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Phys and Pharm > Renal Phys > Flashcards

Renal Phys Flashcards

1
Q

What are the 3 functions of the kidney?

A
  1. Regulatory
    -volume
    -Blood composition
  2. Excretory
    - Nitrogen excretion, protein breakdown
    -drug elimination
  3. Hormonal
    -production of erythropoetin, calcitrol, renin
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2
Q

The functional unit of the kidney is the _____________. What does it consist of?

A

Nephron
consists of:
1. Proximal convoluted tubule (PCT)
2. Loop of Henle
3. Distal convuluted tubule (DCT), which empties into collecting duct

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3
Q

How does the glomerular filtration membrane allow ultrafiltration?

A

it separates out formed elements and proteins from plasma then sends the plasma to Bowman’s capsule

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4
Q

What is the glomerulus?

A

it is a network of twisted capillaries which acts as a filter for the passage of protein free and red blood cell free filtrate to the proximal convuluted tubules

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5
Q

_____________ + ______________ = renal corpuscle

A

Bowman’s capsule, gloerulus

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6
Q

How is the glomerulus clinically significant?

A
  1. certain molecular weights are able to get through the glomerulus but some cannot
  2. sodium/potassium: no problem with passage
  3. Albumin: too large to get through, if glomerulus damaged, albumin will get through and show up in urine
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7
Q

_________________ supply blood to the glomerulus

A

Afferent arterioles

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8
Q

capillaries converge into _________________ and form peritubular capillaries

A

efferent arteriole

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9
Q

Formulation of capillaries lead to the concept of ________________

A

tubular reabsorption/ tubular secretion

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10
Q

What is tubular reabsorption?

A

movement of fluids & solutes from tubular lumen to peritubular capillary plasma (urine to blood)

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11
Q

What is tubular secretion?

A

movements of substances from peritubular capillary plasma to tubular lumen (blood to urine)

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12
Q

What two functions are critical for kidney function?

A

tubular reabsorption, tubular secretion

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13
Q

What does the glomerular filtration rate measure and what is the goal?

A

it measures the amount of fluid pushed through the glomerulus per minute. The goal is 120 ml/minute
approx 180L/day of fluid is filtered and reabsorbed

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14
Q

What 3 labs are critical for assessing kidney function?

A

GFR, BUN, serum creatine

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15
Q

What is the proximal convoluted tubule the site for?

A

site of reabsorption of glucose, amino acids, metabolites, electrolytes from filtrate.
-reabsorbed substances return to circulation

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16
Q

The major function of the _________________ is to get back fluids and electrolytes while getting rid of waste

A

Proximal convoluted tubule

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17
Q

The proximal convoluted tubule reabsorbs sodium/water in equal proportions, ______________ is approx the same going in/out of PCT

A

fluid osmolarity

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18
Q

What is the loop of Henle?

A

it is a hairpin in the medulla, extending from the PCT to DCT, divided into 3 segments:
1. thin descending
2. thin ascending
3. thick ascending

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19
Q

The loop of henle absorbs more _________ and _________ than __________

A

sodium and chloride, water

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20
Q

What is the primary function of the loop of henle?

A

concentration of urine via the countercurrent mechanism

21
Q

What is the countercurrent mechanism?

A

exchange occurs between the ascending/descending LOH and ascending/descending sections of vasa recta. Concentrated water collects in the interstitium triggering ADH release.

22
Q

In the countercurrent mechanism, the degree of concentration depends on the location. What are they?

A
  1. thin descending- highly permeable to water however, as urine filtrate moves down, water moves out of filtrate and into surrounding interstitium
  2. ascending limbs- impermeable to water; solutes are reabsorbed but water cannot follow; result is dilute urine as it enters distal tubule since solutes taken out of tubular lumen
23
Q

In the countercurrent mechanism, in thin descending, once it reaches the _____________, concentration is at its highest

A

elbow of LOH

24
Q

What is the distal convoluted tubule?

A

site from which the filtrate enters the collecting ducts

25
Q

What are the major functions of the distal convoluted tubule?

A

-Hydrogen excretion
-Final sodium reabsorption
-Responds to aldosterone- helps sodium reabsorption by exchanging sodium for hydrogen or potassium
-sodium reabsorbs along with chloride

26
Q

Why is the distal tubule and the collecting duct important?

A

because it is the last place where urine can be concentrated so water can be held onto if needed

27
Q

Aldosterone exerts effect here, helps determine final volume concentration and is also responsible for regulation of potassium excretion

A

Distal tubule

28
Q

Responds to ADH, released in response to hyperosmolality of extracellular fluids.

A

Collecting ducts

29
Q

What structures allows for a high pressure filtration system? It is 2-3x higher pressure than other capillary beds.

A

glomerulus, between two arterioles

30
Q

Constriction of afferent arterioles ________ GFR, constriction of efferent arterioles ________ GFR

A

reduces, increases

31
Q

In the formation of urine, active and passive transport occurs. This leads to tubular reabsorption and secretion of various substances. Which substances are passive, which are active?

A

water, urea- passive
electrolytes- active

32
Q

Which structures can adjust pressures to keep renal blood flow and glomerular filtration constant?

A

afferent arterioles.

33
Q

What are the neural/humoral mechanisms that control renal blood flow?

A

SNS innervation, increased sympathetic activity causes constriction, thereby reducing blood flow

34
Q

What are humoral substances that control renal blood flow?

A

angiotensin II, ADH, also produce constriction

35
Q

What are the 2 mechanisms of autoregulation for the control of renal blood flow?

A

mechanism 1: blood vessels relax when there is an increase in BP, constricts with decrease in BP

mechanism 2: feedback loop by juxtamedullary apparatus, which activates on stretch of afferent arteriole and constricts effent arterole to maintain GFR

36
Q

What are the functions that the juxtaglomerular apparatus are involved in?

A
  1. renin release
  2. control of renal blood flow
  3. glomerular filtration
37
Q

__________ Store and produce renin in response to decreased pressure

A

Juxtaglomerular Apparatus

38
Q

What is the key role of elimination?

A

remove metabolic wastes from blood, maintain normal electrolyte and pH blood composition

39
Q

What do you see accumulation of if renal function declines?

A

urea, phosphate, creatine, potassium

40
Q

How is sodium elimination regulated?

A
  1. Aldosterone release: sodium reabsorbed from distal tubule so urine is sodium free
  2. Atrial natriuretic peptide (ANP): released from atria cells when stretch occurs, inhibits ADH and sodium reabsorption
41
Q

How is pH regulated during elimination?

A

-it conserves bicarb, eliminated hydrogen
-organic anions (drugs, uric acid, bile acids) secreted into tubular fluid

42
Q

What is the role of Renin-angiotensin-aldosterone in kidney function?

A

Renin: no affect on BP on its own but converts angiotensinogen to angiotensin I
Angiotensin I is then converted by ACE in lung to angiotensin II
Angiotensin II: powerful vasoconstrictor; acts directly on kidneys to decrease salt/water excretion
Angiotensin II then stimulates aldosterone secretion by adrenals to maintain BP over a longer term

43
Q

Where is erythropoietin formed?

A

in the kidneys, want to give EPO injections in end stage renal disease

44
Q

Where does vitamin D activation occur?

A

in kidneys, transformed to calcitrol in kidneys, in ESRD give exogenously

45
Q

What is used to measure the amount of functional renal tissue?

A

glomerular filtration rate

(140-age) (wt in kg) / 72 x Scr

multiply above # by 0.85 for females
Goal: as close to 120 ml/minute as possible

46
Q

What are end products of metabolism that are normally excreted via urine?

A

creatine and BUN

47
Q

What is a normal BUN

A

10-20 mg/DL

48
Q

What is a normal serum creatine?

A

0.7-1.5 mg/dL
more sensitive of a marker since it changes very little (based on amount of muscle mass); exception is in elderly patients

Phys and Pharm (16 decks)

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