Veins don’t always conduct oxygen poor blood. The pulmonary vein brings reoxygenated blood from the lungs into the heart
The shape of the earth affects our view of the stars because since we are shaped a sphere, we get more of a view of many different stars and not much is blocking our view
Answer:
The Sun is the main source of energy for most organisms
Explanation:
Producers such as plants, algae, and cyanobacteria use the energy from sunlight to make organic matter from carbon dioxide and water. This establishes the beginning of energy flow through almost all food webs.
The Nebula would be your answer, it is a cloud of dust and gas in outer space :)
Answer:
The correct answer is "There are several mechanisms that explain why a hormone have different effects in different cells. These mechanisms include: multiple receptors for the same hormone, a single receptor coupled to different pathways and hormones interacting with receptors for other molecules".
Explanation:
Hormones are among the most versatile molecules of the body, responsible for different biological processes such as human growth, sex development and metabolisms. Hormones are responsible of these complex biological processes because they have drastically different effects in different cells. There are several mechanisms that explain why a hormone have different effects in different cells. These mechanisms include:
- Multiple receptors for the same hormone. For instance, there are multiple receptor for dopamine, a hormone and neurotransmitter responsible for different functions such as movement, memory, sleep and motivation.
- A single receptor coupled to different pathways. Most hormone receptors act with a cascade of signaling. This in consequence results in a single receptor interacting with different molecules having multiple effects.
- Hormones interacting with receptors for other molecules. One example is the action of one metabolite of progesterone named allopregnanolone. This metabolite interacts with GABA-A receptor, which gives it anxiolitic properties.
