Explain how it is known that the environment changed over time.

When does the circulatory system work with the respiratory system? a. during blood cell formation b. during cellular respiration c. during intestinal digestion d. during a viral infection

Which part of the neuron below is indicated by the arrow, and what is its function? hormones send chemical signals throughout the body to regulate other body processes. hormones are chemical signals that are sent throughout the body to regulate other body processes. hormones send electrical signals throughout the body to regulate other body processes. hormones are electrical signals that are sent throughout the body to regulate other body processes.

Hemoglobin is a proton that carries oxygen around your body what is hemoglobin made from