The inferior region of the brain stem, the houses many vital autonomic centers involved in the control of heart rate, respiratory rhythm, and blood pressure.

The inferior region of the brain stem, the medulla oblongota houses many vital autonomic centers involved in the control of heart rate, respiratory rhythm, and blood pressure.

Explanation:

The medulla oblongata is the part of the brain that joins the spinal cord and forms the lower part of the brain stem. In the bulb there are ascending (sensory) and descending (motor) fascicles that communicate the spinal cord with the brain, in addition to numerous nuclei or centers (masses of gray matter) that regulate various vital functions. The medulla oblongata has the function of controlling vital and unconscious elements such as the heartbeat and blood pressure. Thus, it is responsible for maintaining the heart rate and regulating vasoconstriction. Also, it manages the control of respiratory function, maintaining it at all times.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!

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