Answer:
cappillaries
they connect the arteries and the veins
The structure shown by the red arrow is cell membrane.
In biology, cell membrane refers to the thin layer, which develops the external boundary of a living cell. It has three primary functions, which are as follows:
1. It comprises channels and receptors, which permits particular molecules like nutrients, ions, metabolic components, and wastes to pass between the cell and the outside environment.
2. It prevents toxic components from entering the cell.
3. They distinguish essential but incompatible metabolic procedures conducted within the cell.
The stage at which the development of the brain reaches its adult is the middle childhood. A child's Brain undergoes a period of development from birth to three-producing more than a million neural connections each second. This development is influenced by many factors, which include the child's relationships, experiences and environment.
The hormone described above is the hormone Melatonin.
Melatonin is a hormone secreted by the pineal gland in the brain, which helps regulate other hormones and maintains the body's circadian rhythm. This rhythm is an internal 24 hour clock that plays a critical role when we fall asleep and when awake. When it is dark the body releases more melatonin.