Animal Physiology - Systems

Animal physiology examines how cells, tissues and organs function individually and interact to maintain the life of the organism. At the cellular level, metabolism converts nutrients into energy and building blocks. Specialized tissues—muscle, nerve, epithelium, connective tissue and blood—form organs that perform discrete tasks. Organs come together in systems such as the circulatory (delivery of oxygen and nutrients), respiratory (gas exchange), digestive (breakdown and absorption of food), excretory (removal of waste and water balance), endocrine (hormonal regulation), immune (defence against pathogens), nervous (information processing), musculoskeletal (support and movement), integumentary (barrier and sensory functions) and reproductive (propagation of the species) systems. Each system operates within narrow limits of temperature, pH, ion concentrations and nutrient supply—a state known as homeostasis. Integration across systems is achieved by chemical signals (hormones, cytokines) and electrical communication (nerve impulses), enabling animals to respond to environmental change, to adapt over developmental and evolutionary time, and to perform the complex behaviours required for feeding, locomotion, reproduction and survival.

Research from Nature Portfolio

Intrinsic mitochondrial function has been shown to underpin acute oxygen sensing in arterial chemoreceptors. In models deficient in complex I, reintroduction of a single‐molecule yeast NADH oxidoreductase restores ventilatory reflexes and glomus cell oxygen sensitivity without rescuing proton‐pumping, demonstrating that electron transport alone governs chemoreception. This finding clarifies bioenergetic control of respiratory drive and opens prospects for gene‐therapy of mitochondrial respiratory defects. In a human alveolus‐on‐chip, physiologically relevant breathing‐like cyclic deformations suppress viral replication by activating mechanosensitive pathways. Cyclic stretch enhances barrier integrity, modulates cytokine release and recruits immune cells via TRPV4 ion channels and RAGE signalling, suggesting novel drug targets to treat virus‐induced lung inflammation. Convergent genomic deletions of multiple gastric genes have been identified among stomachless teleost fishes. Loss of proton pump and pepsinogen genes correlates with remodelling of gastric gland architecture and compensatory upregulation of epithelial transporters in agastric species, illustrating how gene loss drives structural adaptation in divergent feeding niches.

Research from all publishers

Comparative transcriptomics of the scallop heart under sustained heat stress has revealed over 3 500 differentially expressed genes associated with signal transduction, oxidative stress responses and DNA repair pathways. Co-expression network analysis highlights activation of base excision repair and gap junction modules, and coordinated regulation of cytoskeletal and calcium signalling components, suggesting intricate control of cardiomyocyte function during thermal acclimation. A broad review of marine heat extremes synthesises physiological and biochemical responses across bivalves, emphasizing rapid heat‐shock protein induction, antioxidant defence upregulation and metabolic reorganisation as core strategies for survival during marine heatwaves. In rainbow trout, chronic crowding stress provokes elevated cortisol, oxidative damage in skeletal muscle and transcriptomic shifts in autophagy, mitophagy and insulin signalling coupled with widespread DNA methylation changes. Integrative epigenomic–transcriptomic analyses reveal bidirectional correlations between methylation and gene expression in pathways of energy metabolism and chromatin remodelling, underscoring how early‐life and environmental stressors imprint lasting epigenetic signatures with implications for aquaculture welfare.

Animal Physiology - Systems publication trend

The graph below shows the total number of articles in animal physiology - systems across all publications each year (not limited to Nature Index journals).

Technical terms

Homeostasis: Maintenance of internal physiological variables within narrow limits.

Persistent inward current (PIC): Sustained depolarizing current in excitable cells that amplifies and prolongs responses to synaptic input.

Chemoreceptor: Sensory cell that detects chemical stimuli such as blood gases and transduces them into neural signals.

Mechanotransduction: Conversion of mechanical forces into biochemical signals by structures such as ion channels and adhesion receptors.

Epigenetic modification: Heritable change in gene expression without alteration of the DNA sequence, such as DNA methylation.

Base excision repair: DNA repair pathway that corrects small base lesions through removal and replacement of damaged nucleotides.

Gap junction: Intercellular channel allowing direct exchange of ions and small molecules between adjacent cells.

Angiotensin II: Peptide hormone that constricts blood vessels and stimulates fluid retention, part of the renin–angiotensin system.

Heat‐shock protein (HSP): Molecular chaperone induced by thermal or other stresses that assists in protein folding and protection.

References

1. Overview of the Internal Physiological System of the Human Body.
2. Transgenic NADH dehydrogenase restores oxygen regulation of breathing in mitochondrial complex I-deficient mice. Nature Communications (2023).
3. Mechanical control of innate immune responses against viral infection revealed in a human lung alveolus chip. Nature Communications (2022).
4. Convergent gene losses and pseudogenizations in multiple lineages of stomachless fishes. Communications Biology (2024).
5. Comparative Analyses of Dynamic Transcriptome Profile of Heart Highlight the Key Response Genes for Heat Stress in Zhikong Scallop Chlamys farreri. Antioxidants (2024).
6. Impacts of marine heat extremes on bivalves. Frontiers in Marine Science (2023).
7. Molecular and epigenetic responses to crowding stress in rainbow trout (Oncorhynchus mykiss) skeletal muscle. Frontiers in Endocrinology (2025).