Renal part 1c

Question 0

WHat two forces promote ultrafiltration out of capillary

Answer 0

1. Intracapillary hydrostatic pressure

2. Interstitial oncotic pressure

Question 1

What are the forces involved in glomerular ultrafiltration

Answer 1

1. Consider first the movement of fluid across systemic capillaries
2. Fluid exchange between plasma and interstitium: Role of Starling Forces

Question 2

What two forces Oppose ultrafiltration out of capillary

Answer 2

1. Plasma oncotic pressure

2. Tissue hydrostatic pressure

Question 3

Generalized edema involves what?

Answer 3

Na retention and expansion of the entire ECF. Commonly seen in Cardiac, hepatic and renal failure

Question 4

T or F, Hydrostatic pressure remains relatively constant along the glomerular capillary. If true, Why?

Answer 4

True, due to presence of resistance points before and after the glomerular capillaries or presence of afferent arteriole and efferent arterioles

Question 5

Does Oncotic pressure decrease or increase along the capillary. This is in contrast to systemic capillaries. Why does this occur?

Answer 5

It progressively increases along the capillary. This is because as fluid is filtered out the concentration of non-filterable proteins increases

Question 6

The Net Filtration Pressure (NFP) = 0 when?

Answer 6

When Oncotic pressure increases to the point that it = [Pgc - Pbs]

Question 7

T or F, NFP is much different in glomerular capillaries compared to systemic capillaries

Answer 7

False, it is similar in glomerular and systemic capillaries (10-20)

Question 8

Even though the NFP is similar in glomerular and systemic capillaries, is the volume filtered across the glomerular capillaries also similar?

Answer 8

No, It is much greater across glomerular capillaries than across systemic capillaries because glomerular capillary ultrafiltration coefficient (Kf) is much higher than in systemic capillaries

Question 9

How do changes in Kf affect filtration dynamics?

Answer 9

Primarily by affecting the rate of change of oncotic pressure

Question 10

GFR (glomerular filtration rate) is regulated primarily by what?

Answer 10

Primarily by regulating glomerular capillary hydrostatic pressure (Pgc)

• Increase in Pgc = Increase in GFR (vice versa)

Question 11

T or F, Alterations in either afferent or efferent arteriolar resistance can affect Pgc

Answer 11

True

Question 12

GFR is physiologically regulated primarily by changing what? via what two things?

Answer 12

Changing resistance (Diameter) of afferent areteriole via:

1. Renal sympathetic nerves (vasoconstrictor thus decrease GFR)
2. Angiotensin II (Vasoconstrictor) - affects both aff. and eff. arteriole

Question 13

What are the Major renal vasodilatory prostaglandins?

Answer 13

PGE2 and PGI2 (prostacyclin)

Question 14

What is Edema?

Answer 14

Abnormal expansion of the interstitial fluid compartment

Question 15

Localized edema due to changes in one or more starling forces can be shown in what 3 examples?

Answer 15

1. Increased Pc (capillary hydrostatic pressure) due to venous obstruction
2. Increased Pc and Kf due to inflammation
3. Increased (pie)i due to lymphatic obstruction (prevents return of protein to the systemic circulation