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HUBS192 > 33 (im Going To Jump Of A Bridge) > Flashcards

33 (im Going To Jump Of A Bridge) Flashcards

1
Q

Reabsorption in the nephron: Water - thee important places where water is reabsorbed in the nephron

A

Proximal convoluted tubule (PCT):
- 67% of filtered load (water) reabsorbed

Descending limb of the nephron loop:
- 25%

Collecting duct:
- 2-8% of filtered load reabsorbed

Excretion:
- < 1- 6% of filtered load is excreted

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2
Q
A
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3
Q

What kind of absorbtion happens in the first two areas

A

Bulk (obligatory) water reabsorption

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4
Q

Bulk (obligatory) water reabsorption

A
  • accounts for 92% of total water reabsorption
  • not regulated – automatic!!
  • leaky epithelia
  • trans-and paracellular water reabsorption
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5
Q
A

Regulated (facultative) water reabsorption

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6
Q

Regulated (facultative) water reabsorption

A
  • accounts for 2-8% of total water reabsorption
  • regulated by anti-diuretic Hormone (ADH)
  • tight epithelia
  • only transcellular reabsorption
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7
Q

Reabsorption in the nephron: Sodium
- 4 important places for reabsortion

A

Proximal convoluted tubule (PCT):
- 67% of filtered load reabsorbed

Ascending limb of the nephron loop:
- 25% of filtered load reabsorbed

Distal convoluted tubule:
- 5% of filtered load reabsorbed

Collecting duct (CD):
- 2-3% of filtered load reabsorbed

Excretion:
- < 1% of filtered load is excreted

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8
Q

What happens here?

A

Bulk sodium (Na+) reabsorption

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9
Q

Bulk sodium (Na+) reabsorption

A
  • accounts for 92% of total sodium reabsorption
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10
Q

What happens here?

A

Regulated sodium (Na+) reabsorption

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11
Q

Regulated sodium (Na+) reabsorption

A
  • accounts for 7-8% of total sodium reabsorption
  • regulated by aldosterone (RAAS)
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12
Q

What drives and regulates body water homeostasis?

A
  • Distribution of body water
  • Osmolarity/tonicity of solutions
  • Changes in blood osmolarity
  • Reabsorption of water and sodium in the nephron
  • Effects of osmotic changes on the kidney
  • Effects of volume changes on the kidney
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13
Q

Reabsorption: Proximal convoluted tubule

A
  • Water reabsorption in the proximal tubule (67% of Na+ the filtered load) is driven by Na+ reabsorption (isosmotic!! - water wants to follow the solute molecule )
  • Transporters such as the glucose co-transporter sodium-glucose co-transporter use the sodium gradient to reabsorb solutes (like glucose)
  • Glucose and sodium (Na+) are transported through
    the proximal tubule cells
  • the proximal tubule is ‘leaky’ epithelia
    • chloride follows via the paracellular pathway
    • water follows by the paracellular and transcellular pathways
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14
Q

Nephron loop
Decending is…

A

Permeable to water (aquaporins)

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15
Q

Nephron loop
Ascending is permeable to

A

Sodium (ion transporters)

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16
Q

How does reabsorbtion of water from the descending loop work? What pathways?

A
  • The descending loop is leaky epithelium, so water (H 2O) is reabsorbed from the nephron into the peritubular fluid
    • via the transcellular pathway: aquaporins
    • via paracellular pathway, across the junctions between
      cells
17
Q

How does reabsorbtion of water from the ascending loop work?

A

The ascending loop reabsorbs Na+ into the peritubular fluid

18
Q

In Juxtamedullary nephrons: what does the different permeability’s in the nephron loops provide?

A

The different permeabilities of the descending (water) and ascending (sodium) parts of the JMNs loop allows them to generate a:

  • Hyper-Osmotic Medullary Gradient (HOMG)

(Deeper u go in the loop the higher the osmolaroty, same with collecting duct - important for water reabsortion form the collecting duct)

19
Q

Reabsorption: Distal convoluted tubule and collecting duct

A

WATER: collecting duct
- Regulated (facultative) water reabsorption
- tight epithelia
- only transcellular reabsorption
- regulated by anti-diuretic hormone (ADH)

Sodium: distal convoluted tubule and collecting duct
- Regulated sodium reabsorption
- regulated by aldosterone (RAAS)

20
Q
A
21
Q

Regulation of body osmolarity - ADH
- TBW changes alter plasma increases due to the gain of water. (ECF) osmolarity

A
  • detected by osmoreceptros in hypothalamus
  • stimulates pituitary gland to secrete more/less ADH
  • ADH alters permeability of collecting duct cells, so water is retained/ excreted to balance the initial change in TBW
    • plamsa osmolarity stable
    • cell volume stable
22
Q
A
23
Q
A
24
Q

To move anything in or out of cell we need:

A
  • driving force
  • a way to move
25
Q

Reabsorption of water in the nephron: Collecting duct
- what is the driving force - what is the way they can move

A
  • HOMG
  • ADH
26
Q

An increase in iso osmotic fluid
Wont set off

A
  • wont set off osmotic receptor
27
Q

Regulation of ECF volume – Aldosterone (RAAS) and ANP

A

Changes in ECF volume:

  • an increase in volume : ANP
  • a decrease in volume : Aldosterone (RAAS)
28
Q
A
29
Q
A
30
Q

Composition of Normal urine:

A
  • Water: 95-98% of urine is water
    →1.5 L/day
  • Creatinine (muscle metabolism)
  • Urea (amino acid breakdown)
  • Uric acid (purine breakdown)
  • H+ (hydrogen ions)
  • Na+ (sodium), K+ (potassium)
  • Medications (anti-viral, diuretics)
  • Toxins
31
Q

Composition of Pathological urine:

A
  • Glucose (glucosuria, diabetes)
  • Protein, especially albumin (proteinuria)
  • Blood: red blood cells/erythrocytes (haematuria)
  • Haemoglobin (haemoglobinuria)
  • White blood cells/leucocytes
  • Bacteria (infection)
32
Q

What can you see - normal urine

A

Clear, to light or dark amber

33
Q

What can u taste - normal urine

A
  • pH dependant on diet (4.6 - 8.0)
  • “Average” person: pH of 6 - 7.5
  • Vegetarians: pH up to 8.0
  • High protein diet (e.g. meat eaters): pH as low as 4.6
34
Q

Smell - normal urine

A

Unremarkable

35
Q

What can u see - Pathological urine:

A

Orange, red, brown, blue/green

36
Q

Ta s t e - pathological urine

A

Sweet: Diabetes mellitus

37
Q

Smell:

Pathological urine:

A
  • “Fruity”: ketones from: fasting, diabetes or chronic alcohol abuse
  • “Rotten”: infection (bacteria), tumour

HUBS192 (39 decks)

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