Physiology and Homeostasis

Fundamental Concepts

Homeostasis: A key principle in physiology, referring to mechanisms that maintain the body's internal environment within optimal ranges for cellular function.
- Prevents the body from being too hot, cold, wet, dry, acidic, or alkaline.
- Described as keeping the body in the 'Goldilocks zone' – conditions must be 'just right'.

Homeostasis: Means 'same standing' (homeo = same, stasis = standing still).
- Implies a dynamic equilibrium — constant fine-tuning to remain within a narrow parameter range.
Disruptor: Anything that changes a homeostatic parameter.
- Example: Exercise or heat disrupts temperature homeostasis; dehydration disrupts fluid balance.
Detectors: Systems that detect changes from the norm.
Control Systems and Effectors: Mechanisms that restore homeostasis by adjusting physiological parameters.

Cells require optimal conditions for biochemical reactions, facilitated by enzymes.
- Enzymes: Proteins that catalyze biochemical reactions; require specific pH and temperature conditions.
- Altered pH or temperature can denature enzymes, halting biochemical and physiological functions.
Mitochondria: Organelles that generate energy (ATP) using glucose and oxygen, found in tissue fluid (extracellular fluid).

Glucose and Oxygen: Essential for ATP production; must be regulated to avoid hyperglycemia or hypoglycemia.
- Blood Supply: Capillaries supply oxygen via red blood cells to tissues.
- Red Blood Cells: Need the right quantity for oxygen transport; imbalance affects blood viscosity and oxygen delivery.
Nutrients: Cells require a variety of nutrients (amino acids, fats, vitamins, minerals) for biochemical processes.

Endocrine System: Regulates cellular activity via hormones.
- Hormones must be at precise levels to prevent endocrine disorders.

Water: Must be regulated to prevent cellular swelling or dehydration.
Electrolytes: Ions (sodium, potassium, chloride) critical for nerve and muscle function.
- Excitable Cells: Nerve and muscle cells require specific electrolyte levels for electrical activity.

Waste Products: Includes carbon dioxide and nitrogenous wastes (e.g., ammonia).
- Must be excreted to prevent toxic buildup and ensure cellular function.

These concepts illustrate the numerous parameters regulated homeostatically to support life in cells.