From the mother through the placenta
The answer is the endogenous opiate.
The human body naturally produces its own opiates like substances and uses them as neurotransmitters. These substances include endorphins, enkephalins, and dynorphin, often collectively known as endogenous opioids. Endogenous opioids modulate our reactions to painful stimuli.
You need more context to answer this.
The proteins in the cell membrane allow the nutrients to go and waste to go out <span>of a cell. Water passes through the cell membrane without the help of proteins.</span>
