Renal Function/Dynamics Glomerular Filtration (Day 1) Flashcards Preview

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Flashcards in Renal Function/Dynamics Glomerular Filtration (Day 1) Deck (68)
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Functions of Kidney

  • Regulation of Water and Electrolyte Balance
  • Excretion of Metabolic Waste
  • Excretion of Bioactive Substances
  • Regulation of Arterial Blood Pressure
  • Regulation of Red Blood Cell Production
  • Regulation of Vitamin D Production
  • Metabolism


What metabolic wastes do the kidneys excrete?


  • Urea (from proteins)
  • Uric Acid (from nucleic acids)
  • Creatinine (from Muscle creatine)
  • Hemoglobin breakdown products
  • Metabolites of various hormones (from endocrine system)

Our bodies continuously form end products of metabolic process.

  • In most cases these end products serve no function and are only harmful at high concentrations


How do the kidneys regulate BP?

  • Blood pressure depends ultimately on blood volume
    • Kidneys' maintenance of Na and H2O balance achieves regulation of blood volume
  • Kidney releases renin from juxtaglomerular cells, acts on angiotensinogen (released by liver) to form angiotensin I
  • Angiotensin I is converted by ACE (mainly by lung, but also renal endothelium) to angiotensin II
  • Angiotensin II acts on:
    • SNS
    • Tubular absorption Na, Cl and K excretion. H2O retention
    • Increase Aldosterone
    • Arteriolar vasoconstriction to increase BP
    • Pituitary gland ADH secretion--> collecting duct H2O absorption


How do the kidneys regulate RBC production?


  • Erythropoietin is released by the kidney and controls erythrocyte production by the bone marrow
    • Secretion is regulated by the partial pressure of oxygen in the kidneys



How does kidney regulate Vitamin D production?


  • Skin exposed by UV radiation (7-dehydrocholesterol--> Cholecalciferol (Vitamine D3)
  • changed by liver to (25-dyroxyvitamin D3)
  •  and then by kidney to (1,25- dihydroxyvitamin D3)--> maintain calcium balance in body
  • 10-15 min exposure needed 2x/week


Why do you need Vitamin D? 

To absorb Calcium


What are some roles kidney plays in metabolism?

  • Glyconeogenesis (from amino acids and glycerol)
  • Renal ammonioagenesis (maintains acid-base balance)


What are the 2 main segments in the kidney?

  • Cortex- function area (outside portion)
    • Area where we actually do things
    • Area of cortex extends into renal columns
    • Cortex is where we have glomeruli and majority of nephrons
    • Bigger need for cortex vs medulla
      • Why we have extensions everywhere in the kidney
  • Medulla- collecting system (inside)
    • Collecting urine as we create it
    • As renal columns extend into medulla, breaks medulla into smaller pieces called renal pyramids


What is the renal papilla? Where is it?

Where we have final urine created.

It is located at top of renal pyramids


What is the renal pelvis?

  • Most dilated area of kidney narros to become ureter--> bladder


Pathway of urine from renal papilla?

Renal papilla--> minor calyx--> major calyx--> renal pelvis--> ureter


What is the renal corpusle?

Renal corpuscle= bowman's capsule and glomerulus

  • Compact tuft of interconnected capillary loops
  • Surrounded by a balloon-like hollow capsule (bowman's capsule)
  • Blood enters and leaves Bowman’s capsule through arterioles
  • A fluid-filled space exists within the capsule
  • This functions to filter the blood


Where is the kidney?

What enters/exits kidney?

What sits on top of kidney?


  • Kidney is retroperitoneal organ
  • Upper part of abd (one portion covered by ribs and portion not)
  • Adrenal gland on top of kidney
  • Each kidney has one artery to them and one vein that exits.


What is a nephron?

  • Nephron- one cell thick tubes, functional unit of kidneys
    • Different segment nephron, different function
    • Heterogenous
    • Mostly cortex nephrons (short nephrons, 80%), some medulla (longer nephrons, 20%)


  • The nephron is very compact
    • Loop of henle and collecting duct= medulla
    • Corpuscle/distal tubule= cortex


What is the proximal tubule?

  • Drains from Bowman’s capsule
  • Consists of two segments, the proximal convuluted tubule and the proximal straight tubule
  • Majority of reabsorption happens here


  • Don’t need to differentiate within proximal tubule
  • 60-70% reabsorption happens in proximal tubule
    • Remainder (~30%) in distal tubule


What is the loop of henle?

  • Made up of descending thin limb, ascending thin limb, and the thick ascending limb
  • Functions to create and maintain a medulla osmotic gradient
  • Macula Densa demarkes the area between the Loop and the Distal Tubule


What is the distal tubule?

  • Only the distal convoluted tubule
  • Functions as continued area of reabsorption and regulation
  • Where rest of absorption happens
  • Looks at Na levels, and changes how much volume needs to be reabsorbed for needs of body at that time


What is the collecting duct?

  • Last portion of an independent nephron
  • Functions as the concentrating mechanism of the nephron


  • Collecting duct uses gradient created by loop of henle
  • Function is to determine concentration and dilution of urine
  • Does this by responding to hormone called ADH (anti-diuretic hormone, also called vasopressin)


What is ADH?

  • ADH  (anti-diuretic hormone or vasopressin) opens up water channels on collecting ducts which allows water to be reabsorbed into blood stream
    • More water reabsorbed, more blood volume you have and higher BP
    • Concentrates urine as it draws water out of urine


What are cell types like in the nepron before the distal tubule?

Homogenous, all same cell types


What are the 2 cell types present in the distal tubule?

  • Principal cells (primary cell type)
  • Intercalated cells (acid/base cells)
    • Actually two kinds (alpha and beta)


What is the juxtaglomerular apparatus?

  • Juxtaglomerular cells- release renin
    • In between distal tubule and afferent arteriole
  • Macula densa cells in between distal tubule
    • Function as sensory cells. Detect level of Na in plasma
    • Also sense drop in amount of filtration happening
    • Indication that we need to increase the amount of filtration happening
    • Sense low flow, and stimulate juxtaglomerular cells to secrete renin. Renin will then be released into blood stream, go to glomerulus


What is important about the loop of henle?

Creates the osmotic gradient necessary in order to reabsorb solutes


What type of nephron creates the largest gradient?

Juxtamedullary nephron (longest loop of henle)


What is blood flow into and out of glomerulus?

Afferent arteriole--> glomerulus--> efferent arteriole


Where does blood go from efferent glomerulus?

  • Depends on type of nephron
    • Cortical nephron: peritubular capillaries
    • Juxtagmedullary: goes to vasa recta


How much cardiac output goes to the kidney?

20% ~1L/min


What is blood flow from renal artery? (unsure if we have to know all of this...)

  • Renal artery
  • interlobar arteries
  • arcuate arteries
  • interlobular (cortical radial arteries)
  • afferent arteriole (site of regulation)
  • glomerular capillaries
  • efferent arteriole (NOT venule)
  • peritubular capillaries (only if cortical nephron, otherwise goes to vasa recta)
  • venule
  • veins


What are peritubular capillaries?

  • Peritubular capillaries extend from cortical efferent arterioles and are profusely distributed throughout the cortex


What are vasa recta?

  • From the juxtamedullary glomeruli, long efferent arterioles extend downward into the outer medulla, where they divide many times to form bundles of parallel vessels called the vasa recta