Physiology: Unit 1: Basics of Cell Biology Flashcards
Conceptually, in what ways can disease affect homeostasis?
Homeostasis can either be primarily affected by a disease process or it may be that the disease has effects that cause secondary efects on systems (e.g. compensatory responses). Ultimately, diseases may either be a structural or functional problem of a system, cell type or tissue.
What is the difference in positive and negative feedback loops?
Negative feedbacks are more common and tend to result in system alterations that reduce the stimulus to a homeostatic level.
Positive feedback mechanisms are essentially the opposite, with a good example being the coagulation cascade.
Describe how the structural components of the cell membrane result in alterations in cell permeability.
The cell membrane consists of opposing molecules of phospholipids. Phosphate groups point outwards and are hydrophilic whereas fatty acid ends point inwards and are hydrophilic. Fat soluble molecules can therefore pass freely through this inner layer, whereas water soluble molecules cannot. Cholesterol exists in the centre of the layer and the amount determines solubility and cell membrane fluidity in more detail.
What is the normal ultrastructure of a cilia filament and how may this be altered with disease?
There are 9 external double microtubules surrounding 2 central microtubules. Various other structures link these together, including ATP responsive dynein which links adjacent outer microtubule pairs.
Diseases such as primary ciliary dyskinesia alter the structure of the cilia ultrastructure in many different ways with the end result being a non-functional cilia.
