Electrolytes MS13 Davis

Card Set Information

Author:
davis10000
ID:
124492
Filename:
Electrolytes MS13 Davis
Updated:
2011-12-19 23:29:48
Tags:
Electrolytes MS13 Davis
Folders:

Description:
Electrolytes MS13 Davis
Show Answers:

Home > Flashcards > Print Preview

The flashcards below were created by user davis10000 on FreezingBlue Flashcards. What would you like to do?


  1. What percentage of the body's total weight is composed of water for a younger adult? For an older adult?
    • Younger Adult: 55-60%
    • Older Adult: 50-55%
    • (p. 170)
  2. What percentage of total body water does extracellular fluid (ECF) make up? What different subcategories make up ECF?
    • The ECF space contains about one third (about 15L) of total body water. The ECF includes interstitial fluid (fluid between cells, sometimes called the "third space"); blood, lymph, bone, and connective tissue water; and the transcellular fluids.
    • (170)
  3. What are transcellular fluids?
    • Transcellular fluids are the fluids in special body spaces and include peritoneal fluid, and pleural fluid.
    • (170-171)
  4. What percentage of total body water does intracellular fluid (ICF) make up?
    • The book says that ECF makes up about 1/3 (15 L) of total body water, and that ICF makes up the ramaining 2/3 (about 25 L according to the book).
    • (171)
  5. These three processes are important to control normal fluid and electrolyte balance and they work together to maintain balance so the internal invironment remains stable even when the external environment changes.
    • These processes are filtration, diffusion, and osmosis. They determine how, when, and where fluids and particles move across cell membranes.
    • (171)
  6. What is Filtration?
    • Filtration is the movement of fluid through a cell or blood vessel membrane because of hydrostatic pressure differences on both sides of the membrane. Filtration occurs because of differences in water volume pressing against the confining walls of the space (hydrostatic pressure). The hydrostatic pressures of two fluid spaces can be compared whenever a porous (permeable) membrane separates the two spaces. When nothing stops it, water moves (filters) through the membrane from the space with higher hydrostatic pressure to the space with lower hydrostatic pressure.
    • (171)
  7. What is hydrostatic pressure?
    • Fluid weight in a confined space is related to the amount of fluid pressent in that area. Water molecules in a confined space constantly press outward against the confining walls. This pressing of water molecules is hydrostatic pressure. It is a "water-pushing" pressure, because it is the force that pushes water outward from a confined space through a membrane.
    • (171)
  8. What happens when two spaces have a graded difference (gradient) for hydrostatic pressure?
    • Because the human body constantly seeks equilibrium, when a gradient exists, water movement (filtration) occurs until hydrostatic pressure is the same in both spaces.
    • (171)
  9. What is Diffusion? Explain how it works?
    • Diffusion is the free movement of particles (solute) across a permeable membrane from an area of higher concentration to an area of lower concentration (down a concentration gradient). This action controlls the movement of solute particles in solution across various body membranes.
    • A concentration gradient exists when two fluid spaces have different numbers of the same type of particles. Particle collisions cause them to move down the concentration gradient. Any membrane that separates two spaces is struck repeatedly by particles. When a particle strikes a pore in the membrane that is large enough for it to pass through, diffusion occurs.
    • This happens more often in the fluid space with the greatest concentration of particles because there are more particles bumping into each other. Consequently, more particles will move from the fluid space with the greatest concentration of particles to the fluid space with the lesser concentration of particles than vice versa. As a result, both fluid spaces will eventually have the same concentration of similar particles. At this point, the concentration gradient will no longer exist, and an even exchange of particles will will take place between the two fluid spaces.
    • (172)
  10. What is facilitated diffusion?
    • Diffusion across a cell membrane that requires the assistance of a membrane-altering system (e.g., insulin) is called facilitated diffusion or facilitated transport. This type of transport is still a form of diffusion.
    • (173)
  11. Are cell membranes selectively permeable when it comes to diffusion?
    • Yes. Unlike capillary membranes, which permit the diffusion of most small-sized particles down a gradient, cell membranes are selective. They permit diffusion of some particles but not others. For example, usually ECF has 10 times more sodium ions ICF.
    • (172-173)
  12. What is Osmosis? How does it work? Explain the process.
    • Osmosis is the movement of water only through a selectively permeable (semipermeable) membrane. For osmosis to occur, a membrane must separate two fluid spaces and one space must have particles that cannot move through the membrane. (The membrane is impermeable to this particle.) A concentration gradient of this particle must also exist. Because the membrane is impermeable to these particles, they cannot cross the membrane but water molecules can.
    • For the fluid spaces to have equal concentrations of the particle, the water molecules move down their concentration gradient from the side with the higher concentration of water molecules (and thus a lower concentration of particles) to the side with the lower concentration of water molecules (and a higher concentration of particles). This movement continues until both spaces contain the same proportions of particles to water. (At this point, the concentrations of particles in the fluid spaces on both sides of the membrane are equal even though the total numbers of particles and volumes of water are different. Equilibrium occurs by the movement of water molecules rather than the movement of particles.)
    • (173)
  13. What are some of the different ways in which particle concentration in body fluids is expressed?
    • milliequivalents per liter (mEq/L)
    • millimoles per liter (mmol/L)
    • milliosmoles per liter (mOsm/L)
    • (173)
  14. What is osmolarity?
    What is Osmolality?
    • Osmolarity is the number of milliosmoles in a liter of solution.
    • Osmolality is the number of milliosmoles in a kilogram of solution.
    • (173)
  15. What is the normal osmolarity value for plasma and other body fluids?
    The normal osmolarity value for plasma and other body fluids ranges from 270 to about 300 mOsm/L. The body functions best when the osmolarity of the fluids in all body fluid spaces is close to 300 mOsm/L. When all body fluids have this particle concentration, the body fluids are isosmotic to each other. Another term with the same meaning is isotonic (also called normotonic).
  16. What is the term for fluids with osmolarities greater than 300 mOsm/L? What is the term for fluids with osmolarities less than 270 mOsm/L?
    • Fluids with osmolarities greater tahn 300 mOsm/L are hyperosmotic, (aka hypertonic,) compared with isosmotic (aka isotonic) fluids.
    • Fluids with osmolarities of less than 270 mOsm/L are hypo-osmotic (aka hypotonic,) compared with isosmotic (aka isotonic) fluids.
  17. What would happen if a hyperosmotic IV solution were infused into a patient with normal ECF osmolarity?
    • The infusing fluid would make the person's blood hyperosmotic. To balance this situation, the interstitial fluid would be pulled into the circulation in an attempt to dilute the blood osmolarity back to normal. As a result the interstitial volume would shrink, and the plasma volume would expand.
    • (174)
  18. What would happen if a hypo-osmotic IV solution were infused into a patient with normal ECF osmolarity?
    • The infusing fluid would make the person's blood hypo-osmotic. According to the book, water tends to be pulled from hypo-osmotic fluid space into isosmotic fluid space.
    • (174)
  19. How does the thirst mechanism work?
    • The feeling of thirst is caused by the activation of cells in the brain called osmoreceptors, which respond to changes in ECF osmolarity. For example, when a person loses body water, but most of the particles remain (ex. excessive sweating), ECF volume is decreased (and osmolarity is increased). As a result the cells in the thirst center shrink, which triggers a person's awareness of thirst, making them want a drink. Drinking replaces the amount of water lost and restores the ECF osmolarity to normal.
    • (174)
  20. Briefly differentiate between filtration, diffusion, and osmosis.
    • Filtration is the movement of fluid through a cell or blood vessel membrane because of hydrostatic pressure differences on both sides of the membrane.
    • Diffusion is the free movement of particles (solute) across a permeable membrane from an area of higher concentration to an area of lower concentration (down a concentration gradient).
    • Osmosis is the movement of water only through a selectively permeable membrane.
  21. What is Lymph?
    • At the capillary level, fluid moves out from the capillary at its arterial end into the interstitial space and moves from the interstitial space back into the capillary at the venous end. Often, a small amount remains in the tissues. It is returned to the systemic circulation as Lymph.
    • (174)
  22. When skeletal muscle contractions are reduced what happens to lymph flow? How can this result in edema?
    • Lymph fluid is returned to the circulation by lymph vessels, or lymphatics. These vessels drain lymph back into the circulatory system at the left and right subclavian veins. Lymph nodes ares situated along the lymphatic paths and filter the lymph fluid. Lymph flow is slower than blood flow because lymph has no pump. flow is enhanced by skeletal muscle contractions, breathing, and a peristalsis like motion in the lymph vessels. When skeletal muscle contrations are reduced, like when a person is sitting for hours during a long airplane trip, lymph moves very slowly in the dependent areas (lower legs and feet) and swelling of the feet and ankles occurs.
    • (174)
  23. Does fat or muscle have more water?
    • Muscle cells contain mostly water, and fat cells have little water.
    • (175)
  24. What is the minimum amount of urine per day needed to excrete toxic waste products?
    • The minimum amount of urine per day needed to excrete toxic waste products is 400 to 600 mL. This minimum volume is called the obligatory urine output. If the 24-hour urine output falls below the obligatory output amount, wastes are retained and can cause lethal electrolyte imbalances, acidosis, and toxic buildup of nitrogen.
    • (175)
  25. What is insensible water loss?
    • Water loss from the skin, lungs, and stool is called insensible water loss, because it cannot be controlled. The amount lost can be significant. In a healthy adult, insensible water loss is about 500 to 1000 mL/day. This loss increases greatly during thyroid crisis, trauma, burns, states of extreme stress, and fever. For every degree increase in body temperature, insensible water loss increases by about 10%.
    • (175)
  26. How much water can be lost per hour by sweating?
    • Loss by sweating is variable and can reach a maximum rate of about 2 L/hr.
    • (175)
  27. What is the role of aldosterone in the regulation of fluid balance?
    • Aldosterone is a hormone secreted by the adrenal cortex whenever sodium level in the extracellular fluid (ECF) is decreasing. Aldosterone prevents both water and sodium loss.
    • When aldosterone is secreted, it acts on kidney nephrons, triggering them to reabsorb sodium and water from the urine back into the blood. This action increases blood osmolarity and blood volume. Aldosterone prevents excessive kidney excretion of sodium. It also helps prevent blood potassium levels from becomming too high.
    • (175)
  28. What is the role of antidiuretic hormone in the regulation of fluid balance? How does it affect the kidney tubules?
    • ADH acts directly on kidney tubules and collecting ducts, making them more permeable to water. As a result, more water is reabsorbed by these tubules and returned to the blood, decreasing blood osmolarity by making it more dilute. When blood osmolarity decreases, especially when the plasma sodium level is below normal, the osmoreceptors swell slightly and inhibit ADH release. Less water is then reabsorbed, and more is lost from the body in the urine. As a result, the amount of water in the extracellular fluid (ECF) decreases, bringing osmolarity to normal.
    • (175)
  29. Where is antidiuretic hormone produced and where is it stored? What controls the release of ADH? What are osmoreceptors?
    • ADH, or vasopressin, is produced in the brain and stored in the posterior pituitary gland. ADH release from the posterior pituitary gland is controlled by the hypothalamus in response to changes in blood osmolarity. The hypothalamus contains specialized cells (osmoreceptors) that are sensitive to changes in blood osmolarity. Increased blood osmolarity, especially an increase in the level of plasma sodium, results in a slight shrinkage of these cells and triggers ADH release form the posterior pituitary gland.
    • (175)
  30. What are natriuretic peptides? What causes them to be secreted? What do they do?
    • Natriuretic peptides (NPs) are hormones secreted by special cells that line the atria of the heart (atrial natriuretic peptide) and the ventricles of the heart (brain natriuretic peptide). They are secreted in response to increased blood volume and blood pressure, which stretch the heart tissue. NP binds to receptor sites in the nephrons, creating effects that are opposite of aldosterone. Kidney reabsorption of sodium is inhibited at the same time that glomerular filtration is increased, causing increased urine output. The outcome is decreased circulating blood volume and decreased blood osmolarity.
    • (175-176)
  31. The endocrine system helps control fluid and electrolyte balance. Three hormones that help control these critical balances are aldosterone, antidiuretic hormone (ADH), and natriuretic peptide (NP). What effect do each of these have on blood volume and osmolarity?
    • Aldosterone: Increases blood osmolarity and blood volume.
    • ADH: Decreases blood osmolarity by making it more dilute, and increases blood volume.
    • NP: (Opposite of aldosterone) decreases blood volume and decreases blood osmolarity.

What would you like to do?

Home > Flashcards > Print Preview