Renal Physiology Flashcards
Hypertonic Expansion
Hypertonic NaCl
NaCl tablets - no liquid involved
Isotonic Expansion
Isotonic Saline
Lactated Ringers Solution
Hypotonic Contraction
Chronic sweating (NaCl depletion) Adrenocortical Insufficiency (no NaCl retention)
Hypertonic Contraction
Sweating without fluid replacement
Diabetes Insipidus
Isotonic Contraction
Diarrhea
Hemorrhage (whole blood loss)
ECF 14L ICF 28L TBW 42L IF 10.5L Plasma 3.5L
20-40-60 rule
20% body weight 1/3 TBW 40% body weight 2/3 TBW 60% body weight (kg) 3/4 ECF Plasma 1/4 ECF
Juxtaglomerular apparatus consist of
Macula densa - thick LOH meets DCT
Juxtaglomerular/granular cells - secrete renin
Extraglomerular mesangial cells - smooth muscle involved in blood flow via sym system
Filtration Fraction
GFR/RPF normally 20%
Constrict AA = smaller GFR & RPF same FF
Constrict EA = greater GFR, large FF
GFR
Kf x Pf
Controlled by BP and AA, EA resistance
Myogenic response
Fast
Increase MAP, greater Na+ influx -> Ca2+ -> SM contracts
Tubuloglomerular Feedback
Up to one minute
Increase MAP = increase GFR and Na & Cl to macula densa, increase in ATP & adenosine release via mesangial cells -> calcium increase -> vasoconstriction of AA (inhibit renin release via juxtagl. Cells) to decrease GFR
Function of ANP and BNP
Decrease Na reabsorption (CT)
Released during high blood volume, reduces blood pressure
ANP - (Atrium stretched)
BNP - (ventricle stretched - natriuretic peptide)
Both cause vascular relaxation of intraglomerular mesangial cells and AA and constriction of EA
Inhibit Renin release, inhibit ADH, inhibit aldosterone,
Inulin clearance
E=F
C inulin = GFR
Creatinine Clearance
E = F + S
All filtered, Never re absorbed
C creat = GFR
GFR inversely proportional to [serum]
PAH Clearance
Freely filtered, complete clearance
C pah = RPF = CV/P
True RPF = C pah/0.9
(90% truly cleared) - 5 vasa recta, 5 fat
Glucose Clearance
Completely reabsorbed
E = F-R = 0
Loop diuretics
Inhibit Na/K/Cl symporter in Thick ALOH
K Sparing Diuretics
Block Na+ or Aldosterone receptor to indirectly inhibit K+ secretion and excretion in the CT
Principle cells controlled by
Hormone aldosterone (Na+ reabsorption)
Na+ excretion depends on
Effective circulating volume (ECV), not [Na plasma]
Renin release stimulated by:
Less AA stretch (low BP)
Less Na+/Cl delivery to macula densa
Sympathetic system
Decreased ANP/BNP
Angiotensin II effects
Vasoconstriction of peripheral vessels (increase BP)
Thirst and salt intake desire
ADH secretion via anterior pituitary
Aldosterone release
Increase Na/K anti porter in PCT & TAL
Contracts AA & EA
Contract intraglomerular mensangial cells to decrease GFR
Actions of Aldosterone
Increase Na reab. (Via principle cells luminal channels = Na, activates basolateral=Na/K)
Increase K secretion (via principle cells, luminal K channels)
Stimulate H ATPase of alpha-intercalated cells
Sympathetic effects on Na+ Reab.
Renin release = Beta-1 receptor
AA & EA vasoconstriction via alpha-1
Na reab. At PCT via alpha-1
Conn’s Syndrone
Hyperaldosterone = hypertension
Increased Na reabsorption at CT
Increased K secretion = hypokalemia
Increased H ATPase activity (increased H secretion, HCO reab.) = metabolic alkalosis
Water diuresis
Increase in urine excretion caused by absence of ADH = hypotonic urine
Anti diuresis
High ADH levels causing high water reabsorption In CT causing hypertonic urine
What stimulates H+ secretion
Increased PCO2
Decreased pH
Increased Aldosterone
Increased Angiotensin II (which acts on Na/H on luminal side)
K+ wasting diuretics
K+ Sparing Diuretics act on
Blocks Principle cell Na+ channels - making lumen more positive therefore excreting H+
Blocks aldosterone receptors
Problems with respiratory acidosis
Sleep apnea
opiates
Problems with respiratory alkalosis
Respiratory diseases
Pneumonia
Problems associated with metabolic acidosis
Diarrhea
Lactic acidosis
Ketoacidosis
Problems associated with metabolic alkalosis
Antacid ingestion Low vascular volume High aldosterone Vomiting Loop/thiazide diuretics
Intracellular buffers and extracellular buffers
Intra - proteins
Extra - phosphate and bicarbonate
Anion Gap
(Na+) - ( HCO - Cl )
Cations - Anions
9-14 normal
Renal response pH equation
pH = 6.1 + log [HCO]/[CO2]
Hypotonic expansion
- H2o
- D5W
- SIADH