Week 4 - tissue level of organisation & the integumentary. When cells come together, we can get di erent tissues forming in the human body out tissues are classi ed into four basic types according to their structure and function: epithelial tissue. Covers body surfaces and lines hollow organs ducts in our body cavities. Responsible for allowing our body to interact with the internal and external environment: connective tissue. Protects and supports the body as well as all of our organs. Can serve as energy reserves or help to provide protection against pathogens: muscular tissue. Generates physical force needed to move body structures. Contraction of muscle tissue can also generate heat to keep us warm. Allows us to respond to stimuli and signals from external environment by generating electrical signals and action potentials and in turn allow us to activate muscular contractions, and glandular sections to respond to these changes in the external environment.