Receptors that work through second messenger systems are called
receptors.

An organ system consists of a group of organs that performs specific functions necessary for the survival of an organism. humans have eleven different organ systems: integumentary, skeletal, muscular, nervous, endocrine, circulatory, lymphatic, respiratory, digestive, urinary, and reproductive. discuss the function of neurons, the brain and the spinal cord within the human nervous system while explaining the interrelationship of each organ.

Will mark brainliest. (20 points) many have pigments structures known as eyespots that detect direction of light. a. b. archaebacteria c. protists d. none of the above

Fredrick griffith made a scientific discovery in 1928