-
transcalciferin (TC)
1,25(OH)2D3 binding globulin
-
Receptor for PTH
GsPCR -> cAMP (bone, kidney distal tubular cells)
-
Overall effects on serum Ca and phosphate level: PTH, 1,25-D3, calcitonin
- increase and decrease
- increase and increase
- decrease and decrease
-
primary hyperparathyroidism
- benign parathyroid neoplasm (adenoma) -> excess PTH secretion -> hypercalcemia -> kidney stones
- mild
-
Secondary hyperparathyroidism
- calcium/vit D deficiency, renal disease -> hypocalcemia -> excessive PTH secretion
- serious due to low [Ca]
-
hypoparathyroidism
surgical/autoimmune damage to parathyroid gland -> low PTH -> low [Ca], high phosphate, -> nerve and muscle hyperexcitability and hypocalcemic tetany
-
minute ventilation (VE)
alveolar ventilation (VA)
- resting tidal volume (VT) x f
- (VT - VD) x f
-
Physiological dead space =
anatomical dead space (conducting airways; body weight in lb) + alveolar dead space (0 in healthy young adults)
-
lung compliance C =
fibrosis
emphysema
- dV/dP
- low compliance, stiff lungs
- loss of elastic tissue, overly-compliant
-
_________ is secreted by _____ to reduce the surface tension between the alveoli.
- Surfacant
- type II pneumocytes
-
Laminar flow follows the law: V =
- dP/R
- V is flow, the volume passed per unit time
- R is the resistance = 8 x viscosity x length / (pi x r^4)
- r is the radius of the tube
-
Turbulent flow happens when
- Reynold's number > 2000
- = density x velocity x diameter / viscosity
- always slower than laminar flow, happens in asthma
- therapy
-
Velocity =
flow / total cross section area
-
PO2, PH2O, and PCO2
in dry air
trachea
alveolar
- 160mmHg, none, none
- 150mmHg, 47mmHg, none
- 100mmHg, 47mmHg, 40mmHg
-
Total O2 content =
- dissolved O2 + Hb-bound O2
- = alpha x PO2 + [Hb] x saturation x 1.34
- alpha: solubility of O2, 0.003ml/dl
-
Right shift of Hb-O2 dissociation curve happens when
- pH decreases
- T increases
- PCO2 increases
-
polycythemia
anemia
CO poisoning
- high [Hb], higher max O2 content
- low [Hb], lower max O2 content
- lower max O2 content, left shift of the curve
-
PAO2 (alveolar O2) =
indication for hypoventilation/hyperventilation
- PIO2 - PACO2/R
- PIO2 depends on the air, mostly stable
- PACO2 is indirectly proportional to VA
- R is usually 0.8, can be 1 if pure carb diet
- hypovent -> decrease VA -> increase PACO2 -> decrease PAO2
- hypervent -> increase VA -> decrease PACO2 -> increase PAO2
-
Fick’s Law for gas transfer across alveolar- capillary membrane
- V = D (P1 – P2)
- = A/T x S/sqrt(MW) x (P1-P2)
- A: surface area
- T: membrane thickness
- S: solubility
-
Hypoxic Pulmonary Vasoconstriction:
blood flow diverted from poorly ventilated regions to better ventilated lung regions
-
Medullary respiratory centers
- Dorsal: N. solitarious (I)
- Ventral: N. ambiguous (E and I)
-
Pontine respiratory centers
- Lower pons: apneustic center
- Middle pons: pneumotaxic center
-
Carotid body
- sensitive to low PaO2 < 60mmHg (dissolved only)
- innervated by CN IX
- highest blood flow per gram tissue in the body
-
Central chemo receptor
- sensitive to inc. PaCO2
- ventral medulla
- main drive of respiration
-
Adaptation to high altitude
- ventilation increases
- polycythemia (inc RBC) and Hb (kidney produces eyrthropoietin in response)
-
Renal circulation
- renal artery
- arcuate artery
- afferent arteriole
- capillary glomerulus
- efferent arteriole
- peritubular capillaries
- vasa recta
- arcuate vein
-
renal plasma flow (RPF) =
- (1-hct)xRBF
- hct: hemocrit, percentage of blood taken by cells, mainly RBC; normally 40%
- RBF: renal blood flow; about 20% of cardiac output, 5L/min x 20% = 1L/min
-
glomerula filtration rate
- 120ml/min
- generates an ultrafiltrate of plasma
-
filtration fraction (FF) =
glomerula filtration rate / renal plasma flow
-
GFR: Starling forces
- GFR = k x (ΔP - Δπ)
- ΔP = PGC - PBS
- Δπ = πGC - πBS
- P: hydrostatic pressure; considered same across the duct.
- p: oncotic pressure; considered zero for the filtrate
- GC: glomerular capillary
- BS: Bowman's space
- never less than 0 (absorption)
-
effect of prostate hypertrophy on GFR
how about hypoproteinemia
- PBS inc, dP dec, GFR dec
- pGC dec, dp dec, GFR inc
-
Clearance C:
- CP=UV
- C=UV/P
- P: concentration of a substance in plasma
- U: concentration of the same sub in urine
- V: amount of urine excreted in unit time
-
for substance only filtered (no resorption or secretion)
- GFR x P = UV
- GFR = UV/P
- inulin
- creatinine
-
for substance fully excreted through one passage
- RPF x P = UV
- RPF = UV/P
- RBF = RPF/(1-hct)
- PHA (Para-AminoHippuric acid)
-
Proximal tubular resorption
- 2/3 of electrolytes and water, most glucose
- basolateral side:
- Na/K-ATPase, Na+ outward
- glu chan
- apical side:
- Na+ chan
- glu/Na-cotransporter
- Cl- follows Na
- Water follows electrolytes
-
Proximal tubular HCO3- resorption
- apical:
- Na/H exchanger, inc H+ in lumen
- HCO3-+H+->->CO2
- CO2 diffuse across, converts back to HCO3-
- basolateral:
- Na/HCO3 cotransporter or Cl/HCO3 exchanger
-
Na sensing mechanism
macula densa (part of JGA, located in distal tubule) sense high [Na] -> stim juxtaglomerula cell (in afferent arteriole) secretes renin -> ... -> aldosterone secreted -> increase Na retention at collecting duct
-
K+ balance
90% absorbed before distal tubule
-
Nephrogenic diabetes insipidus
kidney has no response to ADH
-
How is the osmotic gradient created in kidney?
- Countercurrent multiplication
- Diluting segment:
- thick ascending limb of loop of Henle
- Na-K-2Cl symporter moves salt out
- only segment impermeable to water
-
plasma pH w/ the buffer of H2CO3 =
- pKa + log(A/HA)
- =6.1 + lg([HCO3]/0.03PCO2) = 7.4
- [HCO3]=24mM
- PCO2=40mmHg
-
acid-base balance
- buffer
- respiratory (quick)
- renal (slow)
-
renal regulation on H+
- NH3 most important, adjustable
- HPO42-
- HCO3- lease important
-
acid-base disturbance
pH=pKa (6.1) + lg([HCO3-]/0.03PCO2)
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