A&P Chapter 4: Homeostasis Membrane Transport

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The body's ability to stay relatively unchanged even when the world around it changes
Homeostatic regulation
Physiological adjustment to preserve homeostasis in variable environments
Image: Homeostatic regulation
Most mechanisms of homeostasis depend on a principle called _________________ feedback
Negative feedback
a mechanism of response in which a stimulus initiates reactions that reduce the stimulus
positive feedback mechanism
the result or response enhances the original stimulus so that the response is accelerated.

Ex: contractions during childbirth
Passive transport
transport happens with no need of cellular energy (ATP)

Particles are moving from high to low concentration, follow concentration gradient.
What the 2 types of passive transport?
Facilitated Diffusion and Simple Diffusion
simple diffusion
If particles are small and fat soluble, they can pass the plasma membrane easily
Image: simple diffusion
facilitated diffusion
If particles are large and/or fat insoluble they cannot pass the plasma membrane easily, then they need a big (protein) channel to let them pass through.
Image: facilitated diffusion
Active transport
transport happens with the help of Cellular energy (ATP)

Particles move from low to high concentration, against gradient.
Primary Active transport
particles using ATP molecules directly to move against their concentration gradient.
Secondary Active transport
Particles using ATP molecules indirectly to move against their concentration gradient.

Ex: ATP used to move Na against gradient--->Glucose use established gradient to diffuse easier.
carrier proteins
Proteins that alternate between two conformations (shapes) open and close.

Binding with a specific substance causes the carrier protein to change its shape.

Then once the substance is released it changes back to its original shape.

-Used in Active and Passive transport.
Image: carrier proteins
at which all carriers are occupied by ligand/solute
the movement of materials out of the cytoplasm of a cell via membranous vesicles or vacuoles that fuse with the plasma membrane.
Image: Exocytosis