Renal Physiology - Quiz 2 Flashcards Preview

Summer 2020 - Physiology 2 - Renal > Renal Physiology - Quiz 2 > Flashcards

Flashcards in Renal Physiology - Quiz 2 Deck (54)
Loading flashcards...

What is the purpose of the Glomerulus?

To form an Ultrafiltrate of Plasma from the blood coming in via the Afferent Arteriole


Where does the blood go once it enters the Glomerulus thru the Afferent Arteriole?

Travels thru capillaries in the Bowman's Capsule where Plasma & Small Solutes escape thru openings in the Endothelial Wall


Once the blood reaches the Bowman's Capsule, where does it go?

Thru the basement membrane into the Bowman's Space, which is continuous w/ the Proximal Tubule


What happens when Negatively Charged proteins try to pass the Basement Membrane?

Repelled & Can't Pass d/t the Basement Membrane's Negatively Charged Composition


What size molecules can pass thru the Basement Membrane if they are not Negatively Charged?

Smaller than 50 Angstroms can pass


How is the Glomerular Filtration Rate (GFR) defined?

Total Volume per Minute that leaves the capillaries & Enters the Bowman's Space

~ 120 mL/min (180 L/day)


What are the Two Major Determinants of Filtration Pressure?

Glomerular Capillary Pressure (PGC)


Glomerular Oncotic Pressure (pgc)


What heavily influences the Glomerular Capillary Pressure?

Renal Artery Pressure & Afferent/Efferent Arteriole Tone


How much Cardiac Output goes to Renal Blood Flow?

20% of Cardiac Output - 1200 mL/min

(Only the Liver gets more blood flow than the kidney)


What is the Vasa Recta?

Peritubular Capillaries deep in the Medulla & Parallel the Loops of Henle


If the Hct is 40%, how much is the Renal Plasma Flow?

~ 660 mL/min -->  120 mL/min is Filtered into Bowman's Space & only 1% of that becomes urine

Most of what is filtered is reabsorbed


What are the 4 Factors that Deteremine GFR?

  1. Ultrafiltration Coefficient - Depends on Capillary Permeability & Surface Area
  2. Oncotic Pressure - Force that Opposes Filtration
  3. Net Hydraulic Pressure - Moves fluid from Capillaries to Bowman's Capsule
  4. Capillary Plasma Flow Rate - High Flow = More Filtration


How does the body get back Filtered Plasma?

Glomerular Capillary Filtration & Capillary Hydrostatic Pressure decreases towards the end near the Efferent Arteriole, where there is an Increase in Oncotic Pressure.

This is where Max Reabsorption into the Vasa Recta & Peritubular Plexi happens.


What are the 3 Variables that determine Glomerular Hydrostatic Pressure?

Arterial Pressure

Afferent Arteriolar Resistance

Efferent Arteriolar Resistance


At what BP Range is the Kidney able to Autoregulate to keep the GFR & Renal Blood Flow constant?

SBP 80 - 200 mmHg


How does the Kidney's Autoregulation Mechanism work?

Constriction/Dilation of Precapillary Sphincters in the Afferent/Efferent Arterioles


↑Na delivery to the Macula Densa to↓GFR


What are Macula Densa?

Special Epithelial Cells in the Distal Tubule, containing Golgi Apparatus that secrete substances toward the Afferent & Efferent Arterioles


How does a Sodium Decrease affect the Macula Densa?

↓Afferent Arteriole Resistance


↑Renin Release from the Juxtaglomerular Cells of the Afferent & Efferent Arterioles


What is the Myogenic Reflex Theory of Autoregulation?

↑MAP causes Afferent Arteriole to stretch, then Snap Back & Constrict by Reflex

↓MAP = Afferent Arteriole Dilation by Reflex


What is the Tubuloglomerular Feedback of Autoregulation?

↓RBF & GFR causes Less Chloride delivery to the Juxtaglomerular Apparatus, which causes..

Afferent Arteriole Dilation


Renin Release --> Angiotensin II --> Efferent Arteriolar Constriction


Excretion is the sum of ________ & _______  minus Reabsorption

Excretion is the sum of Filtration & Secretion minus Reabsorption


Reabsorption is more important than secretion, but secretion is important in controlling the amount of _______ & _____ ions that are excreted in the urine

Reabsorption is more important than secretion, but secretion is important in controlling the amount of Potassium & Hydrogen ions that are excreted in the urine


How is Renal Clearance defined?

Volume of Plasma when all substance is removed per unit of time in one pass thru the kidney


What is the Renal Clearance if a substance is neither Secreted nor Reabsorbed?

Clearance = GFR

EX: Inulin


What is the Renal Clearance if a substance is completely Reabsorbed?

Clearance = 0

EX: Glucose


 GFR: 125 = ? % Functioning Nephrons?

GFR: 125 = 100% Functioning Nephrons


GFR: 12 - 80 = ? % of Functioning Nephrons?

GFR 12 - 80 = 10-40% Functioning Nephrons


GFR: < 12 = ? % of Functioning Nephrons?

GFR: < 12 = <10% of Functioning Nephrons


What are the 3 Mechanisms of Reabsorption & Secretion?

  • Active Transport 
  • Passive Transport
    • Simple - Lipid Soluble/Gas Diffusion
    • Facilitated - Uses Protein Channel/Carrier
  • Secondary Active Transport - Moves solute against Concentration Gradient, using Indirect Energy by coupling to an energy source


What are the steps in the Reabsorption of Water & Solutes?

  1. Transport across Tubular Epithelial Membranes into Renal Interstitial Fluid
  2. Thru Peritubular Capillary Membrane back into Blood