Answer:
The human heart has it own nervous system, nodal system. It's made of nodes (that produces nerve impulses) and nerve fibers (running to all parts of the heart). Our nervous system can only increase or decreasing the nodes firing rates.
Starting with deoxygenated blood (oxygen poor blood), it travels from the superior and inferior vena cava into the right atrium, then into the right ventricle via the tricuspid value. There, it enters the pulmonary arteries via the pulmonic value. From there, it heads to the lungs and become oxygenated (rich in oxygen). It re-enters the left atrium of the heart via the pulmonary veins. There, it now travels to the left ventricle via the mitral valve and then into the aorta via the aortic value. From there it travels to the rest of the body supplying cells with oxygen and return back via the vena cava.
A theory is a unifying explanation for a broad range of observations. Science has come up with the scientific method to answer questions through observation. When something has been repeatedly experimented and results are yielded from them scientists cannot conclude answers to their problems just yet.
A controlled experiment needs to be tested multiple times until it yields an average solution that would generally be coming from different testers. Basically, a theory is something that has been repeatedly confirmed through some form of experimentation and observation.
Answers:
1. They're cheaper
2. Consistency when using it
3. Easily Accessible
Answer:
It is found in ice/solid form, not liquid or gas
Explanation:
