Glomerular filtration depends on three main pressures. One pressure promotes
filtration and two pressures oppose filtration:
promotes: filtration by forcing water and solutes in blood plasma through the filtration
membrane
Capsular hydrostatic pressure (CHP) is the hydrostatic pressure which promotes/opposes the filtration
opposes:
by fluid already in the capsular space and renal tubule. (back pressure)
Blood colloid osmotic pressure (BCOP), which is due to the presence of proteins
such as albumin, globulins, and fibrinogen in blood plasma, promotes/opposes filtration?
also opposes filtration.
Net filtration pressure (NFP) is the total pressure that opposes/promotes filtration.
promotes
The amount of filtrate formed in both/one kidney(s) each minute is
the glomerular filtration rate (GFR).
both
In adults, the GFR averages 125 mL/min in males and 105 mL/min in females.
ok
The mechanisms that regulate glomerular filtration rate operate in two main ways:
surface area
Three mechanisms control GFR:
Neural
Renal autoregulation: consists of two mechanisms:
stretch
chemo
Neural Regulation of GFR:
Like most blood vessels of the body, those of the kidneys are supplied by
parasympathetic/sympathetic ANS fibers that release norepinephrine: causes vasodilation/constriction
through the activation of α1 receptors, which are particularly plentiful in the
smooth muscle fibers of afferent arterioles
sympathetic
constriction
With moderate sympathetic stimulation, both afferent and efferent arterioles
constrict to the same degree. Blood flow into and out of the glomerulus is
restricted to the same extent, which decreases GFR only slightly.
This lowering of renal blood flow has two consequences:
greater blood flow to other body tissues.
Hormonal regulation:
AngioX 2 (a very potent vasoconstrictor) is released only when necessary and vasoconstrict
efferent arteriole, increasing GFR.
tensin
ANP , atrial natriuretic peptide, is the only regulation of GFR that in/decreases GFR
increases
The functions of the tubule are:
secretion
Excretion = filtration + secretion - reabsorption
ok
Solutes that are reabsorbed by both active and passive processes include:
- glucose,
- amino acids,
- X, and
- ions: Na+, K+, Ca2+, Cl−, HCO3− (bicarbonate), and HPO42− (phosphate).
urea
Most small proteins and peptides that pass through the filter also are
reabsorbed, usually via pinocytosis
true/false
true
Epithelial cells all along the renal tubule and duct carry out reabsorption, but
proximal X tubule cells make the largest contribution.
convoluted
a substance being reabsorbed can take two routes before entering a peritubular capillary:
between
passing through
obligatory or facultative?
obligatory
obligatory or facultative?
facultative
These transporters in the kidney can reabsorb up to 240 mg / min of glucose ..
ezelsbruggetje?
24/08 is siph dr verjaardag
What will happen if the glucose kidney transporters limit is exceeded?
glycosuria
P.61 for overview of kidney and absorpion/excretion
ok