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Intro Bio II Exam 2 > The Kidney > Flashcards

The Kidney Flashcards

1
Q

What jobs does the kidney do?

A
  1. Water balance (ECF volume, blood pressure, osmolarity)
  2. Ion homeostasis (remove excess Na+)
  3. PH balance
  4. Excretion of water soluble wastes (nitrogenous waste such as urea)
  5. Production of hormones (epinephrine)
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2
Q

Main purpose of kidneys

A

Filter blood every 5-6 min which allows us to intake different food/drinks while maintaining homeostasis.

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3
Q

Outer part of the kidney

A

Cortex

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4
Q

Inner part of the kidney

A

Medulla

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5
Q

Functional Unit of the kidney

A

Nephron

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6
Q

These nephrons make up only 20% of the kidney but are primarily responsible for secretion / reabsorption

A

Juxtamedullary Nephron

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7
Q

The capillary beds around juxtamedullary nephrons

A

Vasa recta

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8
Q

The Renal Corpuscle

A

Glomerulus + Bowman’s Capsule

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9
Q

The parts of the nephron (in order)

A
  1. Bowman’s capsule 2. Proximal Convoluted Tubule 3. Loop of Henle (descending, ascending) 4. Distal Convoluted Tubule 5. Collecting Duct
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10
Q

Renal Pelvis

A

Where all the collecting ducts meet to funnel into the ureter, which leads to the bladder

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11
Q

Three Main Forms of Nitrous Waste

A

Ammonia, Urea, Uric acid

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12
Q

This determines what kind of nitrous waste you produce

A

Storage requirements! Ammonia is very caustic, so needs to be diluted; uric acid is very expensive to make, but requires very little water, which is why birds produce.

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13
Q

Where does the water in our body come from

A

Diet (about 30%), derived from metabolism (10%), ingested via liquid (60%)

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14
Q

In what ways is liquid from our bodies excreted

A

Feces (5%), evaporation (35%), urine (60%)

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15
Q

Where does a kangaroo rat get most of its water??

A

Metabolism!!

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16
Q

What surrounds any average old nephron

A

Peritubular Capillaries

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17
Q

Three key processes of nephron

A

Glomerular filtration, Tubular secretion, Tubular reabsorption

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18
Q

How much of what is filtered is reabsorbed?

A

99% or MORE!

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19
Q

% Water reabsorbed

A

99%

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20
Q

% glucose reabsorbed

A

100% or you’re in trouble

21
Q

% sodium reabsorbed

A

99.5%

22
Q

% urea reabsorbed

A

44%

23
Q

What does glomerulus do

A

Creates the filtrate, and it is the ONLY place in nephron that filters; pushed out everything EXCEPT large molecules and blood cells. Water and small molecules pass through fenestrations.

24
Q

How does glomerulus filter

A

Blood pressure! Anatomy increases blood pressure here, and it is greater than the combined force of osmotic pressure (which would pull liquid back into bloodstream) and fluid pressure in Bowman’s capsule. Net pressure about 10 mm Hg.

25
Q

Journey of molecules from glomerulus to Bowman’s Capsule

A

First push through fenestrations in capillary epithelium, then move through basal lamina, then through slit pores in Bowman’s capsule epithelium created by weird Dr. Seuss like cells called ‘podocytes’. THREE LAYERS OF FILTRATION!

26
Q

Glomerular Filtration Rate

A

The volume filtered through the kidneys per unit time, many kinds of hormonal regulations will regulate GFR

27
Q

Autoregulation of GFR

A

Controlled by constriction / dilation of afferent & efferent arterioles: constrict afferent arteriole and reduce flow to glomerulus, ergo reduce GFR; constrict efferent arteriole and pressure builds up in glomerulus, ergo increase GFR.

28
Q

Myogenic Feedback

A

Control of GFR via myogenic response, aka smooth muscle in arterioles.

If blood flow too high, arterioles constrict, reducing flow. If blood flow too low, arterioles relax, allowing more flow through.

29
Q

Tubuloglomerular Feedback

A
  1. GFR increases.
  2. Flow through Loop of Henle increases.
  3. Macula densa cells sense this.
  4. Paracrine signal (unclear what this is) from macula densa to afferent arterioles.
  5. Constriction of afferent arterioles
  6. Reduction of GFR
30
Q

What is the difference between filtrate and plasma?

A

Filtrate is destined to be excreted unless reabsorbed; plasma contains large molecules, blood cells, proteins, etc.

31
Q

What is the difference between filtrate and urine?

A

Urine WILL be excreted. Filtrate is still undergoing process of secretion and reabsorption. Only becomes urine once leaves collecting duct (point of no return).

32
Q

What the PCT Reclaims

A

Glucose, amino acids, most ions - and water follows

33
Q

How is everything reclaimed in the PCT?

A

Symports - and these are usually symports powered by sodium gradient! (Water follows solute, so doesn’t need any help)

34
Q

How Sodium is Reclaimed in PCT

A

ENaC (Epithelial Sodium Channel) on apical membrane takes sodium down gradient into low concentration of cell. Sodium potassium pump then returns to interstitial fluid (where sodium is high).

35
Q

Apical Membrane

A

The side of the cell that faces the lumen (usually has villi)

36
Q

Basolateral membrane

A

The side of the cell that does NOT face the lumen but instead faces the bloodstream

37
Q

How Glucose is Reclaimed in PCT

A

SGLT carrier protein symport takes sodium down gradient and glucose up gradient across apical membrane. The glucose goes into blood down gradient via GLUT. Sodium leaves via pump, as always.

38
Q

Any restrictions on the GLUT transporter?

A

Yes, transport maximum. If this gets maxed out, reach renal threshold and excrete glucose in urine. Diabetes!

39
Q

Renal Threshold

A

Point at which saturation of GLUT carrier protein occurs and kidneys begin to excrete glucose

40
Q

Filtration of Glucose

A

NEVER AFFECTED because no transport proteins. No matter how much glucose, will ALL get filtered. The trouble is with reabsorption in the PCT and transport max of GLUT.

41
Q

Pressure gradient beyond Bowman’s capsule

A

Changes to filter reabsorption: so hydrostatic pressure decreases and colloidal osmotic pressure increases. Net 20 mm Hg pressure to reabsorb.

42
Q

Clearance

A

A way of determining GFR. If you know that something should be totally excreted, the rate at which it is excreted also tells you the rate at which it is filtered

43
Q

Inulin clearance

A

Plant-derived molecule that will neither be secreted nor absorbed. So its clearance rate can tell us GFR by proxy

44
Q

Glucose clearance

A

NO glucose should be cleared (none should be excreted). ALL should be reabsorbed.

45
Q

Urea clearance

A

Where filtration > excretion, there is net reabsorption. This happens with urea.

46
Q

Penicillin Clearance

A

When filtration < excretion, there is net secretion (movement from bloodstream into filtrate). This happens with penicillin.

47
Q

Micturition

A

aka peeing

  1. Stretch receptors in bladder fire
  2. Parasympathetic neurons fire. This causes the TONIC internal sphincter of bladder to release.
  3. Motor neurons STOP firing. This causes the ‘voluntary’ external sphincter at bottom of urethra to open, as well.
  4. Smooth muscle contracts.
  5. TALLY HO!
48
Q

The Bladder at Rest

A

Bladder surrounded by smooth muscle is not stretched. Internal sphincter, controlled by smooth muscle (not voluntary control) is contracted. External sphincter controlled by SKELETAL MUSCLE (ergo voluntary) is also contracted.

Intro Bio II Exam 2 (8 decks)

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