HOMEOSTASIS BY THE KIDNEY FLUID AND ELECTROLYTE BALANCE Flashcards

1
Q

The maintains the volume and composition of extracellular fluid, what dysfunction could arise from this

A

Fluid overload and metabolic derangement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The kidney does the Excretion of endogenous waste products of metabolism, what dysfunction could arise from this?

A

Reduction in renal excretory function (uraemia and acidosis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The kidneys does excretion of foreign substances and their derivatives e.g. drugs and their metabolites. what dysfunction could arise from this?

A

Drug toxicity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The kidney produce hormones, e.g. renin, erythropoietin, and calcitriol, what dysfunction could arise from this?

A

Hormone function reduced

(anaemia, hypertension, etc)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the Functions of the Kidney?

A

+Volume and composition of extracellular fluid
+Excretion of endogenous
+waste products of metabolism
+Excretion of foreign substances and their derivatives e.g. drugs and their metabolites
+Synthesize prostaglandins and kinins that act within the kidney
+Production of hormones, e.g. renin, erythropoietin, and calcitriol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Which system of the body all work very closely together to maintain fluid and acid-base homeostasis (3)

A

The renal system, cardiovascular system and respiratory system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What can the kidney control?

A

Extracellular, specifically plasma, fluid volume- Effective circulating volume (ECV)

Body fluid osmolality by H2O and electrolyte control

The amount of ultrafiltrate produced in the glomeruli

The amount of H2O and electrolytes reabsorbed in the nephron and tubules

Fluid, electrolyte and H+ and HCO3- balance i.e. the amount gained minus the amount lost each day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

_________ is formed at the glomerulus

A

Ultrafiltrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the normal filtration rate?

A

80-120 ml/min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Does the Kidney control the extracellular or intracellular fluid volume?

A

Extracellular, specifically plasma, fluid volume- Effective circulating volume (ECV)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does the kidney control the body fluid osmolality

A

H20 and electrolyte control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does the kidney control the amount of urine made

A

controlling amount of ultrafiltrate produced in the glomeruli
controlling amount of H2O and electrolytes reabsorbed in the nephron and tubules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How much of the Ultrafiltrate formed at the glomerulus is reabsorbed back into the systemic circulation?

A

> 99%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Nephron controls the osmolality and volume of the urine produced through which mechanism and where?

A

a countercurrent mechanism in the loop of Henle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The descending limb of loop of henle are permeable to _____, but not to solutes

A

water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The ascending limb of loop of Henle is permeable to _____but not to water

A

solutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

______ is a predominantly passive process allows energy efficient ability to produce a dilute or a concentrated urine

A

Countercurrent Mechanism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Changes in ECV trigger which 4 effector pathways that act on the kidney

A

1) Renin Angiotensin Aldosterone System
(2) Sympathetic nervous system
(3) Antidiuretic Hormone (ADH) release

(4) Atrial Natriuretic Peptide (ANP) release which acts to reduce ECV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Apart from ADH, most other pathways (RAAS, SNS, ANP) use changes in ___ excretion to change effective circulating volume

A

Na+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does the RAAS, Sympathetic stimulation, ADH and ANP acts on the kidneys to control effective circulating

A

change renal haemodynamics and Na+ transport by renal tubule cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

_____ is group of specialised cells in distal tubule sensing sodium delivery to distal tubule

A

Macula densa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Central vascular receptors are blood volume receptors that detect changes in the ECV. Where are they found?

A

Large systemic veins
Cardiac atria
Pulmonary vasculature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Peripheral stretch receptors are baroreceptors that detect changes in ECV. Where can these be found?

A

Carotid sinus
Aortic arch
Renal afferent arteriole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Where are the other 2 less important baroreceptor sensors that detect changes in the ECV

A

CNS and liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

ADH is released by posterior pituitary gland in response to ___ and ____

A

hyperosmolality and volume depletion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Antidiuretic effect is mediated by _____ by acting on renal collecting ducts

A

V2 receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Which part of the Nephron is ADH most active on

A

Collecting ducts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

In addition to ADH acting on the renal collecting ducts via V2 receptors It also increases _____ ____ mediated by ___ ___

A

vascular resistance

V1 receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Describe the regulation of ECV by ADH

A

reduced ECV –> peripheral baroreceptors –> hypothalamus –> ADH –> increased water reabsorption –> Increased ECV

30
Q

Actions of ANP are all designed to lower ECV. True or false?

A

true

31
Q

increased ECV causes atrial stretch which leads to ANP release into circulation, ANP promotes

A

natriuresis (increased Na+ and H2O excretion from the kidney)

32
Q

What is the overall effect on ANP in ECV regulation

A

inhibits actions of renin and opposes effects of Ang-II

33
Q

What re the 3 specific ways ANP regulates the ECV

A

Natriuresis, renal vasodilation, inhibits renin through low Na

34
Q

What is the only active process in the loope of Henle (upper 2/3)

A

Reabsorption through the NKC2 channel

35
Q

auto regulation in the kidney is within what range of mean arterial pressure

A

80 and 180mmhg

36
Q

What will be the effect of drop in mean arterial blood pressure below 80mmHg on GFR

A

reduced

37
Q

_____ is the main solute that governs plasma osmolality (number of solutes in solution)

A

Sodium

38
Q

What are the 2 things that stimulate renin release form the juxta glomerular cells

A

reduced arteriolar stretch

reduced NaCl delivery to the macular densa in the distal tubule

39
Q

What are the main functions of angiotensin II in RAAS

A

aldosterone secretion
Renal Na reabsorption
increase systemic blood pressure (Vasoconstriction)

40
Q

Plasma osmolality is sensed by ___ ___ which releases ADH to aid water reabsorption in the collecting ducts

A

Hypothalamic osmoreceptors

41
Q

Which sensors are involved in volume regulation by sensing the circulating/vascular fluid volume

A

Macula densa

Baroreceptors; Atria, Carotid sinus, central veins, pulmonary vasculature, renal afferent arterioles)

42
Q

Sodium and water are regulated independently
Hyponatremia= _______
Hypernatremia=__________

A

too much water

too little water

43
Q

Does too much or too little sodium have effect on plasma concentration?

A

minimal or no effects

44
Q

When two liquids are separated by semipermeable membrane such as cell membrane there are two opposing forces at play called _ and _

A

hydrostatic and osmotic pressure

45
Q

pressure exerted by the volume fluid on the blood vessel that pushes water out is called

A

Hydrostatic pressure

46
Q

The pressure exerted by the solute i.e. Na within the solution the pulls water to itself is referred to as ___

A

osmotic pressure

47
Q

_____ is the number of ‘osmotically’ active particles in solution.

A

Tonicity

48
Q

Larger molecules such as __ and ___ do not significantly contribute to plasma osmotic pressure (cf. plasma Tonicity) as it freely crosses the cell membrane through facilitated diffusion.

A

Urea and Glucose

49
Q

What is the formula for calculating the plasma osmolality

A

2(Na + K) + Urea + Glucose

50
Q

Normal Plasma osmolality

A

280 - 300 mosmol/kg

51
Q

Why calculate difference between measured and calculated plasma osmolality?

A

Osmolar Gap

Identifies alcohol poisoning that might be ingested by the patient- Ethenol, Methanol, Antifreeze (Ethylene glycol)

52
Q

Osmolar gap

A

_____ Identifies alcohol poisoning that might be ingested by the patient- Ethenol, Methanol, Antifreeze (Ethylene glycol)

53
Q

_____ is the most abundant compound in the body

A

Water

54
Q

How much of the water in the body on the ICF and ECF

A

ICF 2/3

ECF 1/3

55
Q

If ECF effective osmolality increases, what happens to the cell and ICF?

A

cells shrinks (ICF↓)

56
Q

If ECF effective osmolality decreases, what happens to the cells and ICF

A

cells swells (ICF↑)

57
Q

What is the distribution of electrolytes in the intracellular and extracellular compartments

A

Intracellular - K+, PO4-. and Mg++

Extra cellular - NA+, Cl-, Ca2++ and HCO3-

58
Q

IF a patients presents with osmolality problems with fluid compartments should we be worried about?

A

ECV

59
Q

What is the effect is the effect of adding salt on plasma Na concentration, ECF volume, Urine Na concentration and ICF volume

A

plasma Na concentration - increases
ECF volume- increases
Urine Na concentration - increases
ICF volume - decreases

60
Q

What is the effect of adding water on plasma Na concentration, ECF volume, Urine Na concentration and ICF volume

A

plasma Na concentration - decreases
ECF volume- decreases (increases initially)
Urine Na concentration - increases
ICF volume - increases

61
Q

What is the effect of adding isotonic saline on plasma Na concentration, ECF volume, Urine Na concentration and ICF volume

A

plasma Na concentration - the same
ECF volume- increases
Urine Na concentration - increases
ICF volume -the same

62
Q

What is the effect of salt loss on plasma Na concentration, ECF volume, Urine Na concentration and ICF volume

A

plasma Na concentration - decreases initially the balances out
ECF volume- the same initially then falls
Urine Na concentration - decreases
ICF volume -increases

63
Q

___ is the commonest electrolyte imbalance/abnormality

A

Hyponatraemia (135-145)

64
Q

What are the some causes of reduced serum osmolality

A

Gastrointestinal losses- eg. Diarrhoea, Vomiting
Burns
renal losses e.g. Diuretic therapy, Addison’s disease
oedematous state - HF, RF, Nephrotic syndrome
SIADH
Hypothyroidism
Psychogenic polydipsia

65
Q

A 32 year old male with 3 day history of watery diarrhoea was admitted with confusion. He was hypotensive with a rapid heart rate. His serum sodium was low at 125 mmol/L (135-145 mmol/L).
What is the most common cause of hyponatraemia in clinical settings?

A

defect in renal water excretion

66
Q

Severe hyponitraemia leads to ____

A

Cerebral oedema

67
Q

What happens with rapid correction of hypernatremia?

A

cerebral oedema

68
Q

How is hyponatraemia diagnosed?

A

Low serum sodium

Simultaneous measurement of plasma and urine osmolality for diagnosis of SIADH

69
Q

How is hyponatraemia treated?

A

Salt replacement
Water restriction
Treatment of underlying cause

70
Q

Rapid correction of (chronic) hyponatremia can lead to ________

A

Central Pontine Myelinosis (intracellular dehydration)

71
Q

In SIADH is plasma and urine osmolality high or low?

A

plasma osmolality - low

urine osmolality - high

72
Q

What are the causes of hypernatreamia?

A

Dehydration
Certain drugs eg, Lithium
Diabetes insipidus- deficiency or renal tubular resistance to ADH