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.