Renal physiology session 2 Flashcards

1
Q

Size of molecules that can be filtered through glomerulus

A

Molecules less than 20 angstroms are freely filtered

More than 42 angstroms are not filtered

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2
Q

How does damage to the glomerular glycocalyx increase susceptibility to proteinuria

A

Glycocalyx covering on the glomerulus endothelium creates a barrier of negative charges that disrupt a proteins ability to diffuse across it
When the barrier is destroyed, more proteins and larger proteins are able to move across

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3
Q

Urinary excretion equation

A

Amount filtered - amount reabsorbed + amount secreted

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4
Q

Tubular reabsorption equation

A

Glomerular filtration - urinary excretion+amount secreted

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5
Q

Filtration fraction

A

Usually about 20% of RPF

FF=GFR/RPF

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6
Q

GFR is directly proportional to renal clearance if

A

Substance must be freely filterable in the glomeruli
Substance must be neither reabsorbed nor secreted by the renal tubules
Substance must not be synthesized, broken down or accumulated by the kidney
Substance must be physiologically inert

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7
Q

Examples of substances that meet the requirements for GFR=Renal clearance

A

Inulin - freely filtered, neither reabsorbed nor secreted
GFR= (Uinulin)(V)/P(inulin)
Creatinine is the same way (except about 10% of the creatinine in urine is secreted)

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8
Q

Sympathetic effect on arterioles, JG cells and tubular epithelial cells

A

Vasoconstriction (mostly afferent arteriole) via a1 adrenergic receptors
Renin release from JG cells via B1 adrenergic receptors
Na-K ATPase increased activity (increased reabsorption of Na) via a1 adrenergic receptors
Know the receptors

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9
Q

Ultrafiltration coefficient equation

A

Kf = Hydraulic conductivity (permeability of endothelium) X Surface area

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10
Q

GFR equation using Kf

A

GFR = Kf x Puf (capillary ultrafiltration pressure)

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11
Q

Capillary ultrafiltration pressure equation

A

Add/subtract glomerular/bowmans capsule forces

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12
Q

Acidosis/alkalosis pH levels

A

Acidosis- less than 7.35

Alkalosis- greater than 7.45

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13
Q

Arterial HCO3 level

A

24

Increases in HCO3 will increase pH

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14
Q

Arterial CO2 level

A

40

Increased CO2 decreases pH

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15
Q

Factors increasing H+ secretion

A
Primary: 
Decrease in plasma HCO3 (decreased pH)
Increase in partial pressure of arterial CO2
Secondary:
Increase in filtered load of HCO3
Decrease in ECF volume
Increase in angiotensin II
Increase in aldosterone
Hypokalemia
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16
Q

Factors decreasing H+ secretion

A
Primary:
Increase in plasma HCO3
Decrease in partial pressure of arterial CO2
Secondary:
Decrease in filtered load of HCO3
Increase in ECF volume
Decrease in aldosterone
Hyperkalemia
17
Q

What are the main molecules that buffer the H+ from bicarbonate in the urine

A

NH3 and PO4-

18
Q

a-intercalated vs b-intercalated cells

A

a-intercalated cells secrete H+ and reabsorb HCO3

b-intercalated cells reabsorb H+ and secrete HCO3-

19
Q

Net acid excretion equation

A

NAE= [(Urine NH x V) + (Urine TA(PO salts) x V) - (Urine HCO3 x V)]

20
Q

Renal tubular acidosis type I

A
Impaired distal collecting duct H+ secretion
Very low bicarbonate <15 or usually <10
Urine pH greater than 5.5
Severe acidosis
Plasma K+ usually low
Caused by autoimmune disorders
21
Q

Renal tubular acidosis type II

A

Impaired proximal HCO3 reabsorption
Plasma HPO3 12-20
Low plasma K+
Caused by Fanconi syndrome, multiple myeloma, drugs

22
Q

Renal tubular acidosis type IV

A

Lack of aldosterone or failure of kidney to respond to it
HCO3 >17
High plasma K+
Caused by drugs

23
Q

High serum anion gap means

A

Anion gap greater than ~16

There are other solutes in plasma (alcohols, lactic acidosis, ketoacidosis)

24
Q

Osmolal gaps

A

Should be 0
If greater than 0 it is due to unmeasured osmotic particles such as NH4
If less than 75 it could be renal tubular acidosis
If 200-300 it could be chronic severe metabolic acidosis

25
Urine anion gap
Becomes negative in metabolic acidosis due to HCO3 loss in diarrhea since excretion of unmeasured NH4+ increases significantly during generation of new bicarbonate In renal tubular acidosis, NH4 excretion is decreased due to the inability to generate new bicarbonate, so value can remain positive despite acidosis
26
Causes of respiratory acidosis (acute)
``` CANS CNS depression (opioids) Airway obstruction Neuromuscular disorders Severe pneumonia, embolism, edema ```
27
Causes of chronic respiratory acidosis
COPD | Anything chronic leading to impaired ventilation
28
Normal adjustments in HCO3 after increases in CO2 in acute vs chronic
pCO2 increases by 10, HCO3 should increase by 1 (acute) or 3.5 (chronic) pCO2 decreases by 10, HCO3 should decrease by 2 (acute) or 5 (chronic)
29
Causes of acute respiratory alkalosis
``` CHAMPS CNS disease- hyperventilation Hypoxia Anxiety Mechanical ventilators Progesterone Salicylates/sepsis ```
30
Carpopedal spasm
Can be caused by respiratory alkalosis due to hypocalcemia from Ca being driven into cells in exchange for H+
31
Compensation vs correction of metabolic acidosis
Compensation is respiratory- hyperventilation to decrease CO2 Correction is increasing bicarbonate regeneration in the kidney
32
HAGMA causes
``` GOLDMARK Glycols Oxoproline (from acetaminophen toxicity) L-lactate D-lactate Methanol Aspirin Renal failure Ketoacidosis ```
33
NAGMA causes
``` HARDUPS Hyperalimentation Acetazolamide Renal tubular acidosis* Diarrhea* Uretosigmoid fistula (colon wastes HCO3) Posthypocapnea Spironolactone ```
34
Determining what PaCO2 should be, given HCO3
PaCO2 = 1.5 x [(HCO3) + (8+/-2)] | If PaCO2 is not the expected number, it is a mixed acid base disorder
35
Metabolic alkalosis causes
``` CLEVER PD Contraction Licorice Endocrine (Conn, cushing syndrome) Vomiting Excess alkali Refeeding alkalosis (eating after long starvation) Post-hypercapnia Diuretics ```
36
Chloride responsive vs resistant metabolic alkalosis
Chloride responsive: vomiting, diuretics, diarrhea Spot urine Cl should be less than 10 since kidney should be conserving chloride Treat with saline Chloride resistant: Hyperaldosteronism resulting in increased H and K excretion in exchange for reabsorption of Na Spot urine Cl greater than 20 despite fact kidney should be conserving Cl Need to treat cause of H+ loss to treat