The Muscular System Does Not Produce Blood Cells
The muscular system does not produce blood cells—this function is performed exclusively by the bone marrow within the skeletal system. While skeletal muscle performs numerous critical functions including movement, posture maintenance, heat generation, and metabolic regulation, hematopoiesis (blood cell production) occurs in the red bone marrow of bones, not in muscle tissue 1.
Primary Functions the Muscular System DOES Perform
To clarify what muscles actually do, the muscular system is responsible for:
Movement and locomotion: Skeletal muscles generate force for voluntary movement, with muscle contraction depending on electrical activation originating from respiratory neurons in the brainstem, carried via motor nerves, and propagating through muscle membranes 2
Posture and stability: Muscles maintain body position and antigravity movement, with postural tone assessed through ventral suspension in infants and truncal positioning when sitting and standing 2
Heat production (thermogenesis): Skeletal muscle comprises approximately 40% of total body weight and 50% of total protein, serving as a crucial tissue for thermogenesis 3
Metabolic homeostasis: Muscle tissue plays a vital role in metabolic regulation and glucose homeostasis 3
Respiratory function: Respiratory muscles enable ventilation through contraction, with the diaphragm and accessory muscles generating pressures, volumes, and flows necessary for breathing 2
What Muscles Cannot Do
Beyond blood cell production, the muscular system also does not:
- Produce hormones in the traditional endocrine sense (though muscle does release myokines during contraction)
- Filter blood or produce urine (kidney function)
- Digest food or produce digestive enzymes (gastrointestinal system function)
- Conduct electrical impulses for coordination (nervous system function, though muscles respond to such signals) 2
Clinical Relevance
Understanding what the muscular system does not do is important when evaluating patients with systemic symptoms. For example, anemia or blood cell abnormalities should prompt investigation of bone marrow function rather than muscle pathology 2. Conversely, muscle wasting conditions like sarcopenia, cachexia, or muscular dystrophies result from imbalances in muscle protein synthesis and degradation, not from loss of hematopoietic function 4, 5, 3.