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a dynamic constancy of the internal physiological environment |
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How is homeostasis controlled? |
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feedback control mechanisms |
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The inability to maintain homeostasis indicates... |
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the study of biological functions and processes of the human body under normal conditions |
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Image for Components of Control Systems |
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What are negative feedback mechanisms? |
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Definition
Action taken by effectors to oppose changes in the controlled variable cause by a stimulus |
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What is the most common feedback mechanism in nature? |
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Definition
negative feedback: it supports homeostasis |
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Look @ images for Negative Feedback mechanisms |
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Define Positive Feedback Mechanism |
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Definition
Response by effectors amplifies changes in the controlled variable cause by a stimulus |
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What are some examples of Positive Feedback Mechanisms? |
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Definition
blood coagulation, child birth, inflammation response |
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What response does not stupport homeostasis? |
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Definition
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Which regulation mechanism is less common in nature? |
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Structure of the plasma membrane (image) |
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Definition
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The plasma membrane is ______ permeable: what does this mean? |
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Definition
selectively: only allows certain molecules to pass through the membrane |
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What type of molecules readily diffuse across the membrane? and Why? |
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Definition
hydrophobic, because the membrane is lipid-like so the hydrophobic molecule can pass easily (without the aid of membrane proteins) |
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What are able to squeeze between tiny spaces created by the phospholipid tails as they sway in the fluid environment? |
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Definition
small, uncharged, polar molecules (such as water) |
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Term
What is Passive transport? |
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Definition
Movement of a substance down its concentration gradient; does not require energy |
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What is active transport? |
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Definition
movement of a substance against its concentration gradient; transport process requires enegy |
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Term
In passive transport, substance moves from [ ] solute concentration to [ ] |
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Definition
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Simple diffusion moves ions in what direction |
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Definition
high --> low concentration; ions are in continuous movement due to their thermal energy. |
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does simple diffusion need a transport protein? |
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Definition
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in channel-mediated facilitated diffusion, what do the specialized channel proteins create? |
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Definition
hydrophilic tunnels in the lipid bilayer |
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Term
What is the point of the protein channels in the lipid bilayer? |
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Definition
they facilitate the transport of small, polar molecules and ions across the membrane at a faster rate than carrier-mediated transport |
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Channel-mediated facilitated diffusion occurs in what direction on the [gradient] |
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Definition
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What type of molecules will channel proteins let pass? |
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Definition
only specific molecules or ions of a certain size to cross the membrane |
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Term
What does carrier-mediated facilitated diffusion refer to? |
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Definition
When specialized proteins facilitate the transport of larger, hydrophilic (polar) molecules across the plasma membrane. (the molecules are generally too large to fit through the channels) |
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Term
How do the carrier proteins make it through the membrane? |
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Definition
It undergoes a confirmational change; this slows the transport of solute |
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Term
T/F Carriers are not selective |
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Definition
False: they are highly selective |
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Term
Carrier mediated facilitated Diffusion moves solute from [ ] to [ ] concentration |
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Definition
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What is this an example of: [image] |
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Definition
Carrier-mediated Facilitated Diffusion |
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What is primary active transport? |
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Definition
When carrier proteins use energy to move a substance against its concentration gradient |
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Term
What is the action behind primary active transport? |
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Definition
Molecules are pumped against a concentration gradient at the expense of energy |
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Term
Primary active transport: [ ] to [ ] concentrations |
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Definition
low to high: directly utilizing ATP |
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Term
In primary active transport, the establishment of a concentration gradient is... |
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Definition
a consequence of transport |
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What is secondary active transport driven by |
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Definition
the energy stored in the concentration gradient of another molecule |
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Term
______ movement of one molecule drive ______ movement of another molecule |
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Definition
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What is used to power the transport of the second molecule in secondary active transport? |
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Definition
the concentration gradient of the first molecule |
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What are the categories of secondary active transport? |
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Definition
cotransport (symport) and countertransport (antiport) |
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Definition
in secondary acive transport: it is when the driver ion and molecule move in the same direction across the plasma membrane |
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Definition
in secondary active transport: it is when the driver ion and molecule move in opposite directions across the plasma membrane |
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Definition
the simple diffusion of water across a selectively permeable membrane: it allows water molecules to freely permeate the membrane but obstructs larger solute molecules |
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In osmosis, what direction does water move? |
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Definition
down it's concentration gradient |
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Term
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Definition
a measure of the osmotic pressure gradient of two solutions separated by a semipermeable membrane |
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What influences tonicity? |
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Definition
non-penetrating solutes (ones that cannot cross the membrane, so they exert an osmotic pressure) |
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Term
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Definition
both solutions have the same concentration of solutes: No net movement of H20 |
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Term
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Definition
a solution in which the concentration fo solute is lower than the solution it is being compared to: cells will lyse |
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Definition
A solution in which the concentration of solute is higher than the solution it is being compared to: cells will crenate |
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