urinary pt 2 Flashcards
The production of urine involves:
Glomerular filtration:, Tubular reabsorption: , and Tubular secretion:
fluid filtered from the blood to the
glomerulus
Glomerular filtration:
amount of filtrate
formed in all the renal corpuscles of both kidneys each
minute.
glomerular filtration rate (GFR):
returning important substances
from the filtrate back to the body
Tubular reabsorbtion
the movement of waste materials
from the body to the filtrate.
Tubular secretion:
_____ s the formation of a protein-free
filtrate (ultrafiltrate) of plasma across the glomerular
membrane.
Glomerular filtration
main force that “pushes”
water and solutes through the filtration membrane
(promotes filtration). *Primary determinant of amount of
filtrate
Blood hydrostatic pressure
from the capsular space
(opposes filtration)
Capsular hydrostatic pressure
osmotic pressure of
plasma proteins “pulling” on water (opposes filtration)
Blood osmotic (oncotic) pressure:
Final part of the ascending limb of the loop of Henle
contacts the afferent arteriole for that _____
renal corpuscle
Columnar tubule cells in the afferent arteiole region are the
macula densa
Wall of the afferent arteriole contains
juxtaglomerular (JG)
cells: modified
smooth muscle fibers
Juxtaglomerular
apparatus (JGA):
juxtaglomerular cells
and macula densa
Regulation of the GFR
- Renal autoregulation: ____
- Neural regulation:______
- Hormonal regulation: ______
-by kidneys
- by the ANS
-by angiotensin II and atrial
natriuretic peptide (ANP)
- Stretching in the glomerular capillaries or pressure and
flow monitored in the JGA, causes - afferent arterioles to constrict (decreasing
blood flow and GFR) or dilate (increasing
blood flow and GFR) appropriately
Renal autoregulation of GFR occurs by two means:
sympathetic ANS fibers
cause vasoconstriction
Neural regulation:
Two hormones contribute to regulation of GFR
Angiotensin II, and ANP (released under high bp)
vasoconstrictor of both afferent and
efferent arterioles (reduces GFR)
Angiotensin II:
_____ causes the
glomerulus to relax,
increasing the surface
area for filtration
atrial natriuretic peptide (ANP). (released under high
bp)
is the process of returning important
substances (“good stuff”) from the filtrate back into the renal
interstitium, then into the renal blood vessels… and
ultimately back into the body.
Tubular reabsorption
The “good stuff” being reabsorbed is ________, and any small proteins that might have
inadvertently escaped from the blood into the filtrate.
glucose, electrolytes, vitamins, water,
amino acids
______ percent of the glomerular filtrate is reabsorbed
(most of it in the PCT)
99
Reabsorption into the interstitium has two routes:
Paracellular reabsorption and transcellular reabsorption
passive process between
adjacent tubule
cells
paracellular reabsorption
through an individual cell.
transcellular reabsorption
Tubular Reabsorption can be active or passive?
both
transported substances include Na+ , Cl– , Ca2+, H+,
HCO3– , glucose, HPO42– , SO42– , NH4+, urea, all amino
acids, and lactic acid.
actively tubular reabsorption
Reabsorption of water can be _____,
but it always moves by osmosis down its concentration
gradient
obligatory or facultative.
water follows solutes as they are
reabsorbed (to maintain the osmotic gradient).
obligatory reabsorb.
variable water reabsorption,
adapted to specific needs.
- regulated by ADH and aldosterone
- through principal cells
facultative reabsorb.
To control water reabsorption, the kidney establishes a
______ flow between the filtrate in the limbs of
the Loops of Henle and the blood in the peritubular
capillaries and Vasa Recta.
countercurrent (a current flowing in an opposite direction to another.)
Two types of countercurrent mechanisms exist in the
kidneys: countercurrent ______ and
countercurrent _______.
multiplication. exchange
increasing osmotic
gradient is formed in the interstitial fluid of the renal medulla
as a result of countercurrent flow
Countercurrent multiplication:
passive exchange of solutes and
water between the blood and interstitial fluid of the renal
medulla as a result of countercurrent flow.
- This provides oxygen and nutrients to the renal medulla
without washing out or diminishing the gradient.
Countercurrent exchange:
_____ mechanisms contribute to reabsorption of fluid and
electrolytes and the formation of concentrated urine
both
is the movement of substances from the
capillaries which surround the nephron into the filtrate
tubular secretion
tubular secretion occurs by
active transport
The process of tubular secretion controls
pH
Hydrogen and ammonium ions are secreted to decrease
_____ in the body, (bicarbonate is conserved.)
acidity
Secreted substances include ______, and some drugs;
amount often controlled
H+, K+, NH4+
Maintaining body’s proper pH primarily uses the lungs and kidneys.
- lungs eliminate _____.
◦ Provides a ____ response (minutes) decreasing H+
- kidneys eliminate ____ and ____ions and conserve bicarbonate.
◦ This is a ___ response (hours-days)
CO2. rapid. H+. NH4+ . slower
Five hormones affect the extent of Na+, Cl–, Ca2+, and
water reabsorption as well as K+ secretion by the renal
tubules. These hormones, all of which are key to
maintaining homeostasis of not only renal blood flow and
B.P., but systemic blood flow and B.P., are
I angiotensin II
l antidiuretic hormone (ADH)
l aldosterone
l atrial natriuretic peptide (ANP)
l parathyroid hormone (PTH)
due to high blood pressure
l increases GFR
l dilutes the medulla
l decreases Na+ reabsorption
l reduces RAAS (renin+aldosterone)
ANP
due to hypertonicity
§increases permeability to water in the collecting duct and
DCT, reabsorbing it.
Hormones and Homeostasis
ADH
Low blood volume and blood pressure, or sympathetic NS
the cells of the JGA secrete
renin
_____ changes angiotensinogen to angiotensin I
renin
Angiotensin converting enzyme (ACE) converts
angiotensin I to angiotensin II, which causes:
- Vasoconstriction decreasing GFR.
- increasing reabsorption of water and electrolytes in the
PCT. - the adrenal cortex to release aldosterone
stimulates the principal cells in the collecting
ducts to reabsorb more Na+ and Cl– and secrete more K+.
§reabsorbing more Na+ and Cl– causes more
water to be reabsorbed,
which increases blood
volume and blood
pressure
aldosterone
