Glomerular Filtration
Juxtaglomerular Cells >>Adrenal Cortex
Angiotensin II Stimulates to secrete aldosterone to promote water retention and sodium retention
Glomerular Endothelial Cells
Have large fenestrations through which solutes pass
Net Filtration Pressure
promotes filtration OUT of the glomerular capillaries NFP=GBHP - (CHP+BCOP)
Filtration Membrane>> Basement Membrane
restricts the passage of particles due to their size and electronegativity. -large plasma proteins (albumins) are too big to pass through membrane; glomerular filtrate is only .3% protein while blood plama is 7% protein.
Renin-Angiotensin Mechanism>>Juxtaglomerular Cells
secrete the enzyme renin, which triggers the conversion of angiotensin to angiotensin II.
Myogenic Mechanism>> When blood pressure RISES
smooth muscle fibers contract and constrict afferent arteriole, which decreases blood flow into glomerulus to reduce GFR
Myogenic Mechanism>> When Blood pressure DROPS
smooth muscle fibers relax and dilate afferent arterioles, which increase blood flow into glomerulus to raise GFR
Filtration Pressure>>Filtration Membrane
thin and porus
Neural regulation
uses sympathetic nerve fibers to send signals to afferent arterioles that constrict them and decrease the flow of blood into the glomerular capillaries in order to reduce GFR and maintain systemic blood pressure.
Glomerular Filtrate
water and substances that are dissolved in blood plasma get forced out of the glomerular capillaries into Bowman's capsule and form glomerular filtrate.
Glomerular Filtrate Composition
water, electrolytes, glucose, fatty acids, amino acds, vitamins, and nitrogenous wastes
Autoregulation
-does not completely block changes in GFR by allows for flucuations within narrow limits. -cannot compensate for extreme variations in blood pressure but it will prevent large changes in water and solute excretion.
Renin-Angiotensin Mechanism
Activated by a drop in blood pressure.
Tubuloglomerular Feedback>> When GFR FALLS
Flow of blood from an afferent arteriole into glomerulus is increased.
Glomerular Filtration Rate (GFR)
Refers to amount of filtrate that is formed per minute in all of the renal corpuscles of both kidneys. Females: 105mL/min which produces 150L of filtrate per day. Males:125mL/min which produces 180 L of filtrate per day
Filtration Pressure>>Blood Pressure
_______in the glomerular capillaries is high
Myogenic Mechanism
occurs when arterial blood pressure changes, which affects smooth muscle cells in walls of the afferent arterioles.
Capsular Hydrostatic Pressure (CHP)
opposes additional filtration because there is a high rate of filtration and because fluid is already present in the renal tubule.
Blood Colloid Osmotic Pressure (BCOP)
also opposes filtration because of the plasma proteins that are present in blood plasma
Juxtaglomerular Cells >>Pituitary Gland
angiotensin II stimulates pituitary gland to secrete ADH to increase water absorption.
Kidney Infection of Kidney Trauma
can damage the filtration membrane and allow plasma proteins and/or formed elements to enter the filtrate causing proteinura and hematuria, respectively.
Juxtaglomerular Cells >>Angiotensin II
constricts both afferent and efferent arterioles to reduce GFR.
Renal Autoregulation
describes ability of the kidneys to maintain constant renal blood flow and glomerular filtration despite changes in arterial blood pressure
Filtration Membrane
endothelial cells in glomerular capillaries join podocytes to form a filtration membrane that filters water and small solutes, but not plasma proteins or formed elements.
Tubuloglomerular Feedback>>When GFR is ELEVATED
filtrate flows through renal tubule too fast for it to reabsorb enough NaCl. -Macula Densa cells release vaso constrictor that decreases flow of blood from afferent arteriole into glomerulus to decrease GFR.
If GFR is Too HIGH
filtrate will flow through the renal tubules too quickly for them to reabsorb water and solutes. -urinary output rises and creates risk for becoming dehydrated.
If GFR is TOO LOW
filtrate will flow through the renal tubules too slowly and wastes will get reapsorbed. -creates a risk for developming azotemia
Filtration Membrane>> Pedicels
foot like extensions from podocytes that wrap around the glomerular capillaries to form filtration slits that can block passage of negative ions
Tubuloglomerular Feedback
involves the juxtaglomerular apparatus
Filtration Pressure>>Glomerular Capillaries
long, and provide a large surface area for filtration
Glomerular Blood Hydrostatis Pressure (GBHP)
main force responsible for moving water and solutes out of blood plasma through the filtration membrane.