Week 11: fluid acid base balance pt 2 Flashcards
When our Na concentrations are getting a bit low, its possible for what?
our kidneys to make urine that is almost Na free
- that is how effective the Aldosterone carrier (Na ion exchanger or Na K exchanger) is.
Usually, we’re gonna adjust our body content of Na by adjusting what?
how much Na is in urine
Where do we lose Na in?
Saliva, gastric secretions, pancreatic secretions, and intestinal secretions
Your digestive tract and salivary glands produce how much digestive fluids?
8 liters of digestive fluids a day
what is the total body pool of Na?
somewhere between 2800-3000 m Eq of Na ( numbers are not important, we’re working our way up to
those 8 liters of digestive juices alone are gonna have you lose?
1200-1400 mEQ
- you’re losing almost half of your sodium a day just in digestive secretion, not counting urine or sweat
we have to be really good at retaining Na and causing ingestion of Na to maintain?
what our body pool is supposed to be
situations that cause my Na levels to go up will also cause what to go up?
my chloride levels to go up
what is the reason?
sodium and chloride hang out together (opposites attract) and so if i have more Na, im going to tend to hold on to more chloride
the total body pool of K is?
4000 mEQ (not important, just for comparison)
the normal range of the plasma Na concentration is?
between 136-146 mEQ
normal K concentration in the blood is?
4-5 mEQ
why is there such a big difference?
the K is inside the cells and the Na is outside the cells
because or normal plasma K levels are so low, what happens?
you can lose a third to a half of your total body K pool before you get low K (goes into the blood and into the urine)
we’re able to maintain our?
normal K levels
how can you lose that much K?
if most of K is inside your cells, to lose K you have to :
- literally lose the whole cell where the cell has to die and rupture and then the K will go into the extracellular fluid.
-
things that are gonna cause a lot of cell death can cause you to?
lose a lot of K (hypokalemia)
what are the causes?
where you have lots of cells die in a short time
- burns
- crash injuries
- starvation
- vomiting
Vomiting: how you secrete HCI acid?
hydrogen ion gets pumped into the lumen of the stomach in exchange for K ion. so gastric juice has a pretty good concentration on K and vomiting a lot (numbers of times not vol) you lose K in the juice and the acid can start damaging cells on the way out.
what is HYPOnatremia?
electrolyte imbalance where a plasma Na concentration BELOW 136mEq/L
what does HYPOnatremia look like?
hypervalemia
usually, we get HYPOnatremic because?
of excess water retention or water ingestion
Aside from those causes, what else are causes?
- overuse of Na wasting diuretics (where we put the Na in the filtrate to trap water. this is where the H20 is gonna go just like the kidneys)
- also large lose of Na like profuse sweating
- adrenal insufficiency (not being able to make enough aldosterone so you won’t be able to absorb the amount of Na i need to reabsorb)
- kidney failure (bc you’re not reabsorbing Na)
- liver failure (bc the fluid thats supposed to be in the blood is elsewhere)
all of this is a problem bc it messes with your?
action potentials
symptoms of HYPOnatremia?
- muscle cramps (Na gradient gets us appropriate contractions of muscles)
- nausea and vomiting
- postural Bp changes (show orthostatic hypotension)
- difficulty breathing and fatigue (can be related to where the fluid is in the body and affecting muscle contractions that you need to breathe in)
you won’t get a very good breath in if you dont have enough?
Na gradient to let you have a respectable action potential to fire your diet from? 2:00:17
what is HYPERnatremia ?
plasma Na concentration is higher than 145 mEq/L
HYPERnatremia looks like?
hypovalemia
it is caused by?
- low water intake or high sodium intake
- diarrhea (losing Na in feces that are leaving but losing more water than sodium so sodium conc goes up)
- kidney problems
- heart disease
- diabetes insipidus (has nothing to do w glucose, all abt antidiuretic hormone) - person is not making enough ADH
if my total Na is normal but my water has left the blood and got into the IF, im now?
hypernatremic
what happens in someone who has diabetes insipidus?
person is not making enough ADH or their ADH receptors on the distal conv tubule and collecting duct don’t work right and so you have a person who is always making dilute urine
- losing more water than they should be losing
someone who has diabetes insipidus is going to be making?
liters and liters of urine everyday. they’re drinking constantly bc its the only way they can keep up with the water loss from huge urine output. if doctor is concerned if someone has it, they ask “do you wake up from dead sleep to get something to drink?”. if you do it on a regular basis is when you have diabetes insipidus
what is HYPOkalemia?
plasma K concentration below 3.5 mEq/L
- can be life threatening condition
what are the causes?
- K wasting diuretics
- vomiting (K in gastric juice)
- ## gastric suction w/o K replacement (machine barfing for you, taking contents out of stomach including all the digestive juices that are there containing K)
why do we care about gastric suction w/o K replacement?
hypokalemia is associated with abnormal rhythms and some can kill you. causes cardiac dysrhythmia (abnormal rhythms)
what do you see in a HYPOkalemic?
- anorexia
- muscle weakness (messing w action potential)
- decreased reflexes (messing w action potential)
- low BP
what is HYPERkalemia?
plasma K concentration ABOVE 5.5 mEq/L
what is the most dangerous electrolyte imbalance?
HYPERkalema
- bc it can stop the heart
causes for HYPERkalemia
- kidney disease/renal failure
- vomiting (if im doing enough vomiting, im killing cells and K is going into the blood. kidneys are built to secrete K, not reabsorb it.)
- Cushing’s disease (when person is early in coarse of disease, they secrete more aldosterone than they should be. reabsorb more Na and secrete lots of K)
- trauma
- burns
when lots of cells die, first you will be?
hyperkalemic and then bc you cant reabsorb any K, once it gets filtered at kidney, you will go hyperkalemic to hypokalemic
hyperkalemic is the precursor for hypokalemic bc?
you have to kill the cells to get the K in the blood, and then once its in the blood, you can lose it
what does pH measure?
concentration of free hydrogen ions
- only free hydrogen ions thats gonna interact w 0:20
the lower the pH is?
the higher the concentration of free hydrogen ions
when looking at pH in the body, we’re mostly looking at?
pH of arterial blood
why just the arterial blood and not everywhere at the same time?
we don’t have any equipment in the venous side to check it, we’re monitoring arterial pH w the chemoreceptors that are involved in controlling respiration
- arterial side delivers oxygen and nutrients. shapes of proteins that move things to the cell are important.
why is the normal range for pH a small range?
the narrower your normal range is, the more important that variable is
when looking at blood and describing someones pH, if their pH of arterial blood is BELOW 7.35, that is considered what?
acidosis
if the only info you have is their pH, you can’t just decide?
what type of acidosis it is
if their pH is ABOVE 7.45, what is that condition called?
alkalosis
if you don’t have the info other than arterial pH,
that is all you can say. you cant decide what type of alkalosis it is
a lot of the pH are produced by?
metabolic pathway
different metabolic pathways produce?
different waste products
- a lot of those things do organic acids
we also have acids that come from?
the diet
- like tomatoes, theyre acidic. while we digest them, they contribute acid to the body
if you are a carnivore as opposed to having a mixed diet or being vegetarian, meat based diet produces more acid while vegetable based diet produces more?
base
different minerals contribute to the?
formation of acid or base in the body
what affects it (important)
diet and types of metabolic pathways
- if you are able to perform aerobic cellular metabolism, you can run Krebs cycle and electron transport, your main waste product is CO2 converted to carbonic acid)
- if you cant run aerobic metabolism, only glycolysis, you get lactic acid
bc we need to have such a narrow range of pH in the body to have things work effectively, we need?
control mechanisms
first category of pH control mechanisms is?
chemical buffers
what is a chemical buffer
the fastest acting of the buffers
- gonna do what they cant do when a base load or acid load gets added to the body within 1-2 minutes
- now we’re talking about things outside the cells, now talking about plasma
we get lots of buffering from?
plasma protein
other major buffer than we can adjust and change is?
bicarbonate
why is bicarbonate more important?
we can change the levels of bicarbonate and carbonic acid and adjust the pH doing that
the second broad category of buffer system is?
physiological buffers
what are the two sub-categories?
- respiratory system
- kidneys
we’re always gonna use these three buffer systems in a particular order
- if we have pH problem, the chemical buffers are the first thing to try and remedy that problem.
- chemical buffers do all they can do for 1-2 mins and if there’s still a pH problem, then breathing will change.
-if changing breathing doesn’t get pH back to normal within about 24 hrs, now my kidneys will take over and are more persistent and will stay working in this
if pH in blood is low, if i got acidosis..
i breathe more
if pH in blood is high,..
i breathe less
breathing more or breathing less changes CO2 level which changes carbonic acid level which changes the bicarb level
kidneys are going to affect pH by?
having you release more hydrogen ions in urine in pH is low or holding on to more hydrogen ions if pH is too high
the renal mechanism for physiological buffering is going to stay active until?
pH actually goes back to normal bc wtvr was causing the problem has retreated or resolved
no switch off time for renal system, so if you have a chronic acid-base imbalance..
you will have chronic response from kidneys
phosphate molecule that has the capability of?
taking up or give off a free hydrogen ion to help regulate intracellular fluid
plasma proteins are gonna be big in?
extracellular buffer
we’re not change plasma protein concentration to?
adjust pH of arterial blood
if PCO2 goes up, pH goes down. why?
bc if i have more CO2 i make more carbonic acid which gives me more free hydrogen ions
if PCO2 goes down, pH goes up. why?
less PCO2, now run reversible reaction the other way, putting H+ with bicarb getting rid of free hydrogen ion. gonna go back all the way to PCO2 to get PCO2 back to where it should be (control of breathing)
we can’t have two compensatory mechanisms working at once, that comes later in other semesters
what your body is going to look at and the things we’re going to change are?
the concentration of bicarb in blood and concentration of carbonic acid
what is a magic ratio?
a ratio of bicarbonate concentration to carbonic acid concentration
if ratio is 20:1, what is your pH?
7.4
i only have ratio of 20:1 if i have?
correct concentration of bicarb and carbonic acid in blood
- this is normal
there are ratios that are equivalent to 20:1 like?
40:2
200:10
anything that is equivalent to 20:1, the pH is?
7.4
if i have normal pH and abnormal bicarb and carbonic acid concentrations, that is called?
compensation
- body responding by changing the two main things that can change to defend pH above all else
-maintaining ration called caompensation
we don’t care if bicarb or carbonic acid concentration is normal. we do care about?
if the ratio is equivalent and pH is normal
if lungs are the cause of acid-base imbalance..
the lungs can’t fix your acid-base imbalance
- assume the 4 acid base imbalances we talk about are long standing
if i have emphysema and i have a chronic disturbance of how my lungs are functioning, those will fall int he category of the imbalances
how can i tell an acid-base balance question from a control of breathing question?
she will tell us in the acid base question that it is a CHRONIC problem , long standing disturbance.
if lungs are not working, they can’t?
fix a problem that cause an acidosis or alkalosis
if kidneys are not working, they can’t?
correct a problem that was caused by chronic kidney function
- if kidneys are not working right, lungs will compensate
-if lungs arent working right, my kidneys will compensate
what happens to your breathing when CO2 levels go up?
you breathe more
- by the time you breathe out, you get rid of CO2, if you got too much CO2 you breath out more.
when CO2 levels go up, i make more?
carbonic acid which breaks down to bicarb and H+ and the reason my pH goes down when my CO2 goes up is because I get more H+
when my PCO2 levels go down, im gna put more bicarb and H+ back together lowering?
free H+ concentration and make carbonic acid and break that down to get water and CO2 and that will raise my PCO2 and i do that by not breathing as much
- PCO2 is high, pH is low=you increase respiration
- PCO2 is low, pH is high=you decrease respiration
- see control of breathing in chp 23
we can secrete H+ in exchange for?
reabsorbing Na
- affect of aldosterone
Na H+ exchanger is under the control of?
aldosterone
another possibility is we put this hydrogen ion on here and connects with a phosphate and that phosphate goes to H2PO4 and it just buffered that free H+
really important bc eventually, if we keep putting free H+ out in filtrate, we will have electrical problems and too much free acid damaging the tubule
- the more we buffer, the more H+ we can get rid of without damaging the kidneys
third possibility is?
H+ and CL ions going out together
- NH3 is ammonia. ammonia is break down product of protein metabolism and its a small non polar molecule and its trouble going anywhere it wants
one of the things when someones liver is not working well is?
ammonia level starts to go up causing a coma
- ammonia and brain cells do not get along together
ammonia thats been filtered can pick up?
H+ and become ammonium (NH4) and that traps the ammonia in the tubule and H+ and it buffers the H+
possibilities options 2 and 3 are gonna help us buffer the H+ we put there which traps then and keep them in the filtrate
the option that we’re gonna be concerned about for talking about acid-base imbalances is #1
we said that H+ goes out
- there is bicarb that gets filtered and now we have a H+ that can connect w a bicarb and that happens and i get carbonic acid breaking down to H2O and CO2 and the water may stay in the tubule or not depending on ANH status is
- but the CO2 profuse back into tubular cell and the last place we will see it but theres carbonic anhydrase in the cells that make up the distal and collecting ducts and the CO2 comes back in the cell. theres water in the cell and carbonic anhydrase in the cell and we make carbonic acid and make bicarb which goes into the blood to the chloride shift
H+ secretion causes?
bicarbonate reabsorption
why we care about this is bc?
we’re going to compensate for pH imbalances by changing the bicarb or carbonic acid concentration
- changing H+ concentration is a way to change the bicarb concentration
assume that metabolic acidosis is related to?
kidneys
we have metabolic alkalosis (assume that metabolisms screwing things up, not the lungs)
pH is higher than it should be
respiratory acidosis
pH is lower than it should be
- problem is caused by some malfunction in the lungs
respiratory alkalosis
pH is high
- problem is caused by malfunction of the lungs
primary disturbance is always going to be about?
something is wrong with bicarb or carbonic acid
- not if pH is too low or high
by adjusting the bicarb and carbonic acid is the free H+ concentration
metabolic acidosis
primary disturbance is the bicarb is too LOW
bicarb is handled by kidneys
carbonic acid is handled by lungs
for a metabolic imbalance, it is always going to be the bicarb that is screwed up
if we’re trying to get an equivalent ratio and the bicarb dropped, the only way to keep those two numbers the right proportion to each other is to have them change?
the same way
when i have metabolic acidosis, my compensation is?
do something that lowers carbonic acid
acid base compensation is the only place in your life where?
two wrongs make a right
we will screw up carbonic acid to?
defend the ratio and get us back to 7.4
i need my bicarb to be low
if im not compensating yet, my CA rn is higher than i want
- if its at 6 and i want it to be at 4 for the right concentration, 6 is higher than 4 so rn my CA is higher than i need to be and i need to lower it
metabolic acidosis arrow
- high CA
- what can I do with lungs to lower CA? if i have low CA that is lower than I want it to be, its bc i have PCO2 that is higher than i want it to be
- what can my lungs do? if i increase resp, my PCO2 will lower which lowers concentration of carbonic acid
to check what we just said actually lowers concentration of free H+
my pH is low, what does that say about H+?
- i have a high H+ concentration is pH is low
if i increase resp, it decreases PCO2, H+ changes in the same direction w
in metabolic imbalances, the compensations don’t directly show the change in H+ so we’re gonna check fro metabolics but for respiratory we do see a change for H+ based on kidneys
the causes for matabolic acidosis:
- certain medications (cause body to produce lactic acid)
- long term diarrhea (losing bicarb in feces)
- poorly controlled diabetes mellitus
metabolic alkalosis what is the primary disturbance?
bicarb is too high
what is the compensation?
carbonic acid has to go up to get to equivalent to 20:1
arrow answer:
carbonic acid to be higher than normal
- start with low conc of carbonic acid
if i have low CA, i have low PCO2
- low PCO2 decreased resp
- increase PCO2
- increase carbonic acid conc
causes of metabolic alkalosis?
- chronic vomiting (throwing up H+, more H+ you throw up, more acid you have to make and what are you putting in the blood? bicarb)
- chronic hyperacidity which leads to tums constant intake which leads to metabolic alkalosis
compensation decreasing resp is going to?
get us where we need to go w respect to CA and pH
what is the most poorly compensated out of the four acid base imbalances and why?
metabolic alkalosis
- decrease breathing (anything that makes you breathe less, your body will be hesitant about)
- can’t compensate as well as other bc we need to breathe at a certain level to get oxygen to do what is supposed to do
Respiratory acidosis primary disturbance?
elevated levels of carbonic acid
arrow answer for respiratory acidosis
how to raise bicarb?
- need smtn renal to raise bicarb
increase H+ secretion which causes bicarb reabsorption which increases bicarb
causes for respiratory acidosis
- pneumonia (thickens reps membrane making it harder for oxygen to get in and CO2 to get out)
- things that suppress breathing (opium, morphine, main meds) and the PCO2 will go up
- emphysema (not moving as much air, more CO2 stays in blood)
clearly see what happens with H+
i have an acidosis, it my pH too high or low?
- low and the conc of H+ is high which is secreting more of them, secreting more of them will lower my H+ conc and raise my pH
- if you have too many H+, that makes pH low. if i have too many of them, i will throw more of them away and so secreting more H+ lowers H+ conc and raises my pH
primary disturbance for respiratory alkalosis?
carbonic acid is lower than is should be
- bicarb needs to be lowered
- pH is high
- H+ conc is low
what are the causes for respiratory alkalosis?
- something that causes chronic hyperventilation
(you cannot hyperventilate yourself voluntary into a long standing alkalosis)
if too much bicarb, i need kidneys to do smtn that help me lose bicarb: arrow answer
decrease H+ secretion cause decrease bicarb reabsorp and if i dont reabsorb and its leaving the body, its gonna lower my bicarb
if i dont put H+ out into the lum, i dont put?
bicarb in the blood
if i dont secrete H+ i dont?
reabsorb the bicarb
what is wrong with H+ conc here
it is low
changing bicarb and CA conc changes?
H+ conc
- if this is all coming back to the H+, doing these things that we talked about changes H+ conc
metabolic imbalances are compensated for with?
respiratory mechanisms
respiratory imbalances are compensated for with?
metabolic compensation which is kidneys
respiratory compensation is less effecting than metabolic compensation bc?
we actually have a limit to how fast we can breathe and have it be effective and how little we can breathe and stay alive
find the patterns: pattern #1, biggest pattern..
bicarb and CA have to change in the same direction or ur not going to move pH back to normal
compensations DO NOT fix the?
primary disturbance
- so if you have a metabolic acidosis, we are fixing bicarb conc which will stay wrong, if writing arrow answer to fix primary disturbance, you are off track. you need to screw up the other thing, not the primary disturbance
primary disturbance always comes first
