Body Fluids & Electrolyte Balance (Final) Flashcards
What are the 3 body fluid compartments?
1) intracellular fluid compartment
2) extracellular
3) transcellular
What makes up the extracellular fluid compartment?
Test q
Interstitial fluid and blood plasma
Note: constituents may be considerably different from plasma or interstitial fluid (Ex: ependymal cells are in ventricles, astrocytes are in BBB)
What 4 fluids are in the transcellular fluid compartment?
1) synovial fluid
2) peritoneal fluid
3) pericardial fluid
4) CSF
Why do women and men have different water composition?
Because of body fat, so men have more fat and water than women in the body
Intracellular fluid makes up ____ of body weight. The constituents may very and concentrations are very similar cell to cell within that tissue
40%
Extracellular body fluid takes up 20% of body weight. What percent of extracellular fluid is interstitial and what is plasma?
75% is interstitial fluid, 25% is plasma
Note: capillary pores help with interstitial exchange
**Plasma and interstitial fluid essentially have the same composition other than plasma proteins
Most body fluid volume is what fluid?
Test q
Intracellular fluid
The blood has what fluid?
Both extracellular and intracellular fluid
What fluid is found in RBCs?
Intracellular fluid
Blood volume is about 7% of body weight in any adult. What is the ratio of plasma to blood?
60% is plasma and 40% is RBCs
What is the first symptom when you have a decrease in RBCs?
Fatigue/tiredness
What is hematocrit?
Test q
Fraction of blood that is RBCs
(For men it’s 40%, women it’s 36%)
What is anemia? What are the causes?
Low RBC count
-pathologies
-chemotherapy
-hemorrhage (leakage of blood)
What is polycythemia? What are the causes?
More RBCs than the normal amount
-caused by severe COPD (lack of oxygen so the body will make more RBCs to compensate)
-also caused by living at high altitudes (will need more oxygen to survive)
What cations are found in extracellular fluid?
Test q
Mostly just sodium
What anions are found in extracellular fluid?
Test q
Cl- and bicarbonate
What cations are the major players of APs?
Sodium and potassium
What cations are the in the intracellular fluid?
Mostly potassium
What sets up the concentration gradient between extracellular and intracellular fluid compartments?
Sodium potassium pump
3 Na out for every 2 K in
What 2 molecules can only travel with sodium between compartments?
Glucose and AAs
What is the transport maximum for reabsorption of glucose?
Hint- it’s a number
Test q
100 mg/dL is the max you can reabsorb glucose and if there’s anymore then you gotta pee it out (more = diabetic)
Should the total intake and output of water be the same?
Yes!!!!
What output numbers will change if the environment is hot?
Insensible skin and lungs, and sweat will increase
T/F insensible loss will be essentially the same in a controlled environment
True
Metabolism of water is synthesized by the metabolism of….
CHO
Insensible water loss is by….
Evaporation (not conscious of the loss)
T/F: fluid and electrolyte balances are necessary in the long term to maintain life
True
Fluid loss = ?
Fluid intake
Electrolyte loss =
Electrolyte intake
Fluid intake is regulated by what?
Thirst mechanism and drinking habits
Electrolyte intake is governed by?
Dietary habits
Fluid output is regulated mainly by?
Kidneys
Electrolyte output is regulated mainly by?
Kidneys
The distribution of body fluid across cell membranes is determined by?
osmotic fluid (mainly electrolytes/small solutes)
The distribution of body fluid across capillaries (plasma and interstitial space) is determined by?
hydrostatic and colloid osmotic forces across capillary membrane
Water moves rapidly across cell membranes bc of ___________, therefore the osmolarities of intracellular and extracellular fluids remain almost exactly equal to each other except for a few minutes after a change in one of the compartments
aquaporins
Cell membranes are almost completely impermeable to many solutes, therefore, the number of osmoles in the extracellular or intracellular fluid generally remains constant unless solutes are added to or lost from the extracellular compartment bc of
transporters/pumps
What are osmoles?
measure of osmotic pressure
The mass of one mole of a substance is equal to the atomic or molecule mass of the substance expressed in grams. This value is called the….
gram molecular mass
A mole is the weight in grams of substance equal to its….
gram atomic or molecular weight
The total number of solute particles in the solution is the….
osmoles per liter solvent
1 osmole = 1 mole of….
solute particles
1 mole of glucose = ___ osmole = 180 grams of glucose
1
1 mole of NaCl = ____ osmoles = 58.5 grams
2
** 2 osmoles bc NaCl dissolves into 2 particles
milimoles are also known as…
test q
milliosmoles or mOsm (milligrams of solute)
What is osmolality?
osmoles per Kg water (osmolarity per L of water for clinical values)
The key to tonicity is knowing the relative concentration of _____________________ in the cell and in the solution
non-penetrating solutes
There are 3 roles to predict tonicity. What are they?
test q
1) If the cell has a higher conc. of nonpenetrating solutes than the solution, there will be net movement of water into the cell. The cell swells/lyses, and the solution is hypotonic
2) If the cell has a lower conc. of nonpenetrating solutes than the solution, there will be net movement of water out of thr cell. The cell shrinks/shrivels/crenation and the solution is hypertonic
3) If the conc. of nonpenetrating solutes are the same in the cell and the solution, there will be no met movement of water at equilibrium. The solution is isotonic to the cell
What happens to fluid if you add isotonic NaCl?
there will be an increase in the extracellular fluid volume
What happens to fluid if you add hypertonic NaCl?
test q
-extracellular osmotic pressure increases
-water leaves cell and goes out into the extracellular space
-there will be a rise in osmolarity in both intracellular and extracellular fluid bc the conc. goes up
What happens if you add hypotonic NaCl?
-the extracellular osmotic pressure decreases
-water will move into the cell from the extracellular space to equalize the osmolarity
What does isotonic mean?
test q
the cell has same osmolarity as body fluids
What does hyperosmotic mean?
test q
higher osmolarity than body fluids
What does hypoosmotic mean?
test q
lower osmolarity than body fluids
When glucose reaches cells it will be converted into….
hexose monophosphate
Why is there phosphocreatine in intracellular fluid but not in plasma or interstitial?
its a high energy phosphate, so it is in the intracellular fluid as storage for energy to be used eventually
Which hormone controls ECF osmolarity and sodium?
ADH
Renal excretion is controlled by what?
1) sympathetic NS
2) ang 2
3) aldosterone
4) ADH
5) ANP
Electrolytes are salts, acids, and bases. Ionic compounds dissociate into water cations and anions. This is a _________________ between an acid and base
neutralization reaction
electrolyte balance usually refers to…
salt balance
Salts enter the body via ingestion and are lost via….
-perspiration
-feces
-urine
Why are salts important for the renal system?
-controlling fluid movements through compartments (osmosis + osmotic pressure)
-excitability of cells with Na+/ K+ (membrane potentials and action potentials)
-secretory action of calcium
-muscle contraction of calcium
-membrane permeability
Electrolyte conc. is expressed in miliequivalents per liter, which is a measure of the number of….
test q
electrical charges per liter of solutions
For single charged ions like Na+, 1 mEq = ?
1 mOsm
For bivalent ions, like Ca+2, 1 mEq = ?
1/2 mOsm
What are the important electrolytes?
-sodium
-potassium
-calcium
-phosphate as HPO4-2, H2PO4, or Ca3(PO4)2
-magnesium
-chloride
Calcium is regulated by
parathyroid hormone
(parathyroid hormone releases calcium by osteoclasts)
What is the most abundant ICF anion in the bones and teeth?
Ca3(PO4)2
Fluid movement among compartments is regulated by
test q
osmotic and hydrostatic pressures
Water movement among compartments moves freely by osmosis bc of aquaporins, osmolalities of all body fluids are almost always….
test q
equal
What is the most abundant cation in the ECF?
sodium
Sodium salts in the ECF contribute __________ of the total 300 mOsm ECF solute concentration
test q
280 mOsm
T/F: Sodium leaks into cells and is pumped out against its electrochemical gradient through Na/ K+ pump. Na+ content may change but ECF Na+ conc. remains stable due to osmosis
true
Changes in plasma sodium levels affect…
test q
-plasma volume and blood pressure
-intracellular ICF and interstitial fluid volumes
Renal acid base control mechanisms are coupled to ________ ion transport
sodium
No receptors are known that monitor Na+ levels directly in body fluids, but macula densa tubular fluid cells and hypothalamic cells have….
test q
osmoreceptors (osmolarity sensors to regulate water)
Na+ water balance is linked to ___________________ control mechanism
blood pressure and blood volume
4 mechanisms regulate circulating volume via modulation of sodium reabsorption. What are they?
test q
1) RAAS
2) aldosterone
3) ADH
4) ANP
What are the other names for ADH?
arginine vasopressin or vasopressin
ADH increases what?
test q
water reabsorption
Aldosterone increases what?
sodium reabsorption (which is regulated by Ang 2)
In RAAS, the first step is the stimulus. What is the stimulus?
low BP (detected by JG apparatus baroreceptors or mechanoreceptors) which would stimulate the sympathetic NS
In RAAS, the first step is the stimulus. The stimulus is low BP (detected by JG apparatus baroreceptors or mechanoreceptors) which would stimulate the sympathetic NS.The next step is the JG apparatus responding to stimuli. Step 3 is the control center, aka JG apparatus releases _______ into the blood
renin
In RAAS, the first step is the stimulus. The stimulus is low BP (detected by JG apparatus baroreceptors or mechanoreceptors) which would stimulate the sympathetic NS.The next step is the JG apparatus responding to stimuli. Step 3 is the control center, aka JG apparatus releases renin into the blood. What does renin do in step 4?
Renin converts angiotensinogen to ang 1, and ACE converts ang 1 to ang 2
In RAAS, the first step is the stimulus. The stimulus is low BP (detected by JG apparatus baroreceptors or mechanoreceptors) which would stimulate the sympathetic NS.The next step is the JG apparatus responding to stimuli. Step 3 is the control center, aka JG apparatus releases renin into the blood. In step 4, renin converts angiotensinogen to ang 1, and ACE converts ang 1 to ang 2. In step 5, there are multiple effectors. What is the net effect?
blood pressure increases
The liver continuously releases…
angiotensinogen
Is angiotensinogen an active or inactive hormone?
inactive, its a zymogen
Is Ang 1 an active or inactive hormone?
inactive
Is Ang 2 an active or inactive hormone?
active
Is Ang 1 or Ang 2 a systemic vasoconstrictor?
ang 2
In RAAS, the first step is the stimulus. The stimulus is low BP (detected by JG apparatus baroreceptors or mechanoreceptors) which would stimulate the sympathetic NS.The next step is the JG apparatus responding to stimuli. Step 3 is the control center, aka JG apparatus releases renin into the blood. In step 4, renin converts angiotensinogen to ang 1, and ACE converts ang 1 to ang 2. In step 5, there are multiple effectors. Ang 2 binds to effectors to cause….
-vasoconstriction in systemic blood vessels (this increases peripheral resistance and increases BP)
-also vasoconstricts renal a.
-the kidneys will decrease GFR (this will decrease urine output to maintain blood volume and BP)
-the hypothalamus and adrenal cortex will work together
-the hypothalamus will activate the thirst center (if fluid intake occurs, then this increases blood volume and BP)
-the hypothalamus will also release ADH from the posterior pituitary (this decreases urine output to maintain blood volume and BP)
-the adrenal cortex will release aldosterone (this decreases urine output to maintain blood volume and BP)
Do systemic blood vessels constrict or dilate in the RAAS system?
vasoconstrict
What do the kidneys do in RAAS?
they decrease GFR, which decreases urine output to maintain blood volume and BP
What does the hypothalamus do in RAAS?
-activates the thirst center (if fluid intake occurs, then this increases blood volume and BP)
-releases ADH from the posterior pituitary (this decreases urine output to maintain blood volume and BP)
What does the adrenal cortex do in RAAS?
releases aldosterone, which decreases urine output to maintain blood volume and BP
65% of sodium reabsorption occurs in the _____________. While 25% is reclaimed in the ______________
proximal tubules, loops of henle
Aldosterone wil actively or inactively reabsorb remaining sodium?
actively
Water follows sodium if _________ is present
ADH
RAAS s the man trigger for ____________ release
test q
aldosterone
_____________ cells of JGA secretes renin in response to sympathetic NS stimulation (low BP). A decrease in filtrate osmolality will be sense by macula densa cells. The extraglomerular mesangial cells and gap junctions communicate to granular cells. A decrease in stretch is due to a decrease in BP through afferent arteriole
Granular/JG
____________ cells are chemoreceptors/osmoreceptors that respond to changes n NaCl conc. (major solute)
Macula densa
Renin converts _________ produced circulating angiotensinogen to ang 1
hepatic
Ang 1 circulates to the _______ where it is converted to ang 2 on a specific receptor by ACE
lungs
(note: drugs can compete against both the ACE enzyme and receptor)
Ang 2 stimulates aldosterone secretion from the _____________
adrenal cortex
Aldosterone release can be triggered by elevated _____ levels in the ECF
K+
Are aldosterone effects slow or fast?
slow (can take hours to days)
Ang 2 is produced with a decrease in BP and increased K+ blood plasma levels. The adrenal cortex will respond to stimuli and release ______________ into the blood. The hormone binds to effector to cause increased K+ secretion into tubular fluid (H+ is substituted for K+ in conditions of low pH). The tubular fluid will have high sodium. There will be increased fluid and water reabsorption into blood
test q
aldosterone
note: this is regulated by negative feedback and when aldosterone is no longer needed, the adrenal cortex will be inhibited
An increase in sodium reabsorption requires ____________________. This will also increase water osmotuc reabsorption through aquaporin channels
test q
increase 3Na+/2K+ activity and pumps (so more will be synthesized)
ANP is released by atrial cells in response to stretch (increased BP and blood volume). What effects does it have?
test q
it will decrease BP and blood volume via:
-decreasing ADH, renin and aldosterone production
-increase excretion of sodium and water through natriuresis (diuresis is just getting rid of water, natriuresis is both water and sodium)
-will promote vasodilation directly and also by decreasing production of ang 2
If renin decreases, will ang 2 increase or decrease?
also decrease
An increased blood volume (as detected by increased stretch of baroreceptors in atria). The receptor, atria, will respond to stimuli. The atria will release ANP into the blood. ANP will bnd to the effectors to cause….
test q
-systemic blood vessel dilation (will decrease peripheral resistance and BP)
-the kidneys will increase GFR (increase urine output to decrease blood volume and BP)
-the kidneys will increase loss of sodium and water in the urine (increases urine output to decrease blood volume and BP)
-decreased release of renin (and interferes with action of ang 2), decreased release of aldosterone and ADH
Ang 2 is released in response to….
BP
Urea s transported via facilitated dffusion out of collecting duct and is more concentrated nb the kidney _______ and urine
test q
medulla
Ang 2 is produced with a decrease in BP. Low blood volume (detected by sensory input from baroreceptors in heart and blood vessels) and increased blood osmolarity (detected by chemoreceptors within hypothalamus). The hypothalamus is the receptor and will respond to stimuli. The hypothalamus will increase nerve signals to the posterior pituitary to release ADH into the blood. ADH binds to effectors to cause….
test q.
-the hypothalamus will activate the thirst center (if fluid intake occurs, it will increase blood volume and BP)
-the kidneys will increase the number of aquaporins (more water is reabsorbed into the blood, which decreases water lost in the kidneys to maintain blood volume and BP and decreases blood osmolarity)
-systemic blood vessels will have high doses of ADH and cause vasoconstriction (increases peripheral resistance and BP)
Ang 2 is produced with a decrease in BP. Low blood volume (detected by sensory input from baroreceptors in heart and blood vessels) and increased blood osmolarity (detected by chemoreceptors within hypothalamus). The hypothalamus is the receptor and will respond to stimuli. The hypothalamus will increase nerve signals to the posterior pituitary to release ADH into the blood. ADH binds to effectors. What is the net effect?
test q
-maintain blood volume and BP
-decrease blood osmolarity
Baroreceptors alert the brain of ncreases in blood volume and BP. Where are they located and what do they do?
located in aorta and carotid sinus
-sympathetic NS impulses the kidneys to decline
-afferent arterioles will dilate
-GFR will increase
-sodium and water OUTUT will increase
Is vasoconstriction of blood vessels with ang 2 a direct or indirect effect?
direct
A decrease n [NaCl] is ascending loop of Henle is interpreted as….
low blood volume to filtrate flow rate
Potassium affects resting membrane potential in neurons and muscle cells (especially cardiac muscle). An increase in ECF potassium conc. will result in decreased resting membrane potential, which causes….
depolarization and reduced excitability
note: H+ shift in and out of cells and this leads to corresponding shifts in K+ in the opposite direction to maintain cation balance. This interferes with the activity of excitable cells
Potassium affects resting membrane potential in neurons and muscle cells (especially cardiac muscle). A decrease in ECF potassium conc. which results in….
hyperpolarization and nonresponsiveness
K+ balance s controlled in the cortical _________ by changing the amount of potassium secreted into filtrate
collecting ducts
ECF K+ conc. will get into _________ via sodium potassium pump
principal cells
High K+ content of ECF favors..
principal cell secretion of K+
When K+ levels are low, _________________ reabsorb some K+ left in the filtrate
type A intercalated cells
What does aldosterone do with K+?
test q
stimulates K+ secretion and sodium reabsorption by principal cells
Increased K+ in the adrenal cortex causes…
test q
-release of aldosterone
-potassium secretion
Calcium in the ECF is important for….
test q
1) neuromuscular excitability
2) blood clotting
3) cell membrane permeability
4) secretory activities
5) cardiac muscle contraction
6) axoplasmic transport
7) vesicle fusion to membrane (ENaC channels and aquaporins)
What is hypocalcemia?
-increased excitability and muscle tetany due to low calcium
-stimulates parathyroid glands to release PTH
What is hypercalcemia?
inhibits neurons and muscle cells and may cause heart arrhythmias due to high calcium levels
Calcium balance is controlled by what hormones?
PTH and calcitonin
What is the largest reservoir for calcium and phosphates?
bones
Which hormone increases in calcium levels by targeting bones, kidneys, and small intestine (indirectly through vitamin D)?
PTH
T/F: calcium reabsorption and phosphate excretion go hand in hand
true
Rising calcium leaves in blood inhibits which hormone from being released?
PTH
PTH activates which bone cel so that calcium and phosphate can be released into blood?
test q
osteoclasts
PTH increases calcium reabsorption in the….
kidney tubules
PTH promotes kidneys activation of ________ which increases calcium absorption from food
vitamin D
Normally 75% of filtered phosphates are actively reabsorbed in the ______. Reduction of _______ inhibits this by decreasing the transport maximum
PCT, PTH
What is the major anion in the ECF?
Cl-
What does Cl- help with in the ECF?
helps maintain the osmotic pressure of the blood
note: 99% of Cl- os reabsorbed under normal pH conditions
When ________ occurs, fewer chloride ions are reabsorbed
acidosis
