Answer:ATP is required for muscle contraction. Four sources of this substance are available to muscle fibers: free ATP, phosphocreatine, glycolysis and cellular respiration. A small amount of free ATP is available in the muscle for immediate use
Explanation:
The main function of the right side of the human heart <span> receives de-oxygenated blood from the body tissues (from the upper- and lower-body via the superior vena cava and the inferior vena cava, respectively) into the </span>right<span> atrium. This de-oxygenated blood passes through the tricuspid valve into the </span>right<span>ventricle</span>
Answer: Vascular smooth muscle cells.
Explanation:
Vascular smooth muscle cells are the contractile tissues which regulates flow blood and pressure of the blood by vasoconstriction (contraction) and/or vasodilatation (relaxation).
Vasoconstriction is the contraction of the blood vessels to increase tge pressure of the blood.
Vasodilatation is the relaxation of the blood vessels which results in a decrease in blood pressure.
