Exam 7: Cells, Tissues and Signals

A type of sensory organ found in many invertebrates consists of a spherical, fluid filled chamber that contains grains of sand or other dense granules. The cells lining the chamber are mechanoreceptors with sensitive cilia that project into the lumen. The granules settle at the low point within the chamber, deforming the cilia underneath and stimulating the cells directly below them. In this sensory organ, the cells lining the chamber are mechanoreceptors specialised for detecting

All animal tissues are composed of differentiated cells

When the vertebrate retina is exposed to light

In mammals, the hormone epinephrine activates an intracellular signalling pathway that leads to the breakdown of glycogen in the liver. The binding of epinephrine to a G-protein linked receptor on the surface of liver cells activates a succession of relay molecules including the adenyl cyclase, cAMP and protein kinase A, the final protein to be activated is the enzyme glycogen phosphorylase, which catalyses the breakdown of glycogen to glucose-1-phosphate. In this signalling pathway, an increase in the concentration of cAMP would lead to an increase in the concentration of