Answer:
Explanation:
Nervous system structure: The central nervous system is made up of the brain and spinal cord. The peripheral nervous system is made up of nerves that branch off from the spinal cord and extend to all parts of the body.
circulatory system structure: The circulatory system consists of three independent systems that work together: the heart (cardiovascular), lungs (pulmonary), and arteries, veins, coronary and portal vessels (systemic).
respiratory system structure: The upper airway system comprises the nasal cavity, sinuses, and pharynx; the lower airway system consists of the larynx, trachea, bronchi, bronchioles, and alveolar ducts.
Muscular system structure: A whole skeletal muscle is considered an organ of the muscular system. Each organ or muscle consists of skeletal muscle tissue, connective tissue, nerve tissue, and blood or vascular tissue.
I hope this helps some! They all work together because they all have functions to do to keep the body going.
