"Body" - what is it, definition of the term
The term denotes the integrated anatomical entity of a rat or mouse, comprising head, trunk, and limbs, enclosing all organ systems and tissues that enable vital functions such as movement, nutrient processing, and reproduction.
Detailed information
Rats and mice share a compact vertebrate framework, yet their dimensions differ markedly. Adult rats typically measure 20–25 cm in body length, excluding the tail, and weigh 250–500 g, while mice range 7–10 cm and 15–30 g. Both species possess a flexible spine composed of cervical, thoracic, lumbar, sacral, and caudal vertebrae, providing agility for burrowing and climbing.
The skull of each animal is reinforced by robust cranial bones that protect the brain and support prominent incisors. Rats exhibit a larger cranial capacity, accommodating a more developed olfactory bulb, whereas mice display a proportionally smaller cranium with a higher eye-to-body ratio.
Muscle architecture emphasizes rapid locomotion. Primary muscle groups include the deltoid, pectoralis, quadriceps, and gastrocnemius, each anchored to a well‑organized skeletal lattice. Fast‑twitch fibers dominate the hind limbs, enabling swift bursts of speed.
Key physiological systems:
- Respiratory: Lungs with a high surface‑area alveolar network for efficient gas exchange.
- Cardiovascular: Four‑chambered heart delivering oxygenated blood throughout the body.
- Digestive: Stomach, small intestine, and cecum adapted for omnivorous diets; the cecum hosts microbial fermentation.
- Reproductive: Females possess a bicornuate uterus; litter sizes average 6–12 for rats and 4–8 for mice.
- Nervous: Central nervous system includes a brain with well‑developed hippocampus and cerebellum, supporting learning and coordination.
Comparative observations reveal that rats have a more pronounced musculature and skeletal robustness, reflecting their larger size and greater strength. Mice display a higher metabolic rate, a proportionally larger auditory apparatus, and a longer tail relative to body length, enhancing balance during rapid movements.