NURS 232 - Fluid & Electrolytes Exam Questions with Verified Solutions Graded A+
Fluid and electrolyte balance - Answers The process of regulating the extracellular fluid volume,
body fluid osmolality, and plasma concentrations of electrolytes
Total body water is __% of body weight, and formed components are __% of body weight -
Answers 60, 40
Total body water - Answers -60% of body weight
-Intracellular: 40% of body weight
-Extracellular: 20% of body weight
Components of extracellular fluid - Answers -Interstitial fluid: 14% of body weight
-Plasma volume: 5% of body weight
-Transcellular volume: 1% of body weight
Interstitial fluid - Answers Ultra filtrate of plasma, very little protein
Transcellular fluid - Answers Lymph, synovial, intestinal, CSF, sweat, urine, pleural, peritoneal,
pericardial, and intraocular fluids
Which populations have lower water content and what is the risk of this? - Answers -Females
have higher % of fatty tissue so have lower water content than males
-Older adults and obese persons
-Risk = more likely to be affected by any fluid imbalance
Populations at greatest risk for fluid and electrolyte imbalances - Answers Pediatrics
-75% to 80% of body weight
-Susceptible to significant changes in body fluids
◦Dehydration in newborns
Aging
-Decreased % of total body water
◦Decreased free fat mass and decreased muscle mass
,◦Renal decline
◦Diminished thirst perception
Capillary network - Answers -Blood flows from arterioles → metarterioles → capillary network
-Venules drain network
-Smooth muscle in arterioles, metarterioles, precapillary sphincters regulates blood flow
Aquaporins - Answers Pores in the cell membrane that let water in and out
Forces for movement of water and solutes - Answers -Filtration:
◦Capillary hydrostatic pressure (blood pressure)
◦Interstitial osmotic pressure (water-pulling)
-Reabsorption:
◦Plasma (capillary) osmotic pressure (water-pulling) (↑ albumin), aka oncotic pressure
◦Interstitial hydrostatic pressure
-Osmotic and hydrostatic pressure are opposing forces that keep the distribution of water
constant
When capillary hydrostatic pressure is greater than osmotic pressure... - Answers fluid leaves
the capillary and enters the tissue
When capillary hydrostatic pressure is less than osmotic pressure... - Answers fluid enters the
capillary because it is pulled back into the bloodstream
Organs involved in fluid and electrolyte balance - Answers Lungs, GI tract, kidneys
Osmolality - Answers -Concentration of fluid
◦Serum osmolality: normal = 280-300 mmol/kg
◦Hyper-osmolar means too many molecules
◦Hypo-osmolar means too dilute
Body mechanisms for fluid control - Answers -Thirst mechanism: osmoreceptors in the
hypothalamus
-Antidiuretic hormone (ADH): promotes reabsorption of water into blood from kidney tubules
, Name three receptors that act on the hypothalamus - Answers 1. Osmolality receptors (thirst
perception)
◦Hyperosmolality and plasma volume depletion
2. Volume receptors
3. Baroreceptors
◦Detect decreased blood pressure
Renin-angiotensin-aldosterone (RAAS) system - Answers 1. Dehydration, Na+ deficiency, or
hemorrhage
2. Decrease in blood volume
3. Decrease in blood pressure
4. Kidneys produce renin
5. Renin converts angiotensinogen in the blood to angiotensin I
6. Angiotensin converting enzyme (ACE) converts angiotensin I to angiotensin II in the lungs
7. Angiotensin II stimulates vasoconstriction and the release of aldosterone
8. In kidneys, aldosterone promotes increased Na+ and water reabsorption and increased
secretion of K+ and H+ into urine ➜ increased blood volume
9. Vasoconstriction and aldosterone cause increased blood pressure until it returns to normal
Aldosterone - Answers Helps regulate blood volume, blood pressure, and levels of Na+, K+, and
H+ in the blood
Parts of a nephron - Answers Renal corpuscle → proximal convoluted tubule → nephron loop
(aka, loop of Henle) → distal convoluted tubule → collecting duct
Reabsorption and secretion in the nephron - Answers -Proximal convoluted tubule: most sodium
reabsorption
-Descending loop of Henle: only permeable to water
-Ascending loop of Henle: only permeable to salts (not water)
Fluid and electrolyte balance - Answers The process of regulating the extracellular fluid volume,
body fluid osmolality, and plasma concentrations of electrolytes
Total body water is __% of body weight, and formed components are __% of body weight -
Answers 60, 40
Total body water - Answers -60% of body weight
-Intracellular: 40% of body weight
-Extracellular: 20% of body weight
Components of extracellular fluid - Answers -Interstitial fluid: 14% of body weight
-Plasma volume: 5% of body weight
-Transcellular volume: 1% of body weight
Interstitial fluid - Answers Ultra filtrate of plasma, very little protein
Transcellular fluid - Answers Lymph, synovial, intestinal, CSF, sweat, urine, pleural, peritoneal,
pericardial, and intraocular fluids
Which populations have lower water content and what is the risk of this? - Answers -Females
have higher % of fatty tissue so have lower water content than males
-Older adults and obese persons
-Risk = more likely to be affected by any fluid imbalance
Populations at greatest risk for fluid and electrolyte imbalances - Answers Pediatrics
-75% to 80% of body weight
-Susceptible to significant changes in body fluids
◦Dehydration in newborns
Aging
-Decreased % of total body water
◦Decreased free fat mass and decreased muscle mass
,◦Renal decline
◦Diminished thirst perception
Capillary network - Answers -Blood flows from arterioles → metarterioles → capillary network
-Venules drain network
-Smooth muscle in arterioles, metarterioles, precapillary sphincters regulates blood flow
Aquaporins - Answers Pores in the cell membrane that let water in and out
Forces for movement of water and solutes - Answers -Filtration:
◦Capillary hydrostatic pressure (blood pressure)
◦Interstitial osmotic pressure (water-pulling)
-Reabsorption:
◦Plasma (capillary) osmotic pressure (water-pulling) (↑ albumin), aka oncotic pressure
◦Interstitial hydrostatic pressure
-Osmotic and hydrostatic pressure are opposing forces that keep the distribution of water
constant
When capillary hydrostatic pressure is greater than osmotic pressure... - Answers fluid leaves
the capillary and enters the tissue
When capillary hydrostatic pressure is less than osmotic pressure... - Answers fluid enters the
capillary because it is pulled back into the bloodstream
Organs involved in fluid and electrolyte balance - Answers Lungs, GI tract, kidneys
Osmolality - Answers -Concentration of fluid
◦Serum osmolality: normal = 280-300 mmol/kg
◦Hyper-osmolar means too many molecules
◦Hypo-osmolar means too dilute
Body mechanisms for fluid control - Answers -Thirst mechanism: osmoreceptors in the
hypothalamus
-Antidiuretic hormone (ADH): promotes reabsorption of water into blood from kidney tubules
, Name three receptors that act on the hypothalamus - Answers 1. Osmolality receptors (thirst
perception)
◦Hyperosmolality and plasma volume depletion
2. Volume receptors
3. Baroreceptors
◦Detect decreased blood pressure
Renin-angiotensin-aldosterone (RAAS) system - Answers 1. Dehydration, Na+ deficiency, or
hemorrhage
2. Decrease in blood volume
3. Decrease in blood pressure
4. Kidneys produce renin
5. Renin converts angiotensinogen in the blood to angiotensin I
6. Angiotensin converting enzyme (ACE) converts angiotensin I to angiotensin II in the lungs
7. Angiotensin II stimulates vasoconstriction and the release of aldosterone
8. In kidneys, aldosterone promotes increased Na+ and water reabsorption and increased
secretion of K+ and H+ into urine ➜ increased blood volume
9. Vasoconstriction and aldosterone cause increased blood pressure until it returns to normal
Aldosterone - Answers Helps regulate blood volume, blood pressure, and levels of Na+, K+, and
H+ in the blood
Parts of a nephron - Answers Renal corpuscle → proximal convoluted tubule → nephron loop
(aka, loop of Henle) → distal convoluted tubule → collecting duct
Reabsorption and secretion in the nephron - Answers -Proximal convoluted tubule: most sodium
reabsorption
-Descending loop of Henle: only permeable to water
-Ascending loop of Henle: only permeable to salts (not water)
