Image: Seals are consumers. An ecosystem is made up of animals, plants and bacteria as well as the physical and chemical environment they live in. The living parts of an ecosystem are called factors while the environmental factors that they interact with are called abiotic factors.
Atrial natriuretic peptide (ANP), also called atrial natriuretic factor (ANF), atrial natriuretic hormone (ANH), cardionatrine, cardiodilatin (CDD), or atriopeptin, is a powerful vasodilator, and a protein (polypeptide) hormone secreted by heart muscle cells.
3. Acetylcholine binds a receptor on the skeletal muscle cell and generates an action potential, increasing Ca++ release from the sarcoplasmic reticulum. 4. Ca++ initiates contraction, resulting in shortening of the muscle cell and, consequently, movement.