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Physiology - Guyton & Hall > Chapter 27 - Glomerular Filtration > Flashcards

Chapter 27 - Glomerular Filtration Flashcards

1
Q

Glomerular filtrate composition

A
  • protein-free
  • devoid of cellular elements
  • similar concentration of salts and organic molecules as the concs in plasma
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2
Q

(True/False)

Fatty acids are completely filtered in the glomerular

A

False

low-molecular weight substances such as calcium and fatty acids are not completely filtered in the glomerulus do to it being partially bounded to plasma proteins

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3
Q

Glomerular filter fluid rate is determined by:

A

(1) the balance of hydrostatic and colloid osmotic forces acting across the capillary membrane

(2) the capillary filtration coefficient (Kf) , the product of permeability, and filtering surface area of the capillaries

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4
Q

High filtration rate of the glomerulus is due to

A
  • high glomerular hydrostatic pressure
  • large capillary filtration coefficient
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5
Q

GFR of an average adult human

A

125 ml/min or 180L/day

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6
Q

Fraction of renal plasma flow that is filtered

A

0.2

20% of plasma flowing through the kidney that is filtered

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7
Q

Filtration fraction

A

filtration fraction = GFR / Renal plasma flow

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8
Q

3 major layers of the glomerular capillary membrane - as the filtration barrier

A

(Lumen)

(1) endothelium of the capillary with fenestrae

(2) basement membrane

(3) a layer of epithelial cells (podocytes) surrounding the outer surface of the capillary basement membrane

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9
Q

ALL LAYERS of the glomerular capillary wall provide a (1) barrier to filtration of plasma protein and

(2) a means to rapid filtration of water and most solutes in the plasma

A

A. Capillary endothelium
(1) fixed negative charges
(2) holes or fenestrae

B. Basement membrane
(1) strong negative electrical charges from proteoglycans
(2) collagen and proteoglycan fibrillae meshwork with large spaces

C. Epithelial cells - podocytes
(1) negative charges
(2) gaps (slit pores) along the footlike processes (pedicles)

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10
Q

Filterability:
(1) 100% -
(2) 75% -
(3) 0% -

A

(1) substance is filtered as freely as water
(2) substance is filtered only 75% as rapidly as water
(3) substance is not filtered

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11
Q

Pore size of glomerular membrane

A

8nm

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12
Q

Proteins excreted in urine

A

proteinuria or albuminuria

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13
Q

(True/False)

The cause of minimal change nephropathy are unclear but are partially related to an immunological response and abnormal T-cell secretion of cytokines - injuring podocytes and increasing premeability

A

True

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14
Q

GFR

A

GFR = (Kf) x (net filtration pressure)
Where net filtration is the sum of osmotic forces (PG - PB - πG + πB)

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15
Q

Osmotic forces in the glomerulus:
1.) PG
2.) PB
3.) πG
4.) πB

A

1.) hydrostatic pressure in the glomerulus - favors filtration (60mmHg)

2.) hydrostatic pressure in the bowman’s capsule - opposes filtration (18mmHg)

3.) colloid osmotic pressure of the glomerulus - opposes filtration (32mmHg)

4.) colloid osmotic pressure of the bowman’s capsule - favors filtration (0mmHg)

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16
Q

Net filtration pressure

A

10mmHg

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17
Q

Kf of the glomerulus

A

12.5 ml/min/mmHg of filtration pressure
400 times as high as Kf of most capilliaries

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18
Q

distention and dilation of the renal pelvis and calyces

A

hydronephrosis

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19
Q

Osmotic pressure of plasma in:
(1) afferent arteries
(2) glomerular capillaries
(3) efferent arteries

A

(1) 28 mmHg
(2) 32 mmHg
(3) 36 mmHg

20
Q

Two factors that influence the glomerular capillary colloid osmotic pressure:

A

(1) the arterial plasma colloid osmotic pressure
(2) fraction of plasma filtered by the glomerular capillaries - filtration fraction

21
Q

INCREASED GLOMERULAR CAPILLARY COLLOID OSMOTIC PRESSURE () GFR

A

DECREASES

22
Q

INCREASED GLOMERULAR HYDROSTATIC PRESSURE () GFR

A

INCREASES

23
Q

Primary means for physiological regulation of GFR

A

changes in glomerular hydrostatic pressure

24
Q

Glomerular hydrostatic pressure is determined by

A

1.) arterial pressure
2.) afferent arteriolar resistance
3.) efferent arteriolar resistance

25
Q

Donan Effect

A

the higher the protein concentration, the more rapidly the colloid osmotic pressure rises because of the interaction of ions bound to the plasma proteins

26
Q

combined blood flow through both kidneys in a 70 kg man

A

1100 ml/min or about 22% of the cardiac output

27
Q

percent of total body weight of 2 kidneys combined

A

0.4%

28
Q

(True/False)

The arterial-venous extraction of oxygen in the kidneys is low but is twice the rate of the brain

A

True

29
Q

Renal oxygen consumption varies in proportion to ()

A

renal tubular sodium reabsorption

30
Q

Renal Blood Flow

A
31
Q

Renal vein pressure

A

3 to 4 mmHg

32
Q

GFR arterial pressure range

A

80 to 170 mmHg

33
Q

(True/False)

Blood flow in renal medulla accounts for only 1% to 2% of total renal blood flow

A

True

34
Q

Activation of sympathetic nerve fibers in the renal arteries lead to

A

decrease renal blood flow and GFR

35
Q

Norepinephrine, epinephrine, and endothelin (1) renal blood vessels and (2) GFR

A

(1) constrict
(2) decrease

36
Q

(True/False)

Angiotensin II preferentially constricts efferent arterioles raising glomerular hydrostatic pressure while reducing renal blood flow

A

True

37
Q

Endothelin-Derived nitric oxide (1) renal vascular resistance and (2) GFR

A

(1) decreases
(2) increases

38
Q

In afferent arterioles of the kidneys, (1) and (2) are released to counteract the vasoconstrictor effects of angiotensin II

A

(1) nitric oxide
(2) prostaglandins

39
Q

Prostaglandins and Bradykinin (1) renal vascular resistance and (1) GFR

A

(1) decreases
(2) increases

40
Q

Tubular reabsorption is () leaving 1.5L/day to be excreted in urine

A

178.5 L/day

41
Q

The juxtaglomerular complex is composed of

A

(1) macula densa cells in the initial portion of the distal tubule

(2) juxtaglomerular cells in the walls of the afferent and efferent arterioles

42
Q

Macula densa cells sense

A

sodium chloride delivery to the distal tubule

43
Q

Decrease in sodium chloride concentration (detected by the macula densa) intiates

A

(1) decrease resistance to blood flow in the afferent arterioles - raises glomerular hydrostatic pressure

(2) INCREASES RENIN RELEASE FROM THE juxtaglomerular cells of the afferent and efferent arterioles

44
Q

GFR changes by only a few percentage points, even with large fluctuations in arterial pressure between ()

A

75 - 160 mmHg

45
Q
A
46
Q

Myogenic mechanism

A

the ability of individual blood vessels to resist stretching during increased arterial pressure to prevent an excessive increase in renal blood flow and GFR

Physiology - Guyton & Hall (21 decks)

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