SA Node<span> which is also known as the sinus node, is the natural pacemaker of
the heart. It controls the heart rate by generating electrical impulses
and then sending electrical signals through the heart muscle, causing
the heart to contract and pump blood throughout the body. </span>
The SA Node is located in the outer layer of the right atrium of the heart, near the superior vena cava. It is made up of a group of cells (myocytes) positioned on the
wall of the right atrium, at the center of the heart and near the
entrance of the superior vena cava. These cells contract at a rate of
about 70-80 times per minute, which make up the natural heart beat.
One structure that can be found is most plant cells is chloroplast. A plant cell may have around 0 to 20 chloroplast, depending on their location in plant or their function.
Chloroplast is the structure that photosynthesis occurs. Photosynthesis is the method that plant make food for themselves. They turn sunlight into food such as starch.
Plants are autotrophs, which means they make food themselves, they don't need food from other sources like animals. Therefore, chloroplast is not found in animal cells because we are heterotrophs, we feed on other food.
Nucleus to the ribosomes, I think.
Oxygen and carbon dioxide travels to and from tiny air sacs in the lungs, through the walls of the capillaries, into the blood. Blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs.
Answer:
What stages of aerobic respiration needs oxygen to happen?
The Krebs cycle and the electron transport system
