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Summer 2020 - Physiology 2 - Renal > Renal Physiology - Quiz 2 > Flashcards

Renal Physiology - Quiz 2 Flashcards

1
Q

What is the purpose of the Glomerulus?

A

To form an Ultrafiltrate of Plasma from the blood coming in via the Afferent Arteriole

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2
Q

Where does the blood go once it enters the Glomerulus thru the Afferent Arteriole?

A

Travels thru capillaries in the Bowman’s Capsule where Plasma & Small Solutes escape thru openings in the Endothelial Wall

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3
Q

Once the blood reaches the Bowman’s Capsule, where does it go?

A

Thru the basement membrane into the Bowman’s Space, which is continuous w/ the Proximal Tubule

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4
Q

What happens when Negatively Charged proteins try to pass the Basement Membrane?

A

Repelled & Can’t Pass d/t the Basement Membrane’s Negatively Charged Composition

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5
Q

What size molecules can pass thru the Basement Membrane if they are not Negatively Charged?

A

Smaller than 50 Angstroms can pass

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6
Q

How is the Glomerular Filtration Rate (GFR) defined?

A

Total Volume per Minute that leaves the capillaries & Enters the Bowman’s Space

~ 120 mL/min (180 L/day)

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7
Q

What are the Two Major Determinants of Filtration Pressure?

A

Glomerular Capillary Pressure (PGC)

&

Glomerular Oncotic Pressure (pgc)

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8
Q

What heavily influences the Glomerular Capillary Pressure?

A

Renal Artery Pressure & Afferent/Efferent Arteriole Tone

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9
Q

How much Cardiac Output goes to Renal Blood Flow?

A

20% of Cardiac Output - 1200 mL/min

(Only the Liver gets more blood flow than the kidney)

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10
Q

What is the Vasa Recta?

A

Peritubular Capillaries deep in the Medulla & Parallel the Loops of Henle

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11
Q

If the Hct is 40%, how much is the Renal Plasma Flow?

A

~ 660 mL/min –> 120 mL/min is Filtered into Bowman’s Space & only 1% of that becomes urine

Most of what is filtered is reabsorbed

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12
Q

What are the 4 Factors that Deteremine GFR?

A
  1. Ultrafiltration Coefficient - Depends on Capillary Permeability & Surface Area
  2. Oncotic Pressure - Force that Opposes Filtration
  3. Net Hydraulic Pressure - Moves fluid from Capillaries to Bowman’s Capsule
  4. Capillary Plasma Flow Rate - High Flow = More Filtration
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13
Q

How does the body get back Filtered Plasma?

A

Glomerular Capillary Filtration & Capillary Hydrostatic Pressure decreases towards the end near the Efferent Arteriole, where there is an Increase in Oncotic Pressure.

This is where Max Reabsorption into the Vasa Recta & Peritubular Plexi happens.

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14
Q

What are the 3 Variables that determine Glomerular Hydrostatic Pressure?

A

Arterial Pressure

Afferent Arteriolar Resistance

Efferent Arteriolar Resistance

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15
Q

At what BP Range is the Kidney able to Autoregulate to keep the GFR & Renal Blood Flow constant?

A

SBP 80 - 200 mmHg

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16
Q

How does the Kidney’s Autoregulation Mechanism work?

A

Constriction/Dilation of Precapillary Sphincters in the Afferent/Efferent Arterioles

&

↑Na delivery to the Macula Densa to↓GFR

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17
Q

What are Macula Densa?

A

Special Epithelial Cells in the Distal Tubule, containing Golgi Apparatus that secrete substances toward the Afferent & Efferent Arterioles

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18
Q

How does a Sodium Decrease affect the Macula Densa?

A

↓Afferent Arteriole Resistance

&

↑Renin Release from the Juxtaglomerular Cells of the Afferent & Efferent Arterioles

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19
Q

What is the Myogenic Reflex Theory of Autoregulation?

A

↑MAP causes Afferent Arteriole to stretch, then Snap Back & Constrict by Reflex

↓MAP = Afferent Arteriole Dilation by Reflex

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20
Q

What is the Tubuloglomerular Feedback of Autoregulation?

A

↓RBF & GFR causes Less Chloride delivery to the Juxtaglomerular Apparatus, which causes..

Afferent Arteriole Dilation

&

Renin Release –> Angiotensin II –> Efferent Arteriolar Constriction

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21
Q

Excretion is the sum of ________ & _______ minus Reabsorption

A

Excretion is the sum of Filtration & Secretion minus Reabsorption

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22
Q

Reabsorption is more important than secretion, but secretion is important in controlling the amount of _______ & _____ ions that are excreted in the urine

A

Reabsorption is more important than secretion, but secretion is important in controlling the amount of Potassium & Hydrogen ions that are excreted in the urine

23
Q

How is Renal Clearance defined?

A

Volume of Plasma when all substance is removed per unit of time in one pass thru the kidney

24
Q

What is the Renal Clearance if a substance is neither Secreted nor Reabsorbed?

A

Clearance = GFR

EX: Inulin

25
Q

What is the Renal Clearance if a substance is completely Reabsorbed?

A

Clearance = 0

EX: Glucose

26
Q

GFR: 125 = ? % Functioning Nephrons?

A

GFR: 125 = 100% Functioning Nephrons

27
Q

GFR: 12 - 80 = ? % of Functioning Nephrons?

A

GFR 12 - 80 = 10-40% Functioning Nephrons

28
Q

GFR: < 12 = ? % of Functioning Nephrons?

A

GFR: < 12 = <10% of Functioning Nephrons

29
Q

What are the 3 Mechanisms of Reabsorption & Secretion?

A
  • Active Transport
  • Passive Transport
    • Simple - Lipid Soluble/Gas Diffusion
    • Facilitated - Uses Protein Channel/Carrier
  • Secondary Active Transport - Moves solute against Concentration Gradient, using Indirect Energy by coupling to an energy source
30
Q

What are the steps in the Reabsorption of Water & Solutes?

A
  1. Transport across Tubular Epithelial Membranes into Renal Interstitial Fluid
  2. Thru Peritubular Capillary Membrane back into Blood
31
Q

Which Mechanism of Reabsorption does Glucose use?

A

Secondary Active Transport

32
Q

What is the Transport Maximum?

A

Limit of Transport d/t Saturation of Specific Transport System when the amount of solute is delivered to the tubule exceeds the carrying capacity of the carrier proteins & enzymes.

33
Q

How much filtrate is Reabsorbed in the Proximal Convoluted Tubule?

A

65% - most active reabsorption of nutrients, ions, small proteins, and some urea & uric acid happens here in an Iso-Osmotic fashion

PCT is only place where there is Carbonic Anhydrase Present & is the preferred site of Bicarb Reabsorption

34
Q

How much filtrate is Reabsorbed from the Nephron Loop?

A

25% - mostly water

35
Q

What is Reabsorbed at the Distal Convoluted Tubule?

A

To a lesser amount than the PCT….

Sodium

Chloride

Bicarb

Water

(Reabsorption here is controlled by Aldosterone & ANP)

36
Q

What are the 4 Areas of the Nephron?

A

Proximal Convoluted Tubule

Loop of Henle

Distal Convoluted Tubule

Collecting Duct

37
Q

What substances are secreted into the PCT?

A

Organic Acids via Anion Pump

Diuretics

Abx

Organic Bases

Ammonia

38
Q

What are the characteristics of the Fluid in the PCT once all the Secretion & Reabsorption is done?

A

Tubular Flow = 1/3 GFR

Absence of Glucose, Protein, & Amino Acids

Increased Chloride Tubular Concentration

39
Q

What are the 3 Segments of the Loop of Henle?

A

Descending Thin

Ascending Thin

Ascending Thick - most important

40
Q

What are the attributes of the Descending Thin Segment of the Loop of Henle?

A

Highly Water Permeable - 20% H2O Reabsorption

Moderate Solute Permeability

Simple Diffusion

41
Q

What substances can travel across the Ascending Thin Segment of the Loop of Henle?

A

Impermeable to Water

Some Reabsorption of Calcium, Bicarb, and Magnesium

42
Q

The Reabsorption capability of the Thick Ascending Limb of the Loop of Henle is comparable to what?

A

Sodium-Potassium ATPase Pump, which maintains a low Intracellular Sodium Concentration

Considered the Diluting Segment & Impermeable to Water

43
Q

Where is the Target Site of Lasix and the only site where Chloride is Actively Transported?

A

Thick Ascending Limb of the Loop of Henle - has a 1Na+ 1K+ 2Cl- Pump

44
Q

What is the Intraluminal Charge of the Thick Ascending Limb of the Loop of Henle?

A

Positive - helps drives Magnesium & Calcium Reabsorption

45
Q

What forms part of the Juxtaglomerular Complex to provide feedback control of GFR & Blood Flow?

A

First Portion of the Distal Convoluted Tubule

46
Q

What is Reabsorbed at the Early Distal Tubule?

A

Sodium

Chloride

Calcium

Magnesium

47
Q

What are the characteristics of the Later Distal Tubule?

A

Controls Dilution/Concentration of Urine

Water Permeability based on ADH

Sodium Reabsorption & Potassium Secretion controlled by Aldosterone

Secretes Hydrogen via Hydrogen-ATPase against gradient

48
Q

What do Principle Cells do?

A

Regulates Hydrogen & Potassium by reabsorbing Sodium & Water and Secreting Potassium into the Lumen

These cells are found in the Late Distal Tubule & Early Collecting Duct

49
Q

What do Intercalated Cells do?

A

Regulate Hydrogen & Potassium by Reabsorbing Bicarb & Potassium and Secreting Hydrogen into the Lumen

These cells are found in the Late Distal Tubule & Early Collecting Duct

50
Q

Where is the Final Site of Urine Processing?

A

Medullary Collecting Duct

51
Q

How much filtered Water & Sodium is Reabsorbed at the Medullary Collecting Duct?

A

< 10%

52
Q

What is the Medullary Collecting Duct permeable to?

A

Water depending on ADH

Urea

53
Q

What happens when Urea is Reabsorbed from the Medullary Collecting Duct into the Interstitial around it?

A

↑Medulla Osmolality & Contributes to forming Concentrated Urine

54
Q

How does the Medullary Collecting Duct regulate Acid-Base Balance?

A

It can secrete Hydrogen Ions against a large concentration gradient

Summer 2020 - Physiology 2 - Renal (5 decks)

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