Lecture 6 - Water Flashcards
Species, activity level, and ambient temperature all affect…
Water requirements
Up to _____% of the body is water, but this may change with age, hydration, and nutritional status
60
True or False: Water is needed to replenish fluids lost during normal physiological activities
True
What does increased osmolarity in the blood activate?
Osmoreceptors that stimulate the hypothalamus (directly or through release of angiotensin II)
A system that increases thirst as a way to increase blood volume
Renin-Angiotensin system
What are some factors that activate the renin-angiotensin system?
High plasma osmolarity, low blood volume, low BP, and stimulation of sympathetic nervous system
Which hormone is important to water conservation during periods of dehydration?
Antidiuretic hormone (ADH)
What will occur if there is a lack of response to ADH in the renal tubules?
Dilute urine and dehydration
ADH is secreted by the __________ gland
Pituitary
ADH acts to _______ the permeability in the tubular cells so that water is absorbed as the interstitial osmolarity is ______ than the filtrate
Increase; higher
Central Diabetes Insipidus is characterized by…
Absence of ADH (resulting in dilute urine)
Nephrogenic DI is characterized by…
Tubules being resistant to ADH (resulting in dilute urine)
True or False: High sodium = decreased plasma osmolarity
False; High sodium = INCREASED plasma osmolarity
Why does blood volume (and sometimes BP) increase when sodium/plasma osmolarity is high in the body?
Fluids are shifting extracellularly
Poor perfusion, electrolyte disturbance, acid-base disturbance, endothelial injury, inflammation, and coagulopathy are all possible consequences of…
Dehydration
Clinical signs of dehydration may not be evident until a patient is at least ___% dehydrated
5
List some clinical/diagnostic indicators of dehydration
Dry MM, longer CRT (>2), skin turgor w/ low elasticity, inc HR, inc resp rate, weak pulses (low BP), low urine output, high PCV/TS, high USG, high lactate, high BUN/CREAT, high osmolarity
What are four ways fluids can be provided to patients?
Orally (PO), intravenously (IV), subcutaneously (SQ), and intraosseously (IO)
True or False: Parenterally provided fluids can be isotonic, hypertonic, or hypotonic
True (though isotonic is most common)
True or False: Parenteral fluids do not need to be administered sterilely
False; they must be administered sterilely/aseptically to avoid infection
What are crystalloid fluids?
Clear fluids w/o lipids or proteins
Examples: saline (0.9% NaCl) and LRS
What are colloid fluids?
Fluids which provide osmotic substance such as starch, albumin, and gelatin
True or False: Patients on IVF should be monitored to ensure rehydration is progressing at a steady pace
True
List some important factors to monitor during rehydration
Changes in clinical signs of dehydration, TPR, body weight, urine production/USG, auscultation, MM color, PCV/TS, BP
What is overhydration?
Excessive hydration, most often iatrogenic and caused by excessive IVF administration
How is overhydration diagnosed?
Resp difficulties, lung edema, pitting edema, confusion/seizures, high BP, tachycardia, excessive MM moisture
How is overhydration treated?
D/C fluids, diuretics, O2
True or False: Patients with feeding tubes never need supplemental hydration with regular water
False; some may require water through the feeding tube, roughly calculated at 1 ml per 1 kcal
Which two organs are most susceptible to damage from overheating?
Kidneys and intestines
Dehydration ___________ the risk for overheating
Increases
What is generally considered a very high and dangerous body temperature?
Anything >104 degrees F
True or False: Drinks with electrolytes are only beneficial to animals who sweat, and will not help animals who do not sweat
True
What are the clinical names for increased drinking and increased urination?
Polydipsia and polyuria
What would be an important initial diagnostic test for a patient exhibiting PU/PD
Urinalysis
What is the numerical range for normal urine concentration (USG)?
1.025 to 1.035
What USG range is indicative of urine that is NOT concentrated (isosthenuria)?
1.008 to 1.012
Hyposthenuria refers to a urine concentration that is less than…
1.008
If urine is adequately concentrated and contains no glucose, but a patient is still exhibiting PU/PD, what are some possible causes?
Behavioral, cystitis, bladder mass, urolithiasis, anatomic/neurologic
When urine is concentrated with glucose, what are two possible medical conditions that could be the cause?
Diabetes mellitus (early) or primary renal glycosuria (rare)
Renal disease, pyometra, hypercalcemia, liver disease, Cushing’s disease, Addison’s disease, and hyperthyroidism are all medical conditions associated with…
Low urine specific gravity
