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104 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Water is the most common substance in the body, making up about __ to __ of total body weight for healthy younger adults
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55% - 60%
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p 170
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water makes up __ to __ for healthy older adults
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50% to 55%
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pg 170
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fluid outside the cells
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extracellular fluid (ECF)
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pg 170
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fluid inside the cells
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intracellular fluid (ICF)
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pg 170
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__ contains 1/3rd of total body water
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ECF
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pg 170
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fluid between cells
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interstitial fluid
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pg 170
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ECF includes
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interstitial fluid, blood, lymph, bone, and connective tissue water, and trans-cellular fluids
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pg 170
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Trans-cellular fluids
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fluids in special body spaces and include cerbrospinal fluid, synovial fluid, peritoneal fluid, and pleural fluid
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pg 170-171
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ICF contains
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remaining 2/3rds of total body water (about 25 L)
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pg 171
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Three process that are important to control normal fluid and electrolyte balance. They determine how, when, and where fluids and particles move across cell membranes.
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filtration, diffusion, and osmosis
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pg 171
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Filtration
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the movement of fluid through a cell or blood vessel membrane because of hydrostatic pressure differences on both sides of the membrane. Occurs because of differences in water volume pressing against the confining walls of the space.
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pg 171
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Hydrostatic pressure
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"water- pushing" pressure. Water molecules in a confined space constantly press outward against the confining walls. The amount of water determines the hydrostatic pressure of that space.
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pg 171
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When hydrostatic pressure difference is the same in both spaces that are separated by a permeable membrane
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hydrostatic pressure is at equilibrium
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pg 171
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When hydrostatic pressure is different between two fluid spaces
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disequilibrium - the two spaces have a graded difference (gradient) for hydrostatic pressure. Water movement (filtration) occurs until the hydrostatic pressure is the same in both spaces
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pg 171
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How is blood pressure an example of a hydrostatic filtering force?
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Blood pressure moves whole blood from the heart to capillaries where filtration can occur to exchange water, nutrients, and waste products between blood and tissues. Capillaries are one cell layer thick with pores in the membrane so water can filter freely when a hydrostatic pressure gradient is present.
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pg 172
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Edema
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tissue swelling with fluid collection
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pg 172
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How right-sided heart failure can lead to edema
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The volume of blood in the right side of the heart increases because the right ventricle is too weak to pump blood. As blood backs up into the venous system, venous hydrostatic pressure rises, which causes capillary hydrostatic pressure to rise until it is higher than the hydrostatic pressure in the interstitial space. Then excess filtration of fluid from the capillaries into the interstitial tissue space occurs, forming visible edema.
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pg 172
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the free movement of particles across a permeable membrane from an area of higher concentration to an area of lower concentration. Controls the movement of solute particles in solution across various body membranes.
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diffusion
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172
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the diffusion of particles into and out from cells and fluid spaces occurs via __
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the energy from the vibration of single molecules. This motion is random and molecules bump into each other within a confined space. Each collision increases the speed of the particles
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172
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Particle collisions cause the molecules in a solution
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to spread out evenly through available space. They move from an area of higher concentration to lower concentration until equal. Higher number of molecules = more collisions.
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172
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A concentration gradient exists when ___ (diffusion)
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two fluid spaces have different numbers of the same type of molecules.
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172
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If a concentration gradient occurs and there is a membrane between the two spaces, how does diffusion occur?
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The membrane is struck repeatedly by particles. When the particle strikes a pore in the membrane that is large enough for it to pass through, diffusion occurs. The chance of this happening is greater in the side with higher particle concentration.
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172
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Diffusion is more rapid when the gradient is
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steeper
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172
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Unlike capillary membranes which permit small-sized particles down a gradient, cell membranes are __
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selective
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172
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Some particles cannot move across a cell membrane, even with a steep gradient, because the membrane is __ to that particle. Therefore the concentration gradient is __
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impermeable, maintained across the membrane
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172
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facilitated diffusion / facilitated transport
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diffusion across a cell membrane that requires the assistance of a membrane-altering system
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172
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Why does the ECF have ten times the amount of sodium ions than the fluid in the ICF?
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It is caused by the cell membrane impermeability to sodium and by special "sodium pumps" that move extra sodium put of the cell against its concentration gradient into the ECF.
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172
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How does glucose diffuse into the ICF?
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Even though the amount of glucose may be much higher in the ECF than in the ICF, glucose cannot cross most cell membranes without the help of insulin. When insulin in present, it binds to insulin receptor sites on cell membranes, which makes the membrane more permeable to glucose. AKA facilitated diffusion
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173
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the movement of water through a selectively permeable (semipermeable) membrane
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osmosis
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173
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How does osmosis occur
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A membrane must separate two fluid spaces and one space must have particles that cannot move through it. A concentration gradient of this particle must also be present. Water must move down their concentration gradient from the side with the higher concentration of water to lower concentration of water. This dilutes the higher concentration of particles and the particles are then equal on both sides, even though the water molecules are not.
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173
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the number of milliosmoles per liter of solution (mOsm/L)
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osmolarity
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173
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the number of milliosmoles in a kilogram of solution
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osmolality
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173
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normal osmolarity value for plasma and other body fluids ranges from __ to __
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270 to 300
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174
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The body functions best when the osmolarity of fluids is ___ mOsm/L. When all body fluids have this particle concentration, the body fluids are ___ to each other.
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300
isosmotic or isotonic |
174
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fluids with osmolarities greater than 300 mOsm/L
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hyperosmotic or hypertonic
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174
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Hypertonic fluids have a __ osmotic pressure than do isotonic fluids.
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greater
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174
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Tend to pull water from the isosmotic fluids space into the hyperosmotic fluid space until an osmotic balance occurs
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hyperosmotic/ hypertonic fluids
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174
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What would happen if a hypersosmotic IV solution were infused into a patient with a normal ECF osmolarity?
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the infusing fluid would make the person's blood hyperosmotic. To balance the 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.
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174
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fluids with osmolarities of less than 270 mOsm/L are
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hypo-osmotic or hypotonic
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174
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Hypo-osmolar fluids have a __ osmotic pressure than isosmotic fluids
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lower
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174
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In hypo-osmolar fluid water is...
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pulled from the hypo-osmotic fluid space into the isosmotic fluid space
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174
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Fluids that have particles with a greater solubility have a ___ osmotic pressure than fluids with insoluble particles
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higher
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174
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the __ mechanism is an example of how osmosis helps maintain homeostasis
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thirst
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174
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the feeling of thirst is caused by the activation of cells in the brain that respond to changes in ___ osmolarity. These cells are called ____.
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ECF, osmoreceptors
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174
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When a person loses body water but most of the particles remain, ECF volume is ___ and osmolarity is ___.
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decreased, increased
(hypertonic conditions) |
174
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The cells in the thirst center __ as water moves from the cells into the hypertonic ECF. This triggers a person's awareness of thirst and increases the urge to drink.
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shrink
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174
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The thirst mechanism is __ sensitive in older adults, making them ore at risk for dehydration.
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less
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174
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If lymph has no pump, how is lymph flow enhanced?
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by skeletal muscle contractions, breathing, and peristalsis like motion in the lymph vessels
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174
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What are the changes and results in age-related changes on fluid balance of the skin?
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changes- loss of elasticity, decreased turgor, decreased oil production
results- an unreliable indicator of fluid status, dry, easily damaged skin |
174
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What are the changes and results in age-related changes on fluid balance of the renal system?
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changes- decreased glomerular filtration, decreased concentrating capacity
results- poor excretion of waste products, increased water loss |
174
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What are the changes and results in age-related changes on fluid balance of the muscular system?
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changes- decreased muscle mass
results- decreased total body water, greater risk of dehydration |
174
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What are the changes and results in age-related changes on fluid balance of the neurologic system?
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changes- diminished thirst reflex
results- decreased fluid intake, increasing the risk of dehydration |
174
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What are the changes and results in age-related changes on fluid balance of the endocrine system?
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changes- adrenal atrophy
results- poor regulation of sodium and potassium, predisposing the patient to hyponatremia and hyperkalemia |
174
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A person's _ , _, and amount of _ affect the amount and distribution of body fluids.
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age, gender, fat
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174
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Which contains more water, fat cells or muscle cells?
How does this affect gender? |
muscle cells
Men have more muscle cells and more water. |
175
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A __ blood osmolarity or a ___ blood volume triggers the sensation of thirst
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rising, decreasing
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175
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An adult drinks an average of __ mL of fluid a day and ingests an additional __ mL of fluid from food
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1500, 800
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175
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The minimum amount of urine per day needed to excrete toxic waste products is __ to __ mL. This minimum volume is called the __ ___ __.
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400 to 600
obligatory urine output |
175
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If urine output falls below the obligatory urine output amount, wastes are retained and can cause...
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lethal electrolyte imbalances, acidosis, and a toxic buildup of nitrogen
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175
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What are the measurable fluid intakes?
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oral fluids, parenteral fluids, enemas, irrigation fluids
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175
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What are the measurable fluid outputs?
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urine, emesis*, feces*, drainage from body cavities
*if liquid form |
175
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What are not measurable for fluid intakes and outputs?
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intake- solid foods, metabolism
output- perspiration, vaporization through the lungs |
175
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Water loss from the skin, lungs, and stool is called ___ because it cannot be controlled
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insensible water loss
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175
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In a healthy adult, insensible water loss is about __ to __ mL/day
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500 to 1000
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175
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For every degree increase in body temp, insensible water loss increases by about __%.
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10
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175
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Patients at risk for increased insensible water loss include
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being mechanically ventilated and those with tachypnea
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175
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The endocrine system helps control fluid and electrolyte balance. Three hormones that help control these critical balances are__, __, and ___.
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aldosterone, antidiuretic hormone (ADH), and natriuretic peptide (NP)
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175
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Aldosterone is a hormone secreted by the adrenal cortex whenever sodium level in the ECF is ___. It prevents both __ and __ loss.
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decreased
water and sodium |
175
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When aldosterone is secreted, it acts on the kidney nephrons, triggering the to __ sodium and water from the urine back into the blood. This __ blood osmolarity and blood volume.
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reabsorb
increases |
175
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Antidiuretic hormone (ADH) is produced in the __ and stored in the ___.
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brain
posterior pituitary glad |
175
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ADH release from the posterior pituitary glad in controlled by the __ in response to change in the blood __.
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hypothalamus
osmolarity |
175
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ADH acts directly on kidney tubules and collecting ducts, making them more ___ to water. As a result, water is reabsorbed by these tubules and returned to the blood, ___ blood osmolarity by making it more dilute.
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permeable
decreasing |
175
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Natriuretic peptides are hormones secreted by special cells that line the __ of the heart and the __ of the heart.
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atria, ventricles
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175
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Natriuretic peptides are secreted in response to __ blood volume and blood pressure, which stretch the heart tissue.
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increased
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175
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NP causes effects that are opposite of aldosterone. The outcome is __ circulating blood volume and __ blood osmolarity.
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decreased
decreased |
176
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common causes of dehydration
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hemorrhage, vomiting, diarrhea, profuse salivation, fistulas, illeostomy, profuse diaphoresis, burns, severe wounds, long term npo, diruretic therapy, GI suction, hyperventilation, renal failure (early phase), diabetes insipidus, difficulty swallowing, impaired thirst, unconsciousness, fever, impaired motor function
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176
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common causes of fluid overload
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excessive fluid replacement, renal failure (late phase), heart failure, long term corticosteroid therapy, syndrome of inappropriate antidiuretic hormone, psychiatric disorders with polydipsia, water intoxication
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176
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What is relative dehydration?
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When there is no actual loss of total body water, but water shifts from the plasma into the interstitial space.
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177
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What is the most common type of fluid volume deficit? Explain it.
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Isotonic dehydration
Fluid is lost only from the ECF space, including both the plasma and the interstitial spaces. There is no shift between spaces so the ICF volume remains normal. |
177
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What is the best way to gauge dehydration?
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daily weight loss
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178
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Cardiovascular changes that are indicators of dehydration
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heart rate increases, pulses are weak, blood pressure decreases, orthostatic hypotension, neck and hand veins are flat
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178
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Respiratory changes that are indicators of dehydration
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increased respiratory rate because the body perceives the decreased blood volume as hypoxia,
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178
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Skin change indicators of dehydration
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assess skin and mucous membranes for color, moisture, and turgor
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179
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Neurologic change indicators of dehydration
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alterations of mental status, body temperature, confusion, low grade fever
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179
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Renal change indicators of dehydration
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urine may be concentrated, specific gravity greater than 1.030, dark amber, strong odor, urine output below 500 mL/day for a pt without renal disease, any weight loss over a half pound per day
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179
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Laboratory indicators of dehydration
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elevated levels of hemoglobin, hematocrit, serum osmolarity, glucose, protein, blood urea nitrogen, and various electrolytes
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179
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three Interventions of dehydration
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patient safety, fluid replacement, and drug therapy
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179
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Two most important areas to monitor during rehydration are...
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pulse rate and quality
urine output |
180
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hypotonic solution
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0.45% saline mOsm/L 154, pH 5
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180
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isotonic solutions
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0.9% saline
5% dextrose in water (D5W) 5% dextrose in 0.225% saline Ringer's lactate |
180
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hypertonic solutions
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10% dextrose in water (D10W)
5% dextrose in 0.9% saline 5% dextrose in 0.45% saline 5% dextrose in Ringer's lactate |
180
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What is the most common type of fluid overload?
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hypervolemia because the problems result from the excessive fluid in the ECF space.
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181
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Most problems caused by fluid overload are related to
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fluid volume excess in the vascular space or to dilution of specific electrolytes and blood components.
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181
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Adaptive mechanisms associated with fluid overload
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1 increased secretion of natriuretic peptide, decreased secretion of ADH and aldosterone, increased renal excretion of sodium and water. 2 fluid shift, formation of visible edema. 1 and 2 lead to normal plasma volume
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181
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compensatory actions of dehydration
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1 increased venous constriction, increased venous return, increased cardiac output. 2 increased cardiac contractitilty, increased heart rate, increased stroke volume, increased cardiac output. 3 increased arterial constriction, increased peripheral resistance. 1,2,3 lead to increased mean arterial pressure
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177
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restorative actions of dehydration
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increased renin secretion, increased angiotensin II formation, increased aldosterone secretion, increased renal sodium reabsorption, increased effective circulating volume
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177
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cardiovascular changes in fluid overload
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increased pulse rate
bounding pulse quality full peripheral pulses elevated blood pressure distended veins weight gain |
182
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respiratory changes in fluid overload
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increased respiratory rate
shallow respirations increased dyspnea with exertion/supine position moist crackles present on auscultation |
182
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skin and mucous membrane changes in fluid overload
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pitting edema in dependent areas
skin pale and cool to touch |
182
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neuromucular changes in fluid overload
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altered level of consciousness
headache visual disturbances skeletal muscle weakness paresthesias |
182
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gastrointestinal changes in fluid overload
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increased motility
enlarged liver |
182
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best fluid overload change to look for
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weight gain
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182
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labs for fluid overload
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decreased hemoglobin, hematocrit, and serum protein levels may result from excessive water in vascular space (hemodilution)
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182
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interventions for fluid overload
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drug therapy- diuretics
nutrition- sodium restriction, monitor I&O |
182
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