How many chambers does a mouse's heart have? - briefly
A mouse’s heart is composed of two chambers: one atrium and one ventricle. This two‑chambered structure is typical of mammalian rodents.
How many chambers does a mouse's heart have? - in detail
A mouse heart contains four distinct chambers: a right atrium, a left atrium, a right ventricle, and a left ventricle.
The atria receive de‑oxygenated blood from the systemic circulation (right) and oxygen‑rich blood from the lungs (left). Each atrium empties into its corresponding ventricle through atrioventricular valves (tricuspid on the right, mitral on the left). The ventricles generate the pressure needed to propel blood forward: the right ventricle sends blood to the pulmonary artery, while the left ventricle drives it into the aorta.
Structural dimensions differ markedly from those of larger mammals. In an adult laboratory mouse, the whole heart weighs roughly 0.1 g and measures about 8–10 mm in length. Wall thickness is greatest in the left ventricle (≈1 mm) to accommodate higher systemic pressures; the right ventricular wall is thinner (≈0.5 mm).
Developmentally, the four‑chambered configuration appears early. By embryonic day 10.5, the primitive heart tube has looped, and by day 13.5 distinct atrial and ventricular regions are evident. Genetic pathways governing chamber formation—such as Nkx2‑5, Tbx5, and Hand1/Hand2—are conserved between mice and humans, making the species a valuable model for congenital heart disease research.
Physiological characteristics reflect the animal’s high metabolic rate. Resting heart rate averages 500–600 beats per minute, producing a cardiac output of 12–15 ml min⁻¹ g⁻¹. The rapid cycle necessitates efficient atrial contraction and ventricular relaxation to maintain adequate filling times.
Key points for reference:
- Four chambers: right atrium, left atrium, right ventricle, left ventricle.
- Total heart mass ≈0.1 g; length ≈8–10 mm.
- Left ventricular wall ≈1 mm; right ventricular wall ≈0.5 mm.
- Chamber formation complete by embryonic day 13.5.
- Resting rate 500–600 bpm; cardiac output 12–15 ml min⁻¹ g⁻¹.
These facts establish the mouse heart as a compact, four‑chambered organ with anatomical and functional parallels to human cardiac physiology.