Answer:
By action potential nerve contract the muscle
Explanation:
The muscle contract when the nervous system sends action potential to the muscle. So the nervous system delivers signal to muscle, the first signal reaches the neuromuscular junction. The signals are passed by a chemical messenger called neurotransmitter release by motor neurons, the chemicals bring reaction and shorten the muscle fibre. When neurotransmitter are absent or reduce in concentration the process reverse and muscle relax again.
Answer: the factors that increase cardiac output include:
--> Nervous stimulation and
--> Hypertrophy of the heart.
Explanation:
Cardiac output can be defined as the quantity of blood pumped into the aorta each minute by the heart. This is also the quantity of blood that flows through the circulation. There are factors that can cause increased cardiac output or that can lead to a hypereffective heart. They are:
--> NERVOUS STIMULATION: The combination of sympathetic stimulation and parasympathetic inhibition does two things to increase the pumping effectiveness or cardiac output of the heart. These include:
• it greatly increase the heart rate from the normal level of 72 beats/mum up to 180 to 200 beats /mom.
• it increases the strength of heart contraction, which is called increased contractility to twice it's normal strength.
--> HYPERTROPHY OF THE HEART: A long term increased workload, but not so much excess load that it damages the heart, causes the heart muscle to increase in mass and contractile strength in the same way that heavy exercise causes skeletal muscles to hypertrophy. This effect of increased muscle mass of the heart, allows the heart to pump much greater than usual amounts of cardiac output.
Answer:
Natural selection
Explanation:
Natural selection is a process that causes heritable/favorable traits that are helpful for survival and reproduction to become more common as time goes on, and it gets passed from generation to generation.
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