The cell theory has six principles.

1
The Plasma Membrane Membrane Potential
Chapter 3, part I
2
The Plasma Membrane

• fluid lipid bilayer
• hydrophobic core surrounds hydrophilic outside
• embedded molecules
• proteins, carbohydrates, cholesterol

3
Plasma Membrane Proteins

• channels
• carrier molecules
• docking-marker acceptors
• membrane-bound enzymes
• receptor molecules
• cell adhesion molecules

4
Cell Adhesions

• desmosomes
• spot rivets
• gap junctions
• tunnels connecting cells
• tight junctions
• points of direct contact

5
Cell-to-Cell Connections
6
Diffusion Net Flux
7
Chemical Driving Forces
8
Membrane Diffusion

• unassisted membrane transport
• depends on the random movement of molecules
• net movement is DOWN the concentration gradient
• diffusion can occur through a permeable membrane

9
Diffusion in the Body

• O2 CO2 exchange in the lungs
• kidney filtration
• Na K ions through channel proteins

10
Five Factors Affect Diffusion

• magnitude of the concentration gradient
• membrane permeability
• surface area of the membrane
• the size of a substance
• the distance through which diffusion takes place

11
Diffusion Over Time
12
The Electrochemical Gradient

• permeable ions move passively
• electrical AND concentration gradients
• difference in charge produces an electrical
  gradient

13
Electrical Driving Force
14
Osmosis
15
Osmosis
penetrating solute
non-penetrating solute
16
The Plasma Membrane Membrane Potential
Chapter 3, part II
17
Tonicity

• the effect the solution has on cell volume
• isotonic solution when nonpenetrating solute
  cells
• hypotonic solution when nonpenetrating solute
  lt cells
• hypertonic solution when nonpenetrating solute
  gt cells

18
Carrier-Mediated Transport

• carrier molecule flipping changing shape
• active or passive (energy use)
• three important characteristics
• specificity
• saturation
• competition

19
Cystic Fibrosis

• impaired release of Cl-
• dehydration of surrounding respiratory
  intestinal mucosa
• impaired sodium reabsorption of the sudoriferous
  glands

20
Carrier-Mediated Transport

• facilitated diffusion
• substance moves along concentration gradient
• requires a carrier molecule
• does not require energy expenditure
• primary active transport
• movement against gradient
• requires a carrier molecule
• direct use of ATP (energy)
• carrier mediated transport

21
Secondary Active Transport

• secondary active transport
• uses previously existing concentration gradient
• co-transporter
• counter-transporter/exchanger

22
Pumps Leaks
23
Membrane Potential

• separation of charges across plasma membrane
• concentration permeability differences of key
  ions
• cell develops a resting membrane
• resting potential

24
Vesicular Transport Systems
25
Epithelium Structure
26
Epithelial Solute Transport
27
Epithelial Water Transport
28
Transcytosis