Renal Function Flashcards
what are the functions of kidney?
- Excretion of metabolic waste + small solutes (urea+proteins)
- Excretion of drugs
- Acid/Base balance
- Electrolyte Balance- K/Mg/Ca
- Regulation of blood pressure
- Production of EPO (promotes RBC formation)
- Vitamin D Hydroxylation
- Toxin Metabolism:
Insulin- Low BG
Beta 2 microglobulin- product of inflammation metabolism
Medicines
what are the body compartments
intracellular space (inside cell) intravascular space (inside blood vessels + circulatory system) interstitial space (space between blood vessels + cells)
what is extracellular fluid made of
interstitial and intravascular
what are the most abundant cation in extracellular and intracellular fluid
Extracellular fluid- Na (sodium)
Intracellular fluid- K (Potassium)
what are the most abundant anion in extracellular and intracellular fluid
Extracellular fluid- Cl (chlorine)
Intracellular fluid- Proteins
what are nephron functions
- Glomerular filtration (filtration of blood to form the glomerular filtrate)
- Tubule Reabsorption (selective reabsoprtion of substances from GF back into blood)
- Tubule Secretion (secretion of substances from blood into filtrate)
what properties does the glomerular filtration have
Fenestrated endothelium
Glomerular basement membrane (thick unique collagen)
Podocyte foot processes
what is the Glomerular filtration rate in a minute or a day
100ml/min
144L/day
describe the tubular reabsorption and secretion in the PCT
PCT:
- Majority reabsoprtion (70% of glomerular filtrate reabsorbed)
- water follows Na/NaCl
- All glucose + amino acids reabsorbed
what is the epithelium found in the PCT
Cuboidal epithelium
what are the channels found in the PCT
AQP1- Transports water
SGLT1/2- Glucose Transport
Both found in microvilli- optimises surface area
Mitochondria found in the PCT provides energy for _____
Na/K ATPase
what is the principle aim of LOH
Principle method by which conc of urine is varied to deal with water depletion and excess
What is the thin descending limb of LOH permeable and impermeable to
Permeable to water
Impermeable to solutes
what epithelium is the thin descending LOH made of
simple squamous epithelium which has AQP1 for water transport
What is the thick ascending limb of LOH permeable and impermeable to
Permeable to solutes
Impermeable to water
Describe the reabsoprtion of solutes in the thick ascending LOH and the channels involved
- Filtrate moves up the lumen
- Gradient created by Na/K ATPase
- Filtrate meets Na/K/2Cl channel
- Channel Opens and Na/K/2Cl move in
- K leaks back out down the conc. gradient if K channel open
- this creates a + gradient in the lumen
- Ca and Mg moves in between the cells and back into circulation
Describe the role DCT plays in reabsorption
- Only 5% of glomerular filtrate reaches DCT
- site for Ca reabsorption
- Na and Cl cotransporter
- Also has Na/K ATPase which sets up gradient
Describe the role collecting duct plays in reabsoprtion
Intercalated and principal cells found here
- Secretes H+
what are the channels found in collecting duct
Epithelium Na channels and K channels
What is the kidney response to increased tubular flow
Sensed by macula densa
MD releases adenosine
Adenosine causes constriction of afferent arteriole- reduces volume of blood going into glomerulus- prevents excess urine
Adenosine also inhibits renin release -> inhibits efferent constriction
where is macula densa found
DCT
what is the kidney response to decreased tubular flow
Sensed by macula densa MD releases NO and PGE2, causing dilation of afferent arteriole = Increases glomerular blood flow Lack of adenosine causes renin release from juxtaglomerular cells Renin makes angiontensin II Angiotensin II: - Increases ADH production - Vasoconstricts efferent arteriole - Increases aldosterone production - Increases Na reabsorption in the PCT
what is kidneys response to reduced sense of volume due to renin
Efferent glomerular arteriolar constriction preserves waste excretion
Avid tubular sodium and water reabsoprtion preserves extracellular fluid volume
what is the effect on urine solute conc when there is reduced sense of volume
Oliguria (low urine)
Concentrated urine
Low urine Na conc
High urine K conc
