Fluid/Electrolyte Balance

Question 1

volume, concentration and pH of ECF and ICF are stabalized by

Answer 1

-fluid balance
-electrolyte balance
-acid base balance

Question 2

what are electrolytes

Answer 2

-ions released through idssociation of inorganic compounds
-can conduct electrical current in solution

Question 3

electrolyte balance

Answer 3

-when gains and losses for every electrolyte are in balance
-primarily involves balancing rates of absorption across digestive tract with rates of lsos at kidneys

Question 4

what does acid base balance actually balcne

Answer 4

0production and loss of hydrogen ions

Question 5

kidney and lung effects on acid base balance

Answer 5

-kidneys secrete H+ into urine and generate buffers that enter the bloodstream
-lungs affect pH through elimantion of CO2

Question 6

4 principles of regulation of fluids and electrolytes

Answer 6

-all homeostatic mechanisms that monitor and adjust body fluid composition respond to changes in the ECF not ICF
-no receptors directly monitor fluid or electrolyte balance, they monitor plama volume and osmotic concentration
-cells cannot move water by active transport
-body wate or electrolyte content willrise or fall accroding to diet

Question 7

primary hormones that regulate fluid and electrolye balance

Answer 7

-ADH
-aldosterone
-natriuretic peptides

Question 8

ADH

Answer 8

-stimulste conservation of water at kidneys
-concentrTes urine
-stimulates hypothalamic thirst center promoting fluid intake

Question 9

ADH production and release

Answer 9

-osmoreceptors in hypothalamus monitor osmotic concentration of ECF
-release ADH near fenestration capillaries in posterior lobe of Pit. gland
-higher osmotic concentration increases ADH release

Question 10

aldosterone function

Answer 10

-secreted by adrenal cortex
-rising K or falling Na levels in blood
-determines rare of Na reabsorption and K loss in the kidneys

Question 11

high aldosterone plasma concentration

Answer 11

-conservation of sodium
-water retention
-water follows salt
-more K in urine

Question 12

natuietic peptides

Answer 12

-ANP and BNP
-released by cardiac muscle cells in response to abnormal stretching of heart walls
-reduce thirst
-block release of ADH and aldosterone
-causes diruesis (fluid loss by kidneys)
-lower blood pressure and plasma volume

Question 13

what are electrolyes in body fluids measured in

Answer 13

-equivalents - amount of positive or negative ion that supplies 1 mol of electrical charge

Question 14

general rules of electrolye balancee

Answer 14

-most common issues are associated with imabalance of sodium
-problems with K balance are less common but more dangerous than sodium

Question 15

hyponatremia

Answer 15

-body water content rises
-soidum concentration of ECF is <135mEq/L

Question 16

hypernatreimia

Answer 16

-water content declines
-sodium concentration of ECF >145mEq/L

Question 17

what happens if ECF volume is inadequate

Answer 17

-blood volume and blood pressure decline
-RAAS system activated
-water and Na losses reduced
-Water and Na gains are increased
-ECF volume increases

Question 18

if plasma volume is too large what happens

Answer 18

-venous return increases stimulating release of ANP and BNP
-reduces thirst
-block secretion of ADH and aldosterone
-salt and water loss at kidneys
-ECF volume decreases

Question 19

dominant cation in ICF

Answer 19

-potassium
-ICF concentration = 160
-ECF concentration = 3.5-5.5

Question 20

potassium balance

Answer 20

-98% of potassium in body is in ICF
-cells use energy to to recover potassium from ECF–> cytoplasm
-concentration of ECF is a balance between gaining though digestive tract and loss in urine

Question 21

potassium losses in urine

Answer 21

-regulated by activities of ion pumps along DCT and collecting system
-Na from tubular fluid are exchanged for K in peritubular fluid
-limited gained from digestive system

Question 22

factors affecting rate of K secretion into urine

Answer 22

-changes in K concentration in ECF
-changes in pH
-aldosterone levels

Question 23

hypokalemia

Answer 23

-deficiency of K in blood stream

Question 24

hyperkalemia

Answer 24

-elevated level of K in bloodstream

Question 25

why does H+ get secreted in exchange for Na+ in peritubular fluid instead of K+ when there is a low pH of ECF

Answer 25

to remove excess H+ ions to restore pH balance

Question 26

aldosterone effects on potassium balance

Answer 26

-affect urinary losses -ion pumps sensitive to aldosterone reabsorb Na from tubular fluid in exhange for K+ from peritubular fluid -high plasma K stimulates aldosterone -K lost in the urine as a result

Question 27

major factors involved in distubances of K ion balance

Answer 27

-

Question 28

acids bases and salts

Answer 28

-acids: gives up H+ when dissociates -bases: gives up ions that combine with H+ when dissociates -Salts: compound with cation, not H+ and anion not OH-

Question 29

acidosis

Answer 29

-abnormally low blood pH -acidemia is when blood pH <7.35

Question 30

alkalosis

Answer 30

-physiological state resulting from abnormally high blood pH -blood pH higher than 7.45

Question 31

what systems to alkilosis and acidosis

Answer 31

particularly nervous and cardiovasciular systems -acidosis more common -because normal cellular activities geenrate acids

Question 32

carbonic anhydrase

Answer 32

-enzyme that catalyzes formation of carbonic acid from carbon dioxide and water -found in : cytoplasm of RBC -Liver and kidney cells -parietal cells or stomach -many other cells

Question 33

what is the most important factor affecting blood pH

Answer 33

-PP of CO2

Question 34

what does most Co2 insolution convert to

Answer 34

-carbonic acid

Question 35

PCO2 and pH relationship

Answer 35

-when CO2 levels rise H+ and HCO3 are released and pH decreases -at alveoli CO2 diffuses into atmosphere, H+ and HCO3 in alveolar capillaries decrease and blood pH rises

Question 36

buffers

Answer 36

-dissolved compounds that stabalize pH of solution by adding or removing H+ -buffer system consists of a weak acid that donate H+ an anion that acts as a weak base

Question 37

three major buffer systems

Answer 37

-phosphate buffer system -protein buffer systems -Carbonic acid and bicarbonate buffer system

Question 38

carbonic acid bicarbonate buffer system

Answer 38

-prevents changes in pH caused by metabolic acids and fixed acids in ECF

Question 39

limitations to buffer systems

Answer 39

-provide only temporary solution to acid base imbalance -do not eliminate H+ -supply of buffer molecules is limited

Question 40

to preserve homeostasis captured H+ must be

Answer 40

-permantently tied up in water molecules through CO2 removal at lungs -removed from body fluids by secretion at kidneys

Question 41

how do respiratory and renal mechanisms support buffer systems

Answer 41

-secreting or absorbing H+ -controlling excretion of acids and bases -generating additional buffers

Question 42

respiratory compensation

Answer 42

-increasing or decreasing rate of respiration alters pH by lowering or raising PCO2

Question 43

where are hydrogen ions secreted into tubular fluid along

Answer 43

-PCT -DCT -collecting system

Question 44

buffers in urine

Answer 44

-required to eliminate large # of H+ -glomerular filtration provides compoennts of Carbonic acid bicarbonate buffer system and phosphate buffer system -Tubule cells of PCT generate ammonia and contribute to the ammonia buffer system

Question 45

renal response to acidosis

Answer 45

-secretion of H+ -Activity of buffers in tubular fluid -removal of CO2 -reabsorbtion of NaHCO3

Question 46

renal responses to alkalosis

Answer 46

-rate of H+ secretion at kidneys declines -tubule cells do not reclaim bicarbonate ions in tubular fluid -colelcting system transports HCO3 into tubular fluid while releasing H+ and Cl- into peritubular fluid