Cells have receptors on their surfaces to sense their environment and to communicate with other cells. viruses use these cell receptors to

Efficiency is the percent of work put into a machine by the user (input work) that becomes work done by the machine (output work)

Body systems are not completely independent they integrate and work together describe one example of the integration between body systems

Fill in the blank 1. digestion occurs in the small intestine through the action of enzymes. 2. urea, excess water, and other waste materials are eliminated in a water fluid called 3. can cause infections by injecting dna or rna into hosts. 4. the human immune system produces in response to a vaccine, which later can bind to and destroy a pathogen if it invades. 5. are structures that link bone to bone at a joint 6. in the heart, blood flows from the right atrium to the right ventricle, where it is pumped to the the words i can use are: lymphocytes gliding pivot gas urine absorption dermis fulcrum lungs chemical viruses capillary vertebrae esophagus tendons antibodies synapses ligaments kidneys pathogens