Introduction to Nephrology Flashcards
essential functions of the kidney
- maintains optimal extracellular environment
- excretes waste products (urea, creatinine, UA, others)
- balanced excretion of water and electrolytes
- hormone production
- clearance of medications
where are glomeruli located?
cortex
where are tubules located?
both cortex and medulla
basic unit of the kidney
nephron
how many nephrons in adult kidney?
1 to 1.3 million
where is the ultrafiltrate of plasma formed?
glomerulus
where is the ultrafiltrate further modified?
tubules
what is reabsorption?
REMOVAL of a substance from the ultrafiltrate
what is secretion?
ADDITION of a substance from the ultrafiltrate
gross components of kidney from out to in
cortex –> inner and outer medulla –> calyces –> pelvis –> and ureter
how are the tubules divided?
- proximal tubule
- loop of Henle
- distal convoluted tubule
- connecting segment
- initial collecting tubule
- cortical and medullary collecting tubule
after modification of the glomerular ultrafiltrate by the tubules, how urine sequentially drained?
calyces –> renal pelvis –> ureter –> bladder
what percentage of cardiac output is sent to the kidneys?
- 20% (1/5 of CO!!!)
- 1 liter/min of BLOOD and 600 mL/min of plasma
circulation of blood to the kidneys
renal artery –> interlobar arteries –> arcuate arteries –> interlobULar arteries –> afferent arteriole into glomerulus
renal circulatory anatomy allows precise modulation of
salt and water balance
the glomerular capillary loop is comprised of what?
- endothelial cell
- glomerular basement membrane (GBM)
- podocyte
the glomerular capillary loop is structurally supported by which cells?
mesangial cells
how does the glomerular capillary wall restrict solute movement?
size and charge
what are the cell types that make up the mesangium?
- mesangial cells
- macrophages and monocytes
major determinant of ultrafiltrate formation from glomerular capillary wall into Bowman space
Starling forces
GFR =
(capillary porosity x surface area) x (pressure of GC - pressure of BS - oncotic pressure of plasma)
GFR rises and falls in proportion to changes in what?
renal plasma flow rate (RPF)
capillary hydrostatic pressure is influenced by which variables?
- aortic (renal artery) pressure
- afferent and efferent arteriolar resistances
afferent and efferent arteriolar resistances are controlled by what?
- myogenic control
- tubuloglomerular feedback (TGF) from macula densa
- vasodilatory/vasocontrictor hormones (A2, NE, PGs, endothelin, ANP, and NO)
which arteriole regulates the RPF and GFR in parallel?
Afferent arteriole
which arteriole regulates the RPF and GFR inversely?
Efferent arteriole
how does body keep RPF and GFR at a constant level?
autoregulation and tubuloglomerular feedback (TGF)
between what MAPs is autoregulation able to maintain a constant GFR?
40 to 70 mmHg
macula densa response to increased NaCl delivery
MD sends signals to afferent arteriole to cause vasoconstriction to decrease GFR and bring it back to normal
macula densa response to decreased NaCl delivery
MD sends signals to afferent arteriole to cause vasodilatation to increase GFR
