BMS 108 Ch. 17 Renal I Flashcards

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0
Q

What are the four things kidneys regulate?

A
  1. Volume of plasma&raquo_space; BP
  2. Waste product removal from plasma
  3. Concentration of electrolytes
  4. Plasma pH
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1
Q

What is the function of the kidneys?

A

to regulate plasma and interstitial fluid by formation of urine

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2
Q

What are the gross anatomy parts of the kidney?

A
Cortex
Medulla
Renal Pyramids
Renal Columns
Minor Calyces
Major Calyx
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3
Q

What is a nephron?

A

The functional unit of a kidney, responsible for forming urine.

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4
Q

How many nephrons per kidney?

A

more than 1 million

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5
Q

What does a nephron consist of?

A

small tubules and associated capillaries

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6
Q

List the specific parts of the nephron tubules.

A
Glomerular capsule
Proximal convoluted tubule
Descending and Ascending limbs of the Loop of Henle
Distal convoluted tubule
Collecting duct
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7
Q

List the renal blood vessels of the nephron.

A
renal artery
afferent arteriole
glomerulus
efferent arteriole
peritubular capillaries
vasa recta
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8
Q

What is the capsule that surrounds the glomerulus called?

A

Glomerular capsule or Bowman’s capsule

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9
Q

What is the structure formed by both the glomerulus and Bowman’s capsule called?

A

the renal capsule

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10
Q

Where does filtrate captured by the renal capsule go?

A

proximal convoluted tubule

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11
Q

What is the function of the nephron?

A

to filter, reabsorb and secrete

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12
Q

Describe the basic pathway that forms urine in the nephron.

A

Filtration in the renal corpuscle
Reabsorption in the PCT, Loop of Henle
Secretion in the DCT
Urine formed after Collecting Duct

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13
Q

What are the three layers that glomerular filtrate must pass through?

A
  1. Glomerular capillaries
  2. Basement membrane
  3. Slit diaphragms of podocytes
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14
Q

Glomerular capillaries are __________ – have large pores between its endothelial cells.

A

fenestrated

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15
Q

What is in the initial filtrate? What doesn’t get through?

A

H2O and everything dissolved (electrolytes, waste products, hormones, glucose and amino acids); proteins

16
Q

A small percentage of proteins (albumin) gets into the filtrate, how is this reabsorbed?

A

receptor-mediated endocytosis in the PCT

17
Q

What is Glomerular Filtration Rate (GFR)?

A

The volume of filtrate produced by both kidneys per minute. Average about 125ml/min in men; totals about 180L/day (45 gallons)

18
Q

What mechanism regulates GFR?

A

Controlled by extrinsic (sympathetic NS) and intrinsic (renal autoregulation) mechanisms. Vasoconstriction or dilation of afferent arterioles affects rate of blood flow to glomeruli and thus GFR.

19
Q

What is renal autoregulation (intrinsic)?

A

the ability of the kidneys to maintain relatively constant GFR in the face of fluctuating BP.

20
Q

What two mechanisms are responsible for renal autoregulation?

A

myogenic constriction and tubuloglomerular feedback

21
Q

What is myogenic constriction?

A

constriction of afferent arteriole due to smooth muscle responding to an increase in arterial pressure.

22
Q

What is tubuloglomerular feedback?

A

achieved via effects of paracrine regulators on afferent arterioles that tell the arterioles to constrict.

23
Q

What kind of feedback is tubuloglomerular feedback?

A

negative feedback

24
Q

How does tubuloglomerular feedback work?

A

Increased flow of filtrate sensed by macula densa (part of the juxtaglomerular apparatus) in think ascending Loop of Henle&raquo_space; signals the afferent arterioles to contrict.

25
Q

Sympathetic (extrinsic) activity ________ the afferent arteriole.

A

constricts

26
Q

How does sympathetic activity in the kidneys help regulate BP?

A

(via blood volume) by decreasing GFR, thus decreasing urine production with increases blood volume.

27
Q

What are the walls of the PCT constructed of?

A

single layer of cuboidal cells with millions of microvilli

28
Q

How does the PCT facillitate reabsorption?

A

During reabsorption, salt, water, and other molecules needed by the body are transported from the lumen through the tubular cells and into surrounding peritubular capillaries.

29
Q

Water is never ________. ___________ are transporter and ________ follows by osmosis.

A

transported; other molecules; water

30
Q

What is the significance of PCT reabsorption?

A
  • about 65% Na+, Cl- and H2O is reabsorbed in PCT and returned to the bloodstream. Glucose and a.a. also reabsorbed here.
  • And additional 20% is reabsorbed in descending Loop of Henle
  • Thus 85% of filtered H2O and salt are reabsorbed early in the tubule
31
Q

Filtered flucose and amino acids are normally _______% reabsorbed from filtrate.

A

100%

32
Q

How are glucose and amino acids reabsorbed by the PCT?

A

via carrier mediated cotransport with Na+

33
Q

Describe the mechanism of reabsorption in the PCT.

A
  1. There is coupled transport of glucose and Na+ into the cytoplasm
  2. Primary active transport of Na+ across basolateral membrane by Na+/K+ pump
  3. Glucose then transported out of the cell via facilitated diffusion and is reabsorbed into the blood
34
Q

Actions in the Loop of Henle depends on ________________.

A

concentration gradients in the kidney’s medulla

35
Q

In order for H2O to be reabsorbed, interstitial fluid must be __________.

A

hypertonic

36
Q

What is the osmolality of the medulla? cortex? What is this concentration gradient the result of?

A

1200 -1400mOsm; 300mOsm; from the relationship between the Loop of Henle and vasa recta

37
Q

What is the Countercurrent Multiplier System?

A

Countercurrent flow and proximity allows the descending and ascending limbs of the Loop of Henle to interact in way that causes osmolality to build in the medulla.

38
Q

Describe Countercurrent Exchange in the Vasa Recta.

A
  • vasa recta is permeable to salt, H2O (via aquaporins) and urea
  • recirculates salt, trapping some in the interstitial fluid of the medulla
  • reabsorbs H2O coming out of the descending limb (due to oncotic pressure)
  • Ascending section has fenestrated capillaries that draw in H2O secreted by the descending limb.