Renal: Tubular Reabsorption and Secretion Flashcards Preview

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Flashcards in Renal: Tubular Reabsorption and Secretion Deck (61):
1

What is the most prevalent cation in the body?

Sodium (Na+)

2

What is the most prevalent anion in the body?

Chloride (Cl-)

3

Creates concentration gradient as moves through medulla and has some reabsorption

Loop of Henle

4

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

Facilitated Diffusion

5

Active Transporter

Primary Active Transport

6

Rely on Na+ gradient by Na+ ATPase active transporter

Secondary Active Transport

7

What's the majority of ions in Extracellular Fluid?

Sodium

8

What's the majority of ions in Intracellular Fluid?

Potassium

9

True/False: Sodium always moves UP its concentration gradient

False. DOWN

10

What transporter is on the Apical membrane?

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

11

What transporters are on the Basolateral membrane?

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

12

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

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

13

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

Longer Prox. Tubule - More Transporters, Higher Tmax
Shorter Prox Tubule - less Transporters, Lower Tmax

14

Tmax value

320 mg/min

15

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

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

16

What helps with reabsorption in the Proximal and Distal Tubule?

Microvilli to increase surface area for reabsorption

17

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

Freely filtered
Reabsorbed similar way to Na+/Glucose
Have Secondary Active Transport
Use Transporters..exhibit Tmax
Has Specificity (D vs. L Glucose

18

Glucose
Amino acids
Acetate
Krebs cycle intermediates
Water-soluble vitamins
Lactate
Acetoacetate
Small ions

Organic Substances

19

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

Transporters

20

GFR X Px

Filtered Load (FL)

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

21

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

True

22

Chloride is an example of Para-cellular Pathway because?

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

23

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

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

24

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

permeable to water
impermeable to solutes

Concentration

25

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

permeable to solutes
impermeable to water

Dilution

26

What are the cell types in the Distal Tubule?

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

27

Aldosterone (steroid) causes:

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

28

Mechanisms at the Early part of Distal Tubule

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

29

Mechanisms at the late part of Distal Tubule and Collecting Duct

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

30

Osmolarity

Concentration of Solutes

31

Potassium (consumed from diet) is stored where?

Stored inside cells

32

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

Secretion

33

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

Re-absorption

34

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?

Para-cellular Pathway
Similar to being pulled like Chloride but isn't electrical charge dependent

35

Majority of Potassium is excreted where?

Urine

36

Least Potassium is excreted where?

Feces

37

Control of Potassium has what kind of feedback?

Negative

38

Aldosterone is impacted by what?

Potassium levels
Blood Pressure Levels (thus, blood volume levels)

39

High Potassium levels cause Aldosterone to be _____?

Secreted

40

Low Potassium levels cause Aldosterone to be _____?

Reabsorbed

41

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

Low BV, Low K+
High BV, High K+

42

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

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

43

Relationship between plasma K+ levels and Aldosterone

Increased plasma K+ concentration, Increased Aldosterone Secretion

Decreased plasma K+ concentration, Increased Aldosterone reabsorption

44

Calcium is important for ______

Muscle contractility and 2nd messenger system

45

Vitamin D is essential for absorption of what?

Calcium

46

True/False:
Calcium is highly reabsorbed

True

Less than 5% of Calcium is in Urine

47

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?

No

48

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

Increases calcium, Decreases Phosphate

49

True/False:
Phosphate is more excreted than Calcium

True.

3-20% of Phosphate is in Urine

50

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

Calcitonin to decrease blood Calcium levels

51

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

Parathyroid Hormone (PTH) to increase blood Calcium levels

52

True/False:
In the Proximal Tubule, the trasnporter for Calcium reabsorption is UNKNOWN

True

53

What part of the Nephron has the most PTH receptors?

Distal Tubule

54

Majority of Calcium reabsorption is where in the Nephron?

Proximal Tubule. 60%

55

Impact of PTH at the Distal Tubule

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

Overall, more Calcium reabsorption

56

Sequence of events for Hypocalcemia

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

Aldosterone at the Distal Tubule/Collecting Duct impacts what?

Increases NaCl, water reabsorption
Increases K+ secretion

58

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

Increases NaCl, water reabsorption
Increases H secretion

59

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

Decreases NaCl reabsorption thus, Decrease Blood Volume

60

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

Pi secretion
Increases Ca reabsorption

61

ADH at the Distal Tubule/Collecting Duct impacts what?

Increases Water reabsorption