Introduction Cells have unique structures, which formed in the process of evolution. Their shapes are conditional upon the functions they perform. As can be seen from previous studies, cells can change under the influence of external circumstances (see Appendix A). Therefore, the shapes of cells are defined by their functions, and they will have a resemblance when performing similar tasks. The combination of cells in any of the organ systems represents a uniform coordinated mechanism providing for their proper work. It leads to a necessity to consider the activities of various cells in different organ systems in relation to their purpose in order to understand the correlation between their shapes and functions. Cells of the Cardiovascular System The cardiovascular system is characterised by the presence of numerous cells comprising the heart, veins, arteries and capillaries. For the purposes of this paper, heart regeneration cells and their shapes and functions are considered (see Appendix C). The first type of cells is cardiac fibroblasts located within the heart. These spindle-like, elongated cells are critical for disposition, maintenance and remodelling of the extracellular matrix that, in turn, provides support for other cells in the cardiovascular system (Feng et al., 2018). The shape of cardiac fibroblasts fully corresponds to their complex task of connecting and ensuring the work of other heart cells. Another type of cell comprising the human cardiovascular system is the endothelial cell, which are located in blood vessels (see Appendix C). They represent a barrier between the blood and the body tissues, ensuring control over its movement throughout the body (Feng et al., 2018). The shape of endothelial cells is elongated, but the difference from other heart cells is in their flat structure, which allows them to extend and form a barrier. Hence, the shape of cells of the cardiovascular system varies depending on their function. Cells of the Nervous System The structure of cells in the nervous system is characterised by their elongated shape, which corresponds to the tasks performed by them (see Appendix A). Thus, for example, long nerve cells or neurons are responsible for making distant connections between the brain and muscles (Haupt & Minc, 2018). They allow for the nervous system’s principal activities, which include transmitting, processing and storing information. The shape of neurons fully corresponds to the task of creating this connection and represents an example of cell formation in the process of evolution. Moreover, the nervous system has different types of neurons, such as, for example, sensory neurons, ensuring the processing of external signals (Haupt & Minc, 2018). However, their shapes are still similar, with only slight differences. Another type of cell of the nervous systems is the glial cell, but their function and, therefore, their shape is different from neurons. They do not process any information or transmit it throughout the human body but serve to support neurons, ensuring their proper work (Haupt & Minc, 2018). Hence, the functioning of neurons is dependent on the glial cells that bind them together. According to their task, their sha