Option A,
both limit movement of substances through the system
The sphincter muscle usually surrounds the openings in the body such as urethra, anus and performs the function of tightly closing the openings. When once the messages are received from the nervous system the sphincter relaxes and releases the material out of the opening during urination of excreting
The same is the function of valves in the circulatory system. They also prohibits the entry of blood from one chamber to other and then to the main circulatory system. The relaxes on receiving a signal from the brain and thus transfer blood from one chamber to the other.
Answer:
first blank is carbon i dk the secon
Explanation:
B . Air that is breathed in
the dense connective tissue is a scar tissue. It doesn't exert forceful contraction like muscle. The muscle as a whole is still functional although the contraction will be weaker.
The muscle is still functional because the connective tissue only replaces the damaged parts of the large muscle.
C. negative proteins inside the cell
