5- The Kidney in Acid Base Balance Flashcards

1
Q

What are the functions of the kidneys

A

Remove waste products/drugs from
the body.

Balance the body’s fluids.
Help maintain blood pH.

Release hormones that regulate
blood pressure.

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2
Q

What is a normal blood pH

A

7.4

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3
Q

What are the symptoms of Acidosis

A

Central Nervous System
Headache
Sleepiness Confusion
Loss of consciousness
Coma

Respiratory System
Shortness of Breath
Coughing

Heart
Arrhythmia
Increased heart rate

Muscular System
Seizures
Weakness

Digestive System
Nausea
Vomiting Diarrhea

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4
Q

Symptoms of Alkalosis

A

Central Nervous System
Confusion Light-headedness Stupor
Coma

PNS
Hand tremor
Numbness in the face hands or feet

Muscular System
Twitching Prolonged spasms

Digestive System
Nausea Vomiting

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5
Q

What does the law of mass action state

A

The rate of a chemical reaction is proportional to the product of the concentration of the reactants.

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6
Q

What is the relationship between blood concentration of HC0-3 and CO2

A

pH= 6.1 + Log ([HCO3]/0.02 x pCO2)

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7
Q

What are sources of H+ gain

A
  • CO2 in blood
  • Non-volatile acids from metabolism (e.g. lactic acid)
  • Loss of bicarbonate in diarrhoea
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8
Q

What are the sources of H+ Loss

A

Use of H+ in metabolism of organic anions
* Loss of H + in vomit (stomach acidic!)
* Loss in urine
* Hyper-ventilation

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9
Q

What are the two main ways the kidneys maintain acid-base balance

A

cells reabsorb bicarbonate HCO3 from the urine back to the blood and they secrete hydrogen H+ ions into the urine.

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10
Q

How does the law of mass action explain the acid-base balance

A

Low molecular weight
compounds are filtered into the lumen of the nephron.

This includes bicarbonate ions which will then be lost in urine unless the body can reabsorb the bicarbonate.

This is achieved by the tubular epithelial cells.

HCO3- in interstitial fluid then gets into capillary

Bicarbonate ions are synthesised
in the tubule cells, as long as a“sink” for hydrogen ions(hereHPO42-) is available.

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11
Q

What are the major hormones involved in the kidneys regulation of blood pressure

A

Angiotensin II
* Antidiuretic hormone (ADH)
* Aldosterone
* Atrial Natriuretic peptide (ANP)

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12
Q

What do juxtaglomerular cells do

A

They are smooth muscle cells in afferent arteriole wall detect changes in blood pressure

Secrete the enzyme renin to trigger RAS if blood pressure fails.

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13
Q

What do macula densa cells do

A

Cells in the wall of the distal tubule in this area monitor the osmotic potential in the filtrate in the distal tubule

stimulate JG cells to release renin if filtrate is too dilute

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14
Q

What is ADH release stimulated by

A

Angiotensin II
Drop in BP
Increase in plasma solute concentration

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15
Q

What does ADH release result in

A

increased water permeability at DCT and collecting duct
Stimulates thirst center in hypothalamus
Changes water permeability by moving intracellular
aquaporins - water channels -to plasma membrane

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16
Q

What stimulates aldosterone release and what does it result in

A

Release stimulated by:
Angiotensin II
Increase in K+ concentration in plasma

Results in:
Reabsorption of Na+
Secretion of K+
Occurs at DCT and collecting ducts

17
Q

In what states are Atrial Natriuretic Hormone released

A

Elevated levels of ANP are found during hypervolemic states (elevated blood volume), such as occurs in heart failure.

18
Q

Where is ANP synthesized and stored

A

ANP is first synthesized and stored in cardiac myocytes as
prepro-ANP, which is then cleaved to pro-ANP and finally to
ANP.

19
Q

What does ANP release cause.

A
  • Inhibition of renin, aldosterone, ADH
  • Opposite of renin-angiotensin system
  • Decrease in sodium reabsorption
  • Dilation of glomerular capillaries, increasing GFR
20
Q

What does sympathetic activation do to kidneys

A
  • Direct, sudden effect of acute crisis
  • Constriction of afferent arterioles
  • Decreases Glomerular Filtration Rate (GFR)
  • Can override local effects to stabilize GFR
  • Indirect effect
  • Shunts blood away from kidneys to perfuse tissues and
    organs with higher needs
  • Problematic in strenuous exercise