A&P - Acid/Base and Fluid-Electrolye Balance Flashcards
The regulation of acid/base balance refers to the control of what?
Regulation of H+ concentration in body fluid (homestatic mechanism)
Between pH 2, pH 6, and pH 10, which has the greatest concentration of H+ ions and which has greatest OH- ions?
pH 2 = greatest [H+]
pH 10 = greater [OH-]
What number on the pH scale represents neutral?
pH 7 ( meaning [H+] = [OH-] )
What are some of the most acidic substances in our bodies?
HCl - stomach acid (somewhere between pH 1 and 2)
What are the pH’s of the following?
1) arterial blood (and upper limit)
2) venous blood (and lower limit)
1) arterial blood - 7.4 (upper limit is 7.45)
2) venous blood - 7.37 (lower limit is 7.35)
At what pH level is blood maintained approximately
7.4
Define pH
Potential hydrogen - represents the negative logarithm of the molar concentration of H+ ions and indicates the degree of alkalinity/acidity of a solution
At what pH would be considered acidosis?
arterial blood pH < 7.35
At what pH would be considered alkalosis?
arterial blood pH > 7.45
Homeostasis of body pH depends largely on the concentration of H+ in the (extracellular/intracellular) fluid
extracellular
Name the 5 different ways in which H+ enters the bodily fluids
1) carbonic acid - glucose catabolism
2) lactic acid - excess lactate and H+ formed from anaerobic glucose catabolism
3) sulfuric acid - from oxidation of sulfur-containing amino acids
4) Phosphoric acid - from breakdown of phosphoproteins and ribonucleotides
5) Acid ketone bodies - formed during fat breakdown
Name the three acidic ketone bodies?
acetone, aetoacetic acid, B-hydroxybutyric acid
Which acid is formed as a result of glucose catabolism?
carbonic acid
Toxic accumulation of acidic ketone bodies is common in untreated what?
diabetes mellitus
Define: acid-forming minerals
minerals that remain after food has been metabolized and contribute to the formation of an acidic medium in the solution
Name three acid-forming elements
chlorine, phosphorus and sulfur
Acid forming elements are common in what type of diet?
Give 3 examples of foods in which you would find these elements.
Mixed diets
- high protein foods (meat, fish poultry, eggs)
- grains: wheat, corn, oats
- others: olive (oil), blueberries, rice, peanuts, red/black beans, butter, cheese, canola oil, sugar
Name two DIRECT acid-forming foods
Rhubarb (oxalic acid)
Cranberries (benzoic acid)
both foods contain acids that cannot be metabolized at all
Define: base-forming minerals
minerals that remain after food has been metabolized and contribute to formation of a basic medium in solution
Name four base-forming minerals
potassium, calcium, sodium, magnesium
Base forming elements are common in what type of diet? Give 3 examples of foods in which you would find these elements.
Strict vegetarian diet
- lots of fruits and veggies
- peppers, tofu, almonds, citrus fruits, grapes, blackberries, bananas, tomatoes, apples, green beans, lettuce broccoli, carrots, and avocado
- sea salt, garlic
- mineral H2O
Give an example of a DIRECT base-forming substance.
Antacids (sodium bicarbonate, calcium bicarbonate)
What are the two major types of control systems for acid-base balance?
Chemical and physiological
How fast do chemical buffers act?
fast as fk
Name the two physiological buffer systems?
Respiratory and Renal/Kidneys
How fast does the respiratory buffering system act?
Minutes
How fast does the renal response system act?
Hours (takes the longest)
Provide three examples of chemical buffer systems
Any of these:
1) bicarbonate (and carbonic acid)
2) phosphate
3) protein (plasma proteins)
4) Hemoglobin
Which is a very powerful physiological buffer system?
Renal (slower acting but more powerful than respiratory)
Acidosis is caused by what?
Too much H+ ion in the body fluids (or too little base)
Alkalosis is caused by what?
Too little H+ ions in the body fluids (or too much base)
What is a buffer?
A substance tha prevents a change in pH when an acid/base is added to it
What is typically the make-up of buffer pairs?
A weak acid and the salt of that acid
Buffers react with a relatively (strong/weak) acid or base to transform it into a relatively (strong/weak) acid or base, respectively.
strong; weak
True or False: A strong acid holds onto its H+ ions while a weak acid dissociates with its H+ ions quickly.
FALSE - strong acids/bases give that shit away, while weak acids hold on to their H+ ions (that’s why buffers make weak acids so there are less H+ floating around wreaking havoc)
When NaOH (sodium hydroxide) is added to the body, would carbonic acid or bicarbonate buffer the NaOH?
carbonic acid (the acid works on the bases aka NaOH) while bicarbonate works on the acids added
What is carbonic anhydrase?
enzyme that is involved in the formation of carbonic acid from CO2 and water
What is a chloride shift?
The process of exchanging a bicarbonate ion formed in RBC with a chloride ion from the plasma
(this happens as CO2 first comes into Hb and combines with H2O to create H2CO3 –> carbonic acid exchanges with potassium salt of Hb –> HCO3- that can leave RBC
True or False: Carbonic acid is buffered primarily inside RBC (red blood cell) which then produces HCO3- that diffuses down the concentration gradient into the blood plasma
True
How does vomiting cause metabolic alkalosis? What is the treatment?
Vomiting means you are puking up contents in your stomach include HCl, meaning that you are losing a lot of Cl- ions. As a result, this leads to an increase in bicarbonate in the ECF.
Tx: Normal saline (0.9% NaCl in water)
What is a volatile acid? Give an example.
Acids that evaporate via lungs (ex. carbonic acid) - buffered by potassium salts of hemoglobin and oxyhemoglobin
What is a non-volatile acid? Give an example.
aka a “fixed acid” and is produced in the body from sources other than CO2 and not excreted by lungs
Examples:
- HCl, lactic acid, ketone bodies (mainly buffered by sodium bicarbonate)
Carbonic acid results from the metabolism of what?
glucose catabolism
Put the following in the appropriate order from least basic (lower pH) to most basic (higher pH).
1) Oven cleaner
2) Baking soda
3) Great salt lake water
4) Household ammonia
Baking soda, great salt lake water, household ammonia, oven cleaner
What is the most rapid acting buffer system?
Chemical
Some athletes engage in a technique called bicarbonate loading that is said to counteract lactic acid buildup. This practice raises concerns because excess bicarbonate intake my lead to/trigger what?
Metabolic alkalosis if long term bicarbonate use (short term can trigger fluid and electrolyte imbalances from diarrhea)
What is the bicarbonate to carbonic acid ratio that must be maintained in the ECF?
20:1
Define compensation (in the context of acid-base balance).
Adjustments in aboslute amounts of acid/base of the buffer pair in order to maintain ratio of 20:1 (ex. 10:0.5, or 40:2)
In uncompensated alkalosis, the BB/CA (bicarbonate to carbonic acid) ratio __________ (increases/decreases) resulting in a __________ (increase/decrease) in pH.
increases, increase
In uncompensated acidosis, the BB/CA (bicarbonate to carbonic acid) ratio __________ (increases/decreases) resulting in a __________ (increase/decrease) in pH.
decreases, decrease
Define correction in the context of acid-base balance.
when correction occurs, components of buffer pairs return to normal 20:1 ratio
True or False: Exhaled air contains carbon dioxide and water.
True
Why does arterial blood (blood that is leaving the heart) have lower hydrogen ion concentration compared to venous blood?
CO2 moves towards the lungs to be exhaled (therefore carried in venous blood and pH is lower). As a result, there is less CO2 that remains in the blood coming back to the heart. Also when you’re breathing in, you’re not inhaling the same about of CO2 that you exhaled so the arterial blood would be more basic (or higher pH) than venous blood.
If blood pH decreases, does respiration rate and depth increase or decrease?
increase (to eliminate more CO2)
How does respiration mechanism work to bring pH back to normal if blood pH decreases (becomes more acidic)
1) neurons in respiratory center in the brain get stimulated by change in blood pH or CO2 concentration
2) increase resp. rate and depth
3) CO2 eliminated with exhaled air
4) decreased H2CO3 and H+
5) pH goes up back to normal
True or false: Carotid chemoreflexes (chemoreceptors) also cause respiratory adjustments.
True
What happens when a patient is hyperventilating for a prolonged period of time (i.e. beyond what is needed to restore normal pH)?
pH increases to produce alkalosis
If blood pH increases, does respiration rate and depth increase or decrease?
decrease - triggers hypoventilation to keep CO2 in the body
What happens when a patient is hypoventilating for a prolonged period of time (i.e. beyond what is needed to restore normal pH)?
pH decreases due to too little CO2 given off causing blood pH to go up - produces acidosis
Carbonic acid levels are regulated by (respiratory/renal) system. Bicarbonate ions are regulared by (respiratory/renal) system
respiratory; renal
How do kidneys help control pH?
By excreting H+ and reabsorbing Na+ via kidney tubules (basically controls urine pH which influences blood pH)
True or false: urinary mechanism is much more effective for adjusting H+ output to input than respiratory mechanisms
True
List the three renal mechanisms that regulate pH and a brief description.
1) Distal tubes + collecting ducts secrete H+ into urine in exchange for basic ions for bicarbonate reabsorption (increases alkalinity of blood by acidifying urine)
2) Renal tubules excrete H+ OR K+ and reabsorb Na+ (but the more H+ is excreted, the less K+ excreted; may lead to hyperkalemia)
3) Proximal tubule cells secrete ammonia which combine with H+ to form NH4, basic ion (Na+) displaced from a salt (NaCl) and Na+ is absorbed back into the blood
Hyperkalemia is going to have major effect on which organ?
the heartttt babbyy
In general, what is the treatment for metabolic and respiratory acidosis?
Sodium lactate via IV (lactate ions are metabolized by liver cells and converted to HCO3- to replaced depleted HCO3- reserves)
How is the acid forming potential of food determined?
By the minerals remaining after metabolism or minerals that are unable to be metabolized by the body that result in formation of acid medium in solution
Susan has been experiencing prolonged hypoventilation. If not treated soon, she may develop what condition?
respiratory acidosis
Give an example of a cause for metabolic acidosis
- untreated diabetes mellitus
- starvation
- some other metabolic conditions like hypoxia from circulatory shock
What does the body do to try and combat metabolic acidosis?
hyperventilate to blow off CO2; excrete H+ and NH3 to bring pH back up to a more normal pH
Give an example of a cause for metabolic alkalosis
- bicarbonate loading
- improper use of antacids
- excessive vomiting
What does the body do to try and combat metabolic alkalosis?
- supress breathing
- kidneys try to excrete excess HCO3-
Give an example of a cause for respiratory acidosis
- pneumonia
- emphysema
- typically any resp disease that causes CO2 retention in the blood
- or conditions that supress breathing (that fentanyl babyyy)
What does the body do to try and combat respiratory acidosis?
the book doesn’t say but i’m assuming hyperventilating to blow off CO2 and excretion of H+ through urine
Give an example of a cause for respiratory alkalosis
hyperventilation from fever or hysteria (lol wtf so specific)
What does the body do to try and combat respiratory alkalosis?
- supress breathing
- kidneys try to excrete excess HCO3-
A pregnant patient has been experiencing repeated vomiting episodes. She is suffering from metabolic alkalosis. An IV of normal saline is ordered. How will that help this patient?
Normal saline is NaCl to restore the depleted Cl- that she vomited up. Cl- ions will replace bicarbonate ions and relieve bicarbonate excess.
True or false: electrolytes dissociate in solution and non-electrolytes do not dissociate in solution.
TRUE
What is the percentage of total body water that is fluid or volume?
45% - 75% of total body weight
List the factors that would affect total body water
age, gender, fat content, weight
Newborns typically have ____% TBW of their total body weight
75%
For young adults, the percentage of body weight composed of water will average what for males (%) and for females (%)
60% (males); 50% (females)
CSF is part of which fluid compartment
extracellular
What is the _____% TBW in older people?
about 45%
What are the two major fluid compartments in TBW and their %?
ECF - 34%
ICF - 66%
ECF contains what components?
plasma, interstitial fluid (IF), lymph, transcellular fluid (CSF, joint fluid humors in eyes)
Aged individuals of either gender may have less total body water, why?
decreased due to less muscle mass which holds water, more fat, kidneys are shot in concentrating urine, and sodium-conserving resonses are not as effective
- also diueretics
Which pair of fluids is almost identical and compared chemically?
plasma and interstitial fluid
True or False: Blood has more proteins compared to IF
True (because capillary membrane is impermeable to proteins so they all stay in the blood)
What are the two ways that H2O enters the body?
1) digestive tract
2) from cells (H2O produced when cells catabolize food)
How many exits are there through which water leaves the body?
4 (urine, sweat, feces, breath)
What does the Renin-Angiotensin-Aldosterone system (RAAS) do? Describe the steps in which normal water volume is restored.
Decreases fluid output to compensate for decreased intake.
1) Decreased fluid intake causes decreased blood volume and BP
2) stimulates cells in kidney to secrete renin
3) renin acts on angiotensin in bloodstream to form angiotension I (then converted to angiotensin II in lungs)
4) angiotensin I and II increase aldosterone secretion and stimulate thirst sensation
True or False: Priority is to maintain blood volume at the expense of IF volume.
True
Where is the thirst centre located?
Subfornical organ (SFO) and supraoptic and paraventricular nuclei (in hypothalamus and involved with ADH production)
Ringer solution is described as normal saline solution modified by the addition of what?
Potassium and calcium
What are the two factors that determine urine volume ?
GFR and rate of water reabsorption by renal tubules
Where is ADH secreted from?
pituitary gland
Where is aldosterone secreted from?
adrenal cortex
How do ADH and Aldosterone differ?
ADH regulates concentration of electrolytes and colloid osmotic pressure by regulating amount of water reabsorbed into blood by the renal tubes.
Aldosterone regulates ECF volume by regulating amount of sodium reabsorbed into the blood by the renal tubes.
Dehydration caused by: (give 3 examples)
vomiting, diarrhea, intestinal drainage
Which body fluid stays constant throughout life?
plasma
Abnormal conditions that cause fluid and electrolyte output to exceed input is what? give 2 examples.
Vomiting, diarrhea, hyperventilation, excessive sweating without drinking water/electrolytes to repleneish
Edema is defined as what?
presence of abnormally large amounts of fluid in intercellular tissue spaces (IF)
Provide three potential causes of edema?
1) increased capillary permeability
2) retention of electrolytes in ECF
3) decreased concentration of plasma proteins normally retained in blood
In patient with severe burns, what mechanism is responsible for the increased risk of hypovolemic shock?
A loss of interstitial fluid causing a drain of blood plasma out of the vessels and into tissue spaces
Edema may occur when?
disturbances in any factors that govern interchange between blood plasma and interstitial fluid compartments.
What is the first step in edema formation caused by infection
increased capillary permeability (then loss of blood proteins to IF, decreased blood colloid osmotic pressure, fluid retention in tissues = edema)
What is the organ that balances sodium and potassium?
Kidney
True or false: hypochloremia is often found in cases of potassium loss. Why or why not?
True - because Cl- is usually secreted as a potassium salt so if potassium goes, so does Cl-
Causes of hypervolemia
Fluid volume excess (kidneys retaining large about of Na+ and H2O)
ex. CHF, nephrotic syndrome, renal/liver failure
An IV with added sodium can be used to treat what?
hyponatremia
