Patho Final Flashcards

1
Q

Concentration of the ICF, ECF, ISF, and plasma

A

ICF = 25L
ECF = 15L
ISF = 12L
Plasma = 3L

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2
Q

Major differences between ECF + ICF

A
  • presence of cell proteins in ICF that cannot permeate the cell membrane to leave the cells
  • unequal distribution of Na+ and K+ and their attendant ions as a result of the action of the NaK ATPase pump
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3
Q

What two factors maintain the body fluid balance?

A
  1. ECF volume
    - helps give enough pressure for blood flow to tissues
    - maintaining salt content in the body is necessary for long-term defense of ECF volume –> ALDOSTERONE
    - lack of “pressure diuresis” keeps volume and pressure steady long term
  2. ECF Na+ concentration/osmolarity
    - helps prevent swelling or shrinking of cells
    - 90% of regulating ECF osmolarity
    - ADH + thirst add H2O to ECF, diluting the salt
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4
Q

osmolarity

A

measure of the concentration of individual solute particles dissolved in fluid

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5
Q

How can you change the osmolarity?

A
  1. Deficit of free water in ECF
    - DEHYDRATION
    - osmolarity = hypertonic
  2. Excess of free water in ECF
    - OVERHYDRATION
    - osmolarity = hypotonic
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6
Q

Causes of hypertonicity, symptoms, effects

A

Causes:
- insufficient water intake
- excessive water loss
- diabetes insipidus

Symptoms/Effects:
- shrinking of brain neurons
confusion, irritability, delirium, convulsions, coma
- circulatory disturbances
lower plasma volume –> lower BP –> circulatory shock
- dry skin, sunken eyeballs, collapsed neck veins, dry tongue

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7
Q

Causes of hypotonicity, symptoms, effects

A

Causes:
- Renal failure –> cannot excrete dilute urine
- Drink water too quickly –> kidneys cannot respond fast enough
- SIADH –> too much ADH secretion –> water retained

Symptoms/Effects:
- WATER INTOXICATION –> swelling of brain cells
confusion, irritability, lethargy, headache, dizziness, vomiting, drowsiness, convulsions, coma, death
- weakness
- circulatory disturbances –> HTN (maybe) and edema

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8
Q

H2O Output - Insensible vs. Sensible Loss

A

Insensible
- NON-neural
- lungs
- non-sweating skin

Sensible
- Neural
- sweating, feces, urine excretion

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9
Q

What stimulates vasopressin? (normal conditions)

A

osmolarity rise

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10
Q

What produces vasopressin? What stores vasopressin?

A

produces: hypothalamus
stores: hypothalamus

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11
Q

hypothalamic osmoreceptors

A

vasopressin-secreting cells and thirst cells

osmolarity increase = vasopressin (ADH) secretion + thirst stimulated
osmolarity decrease = vasopressin (ADH) secretion decreased + thirst suppressed

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12
Q

What stimulates vasopressin? (emergency conditions)

A

drop in volume

  • left atrial receptors monitor pressure of blood flowing through (reflects ECF volume) –> detects major reduction in arterial pressure –> stimulate vasopressin secretion + thirst
    ex. HEMORRHAGES
  • angiotensin II –> stimulates vasopressin secretion + thirst when RAAS system activated to conserve Na+ (secondary)
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13
Q

Normal ABG values (pH, pO2, pCO2, O2 sat, HCO3-)

A

pH = 7.4 (7.37-7.44)
pO2 = 80-100
pCO2 = 36-44
O2 sat. = >95
HCO3- = 22-26

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14
Q

What pH values are deadly?

A

anything outside [6.8 - 8.0]

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15
Q

What is considered acidosis? Alkalosis?

A

Acidosis = below 7.35
Alkalosis = above 7.45

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16
Q

Small changes in pH can produce major disturbances including…

A
  1. dysfunction of enzymes –> work within narrow pH ranges
  2. electrolytes (Na+, K+, Cl-)
  3. hormones
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17
Q

What happens to the excitability of nerve and muscle cells with a fluctuation in pH?

A
  • changes enzyme activity
  • changes K+ levels in body (H+ and K+ compete for secretion into tubules)
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18
Q

Sources of H+ in the body

A
  • carbonic acid formation –> from metabolically produced CO2
  • inorganic nutrients produced during breakdown of nutrients
    proteins in diet –> sulfuric + phosphoric acid
  • organic nutrients resulting from metabolism
    fatty acids (fat), lactic acid (muscles primarily)
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19
Q

The body produces more (acids/bases) than (acids/bases).

A

ACIDS
- foods, metabolism of lipids + proteins, cell metabolism produces CO2

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20
Q

What are the following products?
1. Protein breakdown
2. Anaerobic resp. of glucose
3. Fat metabolism
4. Transporting CO2 as bicarb

A
  1. phosphoric acid
  2. lactic acid
  3. organic acids and ketones
  4. H+

ALL ACIDS

21
Q

What is a buffer?

A

Buffers are solutions which can resist changes in pH when acid or alkali is added

22
Q

Most important buffers

A
  1. phosphate (renal tubular buffer)
  2. ammonia (renal tubular buffer)
    - NH3 (ammonium) is TOXIC
  3. proteins (INTRACELLULAR and PLASMA buffers)
    - HHb predominant protein RBC
  4. bicarbonate (EXTRACELLULAR + renal tubular buffer)
23
Q

Buffers used by the following systems:
1. Respiratory
2. Blood
3. Kidneys

A

Resp. = Bicarb
Blood = bicarb, phosphate, PROTEINS
Kidneys = bicarb, phosphate, AMMONIA

24
Q

Bicarb buffer + function

A

Sodium bicarb (NaHCO3) + carbonic acid (H2CO3)

maintain a 20:1 (HCO3:H2CO3)

25
Q

Most important buffer system in the plasma

A

bicarbonate
- 65% of buffering capacity in plasma
- 40% of buffering capacity of the whole body

26
Q

Why isn’t phosphate buffer the predominating buffer?

A

very effective, but not found in high concentrations in all tissues (mostly renal tubular and intracellular)

  • bicarb better –> higher conc. in all tissues plus carbonic anhydrase
  • low concentration in plasma
  • easy to shift equation to left or right with an addition of H+ or OH- (H2PO4- <-> H+ +HPO4 2-)
27
Q

Primary ICF buffer

A

protein buffers
- includes HgB
carboxyl gives up H+
amino accepts H+

28
Q

What is the primary buffer against carbonic acid changes?

A

protein buffers

29
Q

Most important buffer system in the body cells

A

protein buffer
- HgB
16 histidine residues in albumin
38 histidine residues in HgB

function: accept H+ and act as a buffer in RBCs + plasma

30
Q

Ammonia buffer system

A

inducible in kidneys
- can greatly increase ammonia production from glutamine in chronic acidosis

31
Q

Most important buffer system in the renal system

A

ammonia buffer system
- excess H+ can be picked up by ammonia system
- kidney makes ammonia by breaking down glutamine (AA)
- ammonia secreted into the filtrate while the good products are reabsorbed

32
Q

____% of the buffering capacity is in cells
____% is in RBCs
____% of the buffering capacity is in the extracellular space

A

52% cells
5% RBCs
43% extracellular space
- 40% by bicarb buffer, 1% by proteins, 1% by phosphate buffer system

33
Q

What does the respiratory buffering system do?

A

Controls CO2 levels, while the kidneys secrete bicarb

34
Q

What resp. condition creates an alkaline condition? Acidic conditions?

A

ALKALINE = hyperventilation
- leads to loss of CO2

ACIDIC = hypoventilation
- central receptor increases ventilation as CO2 builds up

35
Q

What detects CO2 concentration changes? Where does it send the appropriate signal to?

A

peripheral receptors

36
Q

Respiratory mechanisms do not work on ________ acids

A

fixed acids (ex. lactic acid)

ONLY volatile acids

37
Q

Kidney excretion

A
  1. EXCRETE large amounts of acid / base
  2. CONSERVE and produce bicarb
  3. MOST EFFECTIVE regulator of pH

kidney fails = pH balance fails

38
Q

How do the kidneys maintain acid-base balance?

A

overall: regulating pH of blood plasma

39
Q

What are the two roles that the kidneys maintain acid-base balance?

A
  1. reabsorb bicarb from urine
  2. excrete H+ into urine
40
Q

What is the major homeostatic control point for maintaining a stable balance?

A

renal excretion

41
Q

How can the kidneys control acids and bases in acidosis?

A

intercalated cells
- secrete excess H+
- binds to buffers in the lumen (ammonia and phosphate bases)
- formation of bicarb

Pee it out, bind to other bases in the wall (lumen), or make bicarb via carbonic anhydrase

42
Q

Respiratory mechanisms take _________ to correct
Renal mechanisms take _________ to correct

A

resp = minutes to hours
renal = hours to days

43
Q

First line of defense against pH shift

A
  1. bicarb buffer system
  2. phosphate buffer system
  3. protein buffer system
44
Q

Second line of defense against pH shift

A
  1. respiratory mechanism (CO2 excretion)
  2. renal mechanism (H+ excretion)
45
Q

What is an anion gap?

A

The difference between the measured anions (-) and cations (+) in serum plasma or urine.

Calculated to determine the cause of metabolic acidosis.

If gap is greater than normal, then noted for a high anion gap metabolic acidosis.

46
Q

What does it mean when if the anion gap is GREATER than the change in [HCO3-] from normal?

A

metabolic alkalosis is present + gap metabolic acidosis

47
Q

What does it mean when if the anion gap is LESSER than the change in [HCO3-] from normal?

A

non-gap metabolic acidosis + gap metabolic acidosis?

48
Q

What does a metabolic acidosis represent?

A

An increase in acid in body fluids]
- reflected by a decrease in [HCO3-] and a compensatory decrease in pCO2