Tetrahydrocannabinol (THC) is a phytocannabinoid that primarily interacts with the CB1 receptor, a type of G protein-coupled receptor (GPCR) predominantly in and around the chemoreceptor trigger zone (CTZ) and emetic center. THC also blocks the serotonin receptor activity in the dorsal vagal complex (DVC) by inhibiting serotonin release. THC exerts its anti-emetic effects through these interactions, which are beneficial for patients undergoing chemotherapy.
Two synthetic agonists of THC,...

There have been five major extinction events throughout geological history, resulting in the elimination of biodiversity, followed by a rebound of species that adapted to the new conditions. In the current geological epoch, the Holocene, there is a sixth extinction event in progress. This mass extinction has been attributed to human activities and is thus provisionally called the Anthropocene. In 2019 the human population reached 7.7 billion people and is projected to comprise 10 billion by...

Seedless Vascular Plants Were the First Tall Plants on Earth

The diverse plant life on Earth—consisting of nearly 400,000 species—can be divided into three broad categories based on biological characteristics: nonvascular, seedless vascular, and seed plants.

A weir is a hydraulic structure designed to partially obstruct an open channel, enabling precise control and measurement of water flow. By forcing water to flow over or through it, a weir allows for accurate determination of discharge rates, making it an essential tool in water resource management. These structures are extensively used in regulating river flows, irrigation systems, and flood control channels.Types of Weirs and Their FeaturesWeirs are categorized primarily into sharp-crested and...

Most plants are seed plants—characterized by seeds, pollen, and reduced gametophytes. Seed plants include gymnosperms and angiosperms.