cell membrane
compartmentalize body into individual cells
- every physiological phenomenon depends on behaviro of cells and membranes
structure-function
the structure of the cell membrane, its polarity and molecules
two basic types of gradients
concentration gradients (osmotic and electrical) & pressure gradients
Homeostasis
a stable internal condition
- fluctuation within a range
What is homeostasis maintained through?
Feedback and feedforward
Feedforward
changing the body in anticipation
- motor center in brain begins to initiate exercise as it sends signals to skeletal muscles
feedback
changing the body in response
- blood sugar level rises after eating, pancreas detects that change and secretes insulin
- insulin permits cells to take glucose out of the blood for use n storage
Negative feedback loop
where the product of the pathway turns the pathway OFF
- keeps the variable within the homeostatic range
positive feedback loop
where the product of the pathway amplifies the strength of the pathway
- always represents a deviation from homeostasis
- pfl spiral and gain momentum until something stops them (child brith)
energy
ingestion of food, digestion and generation of ATP are steps in the process of providing the cell with the energy needed
evolution
humans evolved over hundreds of thousands of years
- bodies have evolved to be efficient with energy and to store as much nutrient as possible