Physiology (6-8) Flashcards Preview

Year 2 - Renal (DP) > Physiology (6-8) > Flashcards

Flashcards in Physiology (6-8) Deck (96)
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1

What is the tonicity of the tubular fluid entering the DCT compared to blood?

hypo-osmotic (~100mosmol/L)

2

What is the collecting duct bathed in?

Progressively increasing [ISF]:
- 300 -> 1200mosmol/L

3

What percentage of filtered ions are reabsorbed before the DCT?

>95%

4

What is the residual load of NaCl that reaches the DCT?

~700-1000nmol/day

5

Why is the residual load of NaCl in the DCT important?

Salt balance

6

What effect does ADH have on the regulation of water and ion balance?

Increases water reabsorption

7

What effect does Aldosterone have on the regulation of water and ion balance?

Increases Na+ reabsorption
Increases H+ and K+ excretion

8

What effect does Atrial Natriuretic hormone have on the regulation of water and ion balance?

Reduces Na+ reabsorption

9

What effect does PTH have on the regulation of water and ion balance?

Increases calcium reabsorption
Decreases phosphate reabsorption

10

What does the DCT have a low permeability to?

Water
Urea

11

What happens in the early segment of the DCT?

NaCl reabsorption via the Triple-transporter

12

Which of the following does not happen in the late segment of the DCT:
- Calcium reabsorption
- H+ secretion
- Na+ reabsorption
- K+ reabsorption
- Phosphate secretion

Phsophate secretion

13

What is the early collecting duct similar to?

Late DCT

14

What is the permeability of the late collecting duct?

Low ion permeability
High water permeability

15

Where is ADH (an octopeptide) synthesised and from what?

Supraoptic nuclei and Paraventricular nuclei in the hypothalamus

16

Where is ADH stored?

In granules in the posterior pituitary

17

What is the approximate half life of ADH in the plasma?

10-15 minutes

18

How does ADH increase water reabsorption?

1. Binds to an Arginine Vasopressin Receptor 2 (V2)
2. ATP -> cAMP
3. cAMP causes increased transcription and insertion of aquaporins in the lumenal/apical membrane

19

In high [ADH]p, what is urine like?

Hypertonic (Up to 1400mosmol/L)
Low volume

20

In low [ADH]p, what is urine like?

Hypotonic urine (

21

What is the dominant factor controling thirst and ADH secretion?

Increased osmolarity activating hypothalamic osmoreceptors

22

When are left atrial volume receptors important in water balance?

In large plasma volume or BP changes

23

What causes left atrial volume receptors to encourage ADH release?

Very low plasma volume
OR
Hugh drop in BP

24

Apart from increasing water reabsorption, how else does ADH increase BP?

Causes peripheral vasoconstriction -> BP rises

25

Where is aldosterone secreted from?

Adrenal cortex

26

When is aldosterone secreted?

In response to:
- Increased [K+]p
- Decreased [Na+]p
Activation of RAAS

27

If aldosterone is absent, how much K+ is present in the urine?

None

28

How does decreased [Na+]p result in aldosterone secretion?

Indirectly via the juxtaglomerular apparatus

29

Where is renin produced and what does it do?

Kidneys:
- Converts Angiotensinogen -> Angiotensin I

30

Where is ACE produced and what does it do?

Lungs:
- Converts Angiotensin I -> Angiotensin II