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233 test 2 > LECTURE 9 > Flashcards

LECTURE 9 Flashcards

1
Q

Glomerular filtration

A

Blood pressure in glomeruli forces plasma contents into glomerular capsule

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2
Q

Tubular reabsorption

A

Substances in tubular fluid are reabsorbed and enter peritubular fluid–May diffuse into peritubular capillaries or vasa recta

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3
Q

Tubular secretion

A

blood and peritubular fluid are transported to lumen of renal tubule.

Important because not all waste products are filtered at renal corpuscle, such as protein-bound drug metabolites

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4
Q

Water conservation

A

ADH, aquaporins, and aldosterone play a big role in this along the DCTs and collecting ducts

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5
Q

Glomerular Filtration

A

Only substances 3nm or smaller can pass filtration membrane of glomerulus

Water, ions, glucose, AAs, FAs, vitamins, and nitrogenous wastes

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6
Q

Fenestrated glomerular endothelium

A

Keeps blood cells and most proteins in the capillaries

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7
Q

Basement membrane

A

glue-like proteoglycans-

Negative charges on which repel negatively charged albumins

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8
Q

Filtration slits

A

Spaces created by network of foot processes (pedicels) of the podocytes that surround the glomerular capillaries

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9
Q

Decrease in renal BP will decrease NFP and GFR, name 2?

A
  • Can be caused hemorrhage or dehydration

* Decrease in filtration can result in azotemia

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10
Q

Increase in GFR may be detrimental, why?

A
  • Filtrate may move through renal tubule too fast to reabsorb solutes
  • Can result in electrolyte depletion and dehydration
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11
Q

Kidneys use autoregulation and both types of extrinsic regulation to control GFR, what are they?

A

Myogenic mechanism and tubuloglomerular feedback

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12
Q

Myogenic mechanism, what causes it? (2)

A

When stretched (due to increase in BP) smooth muscle cells in afferent arteriole contract to decrease blood flow, which decreases GFR

Afferent arteriole smooth muscle relaxes if BP drops, thereby increasing blood flow and GFR

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13
Q

Autoregulation of GFR, If GFR is up what is elevated?

A

NaCl concentration of tubular fluid will be elevated

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14
Q

If GFR is up, it is Sensed by cells of macula densa, which release what?

A

Release ATP that ultimately signals smooth muscle cells of afferent arteriole to contract.

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15
Q

How does the Macula densa function?

A
  1. As GFR increases, NaCl content of tubular fluid increases
  2. Macula densa cells sense this by absorbing more Na+/ K+/ Cl-
  3. Release ATP in response to this
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16
Q

Where does the ATP released from macula densa go?

A

mesangial cells, which are located between the glomerular capillaries

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17
Q

Mesangial cells convert ATP to what?

A

adenosine (a paracrine)

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18
Q

What does ATP arrival do?

A

contracts cells, and constricts capillaries to reduce flow

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19
Q

What does Adenosine signals granular (AKA-juxtaglomerular or JG) cells do?

A

Large smooth muscle cells around afferent arteriole Contract and constrict afferent arteriole in response to adenosine

20
Q

what is the Neural regulation of GFR?

A

Sympathetic division (Fight or flight):

POST-ganglionic fibers innervate blood vessels of kidneys

21
Q

What does Release of NE (NorEpi.) do? (3)

A
  1. Causes vasoconstriction of afferent arterioles
  2. Contraction of granular cells
  3. Reroutes blood flow away from kidneys, toward CNS and skeletal muscles
22
Q

NE release also triggers neuroendocrine reflex, how? (2)

A
  1. Sympathetic stim. of granular cells = release Renin

2. Conserves fluids

23
Q

Renin-angiotensin-aldosterone mechanism operates in response to what?

A

decrease in BP, GFR, and/or tubular fluid osmolarity

all interrelated

24
Q

Renin released by granular cells in response to what? (3)

A
  1. To decreased stretch of afferent arteriole,
  2. signals from macula densa when filtrate Na+is low,
  3. Sympathetic impulses
25
Q

Renin is Enzyme/hormone that converts what to what?

A

angiotensinogen to angiotensin I

26
Q

Angiotensin I -> angiotensin II by what?

A

ACE in capillaries of the lungs

27
Q

Angiotensin II restores fluid volume, BP, and GFR, How? (4)

A
  1. widespread systemic vasoconstriction
  2. Constricts efferent arterioles
  3. Stimulates secretion of aldosterone by adrenal cortex and ADH in the posterior pituitary
  4. Increases reabsorption of Na+and water
28
Q

What is the function of Aldosterone? (2)

A
  1. Increases reabsorption of Na+ & indirectly water
    (in the DCT and collecting ducts)
  2. “ACTH”–Low extracellular Na+or high K+can trigger release of ACTH
29
Q

ADH does what? (3)

A
  1. Stimulates thirst centers of hypothalamus
  2. Increased water reabsorption (Aquaporin formation in DCT and collecting ducts results in increased water reabsorption)
  3. Small volume of concentrated urine formed
30
Q

Atrial natriuretic peptide is released when?

A

response to elevated blood volume and pressure

31
Q

Atrial natriuretic peptide is released from where?

A

cardiac muscle cells of atria in response to excess stretch

32
Q

Atrial natriuretic peptide is released Relaxes what?

A
  1. afferent arteriole

2. mesangial cells, increasing surface area of filtration membrane

33
Q

Atrial natriuretic peptide inhibits the release what?

A

renin from granular cells

34
Q

What effects does this have on downstream chemicals, and ultimately GFR/fluid volumes?

A

Inhibits renin stopping the angiotensinogen –> angiotensin 1. thus stoping ADH and Aldosterone from being produced.

35
Q

Primary site for tubular reabsorption is the?

A

PCT->65% (108 liters) of filtrate reabsorbed by PCT

36
Q

What cells in the microvilli of PCT facilitates absorption?

A

Cuboidal cells

37
Q

Sodium is reabsorbed three ways:

A
  1. Transcellular -Symport w/glucose, AAs, or lactate
  2. Transcellular- Antiport -> Na+and H+
  3. Paracellular -solvent drag
38
Q

Na+/K+ pumps in basal membrane results in what?

A

Transcellular Na+ moving into peritubular capillaries and water follows Na+when it can

39
Q

99% of glucose and AAs reabsorbed transcellularly along PCT, via what?

A

SGLTs (Sodium-Glucose Transporters)

40
Q

How much water per day reabsorbed here through permanent aquaporins and paracellularly via solvent drag?

A

108 liters (65%) of water per day reabsorbed

41
Q

Reabsorption by the Nephron Loop: how much in the Thin Descending limb?

A

15% of water reabsorbed here
(Permeable to water•
Relatively impermeable to solutes)

42
Q

Reabsorption by the Nephron Loop: how much in the Thick Descending limb?

A

25% of sodium and chloride ions

43
Q

Thick ascending limb does what? (3)

A
  1. Cotransport of Na, K, and Chloride into peritubular fluid
  2. K+ is reabsorbed transcellularly and paracellulary
  3. NaCl stays in peritubular fluid
44
Q

What percentage of original filtrate reaches DCT as tubular fluid?

A

20%, but still too large of a volume to be removed as urine

45
Q

DCT selectively reabsorbs in response to what hormones?

A

aldosterone, ADH, and PTH

46
Q

Principal cells have hormone receptors to what? (3)

A
  1. Aldosterone stimulates principal cells (along with thick ascending limb cells, and some collecting duct cells) to reabsorb Na+while secreting K+
  2. ADH causes aquaporins to be created in DCT (along with collecting duct) so that water is reabsorbed
  3. PTH stimulates thick ascending limb and DCT to reabsorb Ca2+ (about 33% of what is filtered)

233 test 2 (8 decks)

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