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Physiological levels:
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Cell
Tissue
Organ
Organ system
Organism

Concept –complementarity of structure and function
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Thin membrane in alveoli allows gas exchange

Organ Systems:
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Integument
Skeletal
Muscular
Nervous
Endocrine
Cardiovascular
Lymphatic
Respiratory
Digestive
Urinary
Reproductive

Physiology and homeostasis:
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Feedback mechanisms
o Positive and negative
Our bodies are always trying to maintain homeostasis, a constant internal environment
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There is a release of hormones that increase uterine contractions
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o Example: high BP, body tries to lower BP
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Not about water
movement
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Iso: concentration of osmotically active particles (stuff) in a solution is the same as inside a cell
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Hyper: concentration of stuff in solution is more than inside a cell
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Answer as -> A is something to B
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Clinical example: someone has brain swelling because brain membrane is allowing water to move
through, which it is not supposed to
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Humans have around 290-300 mOsm osmotic pressure
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Mannitol is not permeable
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There is some stuff that is not permeable, and some
stuff that is
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Must know: Na concentration cannot reach equilibrium, or K
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Cells, membranes, and membrane structures:
Cells: transport is the most important part
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Have a plasma membrane that is differentially permeable
Plasma membrane function?
o Transport, enzymatic, receptor sites
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Parts of the bilayer: integral proteins, peripheral proteins, lipid core, hydrophobic and hydrophilic
regions, cholesterol, carbohydrate rich exterior
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o Non polar molecules or use of channel
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Hexanol: does not have a lot of OH groups, which affect polarity
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Mannitol: same as hexanol but with more OH groups, so it is very polar and cannot cross the membrane
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Hydration shell around ions: sodium hydration shell is bigger than the potassium hydration shell
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Carrier mediated transport can be saturated
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Only passive
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The pump protein hydrolyzes ATP
by itself to do work
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More sodium outside of the cell, but sodium is moved out against the gradient
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Primary active transport: directly uses ATP
Secondary active transport: uses gradient set up by Na/K pump which uses ATP
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Inside of cell is electrically negative with respect to the outside of the cell
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Sodium potassium pump is one cause of the
membrane potential
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 Second thing is the passive movement of Na and K
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1
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Therefore 3 positive charges are moving
out and 2 positive charges are moving in
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2
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More K moves out of the cell than Na moves into the cell, therefore creating a
negative charge
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Na and K concentration gradients causes more Na out than in and more K in than out
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Electrically favored for Na to come in because of the
negative charge within the cell
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What does it really mean to any cell?
Concept of electrochemical equilibrium?
Nernst Equation: 61/z*log (Co/Ci)-> z is charge, Co is concentration out, Ci is concentration in
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Requires energy to reform the membrane

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