Different environments have different requirements.
Oxygen is much more difficult to take up from water than from air. Heat is
conducted at a much faster rate in water than in air.
The surface area or volume ratio: rate of diffusion varies with cell size.
Much more efficient between small cells because of the smaller space to diffuse
Our bodies are over half water with over 60% of that water being within the cells
Homeostasis is the major challenge to survive for organisms
Epithelia: covers surfaces
-made up of cuboidal cells; usually densely packed
-secretions, absorption, lines blood vessels,
connective: bind and support other tissues: blood, bone cariledge and fat
-elastin and collagen
transmits impulses- composed of neurons and glial cells
muscle tissue: skeletal, cardiac, and smooth
- Feedback mechanisms:
- Negative and positive
- Set point controls the “on off” switch
Positive feedback: stimulus leads to a response that leads to a stronger stimulus and
-example is birth and urination(things that must be finished)
feed forward information: changes set point in response to the outside stimulus.
-example is preparing for a state of hibernation
-fever: body t