Glomerular structure and function Flashcards
Basic functions of the urinary system:
- Maintain water balance
- Maintain salt balance
- Maintain pH
- Excrete metabolic waste
- Blood glucose regulation
- Endocrine
- Vitamin D
2 hormones produced by the kidneys:
- Renin
2. EPO
Urethras cross what on the way to the bladder?
Bifurcation of the common illiac vessels
Order of arteries in kidney:
Renal –> Segmental –> interlobar –> arcuate –> cortical radiate
What kind of capilary beds are found in the nephron?
Double capillary beds
Capilaries that follow the renal tubule:
Peritubular capillaries OR vasa recta
What % of nephrons are cortical?
80%
What % of nephrons are juxtamedullary?
15%
Vasa recta are found in what type of nephron?
Juxtamedullar
Special features of renal corpuscle for filtration:
- Fenetrated endothelium
- Basement membrane
- Podocytes, foot processes, filtration slits
Charge of basement membrane:
Negative
Ultrafiltration =
Passive process in which hydrostatic pressure forces fluids and solutes through a membrane
Glomerular filtrate contains:
Amino acids Glucose Ions Water Urea Creatinine etc.
JGA =
Juxtaglomerular appartus
Cells of the JGA =
Juxtaglomerular cells
Macula densa cells
Mesangial cells
Where are juxtaglomerular cells?
Afferent arteriole
Where are macular densa cells?
DCT
Function of mesangial cells =
Communicate between MD and JG cells
Type of autoregulation/intrinsic regulation of GFR =
Tubulo-glomerular feedback
Function of MD cells =
Respond to [NaCl] and release or inhibit vasoconstrictors.
High NaCl = vasoconstrict
Low NaCl = dilate
Ex vasoconstrictor released by MD
ATP
What kind of receptor is a MD cell?
Chemoreceptor
RAAS =
Renin- angiotensin - aldosterone system
Renin is made in the
Kidneys
Function of renin
Converts angiotensinogen into angiotensin I
Angiotensinogen is formed…
In the liver
Function of ACE
Convert angiotensin I to angiotensin II
ACE is made in the …
Lungs
Function of angiotensin II =
- Hypothalamus: Increase thirst and ADH
- Increase Na+ and H2O resorbtion
- Increase K+ excretion
- Vasoconstriction
- Formation of aldosterone
Aldosterone is produces in the
Adrenal glands
What kind of molecule is aldosterone?
Mineralcorticoid
Function of aldosterone:
Upregulate the Na+-K+ exchanger. Increased Na+ and H20 retention. Increased K+ excretion.
What is common in patients activating RAAS?
Hypokalaemia
RC =
Renal clearance. Volume of plasma that is cleared of a substance in 1 min (ml/min)
Quick and dirty measure of GFR =
Creatinine
More accurate measure of GFR =
Renal clearance ratio
GFR =
amount of fluid filtered into the Bowman’s space per unit time.
Equation for RC =
c = ([u]x x V) / [p] x
Conc of substance x in urine times flow rate. divided by Conc of x in plasma
Renal clearance ratio equation =
Cx / Cinulin
Inulin =
Freely filtered not secreted or reabsorbed
RCR = 1
Clearance same as inulin. Neither reabsorbed or secreted.
Ex of substance with RCR =1
Creatinine
RCR < 1
Substance isn’t freely filtered OR is reabsorbed
Ex of substance with RCR < 1
Isn’t freely filtered = albumin
Reabsorbed = glucose
RCR > 1
Substance is secreted
Ex of substance with RCR > 1
Drug metabolites
Common causes of acute renal injury can be broken into …
- Pre-renal
- Renal
- Post-renal
Pre-renal causes of AKI
Hypovolemia, low DP, heart failurw, vasoactive mediators/drugs
Renal causes of AKI
- Acute tubular necrosis (ischemia)
- Glomerularnephritis
- Interstitial nephritis
Post-renal causes of AKI
Uretal/bladder obstruction, kidney/bladder stones
Common causes of CRF:
Hypertension
T2 diabetes
Glomerular diseases
How many stages of chronic kidney diseases are there?
5
stages of CKD:
- Normal GFR, kidney damage
- Mild reduced GFR
- Moderate reduced GFR
- Severe reduced GFR
- End-stage renal disease
Renal function of end-stage renal disease:
< 15 ml/min (or dialysis)
Clinical manifestations of chronic renal failure:
- Accumulation of nitrogenous wastes
- Altered water, electrolyte and acid-base balance
- Mineral and skeletal disorders
- Anemia and coagulation disorders
- Hypertension and alterations in CV function
- Gi disorders
- Neuro complications
- Immunological disorders