Download MBBS (Bachelor of Medicine, Bachelor of Surgery) 1st year (First Year) Biochemistry ppt lectures Topic 89 Water And Electrolyte Notes. - biochemistry notes pdf, biochemistry mbbs 1st year notes pdf, biochemistry mbbs notes pdf, biochemistry lecture notes, paramedical biochemistry notes, medical biochemistry pdf, biochemistry lecture notes 2022 ppt, biochemistry pdf.
Electrolyte and Wate r
Balance
Case Report
? A 55-year-old man was brought to the emergency with severe
multiple injuries in a road traffic accident and crush injuries, fractures
of the legs and scalp lacerations. He was conscious and breathing
spontaneously. Pulse 130/min, BP 60/40 mm Hg, serum sodium 142
mmol/L, potassium 7.9 mmol/L, chloride 110 mmol/L, Blood urea 40
mg/dL, and serum creatinine 1.2 mg/dL.
? Interpret the laboratory data?
? What is the basis of the changes?
The body water compartments
? During oxidation of foodstuffs,
? 1 g carbohydrate produces
? 0.6 mL of water,
? 1 g protein releases
? 0.4 mL water and
? 1 g fat generates
? 1.1 mL of water.
? major factors control ing the intake :
? thirst and
? the rate of metabolism.
Wate r balance in the body
? Osmolarity means osmotic pressure exerted by the
? number of moles per liter of solution.
? Osmolality is the osmotic pressure exerted by the
? number of moles per kg of solvent.
? osmotic balance is mainly maintained by
? Albumin
? the major determinant factor of osmolality is
? the sodium
? The osmolality of plasma varies from
? 285 to 295 mosm/kg
Gamblegrams showing composition of fluid
compartments
Electrolyte and Water Composition of Body Fluid Compartments
Components
Plasma
Interstitial fluid
Intracel ular fluid
Volume, H2O (TBW 3.5 L
10.5 L
28 L
= 42 L)
Na+
142
145
12
K+
4
4
156
Ca+2
2.4
2-3
2.3
Mg2+
2
1-2
26
Trace elements
1
-
-
Total cations
155
Cl-
103
114
4
HCO-
27
31
12
Protein-
16
-
55
Organic acids-
5
HPO2 -
2
SO2 -
1
Total anions
154
Regulation of Sodium and Wate r balance
? ADH
? Renin-Angiotensin system
? Autoregulation
Disturbances in Fluid and Electrolyte balance
? Isotonic contraction- Loss of fluid that is isotonic with plasma--Loss of
GI fluid
? Hypotonic contraction--Predominant Na loss? Infusion of fluids with
low sodium content like dextrose
? Hypertonic contraction ---Predominantly water depletion---Diarrhoea
? Isotonic expansion---Secondary to hypertension
? Hypotonic expansion---ADH excess
? Hypertonic expansion---Conns syndrome & Cushings syndrome_
Excess mineralocorticoid- sodium retention
Reference interval of Sodium:
136-145 mmol/L (Adult)
128-148 mmol/L (New born at 48 h)
Approx 127 mmol/L (From Umbilical cord)
Urinary sodium excretion = 120-240 mmol/day with large diurnal variation
At night = 20% of the peak
Hyponatremia typical y manifests clinical y as
(1) nausea,
(2) generalize weakness, and
(3) mental confusion.
<120 mmol/L: mental confusion
<110 mmol/L : Ocular palsy
90-105 mmol/L: Severe mental impairment
Algorithm for the differential diagnosis of hyponatremia.
Hypernatremia Plasma sodium > 150 mmol/L
Symptoms are primarily neurologic
(because of neuronal cell loss of H2O into the ECF)
1. Tremors
2. Irritability
3. Ataxia
4. Confusion
5. coma
Hypernatremia
HYPOKALEMIA
Reference interval of K+:
1.Muscle weakness
Serum=3.5-5.0 mmol/L (Adult)
2.Irritability
3.Paralysis
Plasma= 3.4-4.8 mmol/L (Adult)
4.Tachycardia
3.7-5.9 mmol/L ( Newborn)
5.Cardiac conduction defect
CSF= 70% that of plasma
6.Flattened T wave
7.Cardiac arrest
Hypokalemia
Hypokalemia (continued)
Metabolic Alkalosis
HYPERKALEMIA
1. Mental confusion
2. Weakness
3. Tingling
4. Flaccid paralysis of the extremities
5. Weakness of the respiratory muscles
6. Bradicardia
7. Conduction defects
8. Peripheral vascular collapse : Prolonged severe hyperkalemia >7 mmol/L
9. Cardiac arrest
Hyperkalemia
MCQ 1
? A patient with diarrhoea may have all the following abnormalities
except:
? A. Metabolic acidosis
? B. Hypertonic contraction of ECF
? C. Urine with a high specific gravity
? D. Isotonic contraction of ECF
MCQ 2
? Which of the following is the major intracellular cation?
? A. Magnesium
? B. Sodium
? C. Calcium
? D. Potassium
MCQ 3
? All 5the following hormones affect fluid and electrolyte balance
except:
? A. Aldosterone
? B. ADH
? C. Cortisone
? D. Thyroxine
This post was last modified on 05 April 2022