Cells from the cheek are a type of epithelial cell, similar to skin. ... They can be seen faintly even at 40x (scanning power), but the most dramatic images are at 400x where the nucleus is clearly visible as a dark spot in the center of the cell.
The process of muscle contraction requires several steps.
The most famous theory on how the contraction and relaxation of muscles take place is the sliding filament theory.
However, this theory has been refined and one important addition to it is the mechanism by which myosin can pull actin and cause shortening of the sarcomere.
For the movement of myosin, it binds and releases actin and forms cross bridges.
Myosin is subdivided into two regions - S1 and S2. The contraction of the S1 region is what constitutes the power stroke.
An important requirement of the power stroke is the hydrolysis of ATP to release an inorganic phosphate which provides energy for the process.
The hypothalamus is involved in different daily activities like eating or drinking, in the control of the body's temperature and energy maintenance, and in the process of memorizing and in stress control. It also modulates the endocrine system through its connections with the pituitary gland.
