MRCEM PART 1|Physiology Part 1

Welcome to the start of our new series! I’m Doctor Vidushi Chaturvedi, and we’re kicking off our Physiology Revision Series for the MRCEM Part 1 exam. This first video dives deep into essential Renal Physiology—specifically, Acid-Base Balance and Calcium Homeostasis.

This is a high-yield, detailed session, so get ready to revise key equations, clinical correlations, and regulatory mechanisms!

📌 High-Yield Topics Covered in Physiology Day 1:

1. Acid-Base Balance

Normal pH Range: Seven point three five to seven point four five.

pH and H+ Relation: The relationship is inverse: when the concentration of Hydrogen ions increases, the pH decreases (Acidosis).

Daily Acid Load: Approximately sixty millimoles of Hydrogen ions is produced daily, primarily buffered by the Bicarbonate buffer system.

Mechanisms of pH Control (The Four Buffers):

Respiratory: Controls Carbon Dioxide. For example, increased Carbon Dioxide leads to Acidosis, which triggers Hyperventilation to wash it out.

Metabolic: Various buffers (Bicarbonate, Phosphate, Protein or Hemoglobin).

Renal: Hydrogen ion excretion in urine and Bicarbonate production or reabsorption.

Potassium Exchange: Acidosis causes Hydrogen ions to shift into cells in exchange for Potassium, leading to Hyperkalemia (The most common electrolyte abnormality in acidosis). Conversely, Alkalosis causes Hypokalemia.

Henderson-Hasselbalch Equation: This equation describes the relationship between pH, the buffering agent, and the corresponding acid.

Clinical Picture:

Acidosis causes Hypotension, Hyperkalemia, Arrhythmias, Confusion, and Kussmaul breathing (in DKA).

Alkalosis causes Tachycardia, Hypokalemia, Arrhythmias, Tetany, and Hypoventilation (to retain Carbon Dioxide).

Metabolic Acidosis Types (The Must-Know Lists):

High Anion Gap (HAGMA): MUDPILERS is the mnemonic (Methanol, Uremia, DKA, Paraldehyde or Phenformin, Iron or Isoniazid, Lactic Acidosis, Ethylene Glycol or Ethanol, Rhabdomyolysis, Salicylates).

Normal Anion Gap (NAGMA): Renal Tubular Acidosis (RTA), Diarrhea, Spironolactone.

2. Calcium Balance (Renal Control)

Normal Range (MRCEM): Approximately two point two to two point six millimoles per liter.

Corrected Calcium Formula: This formula is Total Calcium plus zero point zero two times forty minus Serum Albumin.

Renal Reabsorption: Most is passively reabsorbed in the Proximal Convoluted Tubule (PCT) and Loop of Henle. The remaining approximately ten percent in the Distal Convoluted Tubule (DCT) is regulated by Parathyroid Hormone (PTH) and Vitamin D3.

DCT Mechanism: PTH and Vitamin D3 activate the Calcium ATPase on the Basolateral Membrane (into the blood), and the Sodium Calcium antiporter on the Apical Membrane (from the urine into the cell).
#emergencymedicine #DNBResidency #DNBResident #mrcempreparation #EmergencyMedicineIndia #medicaleducation #residentlife #doctorsofindia #medicolife #medicalcommunity #DNBEmergencyMedicine #MRCEMGuidance #DNBJourney #EmergencyMedicineResident #residencytips #clinicalskills #emergencycare #LifeInER #erdoctor #doctorvlogs #medstudent #futuredoctor #healthcareindia #MedicineCareer #medicalmotivation