Physio glomerular filtration

What is the first step in forming urine?

glomerular filtration

What is the glomerular ultrafiltrate very similar to?

very similar to interstitial fluid

What forces cause filtration?

starling forces cause glomerular capillary hydrostatic fluid

Why is filtration rate higher in glomerular capillaires than the systemic system?

surface area of glomerulus is higher

Podocytes form

barriers against large proteins, second filtration barrier

What is the role of mesangial cells?

Provide structural support to glomerular
capillaries, Contract to regulate capillary surface area, Provide phagocytosis, Secrete substances to modulate GFR and
inflammation

What substances do mesangial cells secrete?

cytokines, growth factors, prostoglandins

What are juxtaglomerular cells?

located in afferent arteriole wall that store and secrete renin

The fenestrated endothelium has a

negative charge to repel plasma proteins

The glomerular basement membrane has a

negative charge and size selection

What is the role of the negative charge on the glomerular capillary barrier?

repel large solutes with negative charges (proteins) and attracts + charges and allows small negative solutes to filter

Where are the location of hydrostatic pressures across glomerular capillaries?

one in capillary blood, the other in the interstitial fluid (Bowman’s space)

Where are the location of oncotic pressure sacross glomerular capillaries?

one in capillary blood, the other in Bowman’s space (should be 0)

The hydrostatic pressure of the glomerular capillaries is

high relative to systemic capillaries, pressure constant along length

Why can hydrostatic glomerular pressure remain constant while oncotic glomerular pressure increases?

we can constrict the efferent arteriole

glomerular capillary blood eventually becomes

peritubular capillary blood

peritubular capillary blood has

high oncotic pressure because it is the driving force for reabsorption

What will cause constrict of afferent arterioles and what are the effects on RPF and GFR?

Resistance increases, RPF and GFR decreases because Pgc decreased, SNS and high angiotensin 2

What are the effects and causes of constriction of efferent arterioles on RPF and GFR?

Resistance increases, RPF decreases, GFR increases because Pgc increased, caused by low angiotensin 2

Which pressure favors filtration from glomerular capillaries into Bowman’s space?

Pgc (hydrostatic pressure of glomerular capillaries)

An increase in plasma protein will cause

an increase in capillary oncotic pressure, decreases filtration pressure, decreases GFR

A decrease in plasma protein will result in

decrease capillary oncotic pressure, increase in filtration pressure, increase GFR (nephrotic syndrome)

A change in Pbs by obstruction of urine flow by stones in ureter will cause

back up in kidneys, fluid/hydrostatic pressure in Bowman’s capsule