Module 1: Cellular Environment PDF

🐥 module 1 Cellular environment 4 levels of organization: Cells, tissues, organs, systems Homeostasis and cell membrane Homeostasis is very important because all environments like to remain in a comfortable range with not...

🐥 module 1 Cellular environment 4 levels of organization: Cells, tissues, organs, systems Homeostasis and cell membrane Homeostasis is very important because all environments like to remain in a comfortable range with not many fluctuations or changes There is a sequence of events to return to homeostasis: The circle is the preferred state. Example: Change in temperature - you burn your skin (disturbance) —> skin cells (system) measure change (measuring element), they send message to brain (controller), which commands the muscles in the arms and fingers (effectors) to back off (feedback). No feedback = injury and disease. One way cells maintain homeostasis: The lipid bilayer module 1 1  Inside vs outside of cell (separated by the plasma membrane, a lipid bilayer, which is the cell membrane) The lipid bilayer is heterogeneous, it has many functions (e.g. structure, protection, cell activation, transport, cell-cell interactions, etc). It also embeds many diverse proteins. All the functions have an important role in maintaining homeostasis. Proteins have many different functions. Cell communication There are three types: Which one is used depends on how close cells are to each other. Modes of chemical signalling Signal transduction Cellular receptors Very close: Contact signalling & diffusion Medium-range: One cell sends signalling molecules to receptors located on the other cell Very distant: A carrier protein brings the signalling molecules to the target cells module 1 2  The modes of chemical signalling relate to the distance from sender to receiver. module 1 3