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✅ Animal Physiology

How this section is organized

Where Animal Anatomy covers structure (histology, named cell types, organ architecture), Animal Physiology covers mechanism and regulation: the ionic basis of a nerve signal, the hormonal control loop behind a kidney’s response to dehydration, the reason a fish gill extracts oxygen more efficiently than a mammalian lung. This section is organized in two tiers:

  • Core Regulatory & Organ-System Physiology (9 pages), one page per major regulatory system or organ system’s functional mechanism, each explicitly paired with the matching Animal Anatomy structural page where one exists.
  • Comparative & Whole-Animal Physiology (4 pages), covering function-across-taxa: how different lineages solve the same physiological problem (osmoregulation, thermoregulation, gas exchange, locomotion) in structurally distinct ways.

Start with Homeostasis & Osmoregulation, it introduces feedback loop theory, the shared regulatory vocabulary every later page in this section assumes.

1. Homeostasis & Osmoregulation
Feedback loop theory, nitrogenous waste trade-offs, kidney function mechanism (RAAS, ADH, countercurrent multiplier), read this first.

Core Regulatory & Organ-System Physiology

2. Endocrine System Physiology
Hormone classes and mechanism, HPA/HPT/HPG axes, endocrine feedback logic
Intermediate
3. Nervous System Physiology
Resting/action potential, synaptic transmission, sensory transduction, reflex arcs
Advanced
4. Muscle Physiology
Sliding filament mechanism, excitation-contraction coupling, fiber types, energy systems
Intermediate
5. Cardiovascular Physiology
Cardiac output, Frank-Starling mechanism, baroreceptor reflex, capillary exchange
Advanced
6. Respiratory Physiology
O2-Hb dissociation curve, Bohr/Haldane effects, control of ventilation, acid-base balance
Advanced
7. Digestive & Metabolic Physiology
Enzymatic digestion, digestive hormones, absorption mechanisms, metabolic rate
Intermediate
8. Immune Physiology
Innate and adaptive immunity, antigen presentation, clonal selection, immunological memory
Advanced
9. Reproductive Physiology
Pregnancy maintenance, parturition as positive feedback, lactation
Advanced

Comparative & Whole-Animal Physiology

10. Comparative Osmoregulation & Excretion
Marine/freshwater fish, elasmobranch urea retention, insect Malpighian tubules, desert mammals
Advanced
11. Comparative Thermoregulation
Endotherm vs. ectotherm, countercurrent heat exchange, torpor/hibernation/estivation
Intermediate
12. Comparative Respiration & Circulation
Gill/lung/tracheal gas exchange compared, diving physiology, high-altitude adaptation
Advanced
13. Locomotion & Energetics
Metabolic scaling (Kleiber’s law), cost of transport, gait transitions, elastic energy storage
Intermediate