Fluid And Electrolytes-Exam 3 Flashcards
Intravascular fluid (blood plasma)
% of total body water: 8%
Definition:
That portion of the total body fluid contained within blood and lymphatic vessels.
Pattern of fluid shifts:
1) Capillary hydrostatic pressure (blood pressure) facilitates the outward movement of water from the capillary to the interstitial space.
Interstitial Fluid
% of total body water: 25%
Definition:
(includes fluid between cells, lymph, GI fluids, spinal fluid, fluid in eyes/tears and synovial fluid
Pattern of fluid shifts:
Third-spacing occurs when too much fluid moves from the intravascular space (blood vessels) into the interstitial or “third” space-the nonfunctional area between cells. This can cause potentially serious problems such as edema, reduced cardiac output, and hypotension
Intracellular Fluid
% of total body water: 66%
Definition:
found inside cells and are made up of protein, water, electrolytes, and solutes. The most abundant electrolyte in intracellular fluid is potassium.
Pattern of fluid shifts:
Identify common reasons someone’s TBW might not be 60%
- women about 50% TBW
- age related
- infants-10 years 65-70% TBW
- as age TBW decreases, elderly about 40% - obesity (40-50% less water in fat vs. muscle)
Anti diuretic hormone/vasopressin
Where is it produced and excreted? HYPOTHALAMUS and released from POSTERIOR PITUITARY
Where does it work?
In the distal tubule, collecting tubule, and collecting duct
What does it do?
-Increases water permeability in the distal tubule, collecting tubule and collecting duct = water reabsorption (or decreased UOP).
-Secreted in response to low intravascular volume.
**without ADH, vasopressin water reabsorption decrease leading to intravascular dehydration
**help with reabsorption of water
Aldosterone
(K+)
Where is it produced and excreted? ADRENAL CORTEX (in kidneys)
Where does it work?
Cells of the late distal tubules and cortical collecting tubules
What does it do?
-Regulates sodium reabsorption and potassium secretion.
- Secretion is regulated by ATCH, angiotension II and increased serum K levels
- stimulates Na-K ATPase pump
***major hormone responsible for potassium homeostasis
Angiotensin II
(Na)
Where is it produced and excreted?
Kidneys
-Secreted in response to decreased blood volume
Where does it work? Loop of Henle and distal tubules; efferent tubules
What does it do?
- Stimulates aldosterone release.
- Directly stimulates Na reabsorption in the proximal tubules, loop of Henle, and distal tubules
- main job is to retain Na
***most powerful Na retaining hormone
Natriuretic Peptide (ANP and BNP)
Where is it produced and excreted?
Cells in the cardiac atria and myoendocrine ventricular cells (BNP) when distended by increased intravascular volume
Where does it work?
Renal tubules, particularly collecting ducts
What does it do?
Increases Na and water excretion in the urine
hydrostatic pressure
fluid movement relative to what happens in the intravascular space
Oncotic pressure
fluid movement relative to what happens in the interstitial space
Osmotic pressure
how the presence of solutes (protein-albumin) changes fluid movement
Sodium
- 90% of extracellular cations, maintains balance extracellular fluid
- sodium balance is main goal of osmosis
Potassium
- K+ maintains intracellular balance
- K+ balance maintained by active transport
- Responds to: acid/bas balance, hyperglycemia, adrenergic antagonists/agonists, cell lysis
Definition of OSMOLALITY
- a measure of the number of dissolved particles in a fluid
- measures the amount of dissolved substances such as sodium, potassium, chloride, glucose, and urea in a sample of blood and sometimes in urine.
Definition of HYDROSTATIC PRESSURE
pressure exerted by or existing within a liquid at rest with respect to adjacent bodies
