Human Anatomy & Physiology: Fluid balance Flashcards

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Identify the major fluid compartments in the body and examples

Intracellular (ICF)

Extracellular (ECF)

  • Interstitial (IF)
  • Plasma


Describe how body water content changes as a person ages.

High body water content as a baby and it gradually declines as you get older.


Compare body water content between genders

More in male than in the female because women have more fat or adipose and men have more muscle which has more fluid than fat.


Define an electrolyte and how electrolyte concentrations in the body are expressed.

Electrolytes are chemical compounds that do dissociate into ions in water.

Expressed in Milliequivalents/Liter (mEq/L), measure of the number of electrical charges in 1 liter of solution.


Describe the distribution of electrolytes in ICF and ECF. What are the major intracellular electrolytes? The major extracellular electrolytes

K+ is largest in intracellular inside of cell also phosphate because used for ATP

Na+ CL- extracellular outside of cell mostly


Describe fluid movement among compartments

Water moves freely to and from Plasma into Interstitial space and to and from Intracellular.

Plasma cannot "jump" to Intracellular, must go through Interstitial space first!


Describe major sources of water intake and output

We get most of our water intake through drinking than eating than metabolism. We lose the most in urine, insensible losses skin and lung, sweat than feces


Describe the thirst mechanism

These 3 stimuli activates the hypothalamic thirst center (TC) in the brain.

  1. Dry mouth that triggers nerves in throat, then TC
  2. Low blood volume or low BP, triggers renin-angiotensin, then TC
  3. Increase in osmolality of the plasma, triggers hypothalamic osmoreceptors, then TC


Describe how ADH is related to water output. Where does ADH target?

ADH is related to water out put because,


Question 9 Describe how ADH is related to water output. Where does ADH target?

ADH determines the amount of water the Kidney withholds in the blood or excretes in the urine.

ADH targets the cells of the tubules and collecting ducts.

Note: With more fluid being reabsorbed the blood volume increases while the solutes concentration becomes more diluted.



List 4 Mechanisms that regulate Water Homeostasis.

  1. ADH secretion = retain water
  2. Thirst mechanism = increased water intake
  3. Aldosterone secretion = increased blood volume
  4. Sympathetic Nervous system activated = form less urine


What does ADH do?

Reabsorbs water to make the urine more concentrated


What is Dehydration?

Cells shrink due to loss of water. You lose more water than what you are gaining, so there is a shortage and ADH is activated.


Describe disorders of water balance: Dehydration

Slide 35

Diabetes mellitus (hypertonic filtrate)

Diabetes insipidis (low insulin)

Hypovolemic shock


  • During exercise/hard work cause organs compete with skin vessels for CO (organs win & temp increases)

Causes of Dehydration: Hemorrhage, diarrhea, burns, vomiting, sweating, deprivation.


What is Hypotonic hydration?

"More" water input than water output. Occurs within the Intracellular fluid (ICF), inside the cell.

Too much water will dilute electrolytes.


Describe disorders of water balance: Hypotonic hydration

Hyponatremia (low Na+ concentration) drinking lots of h2O, but losing Na+ in sweat

Cerebral Edema





What is Edema?

Edema is "too much" water in the extracellular fluid (ECF) that causes tissue to swell. Will block the lymphatic system.


Describe disorders of water balance: Edema

Lymphatic Filariasis Disease

  • Parasitic worm blocking lymph nodes

Blocked Lymphatic vessels

  • Increases OPi


Describe the 4 mechanisms that regulate water balance

If fluid osmolarity increases 1-2 % or if blood volume drops by 10% BP goes down which in turn activates.

  • ADH secretion +retain water
  • Thirst mechanism = higher water intake
  • Aldosterone secretion =rise in BP and volume
  • Sympathetic nervous system activated= form less urine


Describe how aldosterone and ANP affects sodium and water balance

Aldosterone draws in sodium to be reabsorbed in the DCT, which allows water to follow. Slide 29



Describe how aldosterone affects potassium balance

Aldosterone influences K+ secretion into the filtrate by stimulating the cells to reabsorb Na+, while enhancing K+ secretion.

As a result, K+ controls its own concentration within the ECF via feedback regulation on aldosterone release.

Pg 1003


ID the target of aldosterone.

Aldosterone regulates water homeostasis by secretion (blood loss) to increase blood volume. Aldosterone targets kidney tubules. It increases Na+ reabsorption and increases K+ secretion.

Slide 22


Describe what hormones regulate Calcium/phosphate balance in the body and their targets

The parathyroid hormone (PTH) increases Ca+ reabsorption by the renal tubules while decreasing phosphate ion reabsorption. Pg 1003

This enhances the blood Ca+ levels by targeting the bones, kidneys, and intestine.

Pg 1015 section 12/13- Regulation of Calcium/Phosphate Balance in Summary section.


Describe the normal pH of arterial blood, urine, intracellular fluid, stomach and intestine

Arterial blood- 7.35-7.45


Intracellular fluid-7.0

Stomach -2.0



Define acidosis and alkalosis

Acidosis - a drop in arterial blood pH below 7.35

Alkalosis - a pH of arterial blood that rises above 7.45


Describe the effect of H+ and HCO3- ions on pH of a solution

The higher the hydrogen then it is more acidic

The higher the bicarbonate then it is more basic or alkaline and vice versa


Describe the 3 ways the body can regulate H+ concentration in the blood.

  1. Chemical buffers in the ECF and ICF transport hydrogen from the tissues to the kidneys. acts in seconds
  2. The lungs remove hydrogen when the volatile acid H2CO3 is converted to CO2 when exhaled- acts in 1-3 minutes (hyper/hypo ventilation)
  3. The kidneys remove hydrogen from metabolic acids and replenish bicarbonate stores in the ECF-acts in hour to days (kidneys)


Describe the 3 chemical buffer systems and give their locations in the body

Bicarbonate buffer

  • In ECF

Phosphate buffer

  • In ICF and Urine

Protein buffer (Can act as acid or base)

  • In ICF and ECF


Describe the influence of the respiratory system on acid-base balance.

Respiratory system alters carbonic acid (H+) to gain or lose, which changes respiration depth/rate (Hypo/Hyper ventilation) to eliminate CO2


Describe how the kidneys regulate hydrogen and bicarbonate ion concentrations in the blood

Secreted hydrogen ions come from the dissociation of carbonic acid generated within the tubule cells.

To counteract alkalosis, bicarbonate ion is secreted into the filtrate and H+ is reabsorbed.

Pg 1015 section 13 under renal Mechanisms of acid-base baance in Summary section.


Describe metabolic and respiration acidosis

Metabolic acidosis is HCO3 reduction, acid build-up

  • Too much absorption or secretion in Kidney

Respiration acidosis is CO2 buildup, poor gas exchange

  • Breathing rate is hypo or hyper ventilation


Describe metabolic and respiratory alkalosis

Metabolic alkalosis is loss of acid, build-up of HCO3

  • vomiting, over-consumption of antacids, constipation (excess HCO3 absorption)

Respiration alkalosis is hyperventilation, CO2 reduction

  • stress, anxiety, fear


Describe metabolic and respiratory compensation.

  • If a metabolic (renal) problem, then respiratory will compensate by changing PCO2
  • If a respiratory problem, then metabolic (renal) will compensate by changing HCO3-


Name imbalances (too high or too low) of sodium, potassium, phosphate, chloride, calcium and magnesium

We don't need answer's below


potassium imbalance disorders:


HYPERKALEMIA.Hyperkalemiamay becaused byketoacidosis(diabeticcoma),myocardialinfarction (heart attack),severeburns,kidneyfailure,fasting,bulimianervosa,gastrointestinalbleeding,adrenalinsufficiency, orAddison'sdisease.Diureticdrugs,cyclosporin,lithium,heparin,ACEinhibitors,beta blockers,andtrimethoprimcanincreaseserumpotassiumlevels, ascanheavyexercise.Theconditionmayalso besecondary tohypernatremia(lowserumconcentrations ofsodium).Symptomsmayinclude:

  • weakness
  • nausea and/or abdominal pain
  • irregular heartbeat (arrhythmia)
  • diarrhea
  • muscle pain

HYPOKALEMIA.Severedehydration,aldosteronism,Cushing'ssyndrome,kidneydisease,long-termdiuretictherapy,certainpenicillins,laxativeabuse,congestiveheart failure,andadrenalglandimpairmentscanallcausedepletion ofpotassiumlevels inthebloodstream. Asubstanceknown asglycyrrhetinicacid,which isfound inlicoriceandchewingtobacco,canalsodepletepotassiumserumlevels.Symptoms ofhypokalemiainclude:

  • weakness
  • paralysis
  • increased urination
  • irregular heartbeat (arrhythmia)
  • orthostatic hypotension
  • muscle pain
  • tetany


Calcium imbalance


HYPERCALCEMIA.Bloodcalciumlevelsmay beelevated incases ofthyroiddisorder,multiple myeloma,metastaticcancer,multiplebonefractures,milk-alkalisyndrome,andPaget'sdisease.Excessiveuse ofcalcium-containingsupplementsandcertainover-the-countermedications(i.e.,antacids)mayalsocausehypercalcemia. Ininfants,lesserknowncausesmayincludebluediapersyndrome,Williamssyndrome,secondaryhyperparathyroidismfrommaternalhypocalcemia,anddietaryphosphatedeficiency.Symptomsinclude:

  • fatigue
  • constipation
  • depression
  • confusion
  • muscle pain
  • nausea and vomiting
  • dehydration
  • increased urination
  • irregular heartbeat (arrhythmia)

HYPOCALCEMIA.Thyroiddisorders,kidneyfailure,severeburns,sepsis,vitamin Ddeficiency,andmedicationssuch asheparinandglucogancandepletebloodcalciumlevels.Loweredlevelscause:

  • muscle cramps and spasms
  • tetany and/or convulsions
  • mood changes (depression, irritability)
  • dry skin
  • brittle nails
  • facial twitching


magnesium imbalance:


HYPERMAGNESEMIA.Excessivemagnesiumlevelsmayoccurwithend-stagerenaldisease,Addison'sdisease, or anoverdose ofmagnesiumsalts.Hypermagnesemia ischaracterizedby:

  • lethargy
  • hypotension
  • decreased heart and respiratory rate
  • muscle weakness
  • diminished tendon reflexes

HYPOMAGNESEMIA.Inadequatedietaryintake ofmagnesium,oftencaused bychronicalcoholism ormalnutrition, is acommoncause ofhypomagnesemia.Othercausesincludemalabsorptionsyndromes,pancreatitis,aldosteronism,burns,hyperparathyroidism,digestivesystemdisorders,anddiureticuse.Symptoms oflowserummagnesiumlevelsinclude:

  • leg and foot cramps
  • weight loss
  • vomiting
  • muscle spasms, twitching, and tremors
  • seizures
  • muscle weakness
  • arrthymia


Chloride disorder:


HYPERCHLOREMIA.Severedehydration,kidneyfailure,hemodialysis,traumaticbraininjury,andaldosteronismcanalsocausehyperchloremia.Drugssuch asboricacidandammoniumchlorideandtheintravenous(IV)infusion ofsodiumchloridecanalsoboostchloridelevels,resulting inhyperchloremicmetabolic acidosis.Symptomsinclude:

  • weakness
  • headache
  • nausea
  • cardiac arrest

HYPOCHLOREMIA. Hypochloremia usually occurs as a result of sodium and potassium depletion (i.e., hyponatremia, hypokalemia). Severe depletion of serum chloride levels causes metabolic alkalosis.Thisalkalization ofthebloodstream ischaracterizedby:

  • mental confusion
  • slowed breathing
  • paralysis
  • muscle tension or spasm


phosphate disorder:


HYPERPHOSPHATEMIA.Skeletalfractures ordisease,kidneyfailure,hypoparathyroidism,hemodialysis,diabeticketoacidosis,acromegaly,systemicinfection,andintestinalobstructioncanallcausephosphateretentionandbuild-up intheblood.Thedisorderoccursconcurrentlywithhypocalcemia.Individualswithmildhyperphosphatemiaaretypicallyasymptomatic,butsigns ofseverehyperphosphatemiainclude:

  • tingling in hands and fingers
  • muscle spasms and cramps
  • convulsions
  • cardiac arrest

HYPOPHOSPHATEMIA.Serumphosphatelevels of 2mg/dL orbelowmay becaused byhypomagnesemiaandhypokalemia.Severeburns,alcoholism,diabetic ketoacidosis,kidneydisease,hyperparathyroidism,hypothyroidism,Cushing'ssyndrome,malnutrition,hemodialysis,vitamin D deficiency,andprolongeddiuretictherapycanalsodiminishbloodphosphatelevels.Therearetypicallyfewphysicalsigns ofmildphosphatedepletion.Symptoms ofseverehypophosphatemiainclude:

  • muscle weakness
  • weight loss
  • bone deformities (osteomalacia)