Download 2. ______ Active Transport uses the energy

Anatomy & Physiology 34A Lecture
Chapter 3 – Cell Membrane Transport
I. Overview
A. Cell Membranes
B. Body Fluid Compartments
C. Movement Across Cell Membranes
II. Cell Membranes
A. ____________ of the cell membrane include
1. Physical ___________, separating intracellular fluid (____) from the
extracellular fluid (_____)
2. Regulation of ________ of materials with the environment
3. _____________ between the cell and its environment via receptors
4. Structural ___________ – cytoskeletal proteins maintain cell shape and
junctions between adjacent cells and the extracellular matrix
III. Body Fluid Compartments
A. Cell ___________ divide the inside of the body into compartments
1. ________cellular fluid is found within cells
2. ______cellular fluid surrounds cells, and is subdivided into
a. ______________ fluid that bathes the cells
b. ___________, the fluid portion of blood
B. Many solutes can cross ____________ walls from plasma to interstitial fluid but
exchange between the intracellular and extracellular fluids is more restricted by cell
___________
IV. Movement Across Cell Membranes
A. ____________ – movement of particles through a membrane due to
_____________ pressure, the force exerted on a membrane by water (e.g., blood
pressure forces solutes from capillaries to tissues)
B. ____________ (molecular) Motion – the random motion of microscopic particles
in a solid, liquid or gas, caused by ____________ with surrounding molecules – is
the basis for molecular movement
C. Two ____________ of a molecule influence its movement across a cell membrane
– size and polarity
1. _________ molecules, such as O2, CO2, H2O, and nonpolar lipids can ______
freely through most phospholipid bilayers
2. ________ molecules and ions must be ___________ across via membrane
proteins
D. Substances _______ across cell membranes by either passive or active transport
1. __________ transport is down a substance’s concentration gradient (from
______ to ____ concentration), thus doesn’t require ATP energy
2. ________ transport is against a substance’s concentration gradient (from ____
to _______ concentration), which requires _____ energy
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E. ____________ transport includes simple diffusion, osmosis, and facilitated
diffusion
1. Simple _____________ - movement of particles down their concentration
gradient from ________ to _______ concentration until equilibrium is
established. (No ATP required) Diffusion ________ is influenced by
a. Temperature – higher temp. = _________ diffusion
b. Molecular Wt. – ______ particles diffuse faster than large ones
c. Concentration gradient – greater concentration ________ = faster diffusion
d. Distance – diffusion is rapid over ______ distances, but slow over long
distances
e. Membrane surface area – larger _________ = faster diffusion
f. Membrane composition – ___________ membranes = slower diffusion
2. ________ - diffusion of H2O molecules across a membrane, influenced by the
__________ (ability of a solution to affect the fluid volume & pressure in a cell)
of the solutions on both sides of the membrane
a. _______tonic solution has a __________ concentration of nonpenetrating
solute (thus, less water) than another solution. Water diffuses through the
membrane ________ the hypertonic solution
b. _____tonic solution has a solute concentration _______ to another solution.
No ____ diffusion of water occurs across the membrane. (0.9% NaCl normal
saline solution is isotonic to human cells)
c. ______tonic solution has a _________ concentration of nonpenetrating solute
(thus, more water) than another solution. Water diffuses through the
membrane _________ the hypotonic solution
d. _______ is measured in terms of osmolarity or osmolality
1) Osmolarity is the number of solute ___________ per _______ of water (1
osmole = 1 mole of dissolved particles; e.g.: about 300 mOsM NaCl is
isotonic to human cells)
2) Osmolality is the concentration of _____osmoles per ____ water
(mOsm/kg); often used when estimating a person’s body water content
3. ____________ Diffusion (mediated transport) - diffusion of molecules (e.g.:
glucose, amino acids) and ____ (e.g.: Na+, Cl-, K+, Ca2+) down their conc.
gradient across a membrane via specific protein _________ and _________
proteins. No ATP required.
F. ____________-mediated transport exhibits specificity, competition, and saturation
1. _________ – carriers, such as GLUT transporters, generally move only ____
type of molecule, or related molecules
2. ___________ – related molecules compete for binding sites on their transport
proteins. Competitive inhibitors can ____ molecular transport
3. ____________ occurs when a group of transporters are all working at their
maximum rates (transport __________)
G. _________ Transport - carrier proteins in plasma membrane “pump” molecules or
ions into or out of the cell against their concentration gradient (from _______ to
______ concentration). Requires _____ energy.
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1. _________ Active Transport involves ATPases, such as the ___/___ pump,
which pumps Na+ out of cell, K+ into cell
a. Carrier binds intracellular _____
b. Carrier is ___________________ by ATP  ADP + Pi
c. Carrier changes ___________ (shape)
d. Carrier releases ____ to outside of membrane, then binds extracellular K+
e. Pi dissociates from carrier, and carrier releases ____ inside cell
f. Carrier returns to original ____________
2. ___________ Active Transport uses the energy provided by ___________ active
transport to move substances across a membrane. Two types
a. __________ – movement of one substance moving against its gradient by
traveling in the _______ direction as a substance diffusing with its gradient
(e.g., glucose with Na+)
b. __________ – movement of one substance moving against its gradient by
traveling in the __________ direction as a substance diffusing with its gradient
(e.g., Na+ and H+)
H. _______ (vesicular) transport - used to move _______ substances (e. g., proteins,
polysaccharides) into and out of cell (Requires ____)
1. ______cytosis - extracellular substances surrounded by a cell membrane and
brought _____ cell in _______. Includes
a. ______cytosis (cell eating)in which ____ particles are ingested
b. ______cytosis (cell drinking) in which ________ are ingested.
c. __________-mediated endocytosis – ligands (e.g., LDL) bind to
membrane receptors found in clathrin-coated pits
2. _____cytosis - membrane-enclosed secretory ________ fuse with the plasma
membrane, which opens to release their contents __________ the cell.
V. Molecular Movement Across the Epithelium
A. Recall that __________ membranes line body cavities and the tubes within them
B. Molecules moving from one compartment of the body to another (e.g.: through the
epithelium of the GI tract) must cross two cell ___________, the
1. ______ membrane on the luminal side of the tube
2. _________ membrane on the side of the extracellular fluid
C. ______________ transport (the movement across epithelial cells) requires both
active and passive transport; thus the apical and basolateral membranes have
different membrane _________
1. ____/___ ATPases are usually found in the _____lateral membrane
2. Na+/glucose ____________ are usually found in the ________ membrane
3. This “polarized” distribution of transporters allows one way movement of some
molecules across the epithelium
4. Transport of materials from the lumen to the ECF is called absorption
5. Movement of materials from the ECF to the lumen is called secretion
6. Molecules too large to cross the membrane via transport proteins are generally
transported in vesicles (i.e., endo- and exocytosis)