Renal Basics Flashcards
The majority of sodium is reabsorbed in which segment of the nephron?
proximal convoluted tubule (50-55%), Na+/H+ exchangers, Na+ cotransporter (glucose/phosphate), Factors: Angiotensin II, Norepi, Reduced tubular flow.
The major intracellular cation
Potassium
The major extracellular cation
Sodium
Names the parts of the nephron in order
Glomerulus (Afferent and efferent arterioles) , bowman’s Capsule, proximal convoluted tubule, Thin descending limb of loop of Henle, Thin ascending limb of loop of Henle, Thick ascending limb of loop of Henle, Distal convoluted tubule, cortical collecting tubule–> Medullary collecting tubule.
The glomerular filtration barrier consists of what components?
glomerular endothelial cells, glomerular basement membrane, filtration slit diaphragm arising from glomerular epithelial cells (podocytes)
The glomerular filtration barrier is based on selectivity
size and charge. Positive and small gets through
What is the role of the kidney?
1) Clearance: excretion of waste products of metabolism, drugs and toxin
2) Homeostasis: sodium/volume, water/osmolality, electrolytes, acid-base
3) Hemodynamic and endocrine: renin, erythropoeitin, 1, 25- vitamin D
What is the intracellular fluid volume of 70 kg patient
28 liters: Intracellular fluid is 40% of weight
What is the total body water of 70 kg patient
42 liters: total body water is 60% of weight
What is extracellular fluid volume of 70 kg patient
14 liters: extracellular fluid is 20% of weight
What is the plasma volume of 70 kg patient
3.5 liters: plasma volume is 5 % of weight
Extracellular fluid is divided into what two compartments
Plasma volume 5% of total weight and interstitial Space 15 %
Electrolyte composition of intracellular compartment of body fluid
- major cation: K+
- major anions: proteins, phosphates, organic anions
Electrolyte composition of extracellular compartment of body fluid
- major cations: Na+
- major anions: Cl-, HCO3-
Balance what is in input, out and distribution
Input: Intake (enteric, IV) + production (catabolism generates H+).
Output: Excretion + consumption/destruction (metabolism + cellular growth)
Distribution: Intracellular/ extracellular shift and interstitial/ intravascular shift
Sodium homeostasis key point
water follows sodium: changes in sodium homeostasis results in changes in body fluid volume not sodium concentration
An increase of sodium intake will generally result in
net gain in bdy fluid (solute + water). ingestion/retention of proportional amount of water to maintain serum sodium concentration unchanged
Sodium mode of reabsorption in loop of henle
35-40% Na+/K/2CL- co transporter. Flow dependent
Sodium mode of reabsorption in distal tubule
5-8% Na+/Cl- co-transport, flow-dependent
Sodium mode of reabsorption in collecting Tubule
2-3% Na+ Channels. Aldosterone, down-regulated by ANP
Sodium is taken out by
NA/K+-ATPase 3 NA (out cell) and 2 K (in cell)
Renin stimulated how (kidney endocrine function)
when reduced distal tubular flow indicated by fall in tubular Cl-, B-adrenergic sympathetic activity
Renin effects
renin–> activated liver to Release angiotensinogen-> Angiotensin I (ACE from lungs convert it to ) Angiotensin II–> increase vascular tone (Ang II) and activates adrenal to release aldosterone, thus reduce Urine sodium. angII act in proximal and aldosterone in distal tubule
Role of kidney in Erythropoeitin
stimulate erythroid progenitor in bone marrow to differentiate in RBC.
Role of kidney in calcitriol (active vitamin D)
Activates vitamin D in response to hypocalcemia and hypophosphatemia.
parathyroid/ PTH–>kidney and bones. In kidney changes calcidiol to active form in calcitriol
Calcitrol increase small intestine reabsorption of calcium and mobilization of bone –> increase serum calcium
Clearance of waste is achieve by
generation of large volume of glomerular filtrate, of which almost all electrolytes and water are reabsorbed, leaving urine concentration in waste products (urea, creatinine)
Homeostasis is achieve by kidney by
selective reabsorption and secretion by the tubules of key substance such as sodium, water, potassium, bicarbonate/H+, calicum
