MeDi Master

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Some animals possesses olfactory powers that redefine our understanding of sensory limits.

While humans often marvel at the tracking abilities of domestic dogs, which can pick up a scent from nearly 200 yards away, they represent only the baseline of nature's olfactory prowess.

In the wilderness, the stakes of survival have evolved predators with significantly more acute senses. Gray wolves can detect prey from a full mile away, while common bears triple that distance, identifying potential food sources from up to three miles. This biological 'radar' allows terrestrial hunters to navigate vast territories and locate targets long before they are ever seen or heard.

The most extreme examples of scent detection occur where land meets the sea. Sharks are legendary for their ability to sense a single drop of blood across 3.5 miles of ocean, but even they are outperformed by the polar bear. Living in the harsh, expansive environment of the Arctic, polar bears have developed the most powerful nose on the planet, capable of tracking a seal through thick ice from a staggering nine miles away. This incredible sensory reach highlights the specialized adaptations required for apex predators to thrive in some of the most challenging environments on Earth.

source: National Park Service. (2023). The Power of a Bear's Nose. U.S. Department of the Interior.

⚖️ Acidosis — short approach & mnemonic

🔹 When to suspect
• Altered mental status
• Abnormal breathing
• Sepsis, shock, overdose
• Diabetes, starvation
🧠 Mnemonic: “SAD BADS”
• Sepsis
• Altered sensorium
• Drugs
• Breathing abnormal
• Acidosis risk (DM)
• Distress
• Starvation

🔹 Step 1: Confirm acidosis (ABG)
• pH < 7.35
• HCO₃⁻ < 18 or PaCO₂ > 45

🧠 Mnemonic: “LOW pH = ACID”

🔹 Step 2: Respiratory or metabolic?

❓ PaCO₂ > 45?
• Yes → Respiratory acidosis
• No → Metabolic acidosis

🧠 Mnemonic: “CO₂ HIGH = RESP”

🫁 Respiratory acidosis (hypoventilation)

Causes:
• Pulmonary: COPD, asthma, pneumonia, ARDS
• CNS / Neuromuscular: drugs, myasthenia, GBS, ALS
• Chest wall / obesity

🧠 Mnemonic: “LUNG CAN’T BLOW CO₂”

🧪 Metabolic acidosis → check anion gap

AG = Na − (Cl + HCO₃)
Normal: 4–12 mEq/L

🔺 High anion gap metabolic acidosis

Causes:
• Lactic acidosis (sepsis, shock)
• Ketoacidosis (DKA, alcoholic)
• Renal failure
• Toxins

🧠 Mnemonic: “MUDPILES”
(classic exam favorite)

🔻 Normal anion gap (hyperchloremic)

Causes:
• GI HCO₃⁻ loss: diarrhea
• RTA (types 1, 2, 4)

🧠 Mnemonic: “HARD”
• Hyperalimentation
• Acidosis (RTA)
• Renal tubular acidosis
• Diarrhea