OVER HYDRATED as edema or third spacing
EX: 3% saline, 6% Saline, etc.
Hypotonic Solution
HypOtonic solution: O reminds that fluid goes OUT of bloodstream
Given in IV when TISSUE IS DEHYDRATED (diabetic ketoacidosis)
EX: D5W
Fluid overload
Too much fluid of any tonicity or giving fluids too fast.
It happens primarily in the lungs (because the excess fluid in the blood vessels pushes into interstitial lung tissue) - drowning the patient
*assess lungs frequently listen for rhonchi, rales, & crackles
Fluid Challenge = 500ml
Iv fluid is given in increments of 500ml at a time and the patient is assessed (bp and lungs auscultated)
before more fluid is given. if bp is normalized then 500ml can be given. If irregular or wet sounds in the lung then no more can be given and you need to alert the provider.
Edema
Swelling in interstitial tissue
damaging effects of edema
-impaired blood flow (and O2 delivery)
-reduced local healing of tissue
-metabolic wastes cannot easily leave cells so toxins build-up
-increases the workload on the heart as it tries to move fluid through the veins. More pressure is required to push the excess fluid which raises B/P
leads to CHRONIC HYPERTENSION
Life-threatening edema
-Laryngeal edema (causes airway blockage)
-Pleural edema (Breathing impaired)
-Cerebral edema (fluid squashes the brain inside the skull)
Third spacing
too much fluid moves from the intravascular space (blood vessels) into the interstitial third space. (the nonfunctional area between cells where the fluid becomes trapped)
causes: edema, reduced cardiac output, hypotension (because fluid moved out of the blood vessels which results in low bp and cannot get back into the blood stream.
Dependent edema (measuring edema changes)
in legs, is a common finding in congestive heart failure
not precise, but gives nurses a general method of monitoring the changing condition of edema in a patient
Daily weights (measuring edema changes)
Done at the same time every day (after voiding with the same weight clothing on, i.e, hospital gown)
gives an indication of water gain/loss.
-everyone usually weighs 2 lbs less in the morning than at bedtime
Water is lost through respiration and skin evaporation during the night along with the collected urine that is voided in the morning OR to with 2lbs more after eating more than usual the day before
Treatment to reduce edema
diuretic medications (triggers kidneys to release more water) and hypertonic fluids (pulls fluid out of th tissue to be excreted by the kidneys)
Mechanisms of water and sodium regulation *thirst
Controlled by thirst center in hypothalamus and triggered by
-cellular dehydration (caused by ECF osmolality, i.e., blood is thicker than normal)
-hypovolemia (low blood volume) thirst is one of the earliest s/s of hemorrhage
Mechanisms of water and sodium regulation * Antidiretic hormone (ADH)
also called vasopressin
-secreted by the posterior pituitary gland
-released in response to increased osmolality (higher blood concentration)
-regulates water in the body by signaling the kidney to retain water and sodium
-excretion of ADH is caused by LOW BLOOD VOLUME; low sodium; high osmolality of body fluids (i.e. dehydration - ADH will cause fluid retention to relieve the dehydration)
Electrolyte imbalance
4 major cations: Na+, K+, Ca++, Mg+
What is the normal range of each?
Function of each electrolyte: Excites or calms
What tissue do they effect
S/S of imbalance wither each cation (hyper or Hypo)
Fill out Functions of the 4 major cations chart
do it
Ph is balanced by 3 mechanisms
Chemical buffers
respiratory systems
renal system
Chemical buffers
Bicarbonate buffer, phosphate buffer, and protein buffers
functions almost instantaneously
Respiratory system
uses respiration to blow off excess carbon dioxide (an acid) to normalize low ph
respiratory mechanisms take several minutes to hours
