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111: Anatomy/Phys 2 > 8.1 Fluids > Flashcards

8.1 Fluids Flashcards

1
Q

how much water do __ have

infants

adult males

adult females

odler adults

A

infants: 73% water

Adult males: 60%

Adult females 50% (bc higher fat content, less skeletal msucle mass)

old age: 45%

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2
Q

if body weight is ~60% water, what proportion is occupied by intracellular fluid vs extracellular

A
  • Intracellular
    • 25L, 40% of body weight
  • Extracellular
    • 15L, 20% of bdoy weight
      • interstitial fluid = 12L, 80% of ECF
      • Plasma volume = 3L, 20% of ECF
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3
Q

how are solutes in the body classifies

A
  • Electrolytes
    • inorganic salts, all acids and bases, some proteins
    • have greater osmotic power than non electrolytes (bc dissociates into ions, NaCl is worth 2 bc two ions)
  • Nonelectrolytes:
    • glucose, lipids, creatine and urea
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4
Q

hwo is the concentration of electrolytes described

A
  • expressed in milliequivalences/L

*measure of number of electrical changes in 1 L of solution

mEq/L = mmoles/L x numebr of electrical charges on one ion

  • > for single charged ions 1mEq = 1 mOsm
  • > for bivalent ions, 2mEq = 1mOsm
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5
Q

describe electrolyte composition of sodium vs potassium

A

*Extracellular = blood plasa and interstitial fluid, intracellular fluid = intracellular

  • Sodium
    • higher in blood plasma and interstitial (extracellular)
    • low in intracellular fluid
  • Potassium
    • Low in blood plasma and interstitial (extracellular)
    • High in intracellular fluid
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6
Q

describe composiiton of Ca, Mg and, HCO3, and Cl in blood plasma, interstitial fluid, intracellular

A
  • Ca2+
    • higer in blood plasma and interstital fluid
    • low in intracellular fluid
  • Mg2+
    • low in blood plasma and interstital fluid
    • high in intracellular fluid
  • HCO3-
    • higer in blood plasma and interstital fluid
    • low in intracellular fluid
  • Cl-
    • higer in blood plasma and interstital fluid
    • low in intracellular fluid
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7
Q

describe composiiton of HPO42- and SO42- in blood plasma, interstitial fluid, intracellular

A

both low in blood plasna and intersitial fluid

high in intracellular fluid

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8
Q

describe composiiton ofprotein anions in blood plasma, interstitial fluid, intracellular

A

*abnormal dsitribution

  • high in blood plasma, highest in INTRAcellular fluid
  • low in interstitial

*helps pull fluid back into blood from interstitial lfuid

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9
Q

why are Na+ and K+ concentrations in ECF and ICF are nearly opposites

A

due to the activity of ATP-dependent Na+ -K+ pumps

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10
Q

what do roteins, phospholipids, cholesterol, and fats account for:

*plasma, interstitial fluid, intracellualr

A

90% of the mass of solutes in plasma
60% of the mass of solutes in interstitial fluid
97% of the mass of solutes in the intracellular

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11
Q

why dont ions accumulate in different organs

A

cardiovascular system is constantly puping fluid throughout body

-Nutrients, gases, and wastes move unidirectionally

Osmolalities of all body fluids are equal

*but differ einside vs outside cells

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12
Q

water intake vs output

A

Water intake must equal water output

Increases in plasma osmolality trigger thirst and release of antidiuretic hormone (ADH)

*most water lost in urine, second most via insensitble losses via skin and lungs then sweat and feces

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13
Q

describet he thirst mechanism for water intake

A

* governed by hypothalamic thirst centre

  • Inc ECF osmolarity (key regulator)
    • derease in salive causing dry mouth
    • osmoreceptors in hypothalamus
  • Decrease in plasma volume (5-10%) (secondary reg)
    • decrease bP -> gransular cells in kideny actiate renin angiotensin-aldosterone mechanism -> inc angiotensin
  • Both these pathways converge to
    • act on hypothalmic thrist center
    • senation of thirst to drink
    • water moistens mouth, thoat, strethc stomach, intestine (will inhibit hypothalic thirst centre)
    • water is abs from GI tract
    • GET DEC ECF AND INC PLASMA VOLUME
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14
Q

What does ADH do?

A

*osmolarity is much more ipm than changes in plasam volume

*can also be triggered by prolonged fever, excessive sweating, vomiting or diarrhea

  • Inc osmolarity or inc Na conc in plasma
    • stimualtes osmoreceptors in hypothalamus
    • stim posterior pituitary
  • Dec in plasma volume or dec in bp (10-15%)
    • inhibts barreceptors in atrium and large vessels
    • stim post pituitary
  • Both converge to
    • release ADH targeting collecting duct of isneys
    • increae water reabs
    • Dec osmolarity, Inc plasma volume and scant urine
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15
Q

what are the signs and symptoms of dehydration

A

cottonmouth, thirst, dry flushed skin, and oliguria (low urinary output)

Prolonged dehydration: amy lead to weight loss, fever and mental confusion

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16
Q

descritbe hypotonic hydration

A

**taking in pure water

  • Renal insufficiency or an extraordinary amount of water ingested quickly can lead to cellular overhydration
  • can happen from taking in too much pure
  • Must be quickly reversed to prevent severe metabolic disturbances, particularly in neurons
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17
Q

what is edema

A

Fluid accumulation in the interstitial space (tissue swelling)

Caused by 1) increases flow of fluids out of the bloodstream and/or 2) hinders their return

  • hinders fluid return
    • key factor in fluid return is proein conc in blood
    • usually reflects an imbalance in colloid osmotic (oncotic) pressures
    • decreases colloid cosmotic pressure caused by
      • hypoproteinemia (low level plasma proteins)
      • filtered fluids out of capillary beds fail to return
      • results from protein malnutrition and liver disease
    • leaked protein accumualte in interstitial fluid drawing fluid from blood (chronic inflammation)
    • blockes lymph vessels
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18
Q

how if fluid filtration increased

A
  • increased capillary hydrostatic pressue
    • intensifies filtration at capillary beds
    • result from incompetent venous valves, localized blood vessel blockage or high blood volume
  • INcreased capillary permeability
    • due to ongoing inflammation
    • inflammatroy chemicals cause local capillaries t become porous allowing large amounts of exudate
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19
Q
A
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20
Q

why is Na+ and electrolyte balance important

A

Na+ salts (NaHCO3 and NaCl) account for 90-95% of all solutes in ECF and contribute 280 mOsm of toal 300 mOsm ECF

*major role for Na+ in controlling ECF volume

  • > Na exerts significant osmotic pressure
  • changes in plasma Na affects: plasma volume, blood pressure, ICF and interstitial fluid volumes
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21
Q

how does aldosterone regulate sodium and potassium

A

*aldosterone = steroid hormone that is secreted from adrenal cortex

*more sensitive to increased K than dec Na

  1. INC K+ or dec Na in blood plasma OR renin angiotensin mech stim aldreal cortex
  2. adreanl cortex releases aldosterone (note steroid hormone so longer to take effect)
  3. aldosterone targets the kidney tubules to get Na reabs and K secretion
  4. restors the plasma levels of Na and K, get negative inhibtion on adrenal cortex to stop releasing aldosterone
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22
Q

cellular basis of how Na and Alsosterone works

A
  1. Aldosterone combines a cytoplasmic receptor
  2. hormone receptor complex initiates transcription in the nucleus
  3. New protein channle and pumps are made
  4. alsosterone induced proteins modify existing proteins
  5. Result is increased Na reabsorption and K+ secretion
23
Q

what do baroreceoptors do

A

Baroreceoptors alert the brain of increases in blood volume that cause a decrease in SNS impulses to kidney leadings to

  • > arterioles dilation
  • > increase glomerular filtration, increased Na+ and water output (pressure diuresis)
  • since Na+ concentration determines fluid volume baroreceptors can be used as Na receptors
24
Q

what are the mechanisms to increase blood pressure

A
  • renin-angiotensin system
  • neural regulation (sympatheitc NS_
  • effect of ADH release
25
Q

describe how the renin-angiotensin system increases blood pressure

A
  • declining systemic blood pressure/volume
  • get dec stretch in afferent arterioles OR dec filrate NaCl conc in ascending limb of loop of Henle
    • both cause granular cells of kidney to secrete renin
    • Renin catalyses conversion of angiotensinogen (from liver) -> angiotensin I
  • Angiotensin I -> Angiotensin II causes
    • stim systemic arterioles to cause vasoconstriction resulting in increase peripheral resistance
    • also stim adrenal cortx to secrete alsosterone targets distal convoluted tubules to cause inc Na+ (and H2O) reabsorption)
      • get incresing blood volume
    • Both aboe cause INC in blood pressure
26
Q

Neural regulation (sympathetic nervous system effects) contribute to blood pressure homeostasis

A

declining systemic blood presure/volume inhibits barreceptors in blood vessels

  • increases sympathitc nervous system -> stim granuluar cels of kidney OR stim systemic arterioles
  • causes casoconstriction resulting peripheral resistance

increasing blood pressure

27
Q

how does ADH release contribute to blood pressure homeostasis

A
  • declining systemic bp stim the posterior pituitary releases ADH which stimualtes the collecting ducts of the kidneys to increase H2O reabsorption
  • increaes BP
28
Q

How does blood pressure homeostasis cause decrease BP

A
  • increase stretch of atria of heat to to inc BP releases atrial natriuretic peptide targers:
    • adrenal cortex (dec aldosterone) and post pit (dec ADH)
      • both inhibit the collecting duct of the kidneys to dec Na annd H2) reabsorption
    • granular cells of kidney whihc dec renin release
      • can dec Na and H2O reabs OR dec angiotensin II causing vasodilation
  • Dec Na and H2O reabs becauses blood volume, and the vasoilation work together to because blood pressure
29
Q

how is potassium balance regulated

A
  • 60-80% of filtered K+ is absorbed in the proximal convoluted tubule and another 10-20% absorbed in ascenidng limb of nephron loop

*this absorption occurs no matter waht

  • <`5% of filtered K+ is lose to urine reglardless of need
  • excessive K+ is excreted into filtrate in the cortical collecting duct by the principle cells
  • increased K+ in ECR leads to release of aldosterone and resulting in an increase K+ secretion by principal cells
30
Q

what are the 5 main ions in the plasma?

what are the consequences of theri imbalances

A
  • sodium:
    • excess Na: consufion and lethragy, neuromuscular irritability
    • Na deficit: brain swelling, musuclar twitching
  • Potassium
    • excess: flaccif paralysis
    • deficity: flattened T wave
  • Phosphate
    • excess: issues caused by reciprocal changes in Ca levels
  • Chloride
    • no dierct symptoms
  • Calcium
    • excess: decreased neuromuscular excitability
    • deficity: increased neuromuscular excitability
  • Magnesium
    • excess; lathargy, ipmaired CNs functioning
    • Deficit: tremors
31
Q

pH of arterial blood

venous blood

interstitial

intracellular

A

arterial blood: 7.4

venous blood and interstitial: 7.35

intracellular: 7.0

32
Q

what are the sources of H+

A

most from cellular metabolism

Breakdown of phosphorus-containing proteins releases phosphoric acid Anaerobic respiration of glucose produces lactic acid
Fat metabolism yields organic acids and ketone bodies
Transporting CO2 as bicarbonate releases H

33
Q

describe H+ Regulation

A

regulated sequentially by:

  1. Chemical buffer systems - act within seconds
  2. Respiratory center in the brain stem - acts within 1-3 min
  3. Renal mechanisms - require hrs to days
34
Q

what is a chemical buffer system

what are the 3 major buffering systems in the body

A

chemical buffer = one or two molecules that act to resist pH changes when strong acid or base is added

  • > bicarbonate buffer system
  • > phosphate buffer system
  • > protein buffer system

*any drifts in pH are resisted by the entire chemical buffering system

35
Q

describe the bicarbonate buffer system

A
  • carbonic acid (H2CO3, weak acid) and its salt, Na bicarbonate

H2CO3 ↔ H+ + HCO3 ̄

  • if strong acid is added
    • H+ combines with NaHCO3 forming H2CO3 (weak acid)
  • If strong base is added
    • it reacts with H2CO3 to form NaHCO3 (weak base)
    • the pH of the solution rises only slightly
  • in both cases the buffering resists pH

THIS SYSTEM IS THE ONLY IMPORTANT ECF BUFFER

36
Q

Describe the phosphate buffer system

A
  • nearly identical to the bicarbonate system

Na+ of dihydrogen phosphate (H2PO4 ̄), a weak acid

Monohydrogen phosphate (HPO42 ̄), a weak base

**AN EFFECTIVE BUFFER IN URINE AND INTRACELLULAR FLUID

37
Q

describe the protein buffer system

A

some AAs have free organic acid groups (weak acids) and/or groups that act as weak bases (amino groups)

  • amphoteric molecules: protein molecules that can function as both weak acid and weak base
38
Q

Respiratroy buffer systems

A
  • reversible equilibrium between dissolved CO2 and water

CO2 +H2O↔H2CO3 ↔H+ +HCO3 ̄ (memorize)

  • when hypercapnia (rising H+): depper more rapid breathing expels more CO2
  • alkalosis causes slow shallow breathing increasing H+
  • Respiratory system impairment caues acid-base imbalance (respirtaory acidosis or resp alkalosis)
39
Q

how does the renal system ergulate acid-base

A

*ultimate acid abse regulator in the kidneys

  • onyl kidneys can rid body of metaboloc acids (phorphoric, uric, lactic and jetons
  • regualte acid-base by:
    1. conserving (reabsorbing) or generating new NaHCO2 for acidosis
    2. Excreting NaHCO3 for alkalosis
40
Q

how is filterned NaHCO3 reabsorbed

A
  • secretion of H+ occurs mainly in the proximal convoluted tubule (PCT) cells in type A intercalated cells of collecting duct
  • for each H+ secreted, a Na and a NaHCO2 are reansbored

*we are trying re reabs bicarbonate from ruine filtrate

  • take bicarbonate and H ion to form H2CO3 (carbonic acid) then carbonic anhydrase forces reaction to product CO2 and H2O
  • CO2 goes into cell, forms carbonic acid and then bicarbonate and H+

= H+ gets transported back out into urine and Na comes in

  • bicarbonate transported out cell itno capilalry sodium bicarb symptorer and chloride bicarb antiporter
41
Q

how is new NaHCO3 generated

A
  • mainly in PCT cells and in type A intercalated cells of collecting duct
  • kidneys can generate NaHCO3 with equal amounts of H+ secreted into ruine
  • mainly in PCT cells and in type A intercalated cells of collecting duct
  • this method uses ammonium ions (NH4_) producted by metabolism of glutamine
  • each glutamine metabolized productes two NH4 and two NaHCO3
42
Q
A
43
Q

what secretes NaHCO3

A

type B intercalted cells

  • > reverse reactions of type A intercalated cells
  • > exhibit NaHCO3 secretion
  • > reclaims H+
44
Q
A
45
Q

describe respiratory acidosis and alkalosis

A
  • PCO2 is an important indicator or respiratory inadequacy
  • > Normal PCO2 fluctuates between 35 and 45 mmHg
  • > values above 45 hhHg signal respiratory acidosis
  • > values below 35 mmHg indicate respiratory alkalosis

Respiratory acidosis: common cause of acid-base imbalances

  • occurs when a person brethes shallowly or gas exchange is hampered by diseases such as pneumonia, cystic fibrosis or emphysema

respiratory alkalosis is a common result of hyperventilation

46
Q

describe metabolic acidosis

A
  • 2nd most common cause of acid-bae imbalance (NaHCO3 below 22-26 mEq/L)
  • typical causes are ingestion of too much alc and excessive loss of NaHCO3
  • other causes include accumulation of lactic acid, shock, ketosis in diabetic crisis, starvation and kidney failure
47
Q

describe metabolic alkalosis

A

rising of pH and NaHCO3 caused by:

  • > vomiting of acid contents of sotmach
  • > intake of excess base (from antacids)
  • > constipation, in which excessive bicarbonate is reabsorbed
48
Q

how do the respiratory and renal systems compensate for eachother

A
  • Acid-base imbalance due to inadequacy of a physiological buffer system is compensated for by the other system

*Respiratory system will attempt to correct metabolic acid-base imbalances

* Kidneys will work to correct imbalances caused by respiratory disease

49
Q

how will the respiratory system try to compenate for metabolic acidosis

A
  • rate and depth of breathing are elevated
  • blood pH is below 7.35 and low NaHCO3
  • as CO2 is eliminated by the respiratory system, PCO2 falls below normal

*

50
Q

how will the respiratory system try to compenate for metabolic alkalosis

A
  • compensation exhibits slow, shallow breathing allowing CO2 to accumulate in the blood
  • correction is revealed by:

 High pH (over 7.45) and elevated NaHCO3

 Rising PCO2

CO2 +H2O↔H2CO3 ↔H+ +HCO3 ̄

51
Q

how does the renal system compensate for respiratory acidosis or alkalosis

A

acidosis: have higher high PCO2 and high NaHCO3

*  High NaHCO3 indicate the kidneys are retaining NaHCO3 and secreting H+ to offset the acidosis

alkalosis: Low PCO2 and high pH

* Kidneys eliminate NaHCO3 from the body and absorb H+

52
Q
A
53
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111: Anatomy/Phys 2 (31 decks)

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