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Physiology > Renal: Tubular Reabsorption and Secretion > Flashcards

Renal: Tubular Reabsorption and Secretion Flashcards

1
Q

What is the most prevalent cation in the body?

A

Sodium (Na+)

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2
Q

What is the most prevalent anion in the body?

A

Chloride (Cl-)

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3
Q

Creates concentration gradient as moves through medulla and has some reabsorption

A

Loop of Henle

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4
Q

Use a membrane protein to facilitate diffusion of ion from high to low concentration

A

Facilitated Diffusion

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5
Q

Active Transporter

A

Primary Active Transport

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6
Q

Rely on Na+ gradient by Na+ ATPase active transporter

A

Secondary Active Transport

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7
Q

What’s the majority of ions in Extracellular Fluid?

A

Sodium

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8
Q

What’s the majority of ions in Intracellular Fluid?

A

Potassium

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9
Q

True/False: Sodium always moves UP its concentration gradient

A

False. DOWN

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10
Q

What transporter is on the Apical membrane?

A

Na+ - Glucose via Secondary Active Transport by Symport. Glucose moves UP its concentration gradient.

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11
Q

What transporters are on the Basolateral membrane?

A

Na+ - Potassium. Secondary Active Transport by Antiport ; GLUT-2. Sodium and Glucose goes into the blood. Potassium pumped back into blood and tubular lumen

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12
Q

Under normal conditions, Glucose is HIGHLY reabsorbed and freely filtered. What happens with Glucose in Diabetics?

A

High Blood Glucose level. Glucose is in the urine. Glucose is filtered but not reabsorbed, thus it is excreted.

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13
Q

Transporters’ Maximum (Tmax) differs between Nephrons. Which have higher and lower Tmax?

A

Longer Prox. Tubule - More Transporters, Higher Tmax

Shorter Prox Tubule - less Transporters, Lower Tmax

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14
Q

Tmax value

A

320 mg/min

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15
Q

What happens if Glucose levels are “below, at, and above” Tmax?

A

Below Tmax: No Glucose in urine
At Tmax: No Glucose in urine
Above Tmax: Glucose in urine

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16
Q

What helps with reabsorption in the Proximal and Distal Tubule?

A

Microvilli to increase surface area for reabsorption

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17
Q

What are the characteristics of Organic Substances (about 100% are all reabsorbed in Proximal Tubule)?

A 
Freely filtered
Reabsorbed similar way to Na+/Glucose
Have Secondary Active Transport
Use Transporters..exhibit Tmax
Has Specificity (D vs. L Glucose
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18
Q 
Glucose
Amino acids
Acetate
Krebs cycle intermediates
Water-soluble vitamins
Lactate
Acetoacetate
Small ions
A

Organic Substances

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19
Q 
active
Tmax
above what is normally filtered
specificity
inhibitable by drugs and disease
NOT outside the proximal tubule
A

Transporters

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20
Q

GFR X Px

A

Filtered Load (FL)

Ex: 180 L/day X 140 mEq/L=25,200 mEq

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21
Q

True/False: Sodium is reabsorbed in all parts of the Renal Nephron/Tubule

A

True

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22
Q

Chloride is an example of Para-cellular Pathway because?

A

Chloride (neg. charge) is pulled across tight junctions because of Na+ and other organic solutes’ movement/reabsorption
No transporter
Not reabsorbed across membrane

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23
Q

While sodium is reabsorbed along Apical membrane what follows it for re-absorption too?

A

Water. Every time sodium and organic ions are reabsorbed, water follows

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24
Q

Descending limb of Loop of Henle is permeable and impermeable to what?

A

permeable to water
impermeable to solutes

Concentration

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25
Q

Ascending limb of Loop of Henle is permeable and impermeable to what?

A

permeable to solutes
impermeable to water

Dilution

26
Q

What are the cell types in the Distal Tubule?

A 
Principal Cells - in latter DT (Aldosterone-mediated)
Intercalated Cells (alpha and beta) - in medullary collecting duct
27
Q

Aldosterone (steroid) causes:

A

Increase Na+/K+ ATPases on Basolateral membrane
Open Na+ channels on Apical membrane
Open K+ channels on Apical membranr

28
Q

Mechanisms at the Early part of Distal Tubule

A

Block Na+/Cl- transporter. Cause No re-absorption of water and sodium…increase urine

29
Q

Mechanisms at the late part of Distal Tubule and Collecting Duct

A

Block Na+ channels on Apical membrane
Block Aldosterone function
Cause no re-absorption of water and sodium…increase urine

30
Q

Osmolarity

A

Concentration of Solutes

31
Q

Potassium (consumed from diet) is stored where?

A

Stored inside cells

32
Q

What is the net affect of Normal-High K diet on Distal Tubule and Cortical Collecting Duct?

A

Secretion

33
Q

What is the net affect of Low K diet on Distal Tubule and Cortical Collecting Duct?

A

Re-absorption

34
Q

Potassium, cation, is reabsorbed by “Bulk Flow” although a lot is not reabsorbed, it is not reabsorbed across membrane, but is not electrical charge dependent. What pathway and ion is similar?

A

Para-cellular Pathway

Similar to being pulled like Chloride but isn’t electrical charge dependent

35
Q

Majority of Potassium is excreted where?

A

Urine

36
Q

Least Potassium is excreted where?

A

Feces

37
Q

Control of Potassium has what kind of feedback?

A

Negative

38
Q

Aldosterone is impacted by what?

A

Potassium levels

Blood Pressure Levels (thus, blood volume levels)

39
Q

High Potassium levels cause Aldosterone to be _____?

A

Secreted

40
Q

Low Potassium levels cause Aldosterone to be _____?

A

Reabsorbed

41
Q

What is blood volume (blood pressure) relationship to potassium?

A

Low BV, Low K+

High BV, High K+

42
Q

Sequence of events to restore Low Blood Volume levels to normal:

A

Low BV:

Aldosterone release causes Increased Na+/H20 reabsorption which Increases BV, BP, and Potassium secretion levels

43
Q

Relationship between plasma K+ levels and Aldosterone

A

Increased plasma K+ concentration, Increased Aldosterone Secretion

Decreased plasma K+ concentration, Increased Aldosterone reabsorption

44
Q

Calcium is important for ______

A

Muscle contractility and 2nd messenger system

45
Q

Vitamin D is essential for absorption of what?

A

Calcium

46
Q

True/False:

Calcium is highly reabsorbed

A

True

Less than 5% of Calcium is in Urine

47
Q

Calcium and Phosphate are always connected. They bind to one another in bones (shouldn’t bind together in blood). Is Calcium active when bound to Phosphate?

A

No

48
Q

What is Parathyroid Hormone (PTH) impacts on Calcium and Phosphate?

A

Increases calcium, Decreases Phosphate

49
Q

True/False:

Phosphate is more excreted than Calcium

A

True.

3-20% of Phosphate is in Urine

50
Q

When there’s High Blood Calcium levels, Thyroid Gland releases______

A

Calcitonin to decrease blood Calcium levels

51
Q

When there’s Low Blood Calcium levels, Parathyroid Gland releases______

A

Parathyroid Hormone (PTH) to increase blood Calcium levels

52
Q

True/False:

In the Proximal Tubule, the trasnporter for Calcium reabsorption is UNKNOWN

A

True

53
Q

What part of the Nephron has the most PTH receptors?

A

Distal Tubule

54
Q

Majority of Calcium reabsorption is where in the Nephron?

A

Proximal Tubule. 60%

55
Q

Impact of PTH at the Distal Tubule

A

Increases Calcium channels on Apical membrane
Increases Calcium ATPase on Basolateral Membrane

Overall, more Calcium reabsorption

56
Q

Sequence of events for Hypocalcemia

A

Parathyroid releases PTH…Increases Calcium levels..Calcium resorption by Bones.. Increases Blood Calcium levels

Parathyroid releases PTH…Activate Vitamin D..Calcium reabsorption by GI system..Increases Blood Calcium levels

57
Q

Aldosterone at the Distal Tubule/Collecting Duct impacts what?

A

Increases NaCl, water reabsorption

Increases K+ secretion

58
Q

ADH at the Proximal Tubule, Distal Tubule, Collecting Duct impacts what?

A

Increases NaCl, water reabsorption

Increases H secretion

59
Q

ANP (ANF) at the Distal Tubule/Collecting Duct impacts what? ANP = Atrial Natriuretic Peptide/Factor

A

Decreases NaCl reabsorption thus, Decrease Blood Volume

60
Q

PTH at the Proximal Tubule, Thin/Thick Ascending Loop of Henle, Distal Tubule impacts what?

A

Pi secretion

Increases Ca reabsorption

61
Q

ADH at the Distal Tubule/Collecting Duct impacts what?

A

Increases Water reabsorption

Physiology (5 decks)

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