Fluid and Electrolytes Flashcards
(161 cards)
What are the 2 main compartments of total body water and what percent of total body water do they represent?
Intracellular (65%)
Extracellular (35%)
What is the extracellular fluid composed of and by what percent?
-Plasma (8%)
-Interstitial fluid (which includes lymph fluid)- 25%
-Transcellular fluid (2%)
what comprises transcellular fluid?
Gastrointestinal, respiratory, urinary, glandular, interocular, cerebrospinal fluid
How many mL/day of fluid is intake? How many mL/day is output?
Both input and output is 2500 ml/day
What does fluid intake include (3)? Include how many mL per day
Metabolism (400 mL)
Food (500 mL)
Drinking (1600 mL)
What does fluid output include (4)? Include how many mL per day.
Feces (100mL)
Breathing (400 mL)
Skin (500 mL)
Urine (1500 mL)
How are fluids and electrolytes regulated (by what mechanisms)? (3)
- Osmosis and osmotic pressure
- Diffusion
- Filtration
Describe how osmosis regulates fluids
Regulation of intracellular and extracellular fluids is based on fluid shifts from a lower concentration of solute to higher concentration of solute through the membrane separating them
Describe how osmotic pressure regulates fluids
It’s the ability of a solution to draw water across a membrane, and is affected by the tonicity (the ability of solutes to cause an osmotic driving force that promotes the movement of water across a membrane from one compartment to another)
Describe how diffusion regulates fluid and electrolytes
Occurs as a result of the membrane transport system which assists with the passage of a specific ion or molecule through the cell membrane. Any change in concentration of electrolytes in either the interstitial fluid or plasma, the change is swiftly followed by a shift in electrolytes to restore balance in the concentration.
How does filtration regulate fluid and electrolyte balance?
The process by which water and dissolved substances (solutes) cross a membrane as a result of hydrostatic pressure.
What is hydrostatic pressure?
The pressure exerted on the walls of blood vessels by fluid (primarily water). Movement of solutes occurs from an area of high hydrostatic pressure to an area of low hydrostatic pressure
What are examples of filtration regulating fluids and electrolytes?
Glomerular filtration system of the kidneys and the arterial end of the capillary
What are the regulatory mechanisms that maintain homeostasis in fluid and electrolyte balance? (Homeostasis between fluids and regulation of input and output are achieved by what systems?) (3) AND an additional mechanism of fluid loss.
- Renal system
- Endocrine system
- Respiratory system
- Insensible losses
How does the renal system regulate fluid volume and electrolyte balance to maintain homeostasis?
Through the glomeruli and renal capillary network selective reabsorption of water and electrolytes occur maintaining homeostasis of plasma osmolality and fluid. Urine output is 1-2 L per day
What is the average urine output per day?
1-2 L per day
What is the role of the endocrine system in controlling fluid and electrolyte balance? (3)
- Renin-angiotensin-aldosterone system
- Antidiuretic hormone
- Natriuretic peptides
How does natriuretic peptide hormones influence fluid and electrolyte balance?
Released from specialized cells within the walls of the atrium (atrial natriuretic peptide) and ventricles (brain natriuretic peptide) in response to increased blood volume and blood pressure. The walls of the atrial and ventricles stretch beyond their normal size. The stretching of the atrial and ventricle walls stimulates the release of ANP and BNP which results in reabsorption of sodium and water by the kidneys and the increase in glomerular filtration rate result in increased urine output that is high in sodium
In what individuals would you see an increase in ANP and BNP? (natriuretic peptide hormones)
In response to increased circulating blood volume as seen in heart failure or a normal response to fluid volume excess
What is the role of the respiratory system in fluid and electrolyte regulation?
Fluid loss occurs from the lungs through vaporization. With exhalation the warmed humidified air (that was inspired) is released from the lungs.
How may mL of water is lost through the lungs daily? What can increase this amount?
300 mL. This amount can be higher during hyperventilation or tachypnea or if the patient is receiving mechanical ventilization
What does insensible water loss occur through? (3)
Skin, lungs, and feces
What types of patients experience insensible water loss? (6)
Hypermetabolic states such as: trauma, burns, fever, and thyroid crisis
Via GI tract in severe diarrhea or ulcerative colitis
How does trauma and burns contribute to insensible water loss?
Fluid loss from impaired skin integrity