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MD1 URO - EXAM 1 > Le néphron distal (les tubules distal et collecteur) / Le contrôle du volume circulant efficace > Flashcards

Le néphron distal (les tubules distal et collecteur) / Le contrôle du volume circulant efficace Flashcards

1
Q

What are the different parts of the néphron distal?

A
  1. Tubule distale
    1. ** Segment connecteur (transition segment distalo-collecteur)
  2. Tubule collecteur
    1. Cortical
      • Cellules principales
      • Cellules intercalaires
    2. Médullaire
      • Médullaire externe
      • Médullaire interne
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2
Q

What are the functions of the distal nephron? (4)

A

Water reabsorption

Sodium reabsorption

Secretion of potassium

Secretion of hydrogen ions (acid)

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3
Q

What % of NaCl is reabsorbed in each segment of the nephron?

A
  1. Proximal tubule: 70%
  2. Anse of Henle: 20%
  3. Distal tubule: 5%
  4. Collector tubule: 4%
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4
Q

Where does the distal nephron start?

A

Macula densa

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5
Q

What are the different segments of the néphron distal and the hormones/membrane transport used?

A

Tubule distal:

  • Membrane transport:
    • Co-transport: Na+-Cl- —> only found in distal

Tubule collecteur cortical:

  • Membrane transport:
    • Cellule principale
      • Na+ canal
      • K+ canal
      • Transport de l’eau
    • Cellules intercalaire
      • Secretion of H+
  • Hormones:
    • Aldosterone
      • Na+ and K+ channels, H+ secretion
    • ADH
      • Water transport

Tubule collecteur médullaire: médullaire interne

  • Membrane transport:
    • Canal à Na+
    • Transport de l’eau
    • Transport de l’urée
  • Hormones:
    • PNA
      • Canal à Na+
    • ADH
      • Transport de l’eau
      • Transport de l’urée
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6
Q

What do the cellules tubulaire distale look like?

A
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7
Q

What is the segment connecteur?

A

A couple of cells; with characteristics of the distal tubule and collector tubule

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8
Q

What are the functions of the two different cell types in the tubule collecteur cortical?

A

Cellules principales

65% —> reabsorb NaCl, H2O and secrete K+

Cellules intercalaires

35% —> secrete H+

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9
Q

What do the cellules principales look like?

A
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10
Q

What is the motor of of the cellule principale?

A

Basolateral Na+ K+ ATPase

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11
Q

What is the main function of the cellules intercalaires?

A

Equilibre acido-basique

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12
Q

What do the cellules intercalaires look like?

A
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13
Q

What kind of cells are found in the médullaire interne (papille)?

A

cellules du tubule collecteur papillaire

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14
Q

What does PNA do?

A

Block reabsorption of Na+ —> natriurèse

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15
Q

What are the locations/hormones used for the different functions of the distal nephron?

A

H2O reabsorption: tubule collecteur (ADH (vasopressin))

Na+ reabsorption: tubules distal + collecteur (Aldosterone, PNA)

K+ secretion: principal tubule collecteur (Aldosterone)

H+ secretion: tubule collecteur intercalaire (Aldosterone)

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16
Q

What hormone controls Na+ transport in distal tubule?

A

NONE… NOT UNDER HORMONAL CONTROL!!

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17
Q

What hormone controls Na+ transport in the cellules principales du tubule collecteur?

A

Aldosterone

18
Q

What hormone controls K+ secretion in the cellules principales du tubule collecteur?

A

Aldosterone

19
Q

What hormone controls H+ transport in the cellules intercalaires du tubule collecteur?

A

Aldosterone

20
Q

What hormone controls H2O transport in the cellules principales du tubule collecteur?

A

ADH

21
Q

What hormone controls Na+ transport in the cellules du tubule collecteur papillaire?

A

PNA (peptide natriurétique de l’oreillette)

22
Q

What is the VCE?

A

Volume intravasculaire qui perfuse efficacement les tissus

  • Varies with extracellular volume
  • Étroitement liée avec la régulation du balance du Na+
23
Q

Is the VCE measurable?

A

NO! its the “taux de perfusion de la circulation capillaire”

24
Q

What happens when the VCE drops?

A

Drop in urinary Na+ levels….

  • en absence de diurétique ou maladie rénale

If sodium reabsorption is increased… so will water reabsorption which will keep water in

25
Q

How does Na+ balance happen in humans?

A
26
Q

What is the signal that helps Na+ excretion fluctuate according to Na+ taken in by diet?

A

Change in volume… tubules see salt ingestion through volume receptors

27
Q

What are the three locations of volume receptors in the body?

A
  1. Circulation cardio-pulmonaire (oreillette gauche)
  2. Sinus carotidien et crosse aortique
  3. Artérioles afférents
28
Q

What are the principal control mechanisms (effecteurs) of volume regulation? (2)

A

Hémodynamie systèmique

Excrétion rénale de Na+

29
Q

What is hémodynamie systèmique and how is it controlled?

A

Volume control… contenant

  • Système nerveux sympathique
  • Angiotensine II
30
Q

How is sodium excretion dealt with by the kidneys?

A

Contenu:

  1. DFG
  2. Angiotensine II
  3. Hémodynamie du capillaire pétitubulaire
  4. Aldostérone
  5. SNS
  6. PNA
31
Q

What are the effects of angiotensine II? (3)

A
  1. Vasoconstriction
  2. Renal Na+ retention
  3. Stimulation of aldosterone
32
Q

IMPORTANT OVERVIEW OF VCE CONTROL… MEMORIZE THIS!

A
33
Q

What is the emergency mechanism for VCE control?

A

Secretion of ADH (sécrétion hémodynamique non-osmotique)

  • Tubule collecteur:
    • Réabsorption maximale d’eau PEU IMPORTE L’OSMOLALITÉ
  • Vaisseaux sanguins:
    • Effet vasoconstricteur —> helps maintain BP
34
Q

How does the improved “schéma d’hydratation” work?

A
35
Q

Osmorégulation vs régulation volémique:

A
36
Q

What happens when you infuse the body with isotonic saline? (3)

A
  1. increase VCE without increasing osmolality
  2. increase Na+ in urine/water —> urine iso-osmotique
  3. Restore “volume corporel iso-osmotique”
37
Q

What happens when you exercise? (Na loss and water loss)

A

Perte de Na+ —> modérée (CANAL 2)

  • Drop in extra-cellular volume —> drop in VCE
  • Decrease in Na+ urinaire
  • Restore volume corporel iso-osmotique

Perte d’eau —> importante (CANAL 1)

  • Increase in plasmatic osmolality
  • Increase ADH/thirst
  • Retain water (urine hyper-somolaire)
  • Restore volume corporel iso-osmotique
38
Q

What is monitored and adjusted in each canal? (1, 2 and 4)

A
39
Q

What is the normal adjustment site of tubular Na+ reabsorption?

A

Tubule collecteur

40
Q

What will a decrease in NaCl ingestion to to aldosterone secretion?

A

Increase… to keep NaCl inside body

41
Q

Where is the emergency adjustment site of tubular Na+ reabsorption?

A

Tubule proximale (ADH)

42
Q

How do AII and noradrenaline stimulate tubular Na+ reabsorption?

A

Directement et indirectement en resserrant l’artériole efférente…

MD1 URO - EXAM 1 (8 decks)

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