In biology, the nervous system is a highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events. Nervous tissue first arose in wormlike organisms about 550 to 600 million years ago.
Did you know that more than two billion people worldwide are affected by anemia? According to the Cleveland Clinic, not everyone who has it may even realize it. This common condition prevents oxygen from being carried to your body's organs and tissues, often resulting in symptoms such as fatigue, headaches, pale and dry skin, and a fast heartbeat.
Freckles and moles are both darker colored dots on your skin. You might even use the words interchangeably, according to Walk-In Dermatology. Perhaps you have lots of freckles or plenty of moles, or maybe you don't have any or very few. No matter how many moles and freckles you may have, you might not know the differences between them or how to tell which one is which.