Answer:
Blood Brain Barrier(BBB)
Explanation:
This is a biological interface of special endothelial cells of astrocytes, pericytes , capillaries, neurons and other structures, acting as a physical barrier or gate separating the Central Nervous system from the peripheral blood circulations. Thus it formed a tight junction serving as a physical barrier to selectively regulate the entrance of substances from the cerebral blood flow into the brain, therefore maintaining homeostasis of the brain.
From above any substances absorbed into the blood stream irrespective of the mode of entry are transported through the BBB, and are selectively regulated to enter the brain cells by the BBB's interactions with the blood vessels, hormones etc.
Basically it allows the passage of nutrients, a few drug, hormones and resists certain toxins and pathogens for the brain homeostasis.
Answer:
https://phys.org/news/2009-05-bird-songs-environment.html
Explanation:
Answer:
The economic principle that helps ensure that scarce resources are allocated efficiently is "the profit motive."
Explanation:
In economics, the profit motive is the inspiration of organizations that function so as to exploit their profits. Conventional micro-economic concept suggests that the eventual goal of a commercial is to make money. Specified differently, the aim for a business's presence is to chance a profit. The profit motive is the craving to make money. In a free market (where people willingly swap money, goods and services, the profit motive agrees who grows what. In theory, the profit motive dispenses resources efficiently, but in practice there are some problems.
